Current sensor

Abstract

A current sensor 10 according to the present invention includes: a bus bar 11 through which a current to be measured flows; a magnetic sensor 12 which is disposed so as to face the bus bar 11 and detects magnetism generated by the bus bar 11; and a housing 13 having a case 14 and a cover 15, the case 14 and the cover 15 holding the bus bar 11 in between. The housing 13 has a bus bar fixing part 16 made of a metal material, and the bus bar 11 is fixed to the bus bar fixing part 16 in a state of being in contact with the bus bar fixing part 16. Thus, the current sensor 10 according to the present invention allows the housing 13 to be used universally for bus bars of various shapes, thereby suppressing a positional deviation of the bus bar relative to the case and improving measurement accuracy.

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 various devices in order to control the power supply systems of vehicles and other devices. Conventional current sensors require a flux core to collect magnetic flux and a bus bar to be inserted through the opening, making miniaturization difficult. Therefore, various current sensors that do not require a flux core have been proposed.

[0003] Patent document 1 describes an assembly structure for a current detection device that is suitable for miniaturizing the current detection device, in which a convex portion is formed on the cover, a hole is formed in the bus bar that is penetrated by the convex portion of the cover, and a hole is formed on the underside of the housing that fits into the convex portion that penetrates the hole in the bus bar when the bus bar is clamped between the cover and the housing.

[0004] Patent document 2 describes a current sensor that does not require a case or sealing to fix a magnetic body and a magnetic sensing element, and that includes a magnetic sensing element mounted on a substrate, first and second magnetic bodies, a spacer disposed on one side of the substrate, and the first and second magnetic bodies fixed to each other by fixing parts with the substrate and the spacer sandwiched between them.

[0005] Patent document 3 describes a current sensor that is intended to detect current with high accuracy, and that has a substrate that is fixed to the housing and that is arranged so as to sandwich multiple bus bars between the substrate and the housing, and a fixing portion that fixes the substrate to the housing.

[0006] JP 2010-243440 A JP 2014-85251 A JP 2020-128961 A

[0007] The current detection devices and current sensors described in Patent Documents 1 to 3 all measure current values ​​by using a magnetic detection unit to detect the magnetic field generated by current flowing through the bus bar. They also include a configuration in which the bus bar is fixed in place by being sandwiched between a case and a cover. However, this configuration leaves the bus bar with play relative to the case, which can cause the bus bar to shift out of position. That is, the bus bar is prone to shifting out of position relative to the case. Because the case has a magnetic detection unit positioned opposite the bus bar, shifting the bus bar's position relative to the case also shifts the bus bar's position relative to the magnetic detection unit. Therefore, there is a problem in that misalignment of the bus bar can easily cause variations in the measurement accuracy of the current sensor. Variations in measurement accuracy due to misalignment are particularly problematic in current sensors that do not include a flux core.

[0008] If a bus bar is insert-molded into a housing such as a case, the relative positions of the housing and the bus bar are fixed, minimizing misalignment and resulting in a current sensor with high measurement accuracy. However, there are many customer requirements for the shapes of both ends of the bus bar connected to various devices. Therefore, components such as the housing must be individually adapted to accommodate bus bars of various shapes. That is, in power supply systems such as vehicles, the space available for placing a current sensor is limited, so it is necessary to place the current sensor (housing part) in an available location or change the routing direction of both ends of the bus bar when connecting devices. Furthermore, if the shapes of the connection parts of the devices to which the bus bar is connected differ, it may be necessary to adapt the shape of the bus bar. Therefore, insert-molding a bus bar into a housing increases the manufacturing cost of a current sensor. Therefore, an object of the present invention is to provide a current sensor that can be used with bus bars of various shapes, minimizes misalignment of the bus bar relative to the case, and achieves high measurement accuracy.

[0009] As a means for solving the above-described problems, the present invention has the following configuration: A current sensor including a bus bar through which a current to be measured flows, a magnetic sensor disposed opposite the bus bar and configured to detect magnetism emitted by the bus bar, and a housing having a case and a cover, wherein the bus bar is sandwiched and held between the case and the cover, the housing having a bus bar fixing portion made of a metal material, and the bus bar being fixed to the bus bar fixing portion in a state of contact with the bus bar fixing portion. The bus bar fixing portion may be provided on the case.

[0010] Since the bus bar is fixed to the bus bar fixing portion, the positional relationship between the bus bar and the housing can be fixed and misalignment between the bus bar and the housing can be prevented without insert molding the bus bar into the housing.

[0011] The bus bar may be fixed to the bus bar fixing portion by welding. By welding the bus bar to the bus bar fixing portion, the bus bar can be reliably fixed to the housing.

