Current sensor

Abstract

This current sensor (100) is capable of fixing a U-shaped magnetic shield with high positional accuracy with respect to a housing without affecting an external magnetic field attenuation function of the U-shaped magnetic shield, and is provided with: a bus bar (10) extending in a first direction; a magnetic shield (30) having a portion facing the bus bar (10) along the third direction; a magnetic sensor (20) facing the bus bar on the opposite side of the side of the bus bar on which the magnetic shield is disposed along the third direction; and a housing (40) in which a part of the bus bar (10) is integrally formed. The magnetic shield (30) has: a U-shaped portion (31) having a bottom wall portion (31B) including a portion facing the bus bar (10) in the third direction, and two side wall portions (31W, 31W) standing in the third direction from an end portion of the bottom wall portion (31B) in the second direction and disposed facing each other in the second direction; a mounting part (32) connected to the U-shaped part (31) and fixed to the housing; and a connecting part (33) for connecting the U-shaped part (31) and the mounting part (32).

Description

Technical Field

[0001] The present invention relates to a current sensor having a U-shaped magnetic shield. Background Art

[0002] In a current sensor that uses a magnetic sensor to measure the amount of current flowing in a bus bar, a magnetic shield is sometimes provided to reduce the influence of an external magnetic field on the magnetic sensor. For example, Patent Documents 1 to 3 disclose magnetic shields having a U-shaped cross-section (U-shaped magnetic shields).

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2010-223868

[0006] Patent Document 2: International Publication No. 2018-159229

[0007] Patent Document 3: Japanese Patent Application Publication No. 2021-107800 Summary of the invention

[0008] Technical problem to be solved by the invention

[0009] From the perspective of ensuring the measurement accuracy of the current sensor, it is important to appropriately set the relative position of the magnetic shield to the bus bar and the magnetic sensor regardless of its shape. Here, since the magnetic sensor is provided on the substrate and the portion where the bus bar and the magnetic sensor face each other is generally flat, the U-shaped magnetic shield has a three-dimensional shape compared to other components constituting the current sensor. Therefore, various studies have been conducted to appropriately fix the U-shaped magnetic shield to the housing.

[0010] For example, in Patent Document 1, a through hole is provided on the bottom wall of the U-shaped magnetic shield, a convex portion provided on a resin shell is inserted into the through hole, and the U-shaped magnetic shield is fixed to the shell by thermally melting the convex portion protruding from the through hole and cooling it naturally. In Patent Document 2, a support member made of an insulating material such as resin is provided between the sensor substrate and the main substrate, and the magnetic shield is embedded in a recess provided on the support member. In Patent Document 3, the U-shaped magnetic shield is fixed to the substrate by a resin portion covering the bottom wall of the U-shaped magnetic shield and a shield fixing portion, wherein the shield fixing portion has a leg portion extending from the resin portion along the side wall portion and a claw portion provided at the front end of the leg portion and hooked on the substrate.

[0011] In the structure disclosed in Patent Document 1, a through hole is partially provided in the magnetic shield for attenuating the external magnetic field, which may affect the external magnetic field attenuation function. In the structures disclosed in Patent Documents 2 and 3, the possibility of misalignment between the resin holding the magnetic shield and the magnetic shield cannot be ruled out.

[0012] An object of the present invention is to provide a current sensor having a U-shaped magnetic shield capable of fixing the U-shaped magnetic shield with respect to a housing with high positional accuracy without affecting the external magnetic field attenuation function of the U-shaped magnetic shield.

[0013] Means for solving technical problems

[0014] A current sensor according to a technical solution of the present invention for solving the above-mentioned technical problem comprises, when three mutually orthogonal directions are defined as a first direction, a second direction, and a third direction, a bus bar extending in the first direction; a magnetic shield having a portion facing the bus bar along the third direction; a magnetic sensor facing the bus bar on a side of the bus bar opposite to a side on which the magnetic shield is disposed along the third direction; and a housing formed integrally with a portion of the bus bar. In the current sensor, the magnetic shield comprises: a U-shaped portion having a bottom wall portion and two side wall portions, the bottom wall portion including a portion facing the bus bar along the third direction, the two side wall portions standing from an end portion of the bottom wall portion in the second direction along the third direction and facing each other in the second direction; a mounting portion connected to the U-shaped portion and fixed to the housing; and a connecting portion connecting the U-shaped portion and the mounting portion.

[0015] In the magnetic shielding component, when the relative position of the U-shaped part that mainly plays the function of attenuating the external magnetic field is fixed relative to the shell, that is, when it is installed, the U-shaped part can be set to a shape dedicated to the external magnetic field attenuation function by using a mounting part connected from the U-shaped part. On the other hand, since the mounting part can be dedicated to the function of fixing the shell, the configuration accuracy of the magnetic shielding component can be improved, and the measurement accuracy of the magnetic sensor can be expected to be improved.

[0016] In the above-mentioned current sensor, the above-mentioned mounting portion may be provided from the above-mentioned connecting portion located at the end of the above-mentioned bottom wall portion of the above-mentioned U-shaped portion in the above-mentioned first direction. In this case, the side wall portion or a part thereof of the U-shaped portion may be formed by bending a part of a metal plate, and the bottom wall portion or a part thereof of the U-shaped portion, the connecting portion, and the mounting portion may be formed from the original portion of the flat plate, so that the magnetic shielding member can be efficiently formed.

[0017] In the above-mentioned current sensor, a plurality of the above-mentioned bus bars may be arranged in the above-mentioned second direction on the above-mentioned housing. In this case, the above-mentioned magnetic shield preferably has a plurality of the above-mentioned U-shaped parts corresponding to the plurality of the above-mentioned bus bars, and the plurality of the above-mentioned U-shaped parts are connected to the common above-mentioned mounting part.

[0018] Since a plurality of U-shaped parts are connected to one mounting part, the plurality of U-shaped parts can be correctly positioned at the same time by positioning the mounting part. In addition, since the plurality of U-shaped parts are integrated via the mounting part, relative position deviation of the plurality of U-shaped parts is not easy to occur. In addition, the plurality of U-shaped parts can be installed through a single installation process.

