JP2022027164A - Current detection device - Google Patents

Abstract

To improve detection accuracy while suppressing an increase in size.SOLUTION: A current detection device includes: a planar bus bar 10 having surfaces 101a and 102a and the other surfaces 101b and 102b on the sides opposite to the surfaces 101a and 102a and including first and second members 101 and 102 including terminal parts 31 and 32 on the sides of the surfaces 101a and 102a; and a planar shunt resistance 20 having one surface 20a and the other surface 20b on the side opposite to the one surface 20a, arranged in the state that the other surface 20b is parallel to the other surfaces 101b and 102b of the first and second members 101 and 102 between the first and second members 101 and 102 and formed of a material having a resistance temperature coefficient smaller than that of the bus bar 10. Grooves 50 sandwiching the terminal parts 31 and 32 in at least the surfaces 101a and 102a of the first and second members 101 and 102 are formed in a portion positioned on the side opposite to the shunt resistance 20.SELECTED DRAWING: Figure 1

Description

The present invention relates to a current detector having a shunt resistance.

Conventionally, a current detection device having a shunt resistance has been proposed (see, for example, Patent Document 1). Specifically, this current detection device has a bus bar having a flat plate-shaped first member and a second member, and the first member and the second member are arranged so as to sandwich the shunt resistance. The first member and the second member are each provided with a terminal portion connected to an external circuit. In this current detection device, protrusions are formed on the first member and the second member, and each terminal portion is provided on the protrusion. Therefore, in this current detection device, a step is formed between the terminal portion and the shunt resistor. Further, the shunt resistance is made of a material having a temperature coefficient of resistance smaller than that of the bus bar.

In such a current detection device, it becomes difficult for a current to flow in the path connecting the shunt resistor and the terminal portion. That is, it becomes difficult for current to flow through the first member and the second member having a large resistance temperature coefficient located between the shunt resistor and the terminal portion. Therefore, in the current detection device, the potential difference between the shunt resistor and the terminal portion can be reduced. Therefore, by measuring the voltage between the terminal portions arranged so as to sandwich the shunt resistor having a small temperature coefficient of resistance, the current flowing through the current detection device can be detected with high accuracy.

European Patent Application Publication No. 2474008

However, in the current detection device as described above, it is easy to increase the size by forming the protrusions on the first member and the second member. In particular, when such a current detection device is mounted on a vehicle, it is desired to reduce the size of the current detection device so that the mounting space can be reduced.

In view of the above points, it is an object of the present invention to provide a current detection device capable of improving detection accuracy while suppressing an increase in size.

The first aspect of claim 1 for achieving the above object is a current detection device having a shunt resistance (20), which has a flat plate shape having one surface (101a, 102a) and the other surface (101b, 102b) on the opposite side to the one surface. A bus bar (10) having a first member (101) and a second member (102) provided with terminal portions (31, 32) on one side, and one side (20a) and the other side on the opposite side (20a). It is formed into a flat plate having 20b), and is arranged between the first member and the second member so that the other surface is parallel to the other surfaces of the first member and the second member, and the resistance temperature is increased from the bus bar. It has a shunt resistor made of a material having a small coefficient, and has a groove portion (a groove portion) on at least one of the first member and the second member, which is located on the opposite side of the terminal portion on one surface and opposite to the shunt resistance. 50) is formed.

According to this, by forming the groove portion, it becomes difficult for the current to flow in the path connecting the shunt resistor and the terminal portion. That is, it becomes difficult for current to flow through the first member and the second member having a large resistance temperature coefficient located between the shunt resistor and the terminal portion. Therefore, in the current detection device, the potential difference between the shunt resistor and the terminal portion can be reduced. Therefore, by measuring the voltage between the terminal portions arranged so as to sandwich the shunt resistor having a small temperature coefficient of resistance, the current flowing through the current detection device can be detected with high accuracy.

