CN117783631A

CN117783631A - Current detection device

Info

Publication number: CN117783631A
Application number: CN202311250160.7A
Authority: CN
Inventors: 冲拓也; 知屋城悠希
Original assignee: Yazaki Corp
Current assignee: Yazaki Corp
Priority date: 2022-09-27
Filing date: 2023-09-26
Publication date: 2024-03-29
Also published as: JP2024047775A; DE102023126046A1; KR20240043708A

Abstract

The invention provides a current detection device capable of inhibiting the decline of current detection precision. The current detection device (1) is provided with: a shunt resistor (2) having a resistor (20) in which a current flows in a first direction (X), a first conductor (21) connected to one end of the resistor in the first direction, and a second conductor (22) connected to the other end of the resistor in the first direction; a substrate (3) having a current detection unit (31) for detecting the value of the current flowing through the shunt resistor; a first bus bar (4A) which extends in a second direction (Y) orthogonal to the first direction, is fixed to the first conductor and the substrate, and electrically connects the first conductor and the current detection unit; and a second bus bar (4B) that extends in the second direction and is fixed to the second conductor and the substrate, and that electrically connects the second conductor and the current detection unit.

Description

Current detection device

Technical Field

The present invention relates to a current detection device.

Background

Conventionally, there is a shunt resistor. Patent document 1 discloses a shunt resistor having a resistor body at least a part of which has a preset resistance value, wherein the shunt resistor bridges between two electrodes, and detects a voltage drop caused by the resistor body to thereby detect a current value of a current flowing between the electrodes. The shunt resistor of patent document 1 includes: a pair of connection portions fixed via a conductive adhesive material and electrically connected to the respective electrodes; a bridging portion extending from one connecting portion to the other connecting portion, bridging the connecting portions; and a pair of bonding wires for detecting a voltage drop of the resistor, the bonding wires being bonded to the bridge portion.

Prior art literature

Patent literature

Patent document 1: japanese patent laid-open publication 2016-053521

Disclosure of Invention

Technical problem to be solved by the invention

In the shunt resistance type current detection device, it is preferable that a decrease in detection accuracy can be suppressed. For example, when a substrate having a current detecting portion is connected to a shunt resistor by a pair of conductors, if the connection angle of the conductors to the shunt resistor is deviated, the detection accuracy tends to be lowered.

The invention aims to provide a current detection device capable of inhibiting the reduction of current detection precision.

Means for solving the problems

The current detection device of the present invention is characterized by comprising: a shunt resistor, the shunt resistor having: a resistor body, a current of which 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 portion that detects a current value flowing through the shunt resistor; a first bus bar extending in a second direction orthogonal to the first direction and fixed with respect to the first conductor and the substrate, the first bus bar electrically connecting the first conductor and the current detection portion; and a second bus bar extending in the second direction and fixed with respect to the second conductor and the substrate, the second bus bar electrically connecting the second conductor and the current detection portion.

Effects of the invention

In the current detection device according to the present invention, the first bus bar extending in the second direction orthogonal to the current flow direction is fixed to the first conductor and the substrate, and the second bus bar extending in the second direction is fixed to the second conductor and the substrate. According to the current detection device of the present invention, the first bus bar and the second bus bar are rigidly fixed to the shunt resistor and the substrate, and therefore, a reduction in current detection accuracy due to a deviation in connection angle can be suppressed.

Drawings

Fig. 1 is a perspective view of a current detection device according to an embodiment.

Fig. 2 is an exploded perspective view of the current detection device according to the embodiment.

Fig. 3 is a perspective view of the first terminal block and the second terminal block according to the embodiment.

Fig. 4 is a plan view of the first bus bar and the second bus bar according to the embodiment.

Fig. 5 is a perspective view of a first bus bar and a second bus bar according to an 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.

Fig. 9 is a plan view of the current detection device according to the embodiment.

