Current Detector

Abstract

To provide a current detection device capable of suppressing a reduction in current detection accuracy.SOLUTION: A current detection device 1 includes: a shunt resistor 2 including a resistor 20 in which a current flows along a first direction X, a first conductor 21 connected to one end in the first direction of the resistor, and a second conductor 22 connected to the other end in the first direction of the resistor; a substrate 3 having a current detection unit 31 that detects a current value flowing in the shunt resistor; a first bus bar 4A extending in a second direction Y orthogonal to the first direction, fixed to the first conductor and the substrate, and electrically connecting the first conductor with the current detection unit; and a second bus bar 4B extending in the second direction Y, fixed to the second conductor and the substrate, and electrically connecting the second conductor with the current detection unit.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present invention relates to a current detection device. [Background technology]

[0002] Conventionally, there are shunt resistors. Patent Document 1 discloses a shunt resistor that has, at least in part, a resistor with a preset resistance value, bridges two electrodes, and detects a voltage drop caused by the resistor to detect a current value of a current flowing between the electrodes. The shunt resistor in Patent Document 1 includes a pair of connection parts that are fixed to and electrically connected to each electrode via a conductive adhesive, a bridge part that extends from one connection part to the other connection part and bridges the connection parts, and a pair of bonding wires for detecting a voltage drop in the resistor, and the bonding wires are bonded to the bridge parts. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2016-053521 A Summary of the Invention [Problem to be solved by the invention]

[0004] In a shunt resistor-based current detection device, it is desirable to be able to suppress a decrease in detection accuracy. For example, when a substrate having a current detection unit and a shunt resistor are connected by a pair of conductors, if the connection angle of the conductors to the shunt resistor varies, the detection accuracy is likely to decrease.

[0005] An object of the present invention is to provide a current detection device capable of suppressing a decrease in current detection accuracy. [Means for solving the problem]

[0006] The current detection device of the present invention is characterized in that it comprises a shunt resistor having a resistor through which a current flows along a first direction, a first conductor connected to one end of the resistor in the first direction, and a second conductor connected to the other end of the resistor in the first direction, a substrate having a current detection unit that detects the value of a current flowing through the shunt resistor, a first bus bar extending in a second direction perpendicular to the first direction and fixed to the first conductor and the substrate, electrically connecting the first conductor and the current detection unit, and a second bus bar extending in the second direction and fixed to the second conductor and the substrate, electrically connecting the second conductor and the current detection unit. Effect of the Invention

[0007] In the current detection device according to the present invention, a first bus bar extending in a second direction perpendicular to the current flow direction is fixed to the first conductor and the substrate, and a second bus bar extending in the second direction is fixed to the second conductor and the substrate. The current detection device according to the present invention has an advantage that a decrease in current detection accuracy caused by a variation in the connection angle can be suppressed by rigidly fixing the first bus bar and the second bus bar to the shunt resistor and the substrate. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a perspective view of a current detection device according to an embodiment. [Diagram 2] FIG. 2 is an exploded perspective view of the current detection device according to the embodiment. [Diagram 3] FIG. 3 is a perspective view of a first terminal block and a second terminal block according to the embodiment. [Figure 4] FIG. 4 is a plan view of the first bus bar and the second bus bar according to the embodiment. [Diagram 5] FIG. 5 is a perspective view of a first bus bar and a second bus bar according to the embodiment. [Figure 6] FIG. 6 is a plan view of the current detection device according to the embodiment. [Figure 7] FIG. 7 is a cross-sectional view of the current detection device according to the embodiment. [Figure 8] FIG. 8 is a perspective view of the current detection device according to the embodiment. [Figure 9] FIG. 9 is a plan view of the current detection device according to the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, a current detection device according to an embodiment of the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiment. In addition, the components in the following embodiments include those that can be easily imagined by a person skilled in the art or those that are substantially the same.

[0010] [Embodiment] An embodiment will be described with reference to Figs. 1 to 9. The embodiment relates to a current detection device. Fig. 1 is a perspective view of the current detection device according to the embodiment, Fig. 2 is an exploded perspective view of the current detection device according to the embodiment, Fig. 3 is a perspective view of a first terminal block and a second terminal block according to the embodiment, Fig. 4 is a plan view of a first bus bar and a second bus bar according to the embodiment, Fig. 5 is a perspective view of the first bus bar and a second bus bar according to the embodiment, Fig. 6 is a plan view of the current detection device according to the embodiment, Fig. 7 is a cross-sectional view of the current detection device according to the embodiment, Fig. 8 is a perspective view of the current detection device according to the embodiment, and Fig. 9 is a plan view of the current detection device according to the embodiment. Fig. 7 shows a cross section taken along line VII-VII of Fig. 6.

