current sensor

Abstract

Provided are a bus bar (30) that has one direction as a length direction and through which an alternating current flows along the length direction, a sensor portion that outputs a detection signal that is a signal based on a magnetic field generated in accordance with the alternating current flowing in the bus bar (30), and a sensor frame that arranges the bus bar (30) and the sensor portion in a state of facing each other. The bus bar (30) is configured by stacking a first bus bar (310) and a second bus bar (320) along an arrangement direction of the bus bar (30) and the sensor portion, has a covered portion (31) covered by the sensor frame (10) and facing the sensor portion, and has a fastening portion (32) exposed from the sensor frame (10). The first bus bar (310) and the second bus bar (320) are arranged in the covered portion (31) in a state of forming a gap (g) between the first bus bar (310) and the second bus bar (320).

Description

[0001] Cross-references to related applications

[0002] This application is based on Japanese Patent Application No. 2020-200304, filed on December 2, 2020, the contents of which are incorporated herein by reference. Technical Field

[0003] This disclosure relates to a current sensor for detecting alternating current flowing in a busbar. Background Technology

[0004] Previously, a current sensor for detecting the current flowing in a busbar has been proposed (for example, see Patent Document 1). Specifically, in this current sensor, a busbar carrying the current is arranged on a sensor frame, and a sensor unit is arranged to output a detection signal corresponding to a magnetic field. Furthermore, the busbar and the sensor unit are arranged opposite each other. In addition, the busbar is designed as a flat plate with the current flow direction as its length direction, and the cross-sectional shape of the busbar with the current flow direction as its normal direction is designed as a rectangular shape.

[0005] In such a current sensor, if current flows through the busbar, a signal magnetic field is generated around the busbar. Furthermore, the sensor outputs a detection signal corresponding to the signal magnetic field. In this case, if alternating current flows through the busbar, the alternating current tends to concentrate at the end of the section with the flow direction as its normal direction due to the skin effect. Therefore, in a current sensor that carries alternating current through the busbar, if the direction intersecting the length direction of the busbar and the arrangement direction of the busbar and the sensor is taken as the width direction, the sensor is positioned at a location that is a predetermined distance away from the center of the busbar in the width direction. Furthermore, being positioned at a predetermined distance also includes the case where it is positioned at the center of the busbar in the width direction (i.e., the predetermined distance is 0).

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: Patent No. 6462850 Summary of the Invention

[0009] However, in the current sensor described above, because the current density in the width direction of the busbar changes greatly when alternating current flows through it, the detection accuracy is easily affected by assembly errors of the sensor unit and the busbar.

[0010] The purpose of this disclosure is to provide a current sensor capable of suppressing variations in detection accuracy.

[0011] According to one aspect of the present disclosure, a current sensor includes: a busbar that has a length direction as a direction in which an alternating current flows, a sensor portion that outputs a detection signal that is a signal based on a magnetic field generated in accordance with the alternating current flowing in the busbar, and a sensor frame that arranges the busbar and the sensor portion. The busbar is configured by stacking a first busbar and a second busbar in a direction in which the busbar and the sensor portion are arranged. The first busbar and the second busbar are arranged in the sensor frame so as to form a gap between the first busbar and the second busbar.

[0012] Accordingly, in a width direction that intersects the length direction of the busbar and the direction in which the busbar and the sensor portion are arranged, a variation in current density of the busbar can be reduced. Therefore, when the sensor portion is arranged at a target position that is separated from a portion opposite to the center of the busbar by a predetermined distance, even if the sensor portion is misaligned in the width direction, a variation in detection accuracy can be reduced. That is, robustness with respect to misalignment in the width direction of the sensor portion can be improved. BRIEF DESCRIPTION OF DRAWINGS

[0013] Figure 1 is a perspective view of a current sensor of a first embodiment.

[0014] Figure 2 is a perspective view of a first current sensor.

[0015] Figure 3 is a cross-sectional view along the line III-III in Figure 1 .

[0016] Figure 4 is a perspective view of a busbar.

[0017] Figure 5 is a graph showing a relationship between a misalignment amount in the X-axis direction of the sensor portion and an amplitude ratio with respect to a gap length.

[0018] Figure 6 is a graph showing a relationship between a misalignment amount in the X-axis direction of the sensor portion and a gap length.

[0019] Figure 7 is a perspective view of a busbar of a second embodiment.

[0020] Figure 8 is a cross-sectional view of a first current sensor of the second embodiment.

[0021] Figure 9 is a graph showing a relationship between a misalignment amount in the X-axis direction of the sensor portion and an amplitude ratio with respect to a gap length.

[0022] Figure 10is a graph showing the relationship between the displacement amount in the X-axis direction of the sensor portion and the gap length.

[0023] Figure 11 is a graph showing the relationship between the displacement amount in the X-axis direction of the sensor portion and the amplitude ratio with respect to the narrow portion width.

[0024] Figure 12 is a graph showing the relationship between the displacement amount in the X-axis direction of the sensor portion and the narrow portion width.

[0025] Figure 13 is a graph showing the relationship between the displacement amount in the X-axis direction of the sensor portion and the amplitude ratio with respect to the narrow portion length.

[0026] Figure 14 is a graph showing the relationship between the displacement amount in the X-axis direction of the sensor portion and the narrow portion length.

[0027] Figure 15 is a graph showing the relationship between the displacement amount in the Y-axis direction of the sensor portion and the amplitude ratio with respect to the narrow portion length.

[0028] Figure 16 is a graph showing the relationship between the displacement amount in the Y-axis direction of the sensor portion and the narrow portion length.

[0029] Figure 17 is a graph showing the relationship between the displacement amount in the X-axis direction of the sensor portion and the amplitude ratio with respect to the protrusion portion length.

[0030] Figure 18 is a graph showing the relationship between the displacement amount in the X-axis direction of the sensor portion and the protrusion portion length.