[0019] In the above-mentioned current sensor having a magnetic shield having a plurality of U-shaped portions, the two U-shaped portions corresponding to the two adjacent bus bars may be arranged to be staggered in the first direction. Furthermore, the two U-shaped portions corresponding to the two adjacent bus bars may partially overlap when viewed along the first direction. By setting such an arrangement, the interval between the two adjacent bus bars in the second direction can be narrowed.

[0020] In the above-mentioned current sensor, the above-mentioned mounting portion may also be formed of a soft magnetic body and arranged in a manner of being located between the above-mentioned U-shaped portion and the magnetic noise generating source; or it may be connected to both ends of the above-mentioned U-shaped portion in the above-mentioned first direction. By forming the mounting portion of a soft magnetic body, the mounting portion can play a function of attenuating the external magnetic field.

[0021] In the above-mentioned current sensor, a cover may be further provided which abuts against the above-mentioned housing from the above-mentioned third direction relative to the above-mentioned housing. By providing the cover, foreign matter is stably prevented from intruding into the interior of the housing. In addition, even if rust is generated from the components constituting the magnetic shield (particularly the cut surface after the metal plate is cut and processed), the rust is not easy to flow out to the outside of the current sensor, so that adverse conditions caused by rust (such as short circuits as specific examples) can be prevented.

[0022] In the above current sensor, the magnetic shield may be formed of a metal plate, and the side wall of the U-shaped portion may be formed by bending a portion of the metal plate. Since such a magnetic shield has excellent productivity and quality stability, the quality of the current sensor can be expected to be stable.

[0023] In the above-mentioned current sensor, the U-shaped portion may be formed by a laminated body formed by overlapping a plurality of metal plates, and the mounting portion may be connected to at least one of the plurality of metal plates via the connecting portion. In this case, the mounting portion may be formed by a metal plate farthest from the bus bar among the metal plates constituting the laminated body.

[0024] The above-mentioned current sensor may also include a plurality of the above-mentioned magnetic shields; the plurality of the above-mentioned magnetic shields may be fixed to the above-mentioned housing in such a manner that the plurality of the above-mentioned bus bars corresponding to the plurality of the above-mentioned U-shaped portions respectively of the plurality of the above-mentioned magnetic shields are arranged along the second direction. For example, in the case where the magnetic shield has three U-shaped portions, the magnetic shield can be positioned as a measurement unit corresponding to the measurement of three-phase wiring, etc., and there is a case where the degree of freedom of design becomes higher.

[0025] Effects of the Invention

[0026] According to the present invention, a current sensor having a U-shaped magnetic shield can be provided, in which the U-shaped magnetic shield can be fixed with respect to a housing with high positional accuracy without affecting the external magnetic field attenuation function of the U-shaped magnetic shield. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1A It is an explanatory diagram of a current sensor according to the first embodiment of the present invention.

[0028] Figure 1B Yes means Figure 1A Diagram of the cross section at line A-A'.

[0029] Figure 2A It is an explanatory diagram of the magnetic shield included in the current sensor according to the first embodiment of the present invention (a diagram viewed along the Y1 - Y2 direction (first direction)).

[0030] Figure 2B It is an explanatory diagram of the magnetic shield included in the current sensor according to the first embodiment of the present invention (a diagram viewed along the Z1 - Z2 direction (third direction)).

[0031] Figure 3A The diagram shows simulation results for confirming the shielding effect of the magnetic shield included in the current sensor according to the first embodiment of the present invention, viewed along the Y1 - Y2 direction (first direction).

[0032] Figure 3B The diagram shows simulation results for confirming the shielding effect of the magnetic shield included in the current sensor according to the first embodiment of the present invention, viewed along the Z1 - Z2 direction (third direction).

[0033] Figure 4A The diagram shows the simulation results for confirming the shielding effect of the magnetic shield provided in the current sensor according to the conventional technology, viewed along the Y1 - Y2 direction (first direction).

[0034] Figure 4BThe diagram shows the simulation results for confirming the shielding effect of the magnetic shield provided in the current sensor according to the conventional technology, viewed along the Z1 - Z2 direction (third direction).

[0035] Figure 5 It is an explanatory diagram of a magnetic shield included in a current sensor according to a second embodiment of the present invention (a diagram viewed along the Z1 - Z2 direction (third direction)).

[0036] Figure 6 It is an explanatory diagram of a magnetic shield included in a current sensor according to a third embodiment of the present invention (a diagram viewed along the Z1 - Z2 direction (third direction)).

[0037] Fig. 7A It is an explanatory diagram of a magnetic shield included in a current sensor according to a fourth embodiment of the present invention (a diagram viewed along the Z1 - Z2 direction (third direction)).

[0038] Figure 7B It is an explanatory diagram of a magnetic shield included in a current sensor according to a fourth embodiment of the present invention (a diagram viewed along the Y1 - Y2 direction (first direction)).

[0039] Figure 7C It is an explanatory diagram of a current sensor according to a fourth embodiment of the present invention (a diagram viewed along the Z1 - Z2 direction (third direction)).

[0040] Fig. 8A It is an explanatory diagram of a method for manufacturing a part of a magnetic shield included in a current sensor according to a fourth embodiment of the present invention (before bending).

[0041] Figure 8B It is an explanatory diagram of a method for manufacturing a part of a magnetic shield included in a current sensor according to a fourth embodiment of the present invention (a diagram viewed along the Z1 - Z2 direction (third direction) after the bending process).

[0042] Figure 8C It is an explanatory diagram of a method for manufacturing a part of a magnetic shield included in a current sensor according to a fourth embodiment of the present invention (a diagram viewed along the Y1 - Y2 direction (first direction) after the bending process).

[0043] Fig. 9 It is an explanatory diagram of a current sensor according to the conventional art corresponding to the current sensor according to the fourth embodiment of the present invention (a diagram viewed along the Z1 - Z2 direction (third direction)).

[0044] Fig. 10A It is an explanatory diagram of a magnetic shield included in a current sensor according to a fifth embodiment of the present invention (a diagram viewed along the Z1 - Z2 direction (third direction)).

[0045] Fig. 10B It is an explanatory diagram of a magnetic shield included in a current sensor according to a fifth embodiment of the present invention (a diagram viewed along the Y1 - Y2 direction (first direction)).