[0011] As shown in Fig. 1 and Fig. 2, the current detection device 1 of this embodiment includes a shunt resistor 2, a substrate 3, a first bus bar 4A, and a second bus bar 4B. The current detection device 1 is disposed, for example, in a battery of a vehicle, and detects the charge / discharge current of the battery. The current detection device 1 is a so-called shunt type current sensor. That is, the current detection device 1 passes a current through the shunt resistor 2, and measures the current value from the voltage drop when the current is passed and the resistance value of the shunt resistor 2 using Ohm's law. The current detection device 1 may be configured as a monitoring unit that monitors the battery.

[0012] The shunt resistor 2 has a resistor 20, a first conductor 21, and a second conductor 22. The resistor 20 has a predetermined resistance value. The current detection device 1 calculates a current value based on the resistance value of the resistor 20. The illustrated resistor 20 has a rectangular flat plate shape. The first conductor 21 and the second conductor 22 are conductors made of a metal having high conductivity such as copper. The illustrated first conductor 21 and the second conductor 22 have a flat plate shape. The first conductor 21 and the second conductor 22 are so-called bus bars, and are conductors having rigidity. The first conductor 21 and the second conductor 22 are arranged on both sides of the resistor 20 so as to sandwich the resistor 20. The first conductor 21 and the second conductor 22 are physically and electrically connected to the resistor 20.

[0013] One of the first conductor 21 and the second conductor 22 is connected to, for example, the negative electrode of a battery. The other of the first conductor 21 and the second conductor 22 is connected to, for example, a ground part such as a vehicle body. The battery is monitored and controlled based on the current value detected by the current detection device 1.

[0014] A current flows through the resistor 20 along a first direction X. The first direction X is a direction in which the first conductor 21 and the second conductor 22 face each other. The first conductor 21 is connected to one end of the resistor 20 in the first direction X, and the second conductor 22 is connected to the other end of the resistor 20 in the first direction X.

[0015] In the following description, the width direction of the shunt resistor 2 is referred to as the "second direction Y," and the thickness direction of the shunt resistor 2 is referred to as the "third direction Z." The second direction Y is perpendicular to the first direction X. The third direction Z is perpendicular to both the first direction X and the second direction Y.

[0016] 2, the first conductor 21 has a first through hole 21a and a second through hole 21b. The second conductor 22 has a first through hole 22a and a second through hole 22b. The first through holes 21a, 22a are disposed adjacent to the resistor 20. The two first through holes 21a, 22a are disposed at positions symmetrical with respect to the resistor 20.

[0017] A screw 61 for fixing the first bus bar 4A to the first conductor 21 is inserted into the first through hole 21a. A nut 66 for screwing with the screw 61 is fixed to the first conductor 21. The nut 66 is disposed on the rear surface side of the first conductor 21 and is disposed coaxially with the first through hole 21a. A screw 62 for fixing the second bus bar 4B to the second conductor 22 is inserted into the first through hole 22a. A nut 67 for screwing with the screw 62 is fixed to the second conductor 22. The nut 67 is disposed on the rear surface side of the second conductor 22 and is disposed coaxially with the first through hole 22a.

[0018] The second through holes 21b, 22b are disposed at positions farther from the resistor 20 than the first through holes 21a, 22a. Fastening members such as bolts are inserted into the second through holes 21b, 22b. The first conductor 21 and the second conductor 22 are fastened to a mating bus bar or the like by the fastening members inserted into the second through holes 21b, 22b.

[0019] The substrate 3 is, for example, a printed circuit board (PCB). The illustrated substrate 3 has a rectangular shape. The substrate 3 has a current detection unit 31. The current detection unit 31 is, for example, a current detection circuit. The substrate 3 may have a control circuit that monitors and controls the battery.