Further, since it is possible to suppress the deterioration of the detection accuracy by forming the groove portion, it is possible to suppress the increase in size.

The reference numerals in parentheses attached to each component or the like indicate an example of the correspondence between the component or the like and the specific component or the like described in the embodiment described later.

It is a perspective view of the current detection apparatus in 1st Embodiment. It is a top view of the current detection device in 1st Embodiment. It is sectional drawing along the line III-III in FIG. It is a figure which shows the simulation result of the current flowing through the current detection device. It is a top view of the current detection device in the modification of 1st Embodiment. It is a top view of the current detection device in the modification of 1st Embodiment. It is a top view of the current detection device in 2nd Embodiment. It is a top view of the current detection device in the modification of 2nd Embodiment. It is a top view of the current detection device in the modification of 2nd Embodiment. It is a top view of the current detection device in the modification of 2nd Embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In each of the following embodiments, the parts that are the same or equal to each other will be described with the same reference numerals.

(First Embodiment)
The first embodiment will be described with reference to the drawings. The current detection device of the present embodiment is preferably used for detecting the motor current or the like for driving an electric vehicle or the like.

As shown in FIGS. 1 to 3, the current detection device of this embodiment has a bus bar 10, a shunt resistor 20, and a pair of terminal portions 31, 32. The bus bar 10 has a flat plate-shaped first member 101 having one surface 101a and another surface 101b on the opposite side to the one-sided 101a, and a flat plate-shaped second member 101 having one surface 102a and the other surface 102b on the opposite side to the one-sided 102a. It has a member 102. The first member 101 and the second member 102 are made of, for example, copper or the like, and have the same thickness.

The shunt resistor 20 has a flat plate shape having one surface 20a and the other surface 20b on the opposite side to the one surface 20a, and is composed of manganin (registered trademark) or the like having a resistance temperature coefficient smaller than that of the bus bar 10. Further, in the present embodiment, the thickness of the shunt resistor 20 is thinner than the thickness of the first member 101 and the second member 102.

The shunt resistor 20 is arranged between the first member 101 and the second member 102, and is integrated with the first member 101 and the second member 102 by welding or the like. Specifically, the shunt resistor 20, the first member 101, and the second member 102 are integrated so that the other surfaces 20b, 101b, and 102b are located on the same plane. Therefore, the one surface 20a of the shunt resistor 20 is recessed from the one surface 101a of the first member 101 and the one surface 102a of the second member 102. That is, in the current detection device of the present embodiment, the recess 40 is formed in the portion provided with the shunt resistor 20.

The terminal portions 31 and 32 have a rod shape made of copper or the like, and are provided on one surface 101a of the first member 101 and one surface 102a of the second member 102 so as to sandwich the shunt resistor 20. The terminal portions 31 and 32 are provided in the first member 101 and the second member 102 by welding, rivets, soldering, or the like.

The above is the basic configuration of the current detection device in this embodiment. In such a current detection device, the terminal portions 31 and 32 are connected to an external circuit, and the current flowing based on the voltage between the terminal portions 31 and 32 is detected.

Then, in the current detection device of the present embodiment, the groove portion 50 is formed in the first member 101 and the second member 102. Here, in the following, the arrangement direction of the first member 101, the second member 102, and the shunt resistance 20 is defined as the X direction, and the direction orthogonal to the X direction and parallel to the surface direction of the first member 101 and the like is defined as the Y direction. do.

Then, the groove portion 50 of the present embodiment is located on one surface 101a, 102a of the first member 101 and the second member 102 at a position opposite to the shunt resistance 20 with the terminal portions 31, 32 interposed therebetween, along the Y direction. It is formed. The groove portion 50 of the present embodiment is formed by, for example, press molding or the like, and has a triangular cross-sectional shape. However, the cross-sectional shape of the groove portion 50 is not limited to this, and may be rectangular.