[0031] Figure 19 is a graph showing the relationship between the displacement amount in the Y-axis direction of the sensor portion and the amplitude ratio with respect to the protrusion portion length.

[0032] Figure 20 is a graph showing the relationship between the displacement amount in the Y-axis direction of the sensor portion and the protrusion portion length.

[0033] Figure 21 is a cross-sectional view of the first current sensor of the second embodiment.

[0034] Figure 22 is a graph showing the relationship between the displacement amount in the X-axis direction of the sensor portion and the amplitude ratio with respect to the narrow portion width.

[0035] Figure 23 is a graph showing the relationship between the displacement amount in the X-axis direction of the sensor portion and the narrow portion width.

[0036] Figure 24 is a cross-sectional view of the first current sensor of the third embodiment.

[0037] Figure 25 is a graph showing a relationship of a displacement amount in the X-axis direction of the sensor portion and the amplitude ratio with respect to the narrow portion width.

[0038] Figure 26 is a graph showing a relationship of a displacement amount in the X-axis direction of the sensor portion and the narrow portion width.

[0039] Figure 27 is a perspective view of the bus bar of the fourth embodiment. DETAILED DESCRIPTION

[0040] Hereinafter, the embodiments of the present disclosure will be described based on the drawings. Furthermore, for the respective embodiments below, the same reference signs are attached to portions that are the same or equivalent to each other, and the description will be made.

[0041] <First Embodiment>

[0042] The current sensor of the first embodiment will be described with reference to the drawings. Furthermore, the current sensor of the present embodiment is mounted on a vehicle, for example, and is preferably used for detecting an alternating current that flows in an inverter that drives a three-phase motor.

[0043] As shown in Figure 1 , the current sensor 1 of the present embodiment has a first current sensor 1a, a second current sensor 1b, and a third current sensor 1c, and is configured by integrating them. The first current sensor 1a, the second current sensor 1b, and the third current sensor 1c are each provided as a coreless magnetic balance type current sensor that does not require a magnetic core. Hereinafter, the structure of the first current sensor 1a will be described. Furthermore, the second current sensor 1b and the third current sensor 1c are provided in the same structure as the first current sensor 1a except for portions related to the connection terminal 20 and the connector portion 120 described later.

[0044] As shown in Figure 2 and Figure 3 , the first current sensor 1a is provided with a structure including a sensor frame 10, a connection terminal 20, a bus bar 30, a sensor portion 40, a wiring substrate 50, a first shield portion 71, a second shield portion 72, a cover portion 80, and the like. Furthermore, in Figure 2 , the cover portion 80 is omitted. In addition, in Figure 2 , the bus bar 30 is simplified.

[0045] The sensor housing 10 is made of an insulating resin material and has a cuboid base 100 including one side 100a and another side 100b, and a connector portion 120 disposed on the base 100. Hereinafter, a direction along the surface direction of one side 100a of the base 100 will be defined as the X-axis direction, a direction orthogonal to the X-axis direction and along the surface direction of the base 100 will be defined as the Y-axis direction, and a direction along both the X-axis and Y-axis directions will be defined as the Z-axis direction. Furthermore, in this embodiment, the connector portion 120 extends along the Z-axis direction at one end of the base 100 in the X-axis direction. Additionally, the sensor housing 10 is shared with the second current sensor 1b and the third current sensor 1c.

[0046] In the base 100, a first receiving recess 101 is formed on one side 100a, and a second receiving recess 111 is formed on the other side 100b. The first receiving recess 101 includes a guide protrusion 102 corresponding to the guide recess 52 formed on the wiring substrate 50 (described later), a substrate support portion 103 supporting the wiring substrate 50, and a substrate joining portion 104 engaging with the wiring substrate 50. Additionally, the first receiving recess 101 includes a shielding support portion 105 supporting the first shielding portion 71 (described later) and a shielding joining portion 106 engaging with the first shielding portion 71.

[0047] In addition, such as Figure 2 As shown, the substrate support portion 103 and the substrate joining portion 104 are disposed on the inner edge side of the bottom surface of the first receiving recess 101. The shielding support portion 105 and the shielding joining portion 106 are disposed on the bottom surface of the first receiving recess 101 further outward than the portion where the substrate support portion 103 and the substrate joining portion 104 are disposed. More specifically, the shielding support portion 105 and the shielding joining portion 106 are formed at positions that protrude from the outside of the wiring substrate 50 when the wiring substrate 50 is disposed in the first receiving recess 101.

[0048] Furthermore, the substrate support portion 103 is slightly higher than the substrate joining portion 104. The shielding support portion 105 and the shielding joining portion 106 are also higher than the substrate support portion 103 and the substrate joining portion 104. The substrate support portion 103 is slightly higher than the substrate joining portion 104.

[0049] like Figure 3As shown, the second receiving recess 111 has a shielding support portion 112 for supporting the second shielding portion 72 (described later). Furthermore, the second receiving recess 111 is the portion where the second shielding portion 72 (described later) is disposed, and is configured with a shape corresponding to the structure of the second shielding portion 72. In this embodiment, the second shielding portion 72 is configured to have a wall portion 72b; therefore, groove portions 113 along the Z-axis direction are formed at both ends of the second receiving recess 111 in the X-axis direction.

[0050] The connector portion 120 has an opening 121 formed in the portion opposite to the first receiving recess 101. Additionally, on the sensor housing 10, as... Figure 1 and Figure 2 As shown, a connecting protrusion 130 is formed on the outer surface, corresponding to the connecting recess 81 formed in the cover portion 80 described later.

[0051] The connecting terminals 20 are constructed using metal rod-shaped components, and multiple connecting terminals 20 are fixed within the sensor housing 10 by insert molding. Specifically, as... Figure 3 As shown, each connection terminal 20 is embedded in the sensor housing 10 and fixed in such a way that one end protrudes from the first receiving recess 101 and the other end protrudes from the opening 121 of the connector portion 120. Moreover, the other end of the connection terminal 20 is connected to a wire harness or the like to connect to an external circuit.