[0020] A first terminal block 7A and a second terminal block 7B are fixed to the substrate 3. The terminal blocks 7A and 7B are formed of a metal plate having electrical conductivity such as copper. The first terminal block 7A and the second terminal block 7B are each electrically connected to the current detection unit 31. The first terminal block 7A and the second terminal block 7B are disposed at an end portion 3a of the substrate 3. The end portion 3a is an end portion adjacent to the shunt resistor 2 in the second direction Y.

[0021] As shown in FIG. 3, the first terminal block 7A and the second terminal block 7B have a connection portion 71 and two legs 72. The connection portion 71 is connected to the first bus bar 4A and the second bus bar 4B, and is a portion that supports the first bus bar 4A and the second bus bar 4B. The shape of the connection portion 71 is a flat plate. The connection portion 71 has a female thread portion 71a formed thereon. The female thread portion 71a has a cylindrical shape. A screw thread is formed on the inner peripheral surface of the female thread portion 71a.

[0022] The legs 72 are bent at a right angle to the connection portion 71. The legs 72 are arranged on both ends of the connection portion 71 and support the connection portion 71. The legs 72 abut against the substrate 3 and are fixed to the substrate 3 by solder or the like. The connection portion 71 is connected to the current detection portion 31 via the legs 72.

[0023] In this embodiment, bus bars 4 having the same shape are used as the first bus bar 4A and the second bus bar 4B. The bus bar 4 is formed of a metal plate having electrical conductivity, such as copper. As shown in FIG. 4 and FIG. 5, the bus bar 4 has a first terminal portion 41, a second terminal portion 42, and a low rigidity portion 43. The first terminal portion 41 is one end portion of the bus bar 4, and is a fixed portion fixed to the shunt resistor 2. The second terminal portion 42 is the other end portion of the bus bar 4, and is a fixed portion fixed to the terminal blocks 7A and 7B. The low rigidity portion 43 is a portion between the first terminal portion 41 and the second terminal portion 42.

[0024] The first terminal portion 41 has a through hole 41a into which the screws 61, 62 can be inserted. The through hole 41a is disposed in the center of the first terminal portion 41 in the first direction X. In other words, the through hole 41a is disposed in the center of the first terminal portion 41 in the width direction. The illustrated shape of the through hole 41a is an ellipse with a major axis in the second direction Y. As shown in FIG. 5, the bus bar 4 has a first restricting portion 44. The first restricting portion 44 is formed by bending the tip of the bus bar 4 on the side of the first terminal portion 41. The first restricting portion 44 is perpendicular to the first terminal portion 41. The first restricting portion 44 has a restricting surface 44a facing the side of the second terminal portion 42. The restricting surface 44a can restrict the extension direction of the bus bar 4, as described later.

[0025] The second terminal portion 42 has a through hole 42a into which the screws 63, 64 shown in FIG. 2 can be inserted. The through hole 42a is disposed in the center of the second terminal portion 42 in the first direction X. The illustrated through hole 42a has an elliptical shape with its major axis extending in the first direction X. As shown in FIG. 5, the bus bar 4 has a second restricting portion 46. The second restricting portion 46 is formed by bending the tip of the bus bar 4 on the side of the second terminal portion 42. The second restricting portion 46 is perpendicular to the second terminal portion 42.

[0026] The low-rigidity portion 43 is provided in the center of the busbar 4 in the second direction Y. The rigidity of the low-rigidity portion 43 is smaller than the rigidity of the first terminal portion 41 and the rigidity of the second terminal portion 42. The low-rigidity portion 43 is hollowed out to reduce the cross-sectional area in a cross section perpendicular to the second direction Y. The illustrated low-rigidity portion 43 has a through hole 43a, which reduces the cross-sectional area. The through hole 43a penetrates the busbar 4 in the plate thickness direction. The illustrated through hole 43a has a rectangular shape extending along the second direction Y.

[0027] The low rigidity portion 43 has a bent portion 45. The bent portion 45 is formed by bending the bus bar 4 at two locations. The bent portion 45 has a first bent portion 45a and a second bent portion 45b. In the longitudinal direction of the bus bar 4, the position of the first bent portion 45a and the position of the second bent portion 45b are different. The first bent portion 45a is located closer to the first terminal portion 41 than the second bent portion 45b.

[0028] The bus bar 4 is bent at a substantially right angle at a first bent portion 45a and a second bent portion 45b. A portion 45c extending in the third direction Z is provided between the first bent portion 45a and the second bent portion 45b. By providing the bent portion 45, a step in the third direction Z is formed between the first terminal portion 41 and the second terminal portion 42.