Further, the groove portion 50 of the present embodiment is not formed so as to penetrate the first member 101 and the second member 102. That is, the groove portion 50 is configured to have a bottom surface in the first member 101 and the second member 102.

According to the present embodiment described above, a groove 50 is formed on one side 101a of the first member 101 and one side 102a of the second member 102 on the opposite side of the shunt resistance 20 with the terminal portions 31 and 32 interposed therebetween. Therefore, when a current flows through the current detection device, as shown in FIGS. 3 and 4, it becomes difficult for the current to flow in the path connecting the terminal portions 31 and 32 and the shunt resistor 20. That is, it becomes difficult for current to flow through the first member 101 and the second member 102 having a large resistance temperature coefficient located between the terminal portions 31 and 32 and the shunt resistor 20. Therefore, in such a current detection device, it is possible to suppress the occurrence of a potential difference between the terminal portions 31 and 32 and the shunt resistor 20, and it is possible to suppress a decrease in detection accuracy.

Further, in the present embodiment, the groove portion 50 is formed in the first member 101 and the second member 102 to prevent the detection accuracy from being lowered. Therefore, it is possible to prevent the current detection device from becoming large in size. Further, since the groove portion 50 is easily formed by press molding or the like as compared with the case where the protrusion portion or the like is formed on the first member 101 and the second member 102, the manufacturing process is complicated and the yield is lowered. It can also be suppressed.

Further, in the present embodiment, one surface 20a of the shunt resistor 20 is recessed and arranged, and the terminal portions 31 and 32 are arranged on the one surface 101a and 102a side of the first member 101 and the second member 102. ing. Therefore, as compared with the case where one surface 20a of the shunt resistor 20 is located on the same surface as the one surfaces 101a and 102a of the first member 101 and the second member 102, the groove portion of the first member 101 and the second member 102. It is suppressed that the current spreads in the thickness direction of the first member 101 and the second member 102 between the portion where the 50 is formed and the shunt resistor 20. That is, it is possible to further suppress the flow of current in the vicinity of the portions of the first member 101 and the second member 102 where the terminal portions 31 and 32 are provided. Therefore, it is possible to prevent the detection accuracy from further decreasing.

Further, the groove portion 50 is not formed so as to penetrate the first member 101 and the second member 102. Therefore, as compared with the case where the groove portion 50 is formed so as to penetrate the first member 101 and the second member 102 (that is, the through hole is formed), the first member 101 and the second member 102 are formed. It is possible to suppress that the range in which the current flows is small, and it is possible to suppress that the heat generation is large.

(Variation example of the first embodiment)
A modified example of the first embodiment will be described. For example, as shown in FIG. 5A, two groove portions 50 may be formed in each of the first member 101 and the second member 102. Further, although not particularly shown, three groove portions 50 may be formed in each of the first member 101 and the second member 102. Further, the number of grooves 50 formed in the first member 101 may be different from the number formed in the second member 102.

Further, as shown in FIG. 5B, the groove portion 50 may have a longer length (that is, a width) along the X direction as compared with the first embodiment. Even if the groove portion 50 is formed in this way, it is difficult for a current to flow in the vicinity of the terminal portions 31 and 32 due to the formation of the groove portion 50, so that the same effect as that of the first embodiment can be obtained.

(Second Embodiment)
The second embodiment will be described. In this embodiment, the shape of the groove 50 is changed from that of the first embodiment. Others are the same as those in the first embodiment, and thus description thereof will be omitted here.

In the present embodiment, as shown in FIG. 6, the groove portion 50 passes through the terminal portions 31 and 32 in the normal direction (hereinafter, also simply referred to as the normal direction) with respect to the surface direction of the first member 101 and the like. It is extended so as to intersect the virtual line K extending in the Y direction. The normal direction with respect to the surface direction of the first member 101 or the like can also be said to be when viewed from the normal direction with respect to the surface direction of the first member 101 or the like.