[0046] Fig.11 It is an explanatory diagram of a current sensor according to a sixth embodiment of the present invention (a diagram viewed along the Z1 - Z2 direction (third direction)).

[0047] Fig. 12A It is an explanatory diagram of a current sensor according to a seventh embodiment of the present invention (a cross-sectional view as viewed in the Y1 -Y2 direction (first direction)).

[0048] Fig. 12B It is an explanatory diagram of a current sensor according to a modified example of the seventh embodiment of the present invention (a cross-sectional view as viewed in the Y1 - Y2 direction (first direction)). DETAILED DESCRIPTION

[0049] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. In addition, in the following description, the same reference numerals are given to the same components, and the description of the components described once is appropriately omitted. In the following description, the Y1-Y2 direction is defined as the first direction, the X1-X2 direction is defined as the second direction, and the Z1-Z2 direction is defined as the third direction. In addition, there is a case where the Z1 side of the Z1-Z2 direction (the third direction) is referred to as "upper", and the Z2 side of the Z1-Z2 direction (the third direction) is referred to as "lower".

[0050] (First embodiment)

[0051] Figure 1A It is an explanatory diagram of a current sensor according to the first embodiment of the present invention. Figure 1B Yes means Figure 1A A cross section of the line A-A'. The line A-A' has two parts where the direction changes. Figure 1B In the figure, the cover, the fixing member and the substrate are not shown for the purpose of explanation, and the magnetic sensor is set as a virtual line. Figure 2A It is an explanatory diagram of the magnetic shield included in the current sensor according to the first embodiment of the present invention (a diagram viewed along the Y1 - Y2 direction (first direction)). Figure 2B It is an explanatory diagram of the magnetic shield included in the current sensor according to the first embodiment of the present invention (a diagram viewed along the Z1 - Z2 direction (third direction)).

[0052] like Figure 1A and Figure 1BAs shown, the current sensor 100 according to the first embodiment of the present invention includes a bus bar 10, a magnetic sensor 20, a magnetic shield 30, a housing 40, a substrate 50, and a fixing member 60. The bus bar 10 extends in the first direction (Y1-Y2 direction), and the current to be measured flows in the first direction in the bus bar 10. More specifically, when measuring the current flowing from the inverter to the motor in an electric vehicle, one end of the bus bar 10 in the first direction is connected to the inverter, and the other end is connected to the motor. The magnetic sensor 20 has a sensitivity axis along the second direction (X1-X2 direction), and faces the bus bar 10 along the third direction (Z1-Z2 direction) intersecting (orthogonal in this embodiment) the first direction (Y1-Y2 direction). Specifically, the magnetic sensor 20 is arranged to face the bus bar 10 on the Z1 side of the Z1-Z2 direction.

[0053] like Figure 2A and Figure 2B As shown, the magnetic shield 30 includes a U-shaped portion 31 , a mounting portion 32 , and a connecting portion 33 connecting the U-shaped portion 31 and the mounting portion 32 , and is formed by a bent metal plate made of a soft magnetic body in this embodiment.

[0054] The U-shaped portion 31 includes a bottom wall portion 31B including a portion facing the bus bar 10 along the third direction (Z1-Z2 direction), and two side wall portions 31W, 31W standing along the third direction (Z1-Z2 direction) from the end of the bottom wall portion 31B in the second direction (X1-X2 direction) and arranged opposite to each other in the second direction (X1-X2 direction). Therefore, the U-shaped portion 31 has a U-shaped shape when viewed along the first direction (Y1-Y2 direction).

[0055] The U-shaped portion 31 can attenuate the external magnetic field directed toward the magnetic sensor 20 from the opposite side of the side opposite to the magnetic sensor 20, thereby improving the measurement accuracy of the magnetic sensor 20 for detecting the induced magnetic field generated from the bus bar 10. The U-shaped portion 31 has a U-shaped cross section, and since the side wall portion 31W extends toward the Z1 side in the Z1-Z2 direction, not only the external magnetic field from the Z2 side in the Z1-Z2 direction of the bottom wall portion 31B but also the external magnetic field from the side of the side wall portion 31W (the X1 side in the X1-X2 direction, the X2 side in the X1-X2 direction) can be attenuated.

[0056] When viewed along the third direction (Z1-Z2 direction), the bus bar 10 and the magnetic sensor 20 are located between the two side wall portions 31W, 31W. When viewed along the first direction (Y1-Y2 direction), the bus bar 10 is located between the two side wall portions 31W, 31W, so that the U-shaped portion 31 not only has the function of attenuating the external magnetic field, but also can play the role of a yoke that allows the induced magnetic field from the bus bar 10 to pass preferentially.

[0057] In the present embodiment, when viewed along the first direction (Y1-Y2 direction), the magnetic sensor 20 is not located between the two side wall portions 31W, 31W, but is located slightly above the upper ends (ends on the Z1 side in the Z1-Z2 direction) of the two side wall portions 31W, 31W (see Figure 1B ). By configuring in this way, the induced magnetic field from the bus bar 10 passes through the following magnetic circuit, which passes through the interior of the U-shaped portion 31 and is released from the upper end of the side wall portion 31W on one side, and enters the interior of the U-shaped portion 31 from the upper end of the side wall portion 31W on the other side. In this magnetic circuit, the magnetic circuit released from the upper end of the side wall portion 31W on one side and toward the upper end of the side wall portion 31W on the other side has more components passing in the second direction (X1-X2 direction) which is the sensitivity axis direction of the magnetic sensor 20. Therefore, the induced magnetic field from the bus bar 10 is efficiently applied to the magnetic sensor 20.

[0058] Furthermore, the magnetic sensor 20 may be located between the two side wall portions 31W, 31W when viewed along the first direction (Y1-Y2 direction). In the case of such an arrangement, it is expected that the external magnetic field attenuation function of the U-shaped portion 31 becomes particularly high.

[0059] In this embodiment, the U-shaped portion 31 is composed of a bent body of three soft magnetic metal plates 301, 302, and 303, and is a laminated body in which two metal plates 302 and 303 are overlapped in the Z1-Z2 direction on the metal plate 301 (Z1 side in the Z1-Z2 direction). In addition, the metal plate 302 is arranged in a state of close contact with the inner surface of the metal plate 301, and the metal plate 303 is arranged in a state of close contact with the inner surface of the metal plate 302. In addition, the metal plates 301, 302, and 303 are integrally held by caulking or the like.