[0029] The low-rigidity portion 43 can absorb stress when an external force acts on the bus bar 4. For example, the low-rigidity portion 43 has a small cross-sectional area and can absorb stress when a force in the third direction Z is applied to the bus bar 4. For example, the low-rigidity portion 43 has the bent portion 45 and can absorb stress when a force in the first direction X or the second direction Y is applied to the bus bar 4. In this way, the low-rigidity portion 43 can absorb stress caused by both ends of the bus bar 4 being rigidly fixed.

[0030] 6, the first bus bar 4A and the second bus bar 4B of this embodiment are fixed to the shunt resistor 2 and the substrate 3 so as to extend in the second direction Y. The first bus bar 4A and the second bus bar 4B are fixed, for example, so that the center line CL of the bus bar 4 is perpendicular to the first direction X in a plan view. It is preferable that the center line CL of the first bus bar 4A and the center line CL of the second bus bar 4B are parallel to each other.

[0031] The first terminal portion 41 of the first bus bar 4A is fixed to the first conductor 21 of the shunt resistor 2 by a screw 61. The screw 61 is inserted into the through hole 41a of the first terminal portion 41 and the first through hole 21a of the first conductor 21, and is screwed into a nut 66. In other words, the first conductor 21 and the first bus bar 4A are fastened together by the screw 61 and the nut 66.

[0032] The second terminal portion 42 of the first bus bar 4A is fixed to the first terminal block 7A by a screw 63. The screw 63 is inserted into the through hole 42a of the second terminal portion 42 and screws into the female thread portion 71a of the first terminal block 7A. That is, the second terminal portion 42 is fastened to the first terminal block 7A by the screw 63.

[0033] As shown in FIG. 7, the first restricting portion 44 of the first busbar 4A faces the side surface 21c of the first conductor 21. The side surface 21c of the first conductor 21 is perpendicular to the second direction Y and faces the opposite side to the substrate 3. The restricting surface 44a of the first restricting portion 44 faces the side surface 21c and is close to the side surface 21c. The first restricting portion 44 functions as a guide when the busbar 4 is attached to the shunt resistor 2. For example, the first restricting portion 44 positions the first busbar 4A with respect to the first conductor 21 when the first busbar 4A is placed on the first conductor 21. More specifically, the first restricting portion 44 is guided by the side surface 21c so that the extension direction of the first busbar 4A is perpendicular to the first direction X.

[0034] Furthermore, the first restricting portion 44 can restrict the rotation of the bus bar 4 against the rotation torque when the screw 61 is screwed. In other words, when the first bus bar 4A tries to rotate due to the rotation torque transmitted from the screw 61, the restricting surface 44a abuts against the side surface 21c to restrict the rotation of the first bus bar 4A. In this manner, the first restricting portion 44 can restrict the first bus bar 4A from tilting with respect to the second direction Y.

[0035] The second restricting portion 46 of the first bus bar 4A faces an end surface 72a of the first terminal block 7A. teeth, Orthogonal to the second direction Y end face and faces the opposite side to the shunt resistor 2. The second restricting portion 46 has a restricting surface 46a facing the end surface 72a. The second restricting portion 46 is PlacementThe second restricting portion 46 is guided by the end surface 72a so that the extending direction of the first bus bar 4A is perpendicular to the first direction X.

[0036] Furthermore, the second restricting portion 46 can restrict rotation of the bus bar 4 against the rotation torque applied when the screw 61 is screwed. When the first bus bar 4A attempts to rotate due to the rotation torque transmitted from the screw 61, the restricting surface 46a comes into contact with the end surface 72a to restrict the rotation of the first bus bar 4A. In this manner, the second restricting portion 46 can restrict the first bus bar 4A from tilting with respect to the second direction Y.

[0037] The first terminal portion 41 of the second bus bar 4B is fixed to the second conductor 22 of the shunt resistor 2 by a screw 62. The screw 62 is inserted into the through hole 41a of the first terminal portion 41 and the first through hole 22a of the second conductor 22, and is screwed into a nut 67. The second terminal portion 42 of the second bus bar 4B is fixed to the second terminal block 7B by a screw 64. The screw 64 is inserted into the through hole 42a of the second terminal portion 42, and is screwed into a female thread portion 71a of the second terminal block 7B.