[0012] The bus bar fixing portion may have a protrusion that protrudes outward from the housing, and the bus bar may be fixed to the protrusion of the bus bar fixing portion by welding. By welding the bus bar and the bus bar fixing portion to the protrusion of the bus bar fixing portion, heat generated during welding can be released to the outside of the housing from the protrusion that protrudes outward from the housing. Therefore, the risk of deformation of the housing due to heat generated during welding can be reduced.

[0013] The bus bar fixing portions may be provided at a plurality of locations on the housing. By providing the bus bar fixing portions at a plurality of locations, the bus bar can be fixed to the housing more stably and reliably.

[0014] The bus bar fixing portion may be insert-molded into the housing. By insert-molding the bus bar fixing portion into the housing, the bus bar fixing portion can be more firmly fixed to the housing. Therefore, the bus bar can be stably and reliably fixed to the housing via the bus bar fixing portion.

[0015] The bus bar fixing portion may include an anchor portion. The anchor portion acts as a retaining structure that prevents the bus bar fixing portion from coming off the housing, and therefore the bus bar fixing portion can be more firmly fixed to the housing.

[0016] A magnetic shield may be insert-molded into the case, which can suppress magnetic noise to the magnetic sensor, thereby improving the measurement accuracy of the current sensor.

[0017] The case may have a groove portion having a shape corresponding to the outer shape of the bus bar when viewed along the stacking direction of the bus bar and the magnetic sensor, the bus bar fixing portion being provided in the groove portion, and the bus bar being fixed to the bus bar fixing portion with the bus bar and the groove portion fitted together.

[0018] The bus bar can be easily positioned by providing a groove in the housing that corresponds to the outer shape of the bus bar and fitting the bus bar into the groove. Therefore, the bus bar can be easily fixed at a predetermined position in the housing by fitting the bus bar into the groove and fastening it to the bus bar fixing portion provided in the groove.

[0019] The case may have a groove, the bus bar fixing portion is provided in the groove, the bus bar may have a narrowed portion with a first width dimension and a wide portion with a second width dimension larger than the first width dimension, the wide portions may be arranged on both sides of the narrowed portion in the extension direction of the bus bar, the wide portions and the narrowed portion may be connected by a step portion, the groove may have a restricting portion that abuts the step portion, and the bus bar may be fixed to the bus bar fixing portion in a state where the groove and the bus bar are fitted together and the step portion and the restricting portion abut.

[0020] By fitting the bus bar into the groove of the housing and bringing the step of the bus bar into contact with the restricting portion of the groove, the movement of the bus bar in its extension direction can be restricted, making it easier to position the bus bar in the case.

[0021] When the groove is viewed along a stacking direction of the bus bar and the magnetic sensor, a width dimension of a constriction arrangement portion in which the constriction is located may be larger than a width dimension of the constriction.

[0022] By attaching a bus bar having a constriction narrower than the width dimension of the constriction arrangement portion to the groove portion, i.e., by using the same case for multiple types of bus bars having different width dimensions of the constriction portion, the manufacturing cost of the current sensor can be reduced.

[0023] The current sensor of the present invention can suppress misalignment between the housing and the bus bar by providing a bus bar fixing portion on the housing and fixing the bus bar to the bus bar fixing portion. This prevents a decrease in measurement accuracy due to misalignment between the bus bar and the housing, and allows a common housing to be used for bus bars of various shapes, thereby reducing the manufacturing cost of the current sensor.

[0024] 5A. FIG. 5B is a perspective view showing examples of variations in the shapes of both ends of a bus bar. FIG. 5C is a perspective view schematically showing the appearance of the current sensor according to the first embodiment. FIG. 5D is an exploded perspective view showing the configuration of the current sensor of FIG. 2. FIG. 5E is a cross-sectional view schematically showing the configuration of a main part of the current sensor taken along line AA of FIG. 2. FIG. 5F is a cross-sectional view schematically showing a modified example of the current sensor of FIG. 4. FIG. 5G is a perspective view showing examples of the shape of the bus bar fixing portion of FIG. 5A. FIG. 5H is a perspective view showing examples of the shape of the bus bar fixing portion of FIG. 5A. FIG. 5H is a cross-sectional view schematically showing a modified example of the current sensor of FIG. 5A. FIG. 5I is a cross-sectional view schematically showing another modified example of the current sensor of FIG. 4. FIG. 5I is a cross-sectional view schematically showing another modified example of the current sensor of FIG. 7. FIG. 5I is a plan view schematically showing a fitting structure between the bus bar and the housing of the current sensor of FIG. 4. FIG. 9 is a plan view schematically showing a modified example of the fitting structure of FIG. 9. FIG. 9I is a plan view schematically showing another modified example of the fitting structure of FIG. 9. 14 is a plan view schematically showing a state in which a bus bar having a width dimension different from that of FIG. 11 is installed in a constricted portion of the case of FIG. 11. FIG. 15 is a cross-sectional view schematically showing the configuration of a current sensor according to a second embodiment. FIG. 16 is a cross-sectional view schematically showing a modified example of the current sensor of FIG. 13. FIG. 17 is a cross-sectional view schematically showing the current sensor of FIG. 14 seen from another direction. FIG. 18 is a cross-sectional view schematically showing the configuration of a current sensor according to a third embodiment.