[0060] The metal plate 301 which is the farthest from the bus bar 10 (Z2 side in the Z1-Z2 direction) among the three metal plates 301, 302, 303 constituting the laminated body has a connecting portion 33 at the end of the portion constituting the bottom wall portion 31B of the U-shaped portion 31 in the first direction (Y1-Y2 direction). The metal plate 301 has a portion extending from the connecting portion 33 in the first direction (Y1-Y2 direction), and the portion constitutes the mounting portion 32. That is, a portion of the metal plate 301 is bent to constitute a portion of the U-shaped portion 31, and the portion that is not bent constitutes the connecting portion 33 and the mounting portion 32. By having the connecting portion 33, when the metal plate 301 is bent to make the portion constituting the side wall portion 31W stand up, it is possible to reduce the possibility that the portion constituting the side wall portion 31W does not properly stand up due to interference with other portions located around it, or that unexpected deformation occurs in other portions around it.

[0061] In this embodiment, the mounting portion 32 and the connecting portion 33 are provided only on the metal plate 301, but they may be provided on three metal plates 301, 302, and 303. In this case, the mounting portion 32 and the connecting portion 33 provided on the metal plates 301, 302, and 303 are preferably provided at positions overlapping with the same shape when viewed from the Z1-Z2 direction. In addition, the mounting portion 32 and the connecting portion 33 may be provided only on the metal plate 302 or the metal plate 303. In addition, as Figure 1A As shown, the metal plate 301 is fixed to the housing 40 in a state where the U-shaped portion 31 is inserted into the receiving recess 41 provided on the housing 40. Therefore, by providing only the mounting portion 32 and the connecting portion 33 on the metal plate 301 as in the present embodiment, the amount of the U-shaped portion 31 protruding from the receiving recess 41 to the Z2 side in the Z1-Z2 direction can be suppressed to a minimum, and the outer dimensions of the current sensor 100 in the Z1-Z2 direction can be reduced.

[0062] exist Figure 2B The portion 301W indicated by the virtual line in the figure is the shape of the portion of the side wall portion 31W made of the metal plate 301 before being bent. As indicated by the shape of the portion 301W, the metal plate 301 in the state before being bent to form the U-shaped portion 31 has the end portion of the portion that becomes the U-shaped portion 31 in the X1-X2 direction and the end portion of the mounting portion 32 in the X1-X2 direction at the same position in the X1-X2 direction. Therefore, less material is wasted when the metal plate 301 is processed.

[0063] The mounting portion 32 is connected to the U-shaped portion 31 via the connecting portion 33, and is fixed to the housing 40 in the mounting portion 32. In the present embodiment, a plurality of (two in the present embodiment) through holes 32h are provided in the mounting portion 32, and the mounting portion 32 is fixed to the housing 40 by fixing a fixing member 60 inserted through the through holes 32h to the housing 40. A specific example of the fixing member 60 is a screw or a bolt.

[0064] The housing 40 is made of, for example, a resin material. In the housing 40, a portion of the bus bar 10 is embedded, for example, by insert molding. On the lower side (Z2 side in the Z1-Z2 direction) of the housing 40, there is provided a receiving recess 41 that is recessed to match the shape of the U-shaped portion 31 and receives the U-shaped portion 31. Furthermore, on the lower side (Z2 side in the Z1-Z2 direction) of the housing 40, in order to maintain the state in which the U-shaped portion 31 is arranged inside the receiving recess 41, there is provided a fixing hole 43 for receiving a fixing member 60 that inserts the through hole 32h of the mounting portion 32. The fixing of the mounting portion 32 to the housing 40 using the fixing member 60 is easy to improve the positioning accuracy because the flat plate-shaped member (mounting portion 32) is fixed relative to the plane (the lower surface of the housing 40). In contrast, it is not easy to correctly position the U-shaped portion 31 having a three-dimensional shape inside the receiving recess 41. Therefore, by positioning and fixing the mounting portion 32 with respect to the housing 40 , the U-shaped portion 31 connected to the mounting portion 32 via the connecting portion 33 can be accurately positioned with respect to the housing 40 .

[0065] On the upper side of the housing 40 (Z1 side in the Z1-Z2 direction), there are provided a chamber 42 for accommodating the magnetic sensor 20 fixed on the substrate 50 and a fixing hole 44 for fixing the substrate 50. Since the magnetic sensor 20 is positioned and fixed relative to the substrate 50, the magnetic sensor 20 is accurately positioned relative to the housing 40 by fixing the fixing member 60 inserted into the through hole 50h of the substrate 50 to the fixing hole 44, and the chamber 42 is covered by the substrate 50 to form a closed space.

[0066] Figure 3A The diagram shows simulation results for confirming the shielding effect of the magnetic shield included in the current sensor according to the first embodiment of the present invention, viewed along the Y1 - Y2 direction (first direction). Figure 3B The diagram shows simulation results for confirming the shielding effect of the magnetic shield included in the current sensor according to the first embodiment of the present invention, viewed along the Z1 - Z2 direction (third direction). Figure 3A and Figure 3B The magnetic shield 30a shown in the figure has a U-shaped portion 31 formed of a metal plate. Figure 1A and Figure 1B The magnetic shield 30 shown is longer than the side wall portion 31W, and the magnetic sensor 20 is located between the two side wall portions 31W, 31W when viewed along the first direction (Y1-Y2 direction).

[0067] Figure 4A The diagram shows the simulation results for confirming the shielding effect of the magnetic shield provided in the current sensor according to the conventional technology, viewed along the Y1 - Y2 direction (first direction). Figure 4BThe diagram shows the simulation results for confirming the shielding effect of the magnetic shield provided in the current sensor according to the conventional technology, viewed along the Z1 - Z2 direction (third direction). Figure 4A and Figure 4B The magnetic shield 30X shown in FIG. Figure 2A and Figure 2B The magnetic shield 30 a shown in the figure does not have the connecting portion 33 and the mounting portion 32 , and has a structure consisting of the U-shaped portion 31 as a whole.