The groove portion 50 of the present embodiment is substantially V-shaped so as to have a portion intersecting with the virtual line K. Further, the groove portion 50 of the present embodiment is formed so as to reach the end portion of the first member 101 and the second member 102 on the shunt resistance 20 side.

According to this, as compared with the first embodiment, it is possible to reduce the current wrapping around from the Y direction with respect to the portions of the first member 101 and the second member 102 provided with the terminal portions 31 and 32. Therefore, it is possible to prevent the detection accuracy from further decreasing.

(Modified example of the above second embodiment)
A modified example of the second embodiment will be described. In the second embodiment, as shown in FIG. 7A, the groove portion 50 may be substantially U-shaped in the normal direction. In FIG. 7A, the groove 50 has a substantially U-shape having two corners, but the groove 50 may have a substantially U-shape composed of only curved portions having no corners. good.

Further, as shown in FIGS. 7B and 7C, the groove portion 50 may be formed so as not to reach the end portion of the first member 101 and the second member 102 on the shunt resistance 20 side in the normal direction. .. That is, the groove portion 50 may be formed so as to terminate in the first member 101 and the second member 102.

(Other embodiments)
Although the present disclosure has been described in accordance with embodiments, it is understood that the present disclosure is not limited to such embodiments or structures. The present disclosure also includes various variations and variations within a uniform range. In addition, various combinations and forms, as well as other combinations and forms that include only one element, more, or less, are within the scope and scope of the present disclosure.

For example, in each of the above embodiments, the groove 50 may be formed only on one of the first member 101 and the second member 102. Further, in each of the above embodiments, the shunt resistor 20 is arranged so as to be located on the same plane as one surface 101a of the first member 101 and 102a of the second member 102, and the other surface 20b side is recessed. May be good. Further, the shunt resistor 20 may have the same thickness as the first member 101 and the second member 102. Even as a current detection device such as these, the same effect as that of each of the above-described embodiments can be obtained by forming the groove portion 50.

Further, in each of the above embodiments, the shapes of the terminal portions 31 and 32 can be appropriately changed. For example, predetermined areas of the first member 101 and the second member 102 may be designated as terminal portions 31 and 32, and the terminal portions 31 and 32 may be connected to an external circuit by a bonding wire or the like. The 32 may be connected to the printed circuit board as an external circuit by soldering or the like. That is, the terminal portions 31 and 32 may be composed of a part of the first member 101 and the second member 102.

10 Bus bar 20 Shunt resistance 31, 32 Terminal part 50 Groove part 101 First member 101a One side 101b Other side 102 Second member 102a One side 102b Other side

Claims (4)

A current detection device having a shunt resistance (20).
A first member (101) and a first member (101) having a flat plate shape having one surface (101a, 102a) and another surface (101b, 102b) opposite to the one surface, and having terminal portions (31, 32) on the one surface side. A bus bar (10) having two members (102) and
It has a flat plate shape having one surface (20a) and another surface (20b) opposite to the one surface, and the other surface is between the first member and the second member, and the other surface is the first member and the second member. It has the shunt resistance, which is arranged parallel to the other surface and is made of a material having a temperature coefficient of resistance smaller than that of the bus bar.
A current detection device in which a groove portion (50) is formed in at least one of the first member and the second member in a portion located on the opposite side of the shunt resistor with the terminal portion of the one surface interposed therebetween. The current detection device according to claim 1, wherein the first member and the second member each have a groove formed on one surface side thereof. The groove portion passes through the terminal portion in the normal direction with respect to the one surface and intersects the arrangement direction of the first member, the second member, and the shunt resistance, and the first member and the second member. The current detection device according to claim 1 or 2, which is extended so as to intersect with a virtual line (K) extending in a direction parallel to one surface of the member. The current detection device according to claim 3, wherein the groove portion extends to the end portion of the first member and the second member on the shunt resistance side.

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