Description of the reference numerals

1: current detection device

2: shunt resistance, 3: substrate, 4A: first bus bar, 4B: second bus bar

7A: first terminal station, 7B: second terminal block

20: resistor body

21: first conductor, 21a: first through holes, 21b: second through hole, 21c: side surface

22: second conductor, 22a: first through holes, 22b: second through hole, 22c: side surface

31: current detecting unit

41: first terminal portion, 42: second terminal portions, 43: low rigidity portion

44: first restriction portion, 45: bending portion, 46: second limiting part

61. 62, 63, 64: screw, 66, 67: nut, 68, 69: bolt

71: connection portion, 71a: female screw portion, 72: foot, 72a: end face

X: first direction, Y: second direction, Z: third direction of

Detailed Description

Hereinafter, a current detection device according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings. The present invention is not limited to this embodiment. The constituent elements of the following embodiments include elements that can be easily understood by those skilled in the art or substantially the same elements.

Embodiment(s)

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

As shown in fig. 1 and 2, a current detection device 1 according to the present embodiment includes: shunt resistor 2, substrate 3, first bus bar 4A and second bus bar 4B. The current detection device 1 is disposed in, for example, a battery of a vehicle, and detects a charge/discharge current of the battery. The current detection device 1 is a so-called shunt current sensor. That is, the current detection device 1 causes a current to flow through the shunt resistor 2, and measures the current value using ohm's law from the voltage drop at the time of energization and the resistance value of the shunt resistor 2. The current detection device 1 may be configured as a monitoring unit that monitors the battery.

The shunt resistor 2 has: resistor 20, first conductor 21, and 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 shape of the resistor 20 is exemplified as a rectangular flat plate shape. The first conductor 21 and the second conductor 22 are conductors formed of a metal having high conductivity such as copper. The exemplary shapes of the first conductor 21 and the second conductor 22 are flat plate shapes. 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 disposed on both sides with respect to 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.

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

In the resistor 20, a current flows along the 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.

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

As shown in fig. 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 and 22a are disposed adjacent to the resistor 20. The two first through holes 21a and 22a are arranged at symmetrical positions with respect to the resistor 20.

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

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

The substrate 3 is, for example, a Printed Circuit Board (PCB). The exemplary substrate 3 is rectangular in shape. The substrate 3 has a current detecting section 31. The current detection unit 31 is, for example, a current detection circuit. The substrate 3 may have a control circuit for monitoring and controlling the battery.

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 conductivity such as copper. The first terminal block 7A and the second terminal block 7B are electrically connected to the current detecting unit 31, respectively. The first terminal block 7A and the second terminal block 7B are disposed at the end 3a of the substrate 3. The end 3a is an end adjacent to the shunt resistor 2 in the second direction Y.

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

The leg 72 is bent at right angles to the connection 71. The leg portions 72 are disposed at both ends of the connection portion 71, and support the connection portion 71. The leg 72 is in contact with the substrate 3 and fixed to the substrate 3 by solder or the like. The connection portion 71 is connected to the current detection portion 31 via the leg portion 72.

In the present embodiment, the bus bar 4 of the same shape is used as the first bus bar 4A and the second bus bar 4B. The bus bar 4 is formed of a metal plate having conductivity such as copper. As shown in fig. 4 and 5, the bus bar 4 includes: 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 fixing 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 fixing 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.

The first terminal portion 41 has a through hole 41a into which the screw 61 and the screw 62 are inserted. The through hole 41a is disposed in a central portion of the first terminal 41 in the first direction X. In other words, the through hole 41a is disposed in the center portion in the width direction of the first terminal portion 41. The shape of the through hole 41a is exemplified as an oblong shape with the second direction Y being the long axis. As shown in fig. 5, the bus bar 4 has a first restriction portion 44. The first restriction portion 44 is formed by bending the end of the bus bar 4 on the first terminal portion 41 side. The first restriction portion 44 is orthogonal to the first terminal portion 41. The first regulating portion 44 has a regulating surface 44a facing the second terminal portion 42 side. As described later, the restricting surface 44a can restrict the extending direction of the bus bar 4.

The second terminal portion 42 has a through hole 42a into which the screws 63 and 64 shown in fig. 2 can be inserted. The through hole 42a is arranged in a central portion of the second terminal portion 42 in the first direction X. The shape of the through hole 42a is exemplified as an oblong shape having a long axis in the first direction X. As shown in fig. 5, the bus bar 4 has a second restriction portion 46. The second restriction portion 46 is formed by bending the end on the second terminal portion 42 side in the bus bar 4. The second restriction portion 46 is orthogonal to the second terminal portion 42.