[0052] The busbar 30 is constructed by stamping or forming conductor components, and is configured with one direction as the length direction. Furthermore, the busbar 30 is inserted into the sensor housing 10 such that its central portion in the length direction is located between the first receiving recess 101 and the second receiving recess 111, and both ends are exposed. In this embodiment, the busbar 30 is fixed to the sensor housing 10 with its length direction along the Y-axis.

[0053] The following, such as Figure 4 As shown, the portion of the busbar 30 covered by the sensor housing 10 is designated as the covering portion 31, and the portion exposed from the sensor housing 10 is designated as the fastening portion 32. Furthermore, as... Figure 2 As shown, a fastening hole 34 for mounting to the component is formed on the fastening part 32. Furthermore, Figure 4 The dashed line in the diagram represents the boundary between the covering portion 31 and the fastening portion 32. Additionally, in... Figure 4 In the text, the fastening hole 34 is omitted.

[0054] In this embodiment, a narrow portion 31a is formed in the covering portion 31. If the direction intersecting the length direction is set as the width direction (i.e., in...) Figure 3 and Figure 4In the case where the X-axis direction is the longitudinal direction of the busbar 30, the length of the narrow portion 31a in the width direction (hereinafter, also referred to simply as the width) is shorter than the length of the fastening portion 32 in the width direction. In the cover portion 31 of the present embodiment, the narrow portion 31a is configured by forming the notch portion 33. The notch portion 33 of the present embodiment is formed such that, if a face intersecting the XY plane and the YZ plane in the busbar 30 is taken as a side face, the side face configuring the notch portion 33 is parallel to the X-axis direction (i.e., orthogonal to the longitudinal direction of the busbar 30).

[0055] Further, in the present embodiment, the notch portion 33 is formed at a position closer to the cover portion 31 than the boundary portion between the cover portion 31 and the fastening portion 32, but the notch portion 33 can also be formed at the boundary portion between the cover portion 31 and the fastening portion 32. That is, the cover portion 31 can also be configured as a narrow portion 31a as a whole. Furthermore, the shape of the notch portion 33 can be changed as appropriate. For example, the notch portion 33 can also be formed as a tapered portion in which the width gradually decreases toward the narrow portion 31a side. Figure 4

[0056] In addition, the busbar 30 of the present embodiment is configured by stacking the first busbar 310 and the second busbar 320 in the Z-axis direction. Hereinafter, a face of the first busbar 310 on the second busbar 320 side is taken as another face 310b, and a face of the first busbar 310 on the side opposite to the another face 310b is taken as a face 310a. Similarly, a face of the second busbar 320 on the first busbar 310 side is taken as a face 320a, and a face of the second busbar 320 on the side opposite to the face 320a is taken as another face 320b.

[0057] The busbar 30 of the present embodiment is integrated by connecting the first busbar 310 and the second busbar 320 by the fastening portion 32. Specifically, the first busbar 310 and the second busbar 320 are integrated by bending one flat plate. Therefore, the first busbar 310 and the second busbar 320 are in a state of being connected at one end portion in the width direction. Although not particularly limited, in the present embodiment, a copper plate having a plate thickness of 1.6 mm is bent to configure the busbar 30.

[0058] Further, the first busbar 310 and the second busbar 320 are not connected at the narrow portion 31a. In addition, the notch portion 33 configuring the narrow portion 31a can be formed before the flat plate configuring the busbar 30 is bent, or can be formed after the flat plate is bent.

[0059] ​Further, the first bus bar 310 and the second bus bar 320 are configured so as to form a gap g having a prescribed gap length d between the first bus bar 310 and the second bus bar 320 at the narrow portion 31a. The bus bar 30 of the present embodiment configures the first bus bar 310 and the second bus bar 320 in such a manner that the gap g is constant at the fastening portion 32 and the covering portion 31. Further, a plating film or the like for preventing oxidation can also be formed on the bus bar 30 as necessary.

[0060] The sensor portion 40 outputs a detection signal in accordance with a signal magnetic field that has passed through the sensor portion 40, and is configured to include, for example, a Hall element, a TMR (tunnel magneto resistance) element, a GMR (giant magnetic resistance) element, an AMR (anisotropic magneto resistance) element, or the like.

[0061] As shown in Figs. 1 and 2, the sensor portion 40 is mounted on the other face 50b of the wiring substrate 50 in such a manner as to be electrically connected to the wiring pattern and the like. Figure 2 Figure 3 As shown in Figs. 1 and 2, the sensor portion 40 is mounted on the other face 50b of the wiring substrate 50 in such a manner as to be electrically connected to the wiring pattern and the like.

[0062] Further, in the present embodiment, one sensor portion 40 is provided. However, the sensor portion 40 can also be provided in plurality along the Y-axis direction. In addition, the wiring substrate 50 is common to the second current sensor 1b and the third current sensor 1c, and the sensor portion 40 is provided in the portion that constitutes each current sensor.

[0063] A plurality of through-holes 51 are formed in the wiring substrate 50, and a guide recess 52 that corresponds to the guide protrusion 102 formed in the first housing recess 101 is formed. Further, although the detailed structure of the through-hole 51 is omitted, the through-hole 51 is configured so as to have a through-hole electrode or the like that is electrically connected to the wiring pattern formed therein.

[0064] ​Further, the wiring substrate 50 is fixed to the first housing recess 101 of the sensor housing 10 with the other face 50b facing the bus bar 30. Specifically, the wiring substrate 50 is arranged in the first housing recess 101 with the guide recess 52 fitted to the guide protrusion 102. In addition, the wiring substrate 50 has one end portion of the connection terminal 20 inserted in the through-hole 51 and is electrically and mechanically connected to the connection terminal 20 via the conductive member 60 such as solder. Further, the other face 50b of the wiring substrate 50 abuts against the substrate support portion 103, and the wiring substrate 50 is mechanically connected via the joining member 61 such as an adhesive arranged between the wiring substrate 50 and the substrate engaging portion 104.