[0025] [First Embodiment] Hereinafter, an embodiment 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 width dimension direction of the bus bar is defined as the X direction (third direction), the extension direction of the bus bar perpendicular to the X direction is defined as the Y direction (second direction), and the stacking direction of the bus bar and magnetic sensor perpendicular to the X and Y directions is defined as the Z direction (first direction). The X direction is the direction of the sensitivity axis of the magnetic sensor, and the Y and Z directions are perpendicular to the sensitivity axis.

[0026] Magnetic current sensors measure the magnetic field generated from a bus bar when a current to be measured flows, and misalignment of each component can easily affect measurement accuracy. Misalignment between the magnetic sensor and the bus bar in particular can change the direction of the magnetic field measured by the magnetic sensor, which can easily affect measurement accuracy. The magnetic sensor is fixed to the case without any play or play. Therefore, to prevent misalignment between the case (magnetic sensor) and the bus bar, a structure has traditionally been used in which the bus bar is insert-molded into the case to form an integrated unit.

[0027] FIG. 1 is a perspective view showing examples of variations in the shapes of both ends of a bus bar. As shown in the figure, each customer often has different requirements for the shape of both ends of the bus bar, so current sensors are often tailored to meet their needs. In other words, there are many variations in the shapes of the bus bar ends. If a current sensor corresponding to each variation is manufactured by insert-molding the bus bar into a case, a new mold must be created for each variation, which increases the manufacturing cost of the current sensor. Therefore, if the bus bar and the case are separated rather than insert-molded into the current sensor housing, and parts other than the bus bar, which have different shapes, can be standardized across multiple customer requests, the manufacturing cost of the current sensor can be reduced.

[0028] Possible configurations in which the bus bar and the housing are separate include a structure in which the bus bar is press-fitted into a hole provided in the housing, and a structure in which the bus bar is clamped between members that make up the housing. The former structure cannot, for example, press-fit a bus bar with bent ends into a hole in the housing, whereas the latter structure is advantageous in that it can accommodate bus bars with bent ends.

[0029] The current sensor of the present invention employs a structure in which the bus bar is sandwiched between the components constituting the housing, making it possible to accommodate many types of bus bars, including bus bars with bent ends. This structure enables current sensors with a variety of bus bar shapes to standardize components other than the bus bar. This means that there is no need to prepare a molding die for the housing for each bus bar variation, which helps prevent increases in the manufacturing cost of the current sensor.

[0030] Fig. 2 is a perspective view schematically showing the appearance of the current sensor 10 according to this embodiment. Fig. 3 is an exploded perspective view showing the configuration of the current sensor 10 of Fig. 2. Fig. 4 is a cross-sectional view schematically showing the configuration of a main part of the current sensor 10 taken along line AA of Fig. 2. As shown in these figures, the current sensor 10 includes a bus bar 11, a magnetic sensor 12, and a housing 13.

[0031] The bus bar 11 is a conductor formed in a plate shape through which a current to be measured flows, and is made of, for example, copper, brass, aluminum, or the like.

[0032] The magnetic sensor 12 detects the magnetism generated by the bus bar 11 when a current to be measured flows, and is provided on the substrate 17 so as to face the bus bar 11 in the Z direction. The sensitivity axis of the magnetic sensor 12 is the X direction, and the magnetic sensor 12 can detect magnetic fields in the X direction. By facing its detection surface directly to the bus bar 11, the magnetic sensor 12 can accurately detect the magnetism generated by the bus bar 11 as an induced magnetic field. A magnetoresistive element, a Hall element, or the like can be used as the detection element in the magnetic sensor 12. Note that the above-described configuration exemplifies the case where a magnetoresistive element is used as the detection element of the magnetic sensor 12. When using another detection element, the orientation of the detection surface must be appropriately changed.