The low rigidity portion 43 is provided at a central portion in the second direction Y of the bus bar 4. 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 subjected to a thinning process for reducing the cross-sectional area of a cross-section orthogonal to the second direction Y. In the illustrated low rigidity portion 43, the cross-sectional area is small by having the through hole 43a. The through hole 43a penetrates the bus bar 4 in the plate thickness direction. The shape of the through hole 43a is exemplified as a rectangle extending along the second direction Y.

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. The position of the first bent portion 45a is different from the position of the second bent portion 45b in the length direction of the bus bar 4. The first bending portion 45a is located closer to the first terminal portion 41 than the second bending portion 45b.

The bus bar 4 is bent at a substantially right angle at the first bent portion 45a and the 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.

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 can absorb stress when a force in the third direction Z is applied to the bus bar 4 by reducing the sectional area. For example, the low rigidity portion 43 has the bent portion 45, and thus can absorb stress when a force in the first direction X and the second direction Y is applied to the bus bar 4. In this way, the bus bar 4 can absorb stress generated by the rigid fixation of both ends by the low rigidity portion 43.

As shown in fig. 6, the first bus bar 4A and the second bus bar 4B of the present 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 such that, for example, a center line CL of the bus bar 4 is orthogonal to the first direction X in a plan view. It is preferable that the center line CL of the first bus bar 4A is parallel to the center line CL of the second bus bar 4B.

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 with the nut 66. That is, the first conductor 21 and the first bus bar 4A are fastened together by the screw 61 and the nut 66.

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 screwed into the female screw 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.

As shown in fig. 7, the first restriction portion 44 of the first bus bar 4A faces the side surface 21c of the first conductor 21. The side surface 21c of the first conductor 21 is a side surface orthogonal to the second direction Y, and faces the opposite side to the substrate 3 side. The restricting surface 44a of the first restricting portion 44 faces the side surface 21c and is close to the side surface 21 c. The first restriction portion 44 functions as a guide when the bus bar 4 is attached to the shunt resistor 2. For example, when the first bus bar 4A is placed on the first conductor 21, the first restriction portion 44 positions the first bus bar 4A on the first conductor 21. More specifically, the first restriction portion 44 is guided by the side surface 21c so that the extending direction of the first bus bar 4A is orthogonal to the first direction X.

The first restriction portion 44 can restrict rotation of the bus bar 4 with respect to the rotational torque at the time of screwing the screw 61. That is, when the first bus bar 4A is intended to rotate due to the rotational torque transmitted from the screw 61, the restriction surface 44A abuts against the side surface 21c to restrict the rotation of the first bus bar 4A. In this way, the first restriction portion 44 can restrict the first bus bar 4A from tilting with respect to the second direction Y.

The second regulating portion 46 of the first bus bar 4A faces the end face 72a of the first terminal block 7A. The end face 72a of the first terminal block 7A is an end face orthogonal to the second direction Y, and faces the opposite side to the shunt resistor 2 side. The second regulating portion 46 has a regulating surface 46a facing the end surface 72 a. The second regulating portion 46 functions as a guide when the bus bar 4 is placed on the first terminal block 7A. The second restriction portion 46 is guided by the end surface 72a so that the extending direction of the first bus bar 4A is orthogonal to the first direction X.

The second restriction portion 46 can restrict rotation of the bus bar 4 with respect to the rotational torque at the time of screwing the screw 63. When the first bus bar 4A is intended to rotate due to the rotational torque transmitted from the screw 63, the restriction surface 46a abuts against the end surface 72a to restrict the rotation of the first bus bar 4A. In this way, the second restriction portion 46 can restrict the first bus bar 4A from tilting with respect to the second direction Y.

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 with the 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 screwed into the female screw portion 71a of the second terminal block 7B.

The first restriction 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 21 c. The side surface 22c is orthogonal to the second direction Y and faces the side opposite to the substrate 3 side. The first restriction portion 44 of the second bus bar 4B faces the side surface 22c of the second conductor 22, and extends the second bus bar 4B in the second direction Y.

The second restriction 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 restriction portion 46 of the second bus bar 4B faces the end surface 72a of the second terminal block 7B, and extends the second bus bar 4B in the second direction Y.