[0065] In addition, the wiring substrate 50 is arranged in the first housing recess 101 with the YZ plane being the sensing face of the sensor portion 40. That is, the wiring substrate 50 is arranged in the first housing recess 101 so that the sensor portion 40 outputs a detection signal corresponding to a magnetic field in the X-axis direction. Further, the wiring substrate 50 is housed in the first housing recess 101 so that the sensor portion 40 is arranged at a position apart from the bus bar 30 by a predetermined distance from a portion opposite the center in the width direction of the narrow portion 31a (hereinafter, also referred to simply as the center of the narrow portion 31a).

[0066] Further, because the sensor portion 40 is arranged as described above, the arrangement direction of the sensor portion 40 and the bus bar 30 is a direction along the Z-axis direction and is a direction along the stacking direction of the first bus bar 310 and the second bus bar 320. In addition, the so-called sensor portion 40 being arranged at a position apart from the portion opposite the center of the narrow portion 31a by a predetermined distance means that the sensor portion 40 is arranged so that the amplitude becomes 100%, as will be described later. Further, as described above, the shield support portion 105 and the shield engaging portion 106 formed in the first housing recess 101 are formed so as to protrude from the outer side of the wiring substrate 50 to the face 50a side of the wiring substrate 50 when the wiring substrate 50 is arranged in the first housing recess 101.

[0067] The first shield portion 71 and the second shield portion 72 are configured using a material having a higher magnetic permeability than the sensor housing 10 and are configured using a soft magnetic material such as a permalloy or an electromagnetic steel sheet having a high magnetic permeability and are provided in a flat plate shape. The first shield portion 71 and the second shield portion 72 of the present embodiment are provided in a structure in which a plurality of flat plates are laminated together and are integrated by a press-in portion 710. Further, the first shield portion 71 and the second shield portion 72 can be configured separately in the first to third current sensors 1a to 1c or can be shared.

[0068] Further, as Figure 2As shown, the first shielding portion 71 is provided in a rectangular shape when viewed from above in the Z-axis direction, and a notch portion 71a is formed at a corner portion. The second shielding portion 72 is provided in a structure having a flat portion 72a provided in a rectangular shape when viewed from above and a wall portion 72b bent at opposite sides in the flat portion 72a. In the present embodiment, the wall portion 72b is configured by bending both end portions in the X-axis direction for the second shielding portion 72.

[0069] Further, the first shielding portion 71 and the second shielding portion 72 each have a length in the X-axis direction that is longer than a length (i.e., a width) of the bus bar 30 in the X-axis direction.

[0070] Furthermore, the first shielding portion 71 and the second shielding portion 72 are disposed in the sensor housing 10 in a manner in which the wiring board 50 and the bus bar 30 are disposed between the first shielding portion 71 and the second shielding portion 72.

[0071] Specifically, the first shielding portion 71 is disposed on the shielding support portion 105 in a different cross section than the second shielding portion 72, and is disposed in the first housing recess 101 via the engaging member disposed on the shielding engaging portion 106. Figure 3

[0072] The wall portion 72b of the second shielding portion 72 is inserted into the groove portion 113, and the second shielding portion 72 is in abutment with the shielding support portion 112 and is fixed via the engaging member 114 disposed on the bottom surface of the second housing recess 111. Further, the second shielding portion 72 can also be fixed by insert molding in the sensor housing 10.

[0073] The cover portion 80 is configured using a resin material, and is provided in a shape corresponding to the outer shape of the side 100a of the base portion 100 in the sensor housing 10, as shown in Figs. 1 and 2. Figure 1 Figure 2 Further, a coupling recess 81 corresponding to the coupling protrusion 130 of the sensor housing 10 is formed in the cover portion 80. That is, a pair of fitting portions are formed in the sensor housing 10 and the cover portion 80. Furthermore, the cover portion 80 is fixed to the sensor housing 10 by snap-coupling the coupling protrusion 130 to the coupling recess 81 to close the first housing recess 101 of the base portion 100.

[0074] ​​The above is the structure of the current sensor 1 of the present embodiment. In such a current sensor 1, by flowing an alternating current in each bus bar 30 in the first to third current sensors 1a to 1c, a signal magnetic field is generated around each bus bar 30 according to Ampere's law. In the present embodiment, since each bus bar 30 is arranged along the Y-axis direction, the flowing direction of the current is the direction along the Y-axis direction, and thus the signal magnetic field is generated around the Y-axis direction. Also, each sensor portion 40 in the first to third current sensors 1a to 1c outputs a detection signal corresponding to the signal magnetic field. Thereby, the alternating current flowing in each bus bar 30 in the first to third current sensors 1a to 1c is detected.

[0075] Here, in a case where an alternating current flows in the bus bar 30, the alternating current is easily concentrated to the end portion of the bus bar 30 due to the skin effect on a cross section in which the flowing direction of the current is set as the normal direction (i.e., the XZ plane). Also, in the present embodiment, the first bus bar 310 and the second bus bar 320 are laminated to constitute the bus bar 30, and in the narrow portion 31a, a gap g is constituted between the first bus bar 310 and the second bus bar 320. Therefore, in the narrow portion 31a, the other face 310b of the first bus bar 310 and the one face 320a of the second bus bar 320 are also end portions in which the alternating current is easily concentrated. That is, in the narrow portion 31a of the present embodiment, a portion in which the alternating current is easily concentrated is also constituted inside the bus bar 30.