[0068] The simulation results Figure 3A and Figure 3B The multiple arrows shown indicate the directions of the external magnetic field at various locations. Figure 3A and Figure 3B The simulation and Figure 4A and Figure 4B Since the simulation shown is based on a different basic model, although the arrangement density of arrows indicating the simulation results is different, the direction and intensity of the magnetic flux (magnetic flux density) can be compared.

[0069] like Figure 3A and Figure 3B As shown, in the magnetic shield 30a, the external magnetic field from the X1 side in the X1-X2 direction toward the X2 side in the X1-X2 direction is attenuated by the two side wall portions 31W, 31W standing on the Z1 side in the Z1-Z2 direction. In addition, since the mounting portion 32 with a high magnetic permeability is adjacent to the U-shaped portion 31, the magnetic field flowing between the two side wall portions 31W, 31W of the U-shaped portion 31 flows preferentially in the mounting portion 32 rather than in the air. That is, a part of the magnetic field flowing between the two side wall portions 31W, 31W is attracted to the mounting portion 32.

[0070] Therefore, in the magnetic shield 30a, although the external magnetic field that flows into the area where the magnetic sensor 20 is located by bypassing the side wall portion 31W is small, a relatively large external magnetic field flows into the magnetic shield 30X. Reflecting this, when comparing the area on the Y2 side of the magnetic sensor 20 in the Y1-Y2 direction between the two side wall portions 31W, Figure 3B In the simulation results of the magnetic shield 30a shown in FIG. Figure 4B Compared with the simulation result of the magnetic shield 30X shown, the penetration of the external magnetic field is shallow (see the dotted arrow).

[0071] In this case, the external magnetic field enters less in the case of the magnetic shield 30a, so the magnetic flux density passing through the magnetic sensor 20 is lower in the case of the magnetic shield 30a. Specifically, in this simulation where the magnetic flux density of the applied external magnetic field is set to 500 μT, the magnetic flux density passing through the magnetic sensor 20 is ( Figure 4A , Figure 4B) is about 100 μT. In contrast, in the case of the magnetic shield 30a ( Figure 3A , Figure 3B ) is about 30μT. In addition, FIG. 3A to FIG. 4B Since the originally colored figure is converted to monochrome, the depth of the arrow does not correspond to the strength of the magnetic flux density.

[0072] In order to effectively utilize the external magnetic field attenuation function of the mounting portion 32, the mounting portion 32 is preferably disposed close to the noise source. That is, the mounting portion 32 is preferably disposed between the U-shaped portion 31 and the magnetic noise source.

[0073] (Second embodiment)

[0074] Figure 5 This is an explanatory diagram of a magnetic shield included in a current sensor according to a second embodiment of the present invention (a diagram viewed along the Z1-Z2 direction (third direction)). Since the current sensor according to the second embodiment of the present invention is basically the same as the current sensor 100 according to the first embodiment except for the magnetic shield 30A, only the magnetic shield 30A will be described, and descriptions of other structures will be omitted.

[0075] In comparison with the magnetic shield 30 of the current sensor 100 according to the first embodiment, the magnetic shield 30A of the current sensor according to the second embodiment of the present invention uses a metal plate 301A instead of the metal plate 301, so the shape of the mounting portion 32A is different. Specifically, the mounting portion 32A of the magnetic shield 30A further extends to the Y1 side in the Y1-Y2 direction on both sides of the mounting portion 32 of the magnetic shield 30 in the second direction (X1-X2 direction), and four more through holes 32h are provided than in the case of the first embodiment. Since the mounting portion 32A has a large number of through holes 32h, the fixing of the mounting portion 32A to the housing 40 is stabilized in the magnetic shield 30A. This means that the current sensor according to the second embodiment can have higher measurement accuracy than the current sensor 100 according to the first embodiment.

[0076] In addition, similarly to the metal plate 301 of the magnetic shield 30 (see Figure 2B ), the metal plate 301A in the state before being bent to form the U-shaped portion 31 has its end in the X1-X2 direction of the portion that becomes the U-shaped portion 31 arranged close to the portion of the mounting portion 32A that further extends to the Y1 side in the Y1-Y2 direction, forming a rectangular shape. In addition, the connecting portion 33 is formed with the same length as the width dimension of the cut strip used to form the outer shape of the U-shaped portion 31 from the metal plate 301A. That is, when the metal plate 301A is processed, less material is wasted.

[0077] (Third embodiment)

[0078] Figure 6 This is an explanatory diagram of a magnetic shield included in a current sensor according to a third embodiment of the present invention (a diagram viewed along the Z1-Z2 direction (third direction)). The current sensor according to the third embodiment of the present invention is basically the same as the current sensor 100 according to the first embodiment except for the magnetic shield 30B, so only the magnetic shield 30B will be described, and descriptions of other structures will be omitted.

[0079] In comparison with the magnetic shield 30 of the current sensor 100 according to the first embodiment, the magnetic shield 30B of the current sensor according to the third embodiment of the present invention uses a metal plate 301B instead of the metal plate 301, so the shape other than the U-shaped portion 31 is different. Specifically, in the magnetic shield 30, the connecting portion 33 is provided at the end of the bottom wall portion 31B on the Y2 side in the Y1-Y2 direction, but in the magnetic shield 30B, the connecting portions 33B are provided at the ends of the bottom wall portion 31B on both sides in the Y1-Y2 direction. Accordingly, the mounting portions 32B are provided on both sides of the bottom wall portion 31B in the first direction (Y1-Y2 direction).

[0080] If used FIG. 3A to FIG. 4B As described above, the mounting portion 32 has a function of attenuating an external magnetic field. Therefore, by being located on both sides of the first direction (Y1-Y2 direction) in which the bus bar 10 extends, the portion where the magnetic sensor 20 is provided is less susceptible to the influence of the external magnetic field.