[0033] 3 shows a configuration in which screws 18 are used to fix the substrate 17 to the housing 13, but the method for fixing the substrate 17 to the housing 13 is not limited to this. For example, the substrate 17 may be fixed to the housing 13 by heat staking, metal staking, a brace fit, soldering, or the like.

[0034] The housing 13 has a case 14 and a cover 15 made of resin or the like. The case 14 and the cover 15 sandwich and hold the bus bar 11. The case 14 has a groove 141 formed along the Y direction on the surface facing the cover 15. The groove 141 is formed according to the shape of the portion of the bus bar 11 sandwiched between the case 14 and the cover 15. The bus bar 11 is positioned relative to the case 14 by engaging with the groove 141. The case 14 also has a bus bar fixing portion 16 made of a metal material on an inner bottom surface 141b (inner bottom) of the groove 141. Examples of metal materials that make up the bus bar fixing portion 16 include copper, brass, and aluminum. The bus bar fixing portion 16 has an embedded portion 16a embedded in the case 14 and a fixing surface 16b exposed on the surface of the case 14 (the inner bottom surface 141b of the groove 141).

[0035] The cover 15 sandwiches the bus bar 11 between the case 14 and the cover 15, thereby fixing the bus bar 11 and insulating the bus bar 11 from the board 17. Note that Figures 2 to 4 show an embodiment in which the cover 15 is positioned between the bus bar 11 and the board 17. However, if insulation can be ensured by providing a predetermined distance, holes penetrating the cover 15 in the Z direction may be provided in part or all of the area sandwiched between the bus bar 11 and the board 17 and / or part or all of the area sandwiched between the bus bar 11 and the magnetic sensor 12.

[0036] The fixing surface 16b of the busbar fixing portion 16 is fixed to the surface of the busbar 11. With the busbar 11 and the busbar fixing portion 16 in contact with each other, the busbar 11 is fixed to the fixing surface 16b of the busbar fixing portion 16, which is embedded in the case 14 at the embedding portion 16a. This allows the busbar 11 to be firmly fixed to the case 14 via the busbar fixing portion 16, preventing the busbar 11 and the case 14 from shifting.

[0037] The bus bar 11 of the current sensor 10 is fixed to the bus bar fixing portion 16 by welding. By welding the bus bar 11 to the bus bar fixing portion 16, the bus bar 11 can be reliably fixed to the case 14. Note that the bus bar 11 may also be adhered to the bus bar fixing portion 16 with an adhesive or the like.

[0038] In the current sensor 10, the bus bar fixing portions 16 are provided at two locations on the case 14, but the bus bar fixing portions 16 may be provided at one location or at three or more locations. From the viewpoint of stably and reliably fixing the bus bar 11 to the case 14, it is preferable that the bus bar fixing portions 16 are provided at multiple locations on the case 14.

[0039] The bus bar fixing portion 16 is insert-molded into the case 14. By insert-molding the bus bar fixing portion 16 into the case 14, the bus bar fixing portion 16 (embedded portion 16 a) is firmly fixed to the case 14. Therefore, the bus bar 11 can be stably and reliably fixed to the case 14 via the bus bar fixing portion 16.

[0040] By insert-molding the busbar fixing portion 16 used to fix the busbar 11 into the case 14 and fixing the busbar 11 to the busbar fixing portion 16, various busbars 11 with different shapes can be fixed to a common case 14 without insert-molding the busbar 11 into the case 14.

[0041] In the current sensor 10 described above, the bus bar fixing portion 16 is provided on the case 14 , but the present invention can also be implemented in a mode in which the bus bar fixing portion 16 is provided on the cover 15 .

[0042] As described above, in current sensor 10, busbar 11 is fixed to busbar fixing portion 16, and therefore the positional relationship between busbar 11 and housing 13 can be fixed without insert molding busbar 11 into housing 13, thereby preventing misalignment between busbar 11 and magnetic sensor 12. This makes it possible to suppress a decrease in the measurement accuracy of current sensor 10 due to misalignment of busbar 11, and also makes it possible to use a common housing 13 for busbars 11 of various shapes, thereby reducing the manufacturing cost of current sensor 10.

[0043] Here, the positioning and fixing of the components relative to each other in this embodiment will be further described with reference to Figure 3. As described above, the bus bar 11 is positioned relative to the case 14 by engaging with a groove 141 provided on the surface of the case 14 facing the cover 15. In addition to the groove 141, the case 14 is provided with two positioning pins 142 on the surface facing the cover 15. The cover 15 is provided with a through hole 151 at a location corresponding to the positioning pin 142, the through hole having approximately the same shape and size as the positioning pin 142.