[0076] Also, a current sensor in which the bus bar 30 is constituted by one flat plate and the cross-sectional shape in which the flowing direction of the current is the normal direction is set as a rectangular shape is taken as a conventional current sensor (hereinafter, also simply referred to as a conventional current sensor). In this case, in the current sensor 1 of the present embodiment, since a portion in which the alternating current is easily concentrated is also constituted inside the bus bar 30 compared to the conventional current sensor, it is possible to reduce the variation in the current density of the bus bar 30 along the X-axis direction. Therefore, when the sensor portion 40 is arranged at a target position that is separated by a predetermined distance in the X-axis direction from a portion opposite to the center of the bus bar 30, even if the sensor portion 40 is misaligned in the X-axis direction, it is possible to reduce the variation in the detection accuracy. That is, in the current sensor 1 of the present embodiment, it is possible to improve the robustness with respect to the misalignment of the sensor portion 40 in the X-axis direction.

[0077] In addition, in a case where the first bus bar 310 and the second bus bar 320 are stacked to configure the bus bar 30, an alternating current flows in the first bus bar 310 and the second bus bar 320. In this case, by extending the gap length d, it is possible to reduce the influence of the proximity effect, and it is possible to suppress a decrease in the current density of the other face 310b of the first bus bar 310 and the one face 320a of the second bus bar 320. Therefore, according to the current sensor 1 of the present embodiment, the longer the gap length d is, the more it is possible to reduce a variation in the current density of the bus bar 30 along the X-axis direction. Therefore, in the current sensor 1 of the present embodiment, it is possible to improve the robustness with respect to the misalignment of the sensor portion 40 in the X-axis direction.

[0078] Specifically, the relationship between the misalignment amount of the sensor portion 40 in the X-axis direction and the amplitude ratio is as shown in FIG. 8. In addition, the relationship between the misalignment amount of the sensor portion 40 in the X-axis direction and the gap length d is as shown in FIG. 9. Figure 5 Figure 6

[0079] In addition, the amplitude ratio of the present embodiment refers to a ratio of a signal magnetic field formed in a case where a direct current flows in the bus bar 30 to a reference value, and a signal magnetic field formed in a case where an alternating current whose maximum current is equal to the direct current flows. The misalignment amount in the X-axis direction refers to a length from a reference (hereinafter, also simply referred to as the reference) in a case where the sensor portion 40 is disposed offset in the X-axis direction with the portion opposite to the center of the bus bar 30 as the reference. In addition, the reference opposite to the center of the bus bar 30 refers to a position where the misalignment amount in the X-axis direction is 0. In addition, in Figure 5 in the present embodiment, the width of the narrow portion 31a in the bus bar 30 is set to 8 mm.

[0080] Furthermore, in a case where the current sensor 1 like the present embodiment is mounted on a vehicle, in the current sensor 1, among the present requirements, it is expected that the amplitude ratio is set to a range of 99.5 to 100.5%. Hereinafter, the misalignment amount of the sensor portion 40 in the X-axis direction where the amplitude ratio is 100% is referred to as the optimum position. In addition, the misalignment amount of the sensor portion 40 in the X-axis direction where the amplitude ratio is in the range of 99.5 to 100.5% is referred to as the optimum range. Furthermore, in Figure 6 in the present embodiment, the misalignment amount of the sensor portion 40 in the X-axis direction where the amplitude ratio is 100% (i.e., the optimum position) is indicated as a curve. In addition, in Figure 6 in the present embodiment, the misalignment amount of the sensor portion 40 in the X-axis direction where the amplitude ratio is in the range of 99.5 to 100.5% (i.e., the optimum range) is indicated by an arrow.

[0081] As Figure 5 and Figure 6 ​​As shown, in the current sensor 1 of the present embodiment, it is confirmed that, in terms of the amplitude ratio, the longer the gap length d, the smaller the change in the operation of the sensor portion 40 when the sensor portion 40 is misaligned in the X-axis direction. Also, it is confirmed that the longer the gap length d, the more the optimum position of the sensor portion 40 is on the reference side, and the longer the gap length d, the larger the optimum range of the sensor portion 40.

[0082] For example, in the current sensor 1 of the present embodiment, in a case where the gap length d is set to 1 mm, in order to set the amplitude ratio to 99.5 to 100.5%, it is only necessary to arrange the sensor portion 40 at a position misaligned from the reference by 2.0 to 2.4 mm in the X-axis direction. Therefore, according to the current sensor 1 of the present embodiment, it is possible to improve the robustness with respect to the misalignment of the sensor portion 40 in the X-axis direction. Further, as described above, the amplitude ratio changes due to the change in the gap length d. Therefore, with respect to the bus bar 30, it is preferable to fix the fastening portion 32 by riveting or welding or the like, thereby making it difficult for the gap length d to deviate from the target value.

[0083] According to the present embodiment described above, the bus bar 30 is configured by laminating the first bus bar 310 and the second bus bar 320 in a manner that forms the gap g. Therefore, it is possible to improve the robustness with respect to the misalignment of the sensor portion 40 in the X-axis direction.

[0084] (1) In the present embodiment, by forming the notch portion 33 in the cover portion 31 of the bus bar 30, the narrow portion 31a shorter in width than the fastening portion 32 is configured. Therefore, compared to a case where the narrow portion 31a is not formed, it is possible to suppress the reduction in the current density flowing through the center of the narrow portion 31a.

[0085] (2) In the present embodiment, the first bus bar 310 and the second bus bar 320 of the bus bar 30 are connected at one end portion in the width direction, and are configured using one flat plate. Therefore, it is possible to achieve a reduction in the number of components.

[0086] (3) In the present embodiment, the flat plate is laminated to configure the first shield portion 71 and the second shield portion 72. Therefore, compared to a case where the first shield portion 71 and the second shield portion 72 of the same thickness as the present embodiment are configured using one flat plate, it is difficult for eddy currents to flow, and it is possible to reduce the eddy current loss.

[0087] <Variant of the First Embodiment>

[0088] A variation of the first embodiment described above will be explained. In the first embodiment, the busbar 30 may also be in a state where the first busbar 310 and the second busbar 320 abut at the fastening portion 32. For example, the first busbar 310 and the second busbar 320 may also be in a state where they abut at the fastening portion 32 by welding or riveting. Accordingly, at the fastening portion 32, the first busbar 310 and the second busbar 320 abut each other and can act as a conductor, thus suppressing the situation where the resistance increases and the heat generation increases.