[0038] The first restricting portion 44 of the second bus bar 4B can restrict the second bus bar 4B from tilting with respect to the second direction Y. As shown in FIG. 2 , the second conductor 22 has a side surface 22c similar to the side surface 21c. The side surface 22c is perpendicular to the second direction Y and faces the side opposite to the substrate 3. The first restricting portion 44 of the second bus bar 4B faces the side surface 22c of the second conductor 22 and causes the second bus bar 4B to extend in the second direction Y.

[0039] The second restricting portion 46 of the second bus bar 4B can restrict the second bus bar 4B from tilting with respect to the second direction Y. The second restricting portion 46 of the second bus bar 4B faces the end face 72a of the second terminal block 7B and causes the second bus bar 4B to extend in the second direction Y.

[0040] In the current detection device 1 of the present embodiment, the first bus bar 4A and the second bus bar 4B can be rigidly fixed while both of them extend in the second direction Y. The first bus bar 4A and the second bus bar 4B extend in a direction perpendicular to the current flow direction, thereby suppressing fluctuations in the voltage measurement distance. As a comparative example, a configuration in which the shunt resistor 2 and the substrate 3 are connected by an electric wire will be considered. In the comparative example, for example, a terminal attached to the electric wire is screwed to the shunt resistor 2. In this case, it is not easy to extend the electric wire in the second direction Y with high accuracy. For example, the terminal is likely to rotate due to the rotation torque generated when screwing. If the terminal rotates relative to the normal position, the resistance value between the terminals includes the resistance components of the first conductor 21 and the second conductor 22. As a result, the accuracy of the current measurement decreases.

[0041] In contrast, in the current detection device 1 of the present embodiment, the extension directions of the first bus bar 4A and the second bus bar 4B are less likely to vary. For example, if the shunt resistor 2 and the substrate 3 are fixed in advance, the extension directions of the first bus bar 4A and the second bus bar 4B are determined by the relative positions of the shunt resistor 2 and the terminal blocks 7A and 7B. Therefore, it is possible to precisely cause the first bus bar 4A and the second bus bar 4B to extend in the second direction Y.

[0042] Moreover, the bus bar 4 of the present embodiment is configured to facilitate orthogonalization of the bus bar 4 with respect to the first direction X. As described above, the through hole 41a of the first terminal portion 41 is an ellipse extending along the longitudinal direction of the bus bar 4. On the other hand, the through hole 42a of the second terminal portion 42 is an ellipse extending along the width direction of the bus bar 4.

[0043] Since the through hole 41a is an ellipse along the second direction Y, when the first terminal portion 41 is fixed to the shunt resistor 2, the bus bar 4 is unlikely to rotate relative to the shunt resistor 2. Since the through hole 41a is an ellipse along the second direction Y, it is easy to abut the restricting surface 44a of the first restricting portion 44 against the side surfaces 21c, 22c when the first terminal portion 41 is fixed to the shunt resistor 2. Since the through hole 41a is an ellipse along the second direction Y, the position of the first terminal portion 41 in the first direction X is unlikely to shift. That is, the contact position of the first terminal portion 41 with the first conductor 21 and the second conductor 22 is unlikely to shift. Therefore, the contact position of the first terminal portion 41 with the first conductor 21 and the second conductor 22 can be brought closer to the resistor 20, and the resistance components of the first conductor 21 and the second conductor 22 can be minimized.

[0044] Since the through hole 42a has an ellipse shape along the first direction X, it is easy to fix the second terminal portion 42 to the substrate 3 while keeping the bus bar 4 extending in the second direction Y. The bus bar 4 of the present embodiment is preferably fixed to the substrate 3 after being fixed to the shunt resistor 2.

[0045] The current detection device 1 may have a case 10 shown in Fig. 8. The case 10 is molded from, for example, insulating synthetic resin. The case 10 has an accommodation chamber 11 that accommodates the substrate 3 and a holding portion 12 that holds the shunt resistor 2. The accommodation chamber 11 has a box shape and accommodates and holds the substrate 3 therein. The shape of the accommodation chamber 11 in a plan view is rectangular.