[0044] With the positioning pin 142 inserted through the through hole 151, the cover 15 is placed on top of the case 14, thereby positioning the case 14 and the cover 15. At this time, the positioning pin 142 that passes through the through hole 151 protrudes from the back surface of the cover 15 that faces the case 14. A board 17 on which the magnetic sensor 12 is mounted is placed on this surface. The board 17 also has a through hole 171 at a position corresponding to the positioning pin 142, through which the positioning pin 142 can be inserted. By placing the board 17 with the positioning pin 142 inserted through the through hole 171, the board 17 is positioned with respect to the cover 15.

[0045] Positioning and arranging the components relative to one another in this manner determines the positioning of bus bar 11 and magnetic sensor 12. In this state, screws 18 passing through through holes 172 of substrate 17 and through holes 152 of cover 15 are threaded into screw holes 143 provided in case 14, thereby fixing the positional relationship of the components and preventing a decrease in measurement accuracy caused by misalignment of bus bar 11.

[0046] [Modification] Fig. 5A is a cross-sectional view that schematically shows a current sensor 20 that is a modification of the current sensor 10 of Fig. 4. Figs. 5B to 5E are perspective views that show examples of the shape of the bus bar fixing portion 26 in the current sensor 20 of Fig. 5A. The current sensor 20 shown in these figures is similar to the current sensor 10 in that the bus bar fixing portion 26 is insert-molded into the case 14 and includes an embedded portion 16a and a fixing surface 16b. The current sensor 20 differs from the current sensor 10 in that the bus bar fixing portion 26 of the current sensor 20 includes an anchor portion 26c in the embedded portion 16a.

[0047] The anchor portion 26c of the bus bar fixing portion 26 protrudes in the Y direction from the Z1 side end of the embedded portion 16a. Because the resin constituting the case 14 wraps around the Z2 side of the anchor portion 26c, the anchor portion 26c functions as a retaining structure for the bus bar fixing portion 26. By providing the anchor portion 26c, the bus bar 11 can be fixed to the case 14 more strongly and reliably via the bus bar fixing portion 26.

[0048] In terms of low-cost manufacturing, a shape suitable for forming by sheet metal processing is preferable for the bus bar fixing portion 26. Examples of the shape of such a bus bar fixing portion 26 include a plate-like body having a wide portion and a surface parallel to the Z direction as shown in Fig. 5B, a plate-like body in Fig. 5C in which the wide portion is bent in a direction intersecting the Z direction, and a plate-like body in Fig. 5D in which the vicinity of the Z1-side end of a plate-like body having a surface parallel to the Z direction is bent.

[0049] However, other methods may be used to form the bus bar fixing portion 26, and are not limited to sheet metal processing. For example, by cutting, it is possible to form the bus bar fixing portion 26 having the shape shown in Fig. 5E, which includes the anchor portion 26c that surrounds the Z1-side end of the embedded portion 16a and protrudes in the XY plane.

[0050] 6 is a cross-sectional view schematically illustrating a current sensor 21 as a modification of the current sensor 20 of FIG. 5A. In the current sensor 21 shown in the figure, the configuration of the anchor portion 27c in the embedded portion 16a of the bus bar fixing portion 27 is different from that of the anchor portion 26c of the bus bar fixing portion 26 of the current sensor 20.

[0051] Anchor portion 27c of busbar fixing portion 27 is a hole that penetrates embedded portion 16a, and is filled entirely or partially with the resin that constitutes case 14, thereby functioning as a retaining structure for busbar fixing portion 27. Therefore, busbar 11 can be fixed to case 14 more strongly and reliably via busbar fixing portion 27.

[0052] The anchor portion 27c in the current sensor 21 is an example, and the direction of the anchor portion 27c may be other than the X direction. From the viewpoint of the function of preventing the bus bar fixing portion 27 from coming off the case 14, the anchor portion 27c is preferably a hole that penetrates the embedded portion 16a in a direction perpendicular to the Z direction, i.e., in a direction parallel to the XY plane. Note that the anchor portion 27c may be a hole or groove that does not penetrate the bus bar fixing portion 27. Alternatively, the anchor portion 27c may be a notch shape provided at the Y direction end of the embedded portion 16a.

[0053] Anchor portions 26c and 27c act as a retaining structure for busbar fixing portions 26 and 27, thereby enabling busbar fixing portions 26 and 27 to be more firmly fixed to case 14. Busbar 11 can be firmly fixed to case 14 via busbar fixing portions 26 and 27, thereby preventing the measurement accuracy of current sensors 20 and 21 from deteriorating due to misalignment of busbar 11 with respect to case 14.