[0089] <Second Implementation Method>

[0090] The second embodiment will be described. In this embodiment, a protrusion is formed on the first busbar 310, which is different from the first embodiment. As other aspects are the same as in the first embodiment, they are omitted here.

[0091] In this embodiment, such as Figure 7 and Figure 8 As shown, a protrusion 311 protruding towards one side 310a is formed in the narrow portion 31a of the first busbar 310. That is, a protrusion 311 protruding towards the side opposite to the second busbar 320 is formed on the first busbar 310. Therefore, a space S is formed between the first busbar 310 and the second busbar 320 by the protrusion 311. Furthermore, the space S is a portion that expands the gap g, or in other words, a portion where the gap length d increases. Figure 8 Is with Figure 3 For ease of understanding, the corresponding sectional view only shows the positional relationship between the busbar 30, the first shielding part 71, and the second shielding part 72.

[0092] In this embodiment, the protrusion 311, when viewed from above along the X-axis, is shaped as having a rectangular portion and arcuate portions at both ends of the rectangular portion. Furthermore, the protrusion 311 in this embodiment is formed such that its center in the width direction coincides with the center in the width direction of the narrow portion 31a, and its center in the length direction coincides with the center in the length direction of the narrow portion 31a. Moreover, regarding the protrusion 311, in a cross-section where the direction of current flow is set as the normal direction (i.e., Figure 8 In this example, the radius is set to the plate thickness (i.e., 1.6 mm). Furthermore, regarding the protrusion 311, for example, its length in the width direction is set to be at least half the length in the width direction of the narrow portion 31a. Moreover, such a protrusion 311 is formed, for example, by stamping or the like.

[0093] According to the above-described embodiment, since the first busbar 310 and the second busbar 320 are stacked in such a way as to form a gap g to form the busbar 30, the same effect as the first embodiment described above can be obtained.

[0094] (1) In the present embodiment, the protruding portion 311 is formed on the first bus bar 310. Therefore, the robustness with respect to the misalignment of the sensor portion 40 in the X-axis direction can be further improved.

[0095] That is, by forming the protruding portion 311 on the first bus bar 310, the portion of the inner edge portion in the width direction of the bus bar 30 that becomes the end portion can be increased, and the current density at the center in the width direction can be further suppressed from decreasing due to the skin effect. In addition, because the space S is configured by forming the protruding portion 311 on the first bus bar 310, the proximity effect can be further reduced. Therefore, according to the current sensor 1 of the present embodiment, the variation in the current density in the width direction of the bus bar 30 can be further reduced, and the robustness with respect to the misalignment of the sensor portion 40 in the X-axis direction can be further improved.

[0096] Specifically, if the current sensor 1 of the present embodiment is compared with the current sensor 1 described in the above first embodiment, Figure 5 and Figure 6 as shown in Figure 9 and Figure 10 , it can be confirmed that, in the case of the same gap length d, the variation in the amplitude ratio can be greatly reduced with respect to the misalignment amount of the sensor portion 40 in the X-axis direction. For example, in the case where the gap length d is set to 1 mm, in the current sensor 1 of the present embodiment, in order to set the amplitude ratio to 99.5 to 100.5%, it is only necessary to arrange the sensor portion 40 at a position that is misaligned from the reference by 0 to 6 mm in the X-axis direction. Therefore, the robustness with respect to the misalignment of the sensor portion 40 in the X-axis direction can be further improved. Furthermore, Figure 9 and Figure 10 are the results in the case where the width of the narrow portion 31a is set to 8 mm and the radius of the protruding portion 311 is set to the plate thickness (i.e., 1.6 mm).

[0097] In addition, in the case of the current sensor 1 of the present embodiment, the following requirements also affect the amplitude ratio and the like. Therefore, the current sensor 1 is preferably adjusted in accordance with the conditions used (e.g., the maximum value of the alternating current) or the required conditions and the like.

[0098] Specifically, as shown in Figure 11 and Figure 12 , it can be confirmed that the longer the width of the narrow portion 31a, the larger the optimal position of the sensor portion 40. Furthermore, it can be confirmed that the shorter the width of the narrow portion 31a, the longer the optimal range of the sensor portion 40. For example, in the case where the width of the narrow portion 31a is 7 mm, the offset amount of the optimal position of the sensor portion 40 in the X-axis direction from the reference is 3 mm. Furthermore, the offset amount of the optimal range of the sensor portion 40 in the X-axis direction from the reference is about 0 to 5 mm. Furthermore, Figure 11 andFigure 12 is a result when the gap length d is set to 0.1 mm.

[0099] Also, as shown in Figure 7 , the length of the narrow portion 31a in the Y-axis direction is set to a narrow portion length LI, and the length of the protruding portion 311 in the Y-axis direction is set to a protruding portion length L2. In this case, when the protruding portion length L2 is set constant and the narrow portion length LI is changed, the relationship between the displacement amount in the X-axis direction of the sensor portion 40 and the amplitude ratio is as shown in Figure 13 and Figure 14 . Further, Figure 13 and Figure 14 is a result when the width of the narrow portion 31a is set to 8 mm, the protruding portion length L2 is set to 10 mm, and the gap length d is set to 0.1 mm.

[0100] As shown in Figure 13 and Figure 14 , if the narrow portion length LI is made longer, the current density is easily uniformized in the center in the length direction in the narrow portion 31a. Therefore, it is confirmed that if the narrow portion length LI is made longer, the optimum position of the sensor portion 40 moves to the reference side, and the optimum range of the sensor portion 40 also expands. However, in the current sensor 1 of the present embodiment, if the narrow portion length LI is 20 mm or more, the optimum position hardly changes, and thus the narrow portion length LI is preferably set to 20 mm or more.