In the current detection device 1 of the present embodiment, it is possible to extend both the first bus bar 4A and the second bus bar 4B in the second direction Y and rigidly fix the first bus bar 4A and the second bus bar 4B. The first bus bar 4A and the second bus bar 4B extend in a direction orthogonal to the current flow direction, thereby suppressing variation in the voltage measurement distance. As a comparative example, a structure in which the shunt resistor 2 and the substrate 3 are connected by an electric wire was studied. In the comparative example, for example, a terminal attached to an 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 easily rotated by a rotational torque at the time of screw tightening. When the terminals are rotated relative to the normal positions, the resistance 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 is lowered.

In contrast, in the current detection device 1 of the present embodiment, the extending directions of the first bus bar 4A and the second bus bar 4B are less likely to be deviated. For example, if the shunt resistor 2 and the substrate 3 are fixed in advance, the extending directions of the first bus bar 4A and the second bus bar 4B are determined according to the relative positions of the shunt resistor 2 and the terminal blocks 7A and 7B. Therefore, the first bus bar 4A and the second bus bar 4B can be extended in the second direction Y with high accuracy.

The bus bar 4 of the present embodiment is configured such that the bus bar 4 is easily orthogonal to the first direction X. As described above, the through hole 41a of the first terminal portion 41 is oblong along the longitudinal direction of the bus bar 4. On the other hand, the through hole 42a of the second terminal portion 42 is oblong along the width direction of the bus bar 4.

Since the through hole 41a is oblong along the second direction Y, when the first terminal portion 41 is fixed to the shunt resistor 2, the bus bar 4 is hard to rotate relative to the shunt resistor 2. Since the through hole 41a is oblong along the second direction Y, the restricting surface 44a of the first restricting portion 44 is easily brought into contact with the side surfaces 21c and 22c when the first terminal portion 41 is fixed to the shunt resistor 2. Further, since the through hole 41a is oblong along the second direction Y, the position of the first terminal portion 41 in the first direction X is not easily shifted. That is, the contact position of the first terminal 41 with respect to the first conductor 21 and the second conductor 22 is not easily shifted. Therefore, the contact position of the first terminal 41 with respect to the first conductor 21 and the second conductor 22 can be made close to the resistor 20, and the resistance components of the first conductor 21 and the second conductor 22 can be minimized.

Since the through hole 42a is oblong along the first direction X, it is easy to fix the second terminal portion 42 to the substrate 3 in a state where the holding bus bar 4 extends along 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.

The current detection device 1 may have a case 10 shown in fig. 8. The case 10 is molded from, for example, an insulating synthetic resin. The housing 10 has: a housing chamber 11 for housing the substrate 3; and a holding portion 12 for holding the shunt resistor 2. The housing chamber 11 has a box shape, and houses and holds the substrate 3 therein. The housing chamber 11 is rectangular in shape in plan view.

The holding portion 12 protrudes from the outer side surface of the housing chamber 11 in the second direction Y. The exemplary holding portion 12 is in the shape of a rectangular plate. The side wall of the housing chamber 11 has a cutout 11a corresponding to the holding portion 12. The cutout 11a communicates the inner space of the housing chamber 11 with the outer space on the holding portion 12 side. The cutout 11a is formed so that the accommodating 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 holding portion 12 by bolts 68 and 69. The holding portion 12 may have nuts screwed with the bolts 68, 69.

As shown in fig. 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 so that the virtual line 13A connecting the female screw portion 71a of the first terminal block 7A and the first through hole 21a is orthogonal to the first direction X. The holding portion 12 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. That is, the case 10 holds the substrate 3 and the shunt resistor 2 so that the virtual line 13B connecting the female screw portion 71a of the second terminal block 7B and the first through hole 22a is orthogonal to the first direction X.

By holding the substrate 3 and the shunt resistor 2 in one housing 10, the extending directions of the first bus bar 4A and the second bus bar 4B can be easily controlled. That is, the first bus bar 4A and the second bus bar 4B are easily connected to the shunt resistor 2 so as to be orthogonal to the current flow direction.