[0054] 7 is a cross-sectional view schematically illustrating a current sensor 22 as another modified example of the current sensor 10 of FIG. 4. As shown in the figure, the bus bar fixing portion 28 of the current sensor 22 differs from the bus bar fixing portion 16 of the current sensor 10 in that it has a protruding portion 28c that protrudes outward from the case 14 along the Y direction, which is the extension direction of the bus bar 11. The bus bar fixing portion 28 is insert-molded into the case 14 and is the same as the current sensor 10 in that it has an embedded portion 16a and a fixing surface 16b. The portion of the fixing surface 16b that protrudes outward from the case 14 is the protruding portion 28c, and the bus bar 11 is fixed to the protruding portion 28c of the bus bar fixing portion 28 by welding.

[0055] Fig. 8 is a cross-sectional view schematically illustrating a current sensor 23 as a modification of the current sensor 22 in Fig. 7. As shown in the figure, the bus bar fixing portion 29 of the current sensor 23 differs from the bus bar fixing portion 28 of the current sensor 22 in that the entire fixing surface 16b is a protruding portion 29c and that the embedded portion 29a extends in the Y direction. The bus bar fixing portion 29 is the same as the current sensor 20 in that it is insert-molded into the case 14.

[0056] The bus bar fixing portions 28, 29 are provided with protrusions 28c, 29c that protrude outward from the case 14, and the bus bar 11 is welded to the bus bar fixing portions 28, 29 at the protrusions 28c, 29c. This allows heat generated during welding to be released from the protrusions 28c, 29c to the outside of the case 14. This reduces the risk of the case 14 being deformed by the heat generated during welding.

[0057] Furthermore, during welding, heat (e.g., laser irradiation) can be applied from either direction in the Z direction. This allows the direction of heat application to be selected as appropriate, which contributes to improved productivity. Furthermore, compared to the configurations of the current sensor 10 shown in FIG. 4 and the current sensor 20 shown in FIG. 5A, the positional relationship between the busbar 11 and the busbar fixing portion 28 (protrusions 28c, 29c) can be visually confirmed, which makes it easier to adjust and confirm the position where heat is applied for welding, thereby improving productivity.

[0058] 9 is a plan view schematically illustrating the fitting structure between the busbar 11 and the case 14 of the current sensor 10 in FIG. 4. As shown in the figure, the case 14 in the housing 13 has a groove 141 that has a shape corresponding to the outer shape of the busbar 11 when viewed along the Z direction (see FIGS. 3 and 4 ), which is the stacking direction of the busbar 11 and the magnetic sensor 12. With the busbar 11 and the groove 141 fitted together, the busbar 11 is fixed to the busbar fixing portion 16.

[0059] The case 14 having the groove 141 having a shape corresponding to the outer shape of the bus bar 11 means that the groove 141 having the same shape as the outer shape of the bus bar 11 is provided on the surface of the case 14 facing the bus bar 11, and the bus bar 11 can be fitted into the groove 141. Note that the same shape means that the groove 141 is formed with some margin relative to the outer shape of the bus bar 11 so that the bus bar 11 can be fitted into it.

[0060] The busbar 11 has a narrowed portion 111 with a width dimension W1 and a wide portion 112 with a width dimension W2 (second width dimension) larger than the width dimension W1 (first width dimension) (W2>W1). The wide portions 112 are disposed on both sides of the narrowed portion 111 in the Y direction, which is the extension direction of the busbar 11. The wide portions 112 and the narrowed portion 111 are connected by a step portion 113. The groove portion 141 of the case 14 has a restricting portion 144 that abuts against the step portion 113.

[0061] By fitting the bus bar 110 into the groove 141 of the case 14 and abutting the step portion 113 of the bus bar 110 against the restricting portion 144 of the groove 141, movement of the bus bar 110 in the Y direction, which is its extension direction, can be restricted.

[0062] By fitting the bus bar 11 into the groove 141 of the case 14, the bus bar 11 can be arranged at a predetermined position in the X direction and the Y direction of the case 14. That is, by providing the above-described groove 141 in the case 14, it becomes easy to position the bus bar 11 in the case 14. Therefore, when the bus bar 11 is fitted into the groove 141 of the case 14, by welding the bus bar 11 to the bus bar fixing portion 16 provided in the groove 141, the bus bar 11 can be easily fixed at a predetermined position in the case 14.

[0063] [Modification] Fig. 10 is a plan view schematically showing a modification of the fitting structure of Fig. 9. The configuration of busbar 110 shown in Fig. 10 is the same as busbar 11 of Fig. 9 except for the position of constricted portion 111. By fitting busbar 110 shown in Fig. 10 into groove portion 141 of case 14, it is possible to position busbar 110 in case 14.