[0046] The retaining portion 12 protrudes from the outer surface of the accommodation chamber 11 in the second direction Y. The illustrated shape of the retaining portion 12 is a rectangular plate. The side wall of the accommodation chamber 11 has a notch 11a corresponding to the retaining portion 12. The notch 11a communicates the internal space of the accommodation chamber 11 with the external space on the side of the retaining portion 12. The notch 11a is formed so that the accommodation chamber 11 does not interfere with the first bus bar 4A and the second bus bar 4B. The shunt resistor 2 is fixed to the retaining portion 12 by bolts 68, 69. The retaining portion 12 may have nuts that screw into the bolts 68, 69.

[0047] 9, the holding portion 12 faces the first through hole 21a of the first conductor 21 in the second direction Y to the female screw portion 71a of the first terminal block 7A. In other words, the case 10 holds the substrate 3 and the shunt resistor 2 such that a virtual line 13A connecting the female screw portion 71a of the first terminal block 7A and the first through hole 21a is perpendicular to the first direction X. The holding portion 12 also faces the first through hole 22a of the second conductor 22 in the second direction Y to the female screw portion 71a of the second terminal block 7B. In other words, the case 10 holds the substrate 3 and the shunt resistor 2 such that a virtual line 13B connecting the female screw portion 71a of the second terminal block 7B and the first through hole 22a is perpendicular to the first direction X.

[0048] The substrate 3 and the shunt resistor 2 are held in one case 10, which makes it easy to control the extension direction of the first bus bar 4A and the second bus bar 4B. In other words, it makes it easy to connect the first bus bar 4A and the second bus bar 4B to the shunt resistor 2 so as to be perpendicular to the current flow direction.

[0049] As described above, the current detection device 1 of the present embodiment includes the shunt resistor 2, the substrate 3, the first bus bar 4A, and the second bus bar 4B. The shunt resistor 2 includes the resistive element 20 through which a current flows along a first direction X, a first conductor 21, and a second conductor 22. The first conductor 21 is connected to one end of the resistive element 20 in the first direction X. The second conductor 22 is connected to the other end of the resistive element 20 in the first direction X. The substrate 3 includes a current detection unit 31 that detects the value of a current flowing through the shunt resistor 2.

[0050] The first busbar 4A extends in a second direction Y perpendicular to the first direction X, and is fixed to the first conductor 21 and the substrate 3, and electrically connects the first conductor 21 and the current detection unit 31. The second busbar 4B extends in the second direction Y, and is fixed to the second conductor 22 and the substrate 3, and electrically connects the second conductor 22 and the current detection unit 31. In the current detection device 1 of this embodiment, the first busbar 4A and the second busbar 4B are fixed to the shunt resistor 2 and the substrate 3. Therefore, it is easy to make the extension directions of the first busbar 4A and the second busbar 4B perpendicular to the first direction X. In addition, it is easy to make the first busbar 4A and the second busbar 4B extend in parallel. Therefore, the current detection device 1 of this embodiment can suppress a decrease in the current detection accuracy.

[0051] The first conductor 21 and the second conductor 22 of this embodiment have side surfaces 21c, 22c perpendicular to the second direction Y. The first busbar 4A and the second busbar 4B have a first restricting portion 44 formed by bending the end portion on the shunt resistor 2 side. The first restricting portion 44 faces the side surfaces 21c, 22c in the second direction Y and restricts the first busbar 4A and the second busbar 4B from tilting with respect to the second direction Y. Therefore, the current detection device 1 of this embodiment can suppress a decrease in current detection accuracy.

[0052] The first bus bar 4A and the second bus bar 4B of this embodiment have a low-rigidity portion 43 between a fixed portion for the shunt resistor 2 and a fixed portion for the substrate 3. In the low-rigidity portion 43, a through hole 43a is formed in the first bus bar 4A and the second bus bar 4B. The low-rigidity portion 43 can absorb stress generated in the first bus bar 4A and the second bus bar 4B. Note that the low-rigidity portion 43 may have a notch instead of or in addition to the through hole 43a.

[0053] The low-rigidity portion 43 of the present embodiment has a bent portion 45. The bent portion 45 is formed by bending the first bus bar 4A and the second bus bar 4B at two different positions in the longitudinal direction. The bent portion 45 includes a portion 45c extending in a third direction Z perpendicular to both the first direction X and the second direction Y. The low-rigidity portion 43 may be bent at three or more positions.