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

The first bus bar 4A extends in a second direction Y orthogonal to the first direction X, is fixed to the first conductor 21 and the substrate 3, and electrically connects the first conductor 21 and the current detection portion 31. The second bus bar 4B extends in the second direction Y, is fixed to the second conductor 22 and the substrate 3, and electrically connects the second conductor 22 and the current detecting portion 31. In the current detection device 1 of the present embodiment, the first bus bar 4A and the second bus bar 4B are fixed to the shunt resistor 2 and the substrate 3. Therefore, the extending direction of the first bus bar 4A and the second bus bar 4B is easily orthogonal to the first direction X. In addition, it is easy to extend the first bus bar 4A in parallel with the second bus bar 4B. Therefore, the current detection device 1 of the present embodiment can suppress a decrease in current detection accuracy.

The first conductor 21 and the second conductor 22 of the present embodiment have side surfaces 21c and 22c orthogonal to the second direction Y. The first bus bar 4A and the second bus bar 4B have a first restriction portion 44 formed by bending an end portion on the shunt resistor 2 side. The first regulating portion 44 faces the side surfaces 21c, 22c in the second direction Y, and regulates the first bus bar 4A and the second bus bar 4B from tilting with respect to the second direction Y. Therefore, the current detection device 1 of the present embodiment can suppress a decrease in current detection accuracy.

The first bus bar 4A and the second bus bar 4B of the present embodiment have a low rigidity portion 43 between a fixing portion with respect to the shunt resistor 2 and a fixing portion with respect to 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. The low rigidity portion 43 may have a cutout instead of the through hole 43a or in addition to the through hole 43a.

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 orthogonal to both the first direction X and the second direction Y. The low rigidity portion 43 may be bent at three or more positions.

The current detection device 1 may have a housing 10, a first terminal block 7A, and a second terminal block 7B. The case 10 has a housing chamber 11 for housing the substrate 3 and a holding portion 12 for holding 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 detecting 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 detecting portion 31 via the second terminal block 7B. The shunt resistor 2 and the substrate 3 are disposed in the case 10, so that an appropriate relative position between the shunt resistor 2 and the substrate 3 is easily ensured.

The case 10, the shunt resistor 2, the substrate 3, the first bus bar 4A, and the second bus bar 4B constitute a monitor unit assembled with each other. In the stage of constituting the monitoring unit, it can be checked whether or not the resistance value between the bus bars 4A, 4B is a desired value. By assembling the monitoring unit, which is confirmed to have a desired resistance value, to the battery, the accuracy of current detection is less likely to be degraded.

The manner of fixing the shunt resistor 2 to the case 10 is not limited to the bolts 68 and 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 also have a recess for accommodating the shunt resistor 2. In this case, the shunt resistor 2 may be pressed into the concave portion of the holding portion 12.

The disclosure of the above embodiments can be performed in appropriate combination.

Claims

1. A current detection device is characterized by comprising:

a shunt resistor, the shunt resistor having: a resistor body, a current of which 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 portion that detects a current value flowing through the shunt resistor;

a first bus bar extending in a second direction orthogonal to the first direction and fixed with respect to the first conductor and the substrate, the first bus bar electrically connecting the first conductor and the current detection portion; and

and a second bus bar extending in the second direction and fixed with respect to the second conductor and the substrate, the second bus bar electrically connecting the second conductor and the current detection portion.

2. The apparatus according to claim 1, wherein,

the first conductor and the second conductor have sides orthogonal to the second direction,

the first bus bar and the second bus bar have first restriction portions formed by bending end portions on the shunt resistance side,

the first restricting portion is opposed to the side surface in the second direction, and restricts tilting of the first bus bar and the second bus bar with respect to the second direction.

3. The apparatus according to claim 1, wherein,

the first bus bar and the second bus bar have a low rigidity portion between a fixing portion with respect to the shunt resistor and a fixing portion with respect to the substrate,

in the low rigidity portion, a through hole or a cutout is formed in the first bus bar and the second bus bar.

4. A current detecting device according to claim 3, wherein,

the low rigidity portion has a curved portion,

the bent portion includes a portion formed by bending the first bus bar and the second bus bar at a plurality of portions and extending in a third direction orthogonal to both the first direction and the second direction.

5. The current detecting device according to any one of claims 1 to 4, wherein,

the current detection device is provided with:

a case having a housing chamber housing the substrate and a holding portion holding the shunt resistor; and

a conductive first terminal block and a conductive second terminal block, the first terminal block and the second terminal block being fixed to the substrate,

the first bus bar is fixed relative to the first terminal block and connected to the current detecting portion 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.