[0064] 11 is a plan view schematically illustrating another modification of the fitting structure of FIG. 9 . When groove 141 of case 14 is fitted to busbar 110, groove 141 is viewed in a plan view along the Z direction. A width dimension W3 (third width dimension) of constriction arrangement portion 145 of groove 141, where constriction 111 is located, is larger than width dimension W1 of constriction 111. When width dimension W3 of constriction arrangement portion 145 of groove 141 is larger than width dimension W1 of constriction 111 (W3 > W1), a gap is formed between constriction 111 and constriction arrangement portion 145. In this case, busbar 110 can be positioned in case 14 by abutting step portion 113 and restriction portion 144.

[0065] Fig. 12 is a plan view schematically illustrating a state in which busbars 110 having different width dimensions W1 of constricted portions 111 are installed in case 14 of Fig. 11. As shown in the figure, the same case 14 as in Fig. 11 can be used for busbars 110 in which width dimension W1 of constricted portions 111 is smaller than width dimension W3 of constricted portion arrangement portion 145.

[0066] That is, the same case 14 can be used for busbars 110 in which the width dimension W1 of the constricted portion 111 is the same as or smaller than the width dimension W3 of the constricted portion arrangement portion 145 (W1≦W3). In this way, a common case 14 can be used for multiple types of busbars 110 in which the width dimension W1 of the constricted portion 111 is different. For example, if a customer requests a larger current to be measured, this can be achieved simply by switching only the busbar 110 to one with a larger width dimension W1. In other words, being able to accommodate variations in busbars 110 in which the width dimension W1 of the constricted portion 111 is different is effective in reducing the manufacturing cost of the current sensor.

[0067] The Y-direction lengths of the constriction portion 111 and the constriction portion arrangement portion 145 may be set so that the position of the busbar 110 relative to the case 14 in the X and Y directions is determined by the abutment between the step portion 113 of the busbar 110 and the regulating portion 144 of the groove portion 141.

[0068] Second Embodiment Fig. 13 is a cross-sectional view schematically illustrating the configuration of a current sensor 30 according to this embodiment. As shown in Fig. 13, the current sensor 30 differs from the current sensor 10 in Fig. 4 in that a magnetic shield 35 is insert-molded into the case 14 of the housing 13. In addition to the magnetic shield 35 insert-molded into the case 14, the current sensor 30 also includes a magnetic shield 35 on the surface of the substrate 17 opposite to the surface on which the magnetic sensor 12 is provided.

[0069] For example, a plurality of identically shaped metal plates stacked on top of each other can be used as the magnetic shield 35. The magnetic shield 35 can suppress magnetic noise to the magnetic sensor 12, thereby improving the measurement accuracy of the current sensor 30.

[0070] Although FIG. 13 shows a pair of parallel plate-type magnetic shields 35 in which the bus bar 11 and the magnetic sensor 12 are located between the pair of magnetic shields 35, only one of the magnetic shields 35 may be provided.

[0071] [Modification] Fig. 14 is a cross-sectional view schematically showing a current sensor 31 as a modification of the current sensor 30 shown in Fig. 13. Fig. 15 is a cross-sectional view schematically showing the current sensor 31 of Fig. 14 as viewed from a different direction, showing a cross section of a portion corresponding to the cross section of the current sensor 10 taken along line BB in Fig. 3. The current sensor 31 shown in these figures differs from the current sensor 30 in that it includes a U-shaped magnetic shield 36 instead of the parallel plate-type magnetic shield 35. The magnetic shield 36 has sidewalls 36a spaced apart on both sides in the X direction and a bottom 36b connecting the two sidewalls 36a, and is U-shaped when viewed along the Y direction.

[0072] The bottom portion 36b is formed in a flat plate shape having a plate surface parallel to the XY plane, and is disposed on the Z1 side in the Z direction with respect to the bus bar 11, facing the bus bar 11. The side wall portion 36a is made of a flat plate having a plate surface parallel to the YZ plane, and extends from both ends of the bottom portion 36b in the X direction toward the Z2 side in the Z direction.

[0073] 15 , the magnetic sensor 12 is disposed in a position near the end 36 ae of the magnetic shield 36, but not sandwiched between the side wall portions 36 a. With this configuration, the magnetic shield 36 functions as a core, and the magnetic field of the measurement target can be concentrated in the magnetic sensor 12.

[0074] The magnetic sensor 12 may be disposed between the side wall portions 36a of the magnetic shield 36. That is, the magnetic sensor 12 may be disposed on the Z1 side of the end portion 36ae of the side wall portion 36a, and the magnetic sensor 12 may overlap the side wall portion 36a of the magnetic shield 36 when viewed along the X direction. By disposing the magnetic sensor 12 between the side wall portions 36a in this manner, the magnetic shield 36 can effectively suppress disturbance magnetic fields with respect to the magnetic sensor 12.