[0054] The current detection device 1 may have a case 10, a first terminal block 7A, and a second terminal block 7B. The case 10 has an accommodation chamber 11 that accommodates the substrate 3 and a holding portion 12 that holds the shunt resistor 2. The first terminal block 7A and the second terminal block 7B are fixed to the substrate 3. In this case, the first bus bar 4A is fixed to the first terminal block 7A and connected to the current detection portion 31 via the first terminal block 7A. The second bus bar 4B is fixed to the second terminal block 7B and connected to the current detection portion 31 via the second terminal block 7B. By arranging the shunt resistor 2 and the substrate 3 in the case 10, it is easy to ensure an appropriate relative position between the shunt resistor 2 and the substrate 3.

[0055] The case 10, the shunt resistor 2, the substrate 3, the first bus bar 4A, and the second bus bar 4B are assembled together to form a monitoring unit. Once the monitoring unit is assembled, it is possible to inspect whether the resistance value between the bus bars 4A and 4B is a desired value. By assembling a monitoring unit that has been confirmed to have the desired resistance value to a battery, the accuracy of current detection is less likely to decrease.

[0056] It should be noted that the means for fixing the shunt resistor 2 to the case 10 is not limited to the bolts 68, 69. For example, the holding portion 12 of the case 10 may have a holding structure for holding the shunt resistor 2. The holding structure may have a recess for accommodating the shunt resistor 2. In this case, the shunt resistor 2 may be press-fitted into the recess of the holding portion 12.

[0057] The contents disclosed in the above embodiments can be implemented in appropriate combinations. [Explanation of symbols]

[0058] 1: Current detection device 2: shunt resistor, 3: circuit board, 4A: first bus bar, 4B: second bus bar 7A: First terminal block, 7B: Second terminal block 20: Resistor, 21: First conductor, 21a: First through hole, 21b: Second through hole 21c: Side 22: Second conductor, 22a: First through hole, 22b: Second through hole, 22c: Side surface 31: Current detection section 41: First terminal part, 42: Second terminal part, 43: Low rigidity part, 44: First regulating part 45: Bent part, 46: Second regulating part 61, 62, 63, 64: Screws, 66, 67: Nuts, 68, 69: Bolts 71: Connection portion, 71a: Female thread portion, 72: Leg portion, 72a: End surface X: first direction, Y: second direction, Z: third direction

Claims

1. a shunt resistor including a resistor through which a current flows in a first direction, a first conductor connected to one end of the resistor in the first direction, and a second conductor connected to the other end of the resistor in the first direction; a substrate having a current detection unit for detecting a value of a current flowing through the shunt resistor; A conductive first terminal block and a conductive second terminal block fixed to the substrate; a first bus bar extending in a second direction perpendicular to the first direction and fixed to the first conductor and the substrate, electrically connecting the first conductor and the current detection unit; a second bus bar extending in the second direction and fixed to the second conductor and the substrate, electrically connecting the second conductor and the current detection unit; Equipped with the first bus bar is fixed to the first terminal block and connected to the current detection unit via the first terminal block, the second bus bar is fixed to the second terminal block and connected to the current detection unit via the second terminal block, the first conductor and the second conductor have a side surface perpendicular to the second direction, the first bus bar and the second bus bar each have a first limiting portion formed by bending an end portion on the shunt resistor side and a second limiting portion formed by bending an end portion on the substrate side, the first restricting portion faces the side surface in the second direction and restricts the first bus bar and the second bus bar from inclining with respect to the second direction; the second restricting portion of the first bus bar faces an end surface of the first terminal block and restricts the first bus bar from being inclined with respect to the second direction; The second restricting portion of the second bus bar faces an end surface of the second terminal block and restricts the second bus bar from being inclined with respect to the second direction. A current detection device comprising:

2. the first bus bar and the second bus bar each have a low rigidity portion between a fixed portion for the shunt resistor and a fixed portion for the substrate, In the low rigidity portion, the first bus bar and the second bus bar are formed with a through hole or a notch. The current detection device according to claim 1 .

3. The low rigidity portion has a bent portion, The bent portion is formed by bending the first bus bar and the second bus bar at a plurality of locations, and includes a portion extending in a third direction perpendicular to both the first direction and the second direction. The current detection device according to claim 2 .

4. The device further includes a case having a chamber for accommodating the substrate and a holder for holding the shunt resistor. The current detection device according to claim 1 .

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