[0081] (Fourth embodiment)

[0082] Fig. 7A It is an explanatory diagram of a magnetic shield included in a current sensor according to a fourth embodiment of the present invention (a diagram viewed along the Z1 - Z2 direction (third direction)). Figure 7B It is an explanatory diagram of a magnetic shield included in a current sensor according to a fourth embodiment of the present invention (a diagram viewed along the Y1 - Y2 direction (first direction)). Figure 7C This is an explanatory diagram of a current sensor according to a fourth embodiment of the present invention (a diagram viewed along the Z1-Z2 direction (third direction)). The current sensor 110 according to the fourth embodiment of the present invention is basically the same as the current sensor 100 according to the first embodiment except for the magnetic shield 30C, so only the magnetic shield 30C will be described, and the description of other structures will be omitted or simplified. Figure 7C , only the arrangement of the bus bar 10 , the magnetic sensor 20 , and the magnetic shield 30C is shown.

[0083] In the current sensor according to the fourth embodiment of the present invention, a plurality of (specifically, three) bus bars 10 are arranged in the second direction (X1-X2 direction) on the housing 40. The magnetic shield 30C has three U-shaped portions 31C1, 31C2, and 31C3 corresponding to the three bus bars 10, respectively, and the three U-shaped portions 31C1, 31C2, and 31C3 are connected to a common mounting portion 32C via respective connecting portions 33C.

[0084] Since a plurality of U-shaped portions 31C1, 31C2, 31C3 are connected to one mounting portion 32C, the plurality of U-shaped portions 31C1, 31C2, 31C3 can be correctly positioned simultaneously by positioning the mounting portion 32C. In addition, since the plurality of U-shaped portions 31C1, 31C2, 31C3 are integrated via the mounting portion 32C, relative positional deviation of the plurality of U-shaped portions 31C1, 31C2, 31C3 is less likely to occur. Furthermore, since the plurality of U-shaped portions 31C1, 31C2, 31C3 can be mounted in one mounting process, it is also advantageous from the viewpoint of productivity.

[0085] like Fig. 7A As shown in FIG. 1 , among the three U-shaped portions 31C1, 31C2, and 31C3 arranged along the second direction (X1-X2 direction), the central U-shaped portion 31C2 is located closer to the Y2 side of the Y1-Y2 direction than the two U-shaped portions 31C1 and 31C3 at the two ends. That is, the three U-shaped portions 31C1, 31C2, and 31C3 are so-called staggered arrangements. Figure 7B As shown, when viewed along the first direction (Y2 side in the Y1-Y2 direction), the side wall portion 31W on the X1-X2 direction X1 side of the U-shaped portion 31C1 overlaps with the side wall portion 31W on the X1-X2 direction X2 side of the U-shaped portion 31C3 located on the X1-X2 direction X1 side of the U-shaped portion 31C1, and the side wall portion 31W on the X1-X2 direction X2 side of the U-shaped portion 31C1 overlaps with the side wall portion 31W on the X1-X2 direction X1 side of the U-shaped portion 31C2 located on the X1-X2 direction X2 side of the U-shaped portion 31C1. By configuring the three U-shaped portions 31C1, 31C2, and 31C3 in this way, as shown in FIG. Figure 7C As shown, the interval between the adjacent bus bars 10 can be narrowed, thereby achieving miniaturization of the current sensor 110 in the Y1 - Y2 direction.

[0086] like Figure 7BAs shown, the magnetic shield 30C includes three metal plates 301C, 302, and 303. The metal plate 301C forms a part of three U-shaped parts 31C1, 31C2, and 31C3, three connecting parts 33C, and a mounting part 32C. The two metal plates 302 and 303 are overlapped with the metal plate 301C forming a part of the U-shaped part 31C1, and the three U-shaped parts 31C1, 31C2, and 31C3 are formed as a laminate of these metal plates 301C, 302, and 303.

[0087] Fig. 8A It is an explanatory diagram of a method for manufacturing a part of a magnetic shield included in a current sensor according to a fourth embodiment of the present invention (before bending). Figure 8B It is an explanatory diagram of a method for manufacturing a part of a magnetic shield included in a current sensor according to a fourth embodiment of the present invention (a diagram viewed along the Z1 - Z2 direction (third direction) after the bending process). Figure 8C It is an explanatory diagram of a method for manufacturing a part of a magnetic shield included in a current sensor according to a fourth embodiment of the present invention (a diagram viewed along the Y1 - Y2 direction (first direction) after the bending process).

[0088] The metal plate 301C is in the form of a flat plate as a whole before the U-shaped portions 31C1, 31C2, and 31C3 are processed. Fig. 8A As shown, the gap between the U-shaped portion 31C1 and the U-shaped portion 31C2, the gap between the U-shaped portion 31C1 and the U-shaped portion 31C3, the gap between the U-shaped portion 31C2 and the mounting portion 32C, and the gap between the U-shaped portion 31C3 and the mounting portion 32C are formed by punching. Thus, three connecting portions 33C located between the U-shaped portions 31C1, 31C2, 31C3 and the mounting portion 32 are formed. By providing the gaps in this way, in other words, by providing the connecting portions 33C, when the portion constituting the side wall portion 31W is erected in the bending process as the next step, the possibility of interfering with other portions located around and causing the portion constituting the side wall portion 31W to improperly stand up, or unexpected deformation in other portions around, can be reduced.

[0089] In addition, similarly to the metal plate 301 of the magnetic shield 30 and the metal plate 301A of the magnetic shield 30A, the metal plate 301C in the state before being bent to form the U-shaped portion 31 is arranged such that the end portion of the side wall portion 31W on the X2 side in the X1-X2 direction of the U-shaped portion 31C2 and the end portion of the mounting portion 32C on the X2 side in the X1-X2 direction are located at the same position in the X1-X2 direction. Similarly, the end portion of the side wall portion 31W on the X1 side in the X1-X2 direction of the U-shaped portion 31C3 and the end portion of the mounting portion 32C on the X1 side in the X1-X2 direction are located at the same position in the X1-X2 direction. In addition, the mounting portion 32C corresponding to each of the U-shaped portion 31C1 and the U-shaped portion 31C3 is not separately provided, but is connected to the common mounting portion 32C via the connecting portion 33C. Therefore, less material is wasted when processing the metal plate 301C.

[0090] If bending is performed, Figure 8B and Figure 8C As shown, the portion constituting the side wall portion 31W stands in the third direction. Once the portion constituting the side wall portion 31W and the portion constituting the bottom wall portion 31B are formed in this way, the U-shaped portion 31 consisting of a laminate is formed by sequentially stacking the metal plates 302 and 303 that have been subjected to the same bending process, and the manufacture of the magnetic shield 30C is completed.