[0075] Third Embodiment (Reference Example) FIG. 16 is a cross-sectional view schematically illustrating a configuration of a current sensor 40 according to a third embodiment. As shown in the figure, the busbar 11 of the current sensor 40 is insert-molded into the case 14, and an extended busbar portion 41 is welded to the portion of the busbar 11 that protrudes outside the case 14. By electrically connecting the extended busbar portion 41 to the busbar 11 insert-molded into the case 14 by welding, the busbar 11 can have a greater degree of freedom in its shape outside the case 14, even if its shape inside the case 14 remains the same. By insert-molding the busbar 11 into the case 14, the positional relationship between the case 14 and the busbar 11 can be stabilized. Therefore, the measurement accuracy of the current sensor 40 can be improved by suppressing a decrease in measurement accuracy due to misalignment between the busbar 11 and the case 14, while maintaining good measurement accuracy.

[0076] 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 the power supply system of a vehicle or the like equipped with various equipment.

[0077] 10: Current sensor 11: Busbar 110: Busbar 111: Narrowed portion 112: Wide portion 113: Step portion 12: Magnetic sensor 13: Housing 14: Case 141: Groove portion 141b: Inner bottom surface 142: Positioning pin 143: Screw hole 144: Restriction portion 145: Narrowed portion arrangement portion 15: Cover 151: Through hole 152: Through hole 16: Busbar fixing portion 16a: Embedded portion 16b: Fixing surface 17: Board 171: Through hole 172: Through hole 18: Screw 20: Current sensor 21: Current sensor 22: Current sensor 23: Current sensor 26: Busbar fixing portion 26c: Anchor portion 27: Busbar fixing portion 27c: Anchor portion 28: Busbar fixing portion 28c: Protruding portion 29: Busbar fixing portion 29a: Buried portion 29c: Protruding portion 30: Current sensor 31: Current sensor 35: Magnetic shield 36: Magnetic shield 36a: Side wall portion 36ae: End portion 36b: Bottom portion 40: Current sensor 41: Extended busbar portion W1: Width dimension W2: Width dimension W3: Width dimension

Claims

1. A current sensor comprising a bus bar through which a current to be measured flows, a magnetic sensor arranged opposite the bus bar and detecting the magnetic field emitted by the bus bar, and a housing having a case and a cover, wherein the bus bar is sandwiched and held between the case and the cover, wherein the housing has a bus bar fixing portion made of a metal material, and the bus bar is fixed to the bus bar fixing portion while in contact with the bus bar fixing portion.

2. The current sensor according to claim 1, wherein the bus bar fixing portion is provided on the case.

3. The current sensor according to claim 1, wherein the bus bar is fixed to the bus bar fixing portion by welding.

4. The current sensor according to claim 1, wherein the bus bar fixing portion has a protruding portion that protrudes to the outside of the housing, and the bus bar is fixed to the protruding portion of the bus bar fixing portion by welding.

5. The current sensor according to claim 1 or 4, wherein the bus bar fixing portions are provided at a plurality of locations on the housing.

6. The current sensor according to claim 1, wherein the bus bar fixing portion is insert molded into the housing.

7. The current sensor according to claim 6, wherein the bus bar fixing portion is provided with an anchor portion.

8. The current sensor according to claim 1, wherein a magnetic shield is insert-molded into said case.

9. A current sensor as described in claim 1, wherein the case has a groove portion having a shape corresponding to the outer shape of the bus bar when viewed along the stacking direction of the bus bar and the magnetic sensor, the bus bar fixing portion is provided in the groove portion, and the bus bar is fixed to the bus bar fixing portion with the bus bar and the groove portion engaged.

10. The current sensor as described in claim 1, wherein the case has a groove portion, the bus bar fixing portion is provided in the groove portion, the bus bar has a narrowed portion with a first width dimension and a wide portion with a second width dimension larger than the first width dimension, the wide portions are arranged on both sides of the narrowed portion in the extension direction of the bus bar, and the wide portions and the narrowed portion are connected by a step portion, the groove portion has a restricting portion abutting against the step portion, and the bus bar is fixed to the bus bar fixing portion in a state where the groove portion and the bus bar are engaged and the step portion and the restricting portion are in contact with each other.

11. A current sensor as described in claim 10, wherein when the groove is viewed along the stacking direction of the bus bar and the magnetic sensor, the width dimension of the constriction arrangement portion in which the constriction is located is larger than the width dimension of the constriction.

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