[0101] In addition, when the protruding portion length L2 is set constant and the narrow portion length LI is changed, the relationship between the displacement amount in the Y-axis direction of the sensor portion 40 and the amplitude ratio is as shown in Figure 15 and Figure 16 . Further, Figure 15 and Figure 16 is a result when the width of the narrow portion 31a is set to 8 mm, the protruding portion length L2 is set to 10 mm, and the gap length d is set to 0.1 mm.

[0102] As shown in Figure 15 and Figure 16 , it is confirmed that, in terms of the displacement amount in the Y-axis direction of the sensor portion 40 at which the amplitude ratio becomes 100%, the displacement amount hardly changes even if the narrow portion length LI is changed. However, in terms of the amplitude ratio, because the farther from the center in the Y-axis direction of the narrow portion 31a, the more difficult it is to uniformize the current density, the larger the displacement amount in the Y-axis direction, the more easily the above-described amplitude ratio changes. Therefore, the sensor portion 40 is preferably disposed in opposition to the center in the Y-axis direction of the narrow portion 31a.

[0103] Furthermore, with the narrow section length L1 set constant, the relationship between the misalignment amount and amplitude ratio in the X-axis direction of the sensor section 40 is as follows: Figure 17 and Figure 18 As shown. Furthermore, Figure 17 and Figure 18 This is the result when the width of the narrow section 31a is set to 8mm, the length L1 of the narrow section is set to 20mm, and the gap length d is set to 0.1mm. For example... Figure 17 and Figure 18 As shown, it can be confirmed that the longer the length L2 of the protrusion is extended, the larger the optimal range can be, but the optimal position is hardly affected.

[0104] Furthermore, with the narrow section length L1 set constant, the relationship between the misalignment amount and amplitude ratio in the Y-axis direction of the sensor section 40 is as follows: Figure 19 and Figure 20 As shown. Furthermore, Figure 19 and Figure 20 This is the result when the width of the narrow section 31a is set to 8mm, the length L1 of the narrow section is set to 20mm, and the gap length d is set to 0.1mm. For example... Figure 19 and Figure 20 As shown, it can be confirmed that the length L2 of the protrusion has almost no effect on the optimal position or the optimal range.

[0105] Furthermore, in the current sensor 1 described above, shortening the width of the narrow portion 31a reduces the cross-sectional area for alternating current flow, thus increasing heat generation. In this case, the thermal stress generated on the sensor housing 10 is transmitted to the wiring board 50, potentially reducing detection accuracy. Therefore, the current sensor 1 preferably adjusts the width of the narrow portion 31a, the gap length d, and the shape of the protrusion 311 of the busbar 30 according to the conditions used (e.g., the maximum value of the alternating current) or the required conditions.

[0106] <Modifications of the Second Embodiment>

[0107] A variation of the second embodiment will be described. In the second embodiment described above, as... Figure 21 As shown, instead of forming the protrusion 311 on the first busbar 310, a protrusion 321 protruding towards the other side 320b can be formed on the second busbar 320. Furthermore, Figure 21 Is with Figure 3 For ease of understanding, the corresponding sectional view only shows the positional relationship between the busbar 30, the first shielding part 71, and the second shielding part 72.

[0108] In this case, such as Figure 22 and Figure 23As shown, it is confirmed that the longer the width of the narrow portion 31a, the farther the optimal position is from the reference in the X-axis direction. Also, it is confirmed that the shorter the width of the narrow portion 31a, the longer the optimal range. In addition, Figure 22 and Figure 23 are results in the case where the gap length d is set to 0.1 mm. In addition, if the gap length d is set to 0.2 mm, Figure 22 and Figure 23 and the Figure 11 and Figure 12 compared, it is confirmed that the optimal range can be enlarged more in the case where the protrusion portion 311 is formed on the first bus bar 310. Therefore, although the space S can be constituted by forming the protrusion portion on the second bus bar 320, if the protrusion portion is formed on the first bus bar 310, the optimal range can be enlarged, and thus it is preferable.

[0109] In addition, in the above-described second embodiment, the shape of the protrusion portion 311 can be appropriately changed. For example, when viewed from the top in the X-axis direction, the protrusion portion 311 can be provided in any one of a triangular shape, a rectangular shape, a trapezoidal shape, and an arcuate shape, or can be provided in other shapes.

[0110] <Third Embodiment>

[0111] The third embodiment will be described. The present embodiment is different from the second embodiment in that the protrusion portions are formed on the first bus bar 310 and the second bus bar 320. As for the others, because they are the same as the second embodiment, the description thereof will be omitted here.

[0112] In the current sensor 1 of the present embodiment, as shown in Figure 24 , the protrusion portion 311 is formed on the first bus bar 310, and the protrusion portion 321 is formed on the second bus bar 320. In addition, Figure 24 is a cross-sectional view corresponding to Figure 3 , and only the positional relationship of the bus bar 30, the first shield portion 71, and the second shield portion 72 is shown for easy understanding.

[0113] Specifically, the second bus bar 320 is formed with the protrusion portion 321 protruding to the side opposite to the first bus bar 310 side at the portion opposite to the protrusion portion 311 of the first bus bar 310. In addition, in the present embodiment, the protrusion portion 311 formed on the first bus bar 310 and the protrusion portion 321 formed on the second bus bar 320 are provided in the same shape.

[0114] According to the above-described present embodiment, because the first bus bar 310 and the second bus bar 320 are stacked to constitute the bus bar 30 in a manner that constitutes the gap g, the same effects as the above-described first embodiment can be obtained.

[0115] (1) In the present embodiment, since the protruding portion 311 is formed on the first bus bar 310 and the protruding portion 321 is formed on the second bus bar 320, the space S can be increased, and the robustness with respect to the misalignment of the X-axis direction of the sensor portion 40 can be further improved.

[0116] Specifically, in the current sensor 1 of the present embodiment, the relationship between the misalignment amount of the X-axis direction of the sensor portion 40 and the amplitude ratio is as shown in Figure 25 and Figure 26 Further, the Figure 25 and Figure 26 are results in the case where the gap length d is set to 0.1 mm.