[0091] Fig. 9 1 is an explanatory diagram of a current sensor according to a conventional technique corresponding to the current sensor according to the fourth embodiment of the present invention (a diagram viewed along the Z1-Z2 direction (third direction)). Fig. 9 In the current sensor 110X shown, three magnetic shields 30X composed of U-shaped parts 31 without mounting parts 32 and connecting parts 33 are arranged alternately, similarly to the three U-shaped parts 31C1, 31C2, and 31C3 of the magnetic shield 30C of the current sensor 110 of the fourth embodiment of the present invention. The influence of the external magnetic field on the current sensor 110X was measured, and the result was 1.8% of the external magnetic field strength. In contrast, in the case of the current sensor 110 related to the fourth embodiment of the present invention, the influence of the same external magnetic field was measured, and it was 0.8% of the external magnetic field strength. That is, the influence of the external magnetic field strength is less than 1 / 2.

[0092] If this is further quantitatively studied, when the rated current is 1000A, the current sensor 110X has a maximum measurement error of 18A. In contrast, the current sensor 110 has a measurement error of 8A, which is a difference of 10A. Even if the rated current is 1000A, since the current range normally used is about 100A to 200A, if an abnormal state is assumed in which the full rated current flows to the adjacent bus bar 10 of the bus bar 10 used in the normal current range, the error due to the external magnetic field is about 10% to about 20% in the case of the current sensor 110X, while it is about 5% to about 10% in the case of the current sensor 110. When the current sensor is applied to an electric vehicle, the difference of 5% to 10% in their errors is a size that cannot be ignored when calculating the cruising distance (power consumption) per unit power amount.

[0093] (Fifth embodiment)

[0094] Fig. 10A It is an explanatory diagram of a magnetic shield included in a current sensor according to a fifth embodiment of the present invention (a diagram viewed along the Z1 - Z2 direction (third direction)). Fig. 10B This is an explanatory diagram of a magnetic shield included in a current sensor according to a fifth embodiment of the present invention (a diagram viewed along the Y1-Y2 direction (first direction)). Since the current sensor according to the fifth embodiment of the present invention is basically the same as the current sensor 100 according to the first embodiment except for the magnetic shield 30D, only the magnetic shield 30D will be described, and description of other structures will be omitted.

[0095] Fig. 10A and Fig. 10B The magnetic shield 30D shown has two U-shaped parts 31D1 and 31D2. The two U-shaped parts 31D1 and 31D2 are provided with connecting parts 33D at both ends of the bottom wall part 31B in the first direction (Y1-Y2 direction). As a result, the two U-shaped parts 31D1 and 31D2 are structured so that the mounting part 32D extends to both sides of the first direction (Y1-Y2 direction).

[0096] In addition, the metal plate 301D constituting a part of the U-shaped parts 31D1 and 31D2, the connecting part 33D, and the mounting part 32D can be formed by punching and bending a flat plate, similarly to the magnetic shield 30C of the fourth embodiment. A part of the side wall part 31W on the X1 side in the X1-X2 direction of the U-shaped part 31D1 is formed by bending the metal plate at the position of the gap part HP on the X1 side in the X1-X2 direction of the U-shaped part 31D1. A part of the side wall part 31W on the X2 side in the X1-X2 direction of the U-shaped part 31D2 is formed by bending the metal plate at the position of the gap part HP on the X2 side in the X1-X2 direction of the U-shaped part 31D2.

[0097] Furthermore, if Fig. 10A As shown in FIG. 1 , the magnetic shield 30D has a point-symmetrical shape when viewed along the third direction (Z1-Z2 direction). Fig. 10A The two U-shaped parts 31D1, 31D2, two mounting parts 32D, etc. are arranged at the intersection point P of the virtual line L1 that bisects the magnetic shield 30D in the X1-X2 direction and the virtual line L2 that bisects the magnetic shield 30D in the Y1-Y2 direction. In some cases, such a design with excellent symmetry is advantageous from the perspective of productivity (manufacturing efficiency, shape processing and assembly of the metal plate 301D). More specifically, there is an advantage that it is not easy to make a mistake in the mounting direction when mounting the magnetic shield 30D to the housing (not shown).

[0098] (Sixth embodiment)

[0099] Fig.11 1 is an explanatory diagram of a current sensor according to a sixth embodiment of the present invention (a diagram viewed along the Z1-Z2 direction (third direction)). The current sensor 200 according to this embodiment includes a plurality of bus bars 10 and a plurality of magnetic shields. Specifically, Fig.11 As shown in FIG. 1 , the magnetic shield 30B according to the third embodiment and two magnetic shields 30C according to the fourth embodiment are arranged in the second direction (the X1 - X2 direction).

[0100] By providing a plurality of magnetic shields corresponding to a plurality of bus bars 10 in one housing 40 in this manner, it is possible to easily form the current sensor 200 capable of measuring a large number of bus bars 10 .

[0101] In addition, in the current sensor 200, by making the same magnetic shield correspond to the bus bar 10 of the same purpose of use, the measurement unit can be configured as a unit of the magnetic shield. As a specific example, when the current sensor 200 is used in an electric vehicle, the unit U1 including the magnetic shield 30B having one U-shaped portion 31 is used for the purpose of current detection of a boost converter, and the unit U2 and the unit U3 including the magnetic shield 30C having three U-shaped portions 31 are used for the purpose of current measurement of different three-phase motors. If configured in this way, even if the rated current amount is different for the three-phase motor measured by the unit U2 and the three-phase motor measured by the unit U3, the rated current amount can be corresponded to each other by the magnetic shield 30C, so that the design of the current sensor 200 can be facilitated.

[0102] Fig. 12A It is an explanatory diagram of a current sensor according to a fourth embodiment of the present invention (a cross-sectional view as viewed in the Y1 -Y2 direction (first direction)). Fig. 12B It is an explanatory diagram of a current sensor according to a seventh embodiment of the present invention (a cross-sectional view as viewed in the Y1 -Y2 direction (first direction)).