[0117] As shown in Figure 25 and Figure 26 , in the case where the width of the narrow portion 31a is 8 mm or more, it is confirmed that the optimum range can be expanded compared to the Figure 11 and Figure 12 explained in the above-described second embodiment. Therefore, in the current sensor 1 of the present embodiment, the robustness with respect to the misalignment of the X-axis direction of the sensor portion 40 can be further improved.

[0118] <Fourth Embodiment>

[0119] The fourth embodiment will be described. The present embodiment is different from the second embodiment in that a stepped portion is formed on the first bus bar 310 and the second bus bar 320. As for the others, since it is the same as the second embodiment, the description will be omitted here.

[0120] As shown in Figure 27 , the bus bar 30 of the present embodiment is such that, in the narrow portion 31a, the stepped portion 312 which is entirely bent is formed on the first bus bar 310, whereby the space S is constituted between the first bus bar 310 and the second bus bar 320.

[0121] According to the present embodiment described above, since the first bus bar 310 and the second bus bar 320 are laminated in a manner to constitute the gap g to constitute the bus bar 30, the same effect as the above-described first embodiment can be obtained.

[0122] (1) In the present embodiment, the stepped portion 312 is formed on the first bus bar 310. Therefore, the space S is constituted between the first bus bar 310 and the second bus bar 320, and the robustness with respect to the misalignment of the X-axis direction of the sensor portion 40 can be further improved, as in the above-described second embodiment.

[0123] <Modification of the Fourth Embodiment>

[0124] A modification of the above-described fourth embodiment will be described. In the above-described fourth embodiment, the stepped portion 312 can not be formed on the first bus bar 310, but can be formed on the second bus bar 320 on the other side 320b. Also, the stepped portion 312 can be formed on the first bus bar 310, and the stepped portion can be formed on the second bus bar 320.

[0125] <Other Embodiments>

[0126] The present disclosure is described based on an embodiment, but it should be understood that the present disclosure is not limited to the embodiment and the structure. The present disclosure also includes various modifications and modifications within the equivalent scope. Furthermore, various combinations or modes, and other combinations and modes including only one element, more elements, or less elements among them also fall within the scope and the idea of the present disclosure.

[0127] For example, in each of the above-described embodiments, instead of the wall portion 72b formed on the second shield portion 72, wall portions extending to the second shield portion 72 side can be provided on both end portions of the first shield portion 71 in the X-axis direction. Also, in each of the above-described embodiments, wall portions can be provided on each of the first shield portion 71 and the second shield portion 72. Also, the first shield portion 71 and the second shield portion 72 can be configured using one flat plate.

[0128] Also, in each of the above-described embodiments, the bus bar 30 can not constitute the narrow portion 31a on the cover portion 31, and the width of the cover portion 31 and the width of the fastening portion 32 can be equal.

[0129] Also, in each of the above-described embodiments, the first bus bar 310 and the second bus bar 320 can be configured by laminating different copper plates. Furthermore, in the case where the first bus bar 310 and the second bus bar 320 are configured by different copper plates, two different copper plates can be used, or one copper plate can be bent and cut. In the case where the first bus bar 310 and the second bus bar 320 are configured by two different copper plates, the bending process and the like can not be performed, and thus the simplification of the manufacturing process can be achieved.

[0130] Also, in each of the above-described embodiments, the current sensor 1 can be configured using only one first current sensor 1a.

[0131] Also, in each of the above-described embodiments, the current sensor 1 can be configured using only one first current sensor 1a.

[0132] The above-described embodiments can be combined. For example, the above-described fourth embodiment can be combined with the above-described second and third embodiments, and the stepped portion 312 can be formed on the first bus bar 310. In this case, the protruding portion 311 of the first bus bar 310 is formed on the stepped portion 312.

Claims

1. A current sensor for detecting an alternating current flowing in a bus, characterized by, Possessing: the bus bar, which takes one direction as a length direction, and supplies the alternating current to flow along the length direction; a sensor portion which outputs a detection signal that is a signal based on a magnetic field generated in accordance with the alternating current flowing in the bus bar; and a sensor frame which arranges the bus bar and the sensor portion; the bus bar is configured by laminating a first bus bar and a second bus bar along an arrangement direction of the bus bar and the sensor portion, has a covered portion covered by the sensor frame and a fastening portion exposed from the sensor frame, the first bus bar and the second bus bar are arranged in the covered portion in a state in which a gap is formed between the first bus bar and the second bus bar, the sensor portion is arranged on the side opposite to the second bus bar through the first bus bar which is a part of the covered portion.

2. The current sensor according to claim 1, wherein in the bus bar, if a length in a width direction intersecting the length direction and the arrangement direction is set as a width, a narrow width portion in which the width is narrower than that of the fastening portion is provided in the covered portion, the sensor portion is arranged on the narrow width portion.

3. The current sensor according to claim 1, wherein the first bus bar and the second bus bar are connected through the fastening portion.

4. The current sensor according to claim 1, wherein the first bus bar and the second bus bar are configured using different flat plates.

5. The current sensor according to claim 1, wherein in the fastening portion, the opposing portions of the first bus bar and the second bus bar abut.

6. The current sensor according to any one of claims 1 to 5, wherein at least one of the first bus bar and the second bus bar is formed with a protruding portion protruding toward the side opposite to the side of the bus bar of the other in the covered portion.

7. The current sensor according to claim 6, wherein in the first bus bar and the second bus bar, the first bus bar is opposite to the sensor portion, the protruding portion is formed at least in the first bus bar.

8. The current sensor according to any one of claims 1 to 5, wherein at least one of the first bus bar and the second bus bar is formed with a stepped portion bent toward the side opposite to the side of the bus bar of the other in the covered portion.

9. The current sensor according to claim 8, wherein in the first bus bar and the second bus bar, the first bus bar is opposite to the sensor portion, the stepped portion is formed at least in the first bus bar.

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