[0103] Fig. 12A The current sensor 120 according to the fourth embodiment shown in FIG. Figure 1A In the comparison of the current sensor 100 of the first embodiment shown in the figure, the magnetic shield 30C is different in that it has three U-shaped portions 31, but the basic structure is the same. Therefore, the fixing member 60 is inserted through the through hole 32h of the mounting portion 32 or the through hole 50h provided on the substrate 50 and is fixed to the housing 40. In contrast, Fig. 12B In the current sensor 130 of the seventh embodiment shown in the figure, in comparison with the current sensor 120 of the fourth embodiment, a cover member 71 is provided on the lower side (Z2 side in the Z1-Z2 direction) of the mounting portion 32, and a cover member 72 is also provided on the upper side (Z1 side in the Z1-Z2 direction) of the substrate 50. In addition, since the mounting portion 32 is entirely accommodated in the recess provided in the cover member 71, the magnetic shield 30C is not exposed to the outside.

[0104] exist Fig. 12B In the current sensor 130 shown, through holes (through hole 71h, through hole 40h) are provided in the cover member 71 and the housing 40, and the fixing member 60 is inserted from the bottom (Z1-Z2 direction Z2 side) through the through hole 71h of the cover member 71, the through hole 32h of the mounting portion 32, and the through hole 50h of the substrate 50. In addition, the front end of the fixing member 60 is embedded in the cover member 72, so that the positions of the components constituting the current sensor 130 are fixed.

[0105] By providing the cover members 71 and 72 in this manner, even if rust forms on a portion (particularly a cut surface) of the magnetic shield 30C, the rust does not overflow to the outside of the current sensor 130. Therefore, the rust overflowing to the outside is prevented from falling between the wirings and causing a short circuit.

[0106] The embodiments described above are described to facilitate understanding of the present invention, and are not described to limit the present invention. Therefore, the elements disclosed in the embodiments described above are intended to include all design changes or equivalents that fall within the technical scope of the present invention.

[0107] For example, in the above-mentioned embodiment, the connection portion 33 is provided at the end of the bottom wall portion 31B, but it may be provided at the side wall portion 31W. As a specific example of such a case, the connection portion 33 may be provided at the upper end (the end on the Z1 side in the Z1-Z2 direction) of the side wall portion 31W, and the mounting portion 32 may extend to the outside in the second direction (X1-X2 direction).

[0108] Description of symbols

[0109] 100, 110, 110X, 120, 130, 200: Current sensor

[0110] 10: Busbar

[0111] 20: Magnetic sensor

[0112] 30, 30a, 30A, 30B, 30C, 30D, 30X: Magnetic shielding

[0113] 31, 31C1, 31C2, 31C3, 31D1, 31D2: U-shaped part

[0114] 31B: Bottom wall

[0115] 31W: Side wall

[0116] 32, 32A, 32B, 32C, 32D: Installation

[0117] 32h, 40h, 50h, 71h: through hole

[0118] 33, 33B, 33C, 33D: Connection

[0119] 40: Shell

[0120] 41: Containment recess

[0121] 42: Chamber

[0122] 43, 44: Fixing holes

[0123] 50: Substrate

[0124] 60: Fixed parts

[0125] 71, 72: Cover parts

[0126] 301, 301A, 301B, 301C, 301D, 302, 303: Metal plates

[0127] 301W: Part of the metal plate 301 before bending

[0128] HP: gap

[0129] L1, L2: Virtual lines

[0130] P: intersection of virtual line L1 and virtual line L2

[0131] U1, U2, U3: Unit

Claims

1. A current sensor, comprising: A bus bar extending in the first direction; a magnetic shield having a portion facing the bus bar along the third direction; a magnetic sensor facing the bus bar along the third direction on a side of the bus bar opposite to a side on which the magnetic shield is disposed; and The housing is integrally formed with a portion of the bus bar. It is characterized in that The magnetic shielding member has: The U-shaped portion has a bottom wall portion and two side wall portions, the bottom wall portion includes a portion facing the bus bar along the third direction, and the two side wall portions stand along the third direction from the end of the bottom wall portion in the second direction and are arranged facing each other in the second direction; A mounting portion connected to the U-shaped portion and fixed to the housing; and The connecting portion connects the U-shaped portion and the mounting portion.

2. The current sensor according to claim 1, characterized in that The mounting portion is provided from the connecting portion located at an end portion of the bottom wall portion of the U-shaped portion in the first direction.

3. The current sensor according to claim 1, characterized in that In the housing, a plurality of the bus bars are arranged in the second direction; The magnetic shield includes a plurality of the U-shaped portions corresponding to the plurality of bus bars, respectively, and the plurality of U-shaped portions are connected to the common mounting portion.

4. The current sensor according to claim 3, characterized in that The two U-shaped portions corresponding to the two adjacent bus bars are arranged to be offset in the first direction.

5. The current sensor according to claim 4, characterized in that: The two U-shaped portions corresponding to the two adjacent bus bars partially overlap when viewed along the first direction.

6. The current sensor according to claim 1, characterized in that: The mounting portion is made of a soft magnetic material and is disposed so as to be located between the U-shaped portion and a magnetic noise generation source.

7. The current sensor according to claim 1, characterized in that: The mounting portion is made of a soft magnetic body and is connected to both ends of the U-shaped portion in the first direction.

8. The current sensor according to claim 1, wherein: A cover is further provided which abuts against the housing from the third direction.

9. The current sensor according to claim 1, wherein: The magnetic shield is formed of a metal plate, and the side wall portion of the U-shaped portion is formed by bending a portion of the metal plate.

10. The current sensor according to claim 1, wherein: The U-shaped portion is formed of a laminated body formed by stacking a plurality of metal plates, and the mounting portion is connected to at least one of the plurality of metal plates via the connecting portion.

11. The current sensor according to claim 10, characterized in that The mounting portion is formed of a metal plate that is farthest from the bus bar among the metal plates constituting the laminate.

12. The current sensor according to claim 1 or 2, characterized in that: A plurality of magnetic shielding members are provided; The plurality of magnetic shields are fixed to the housing so that the plurality of bus bars corresponding to the plurality of U-shaped portions of the plurality of magnetic shields are arranged along the second direction.

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