Current detection device

Abstract

A current detection device (30) is provided with a resistor (5) and a pair of electrodes (6, 7). The current detection device (30) includes a protruding portion (11). The protruding portion (11) includes a part of the resistor (5) and parts of the pair of electrodes (6, 7). The electrodes (6, 7) each has a first wall portion (66b, 67b) forming a part of the protruding portion (11), and a second wall portion (66a, 67a) forming a part of the protruding portion (11). The electrodes (6, 7) each have a detecting region (66, 67) defined by the first wall portion (66b, 67b), the second wall portion (66a, 67a), a start-end portion (66c, 67c), and a contact surface (6a, 7a). The electrodes (6, 7) each have a voltage detecting portion (20, 21) disposed in the detecting region (66, 67) with a gap from the start-end portion (66c, 67c).

Description

Technical Field

[0001] The present invention relates to a current detection device, particularly a current detection device using a shunt resistor.

Background Art

[0002] Shunt resistors are widely used for current detection purposes. Such a shunt resistor includes a resistor body and electrodes joined to both ends of the resistor body. Generally, the resistor body is made of a resistance alloy such as a copper-nickel alloy, a copper-manganese alloy, an iron-chromium alloy, a nickel-chromium alloy, etc., and the electrodes are made of a highly conductive metal such as copper. A voltage detection unit is provided on the electrodes, and by connecting a conducting wire (for example, an aluminum wire) to the voltage detection unit, the voltage generated at both ends of the resistor body is detected.

[0003] Examples of conventional shunt resistors are shown in FIGS. 33 and 34. As shown in FIGS. 33 and 34, the shunt resistor 100 includes a resistor body 105 made of a plate-shaped resistance alloy having a predetermined thickness and width, and a pair of electrodes 106 and 107 made of a highly conductive metal connected to both ends of the resistor body 105. Bolt holes 108 and 109 for fixing the shunt resistor 100 with a screw or the like are formed in the electrodes 106 and 107, respectively.

[0004] The shunt resistor 100 further includes voltage detection units 120 and 121 for measuring the voltage of the resistor body 105. In the example shown in FIG. 33, the voltage detection units 120 and 121 are integrally formed with the electrodes 106 and 107, respectively. The voltage detection units 120 and 121 extend in the width direction of the electrodes 106 and 107 from the side surfaces of the electrodes 106 and 107. The voltage detection units 120 and 121 are arranged in the vicinity of the resistor body 105.

[0005] In the example shown in FIG. 34, the voltage detection units 120 and 121 are pins that respectively extend perpendicularly from the surfaces of the electrodes 106 and 107. The voltage detection units 120 and 121 are arranged in the vicinity of the resistor body 105.

Prior Art Documents

[0006] [Patent Document 1] Japanese Patent Publication No. 2017-5204 [Patent Document 2] Japanese Patent Publication No. 2007-329421 [Overview of the project] [Problems that the invention aims to solve]

[0007] In shunt resistors, the temperature coefficient of resistance (TCR) is important for enabling current detection under conditions where temperature fluctuations have little effect. The temperature coefficient of resistance is an indicator of the rate at which the resistance value changes with temperature. Therefore, the present invention aims to provide a current detection device using a shunt resistor that can satisfy a desired temperature coefficient of resistance with a simple structure. [Means for solving the problem]

[0008] In one embodiment, a current detection device used for detecting current is provided, comprising a resistor and a pair of electrodes connected to both ends of the resistor in a first direction, wherein the current detection device has a projection that protrudes in a second direction, the projection having a part of the resistor and a part of the pair of electrodes, the first direction being the direction in which the pair of electrodes are arranged, and the second direction being perpendicular to the first direction, each electrode having a first wall portion along the first direction that forms a part of the projection and a second wall portion along the second direction that forms a part of the projection, each electrode having a detection area defined by the first wall portion, the second wall portion, a starting end portion which is the boundary line between the projection and the body of the electrode, and a contact surface in which at least a part of it contacts the resistor, and each electrode having a voltage detection portion arranged in the detection area with a gap between it and the starting end portion.

[0009] In one embodiment, the voltage detection unit is positioned closer to the resistor than to the center of the detection area. In one embodiment, the detection region protrudes more than the resistor in the thickness direction of the current detection device. In one embodiment, the length of the first wall is longer than the length of the second wall. In one embodiment, the current detection device further comprises a wiring board, the wiring board comprising a detection pad connected to the voltage detection unit.

[0010] In one reference example, a plate-shaped shunt resistor used for current detection is provided, comprising a resistor and a pair of electrodes connected to both ends of the resistor in a first direction, wherein the shunt resistor has a projection formed on a first side surface of the shunt resistor which is parallel to the first direction, and a recess formed on a second side surface of the shunt resistor which is opposite to the first side surface and extends in the same direction as the projection, wherein the projection has a part of the resistor and a part of the pair of electrodes, and the recess has a side surface of the resistor parallel to the first direction.

[0011] In one example, the length of the recess in the second direction perpendicular to the first direction is the same as the length of the protrusion in the second direction. In one example, the protruding portion includes a pair of voltage detection units connected to both ends of the resistor in the first direction. In one example, the protruding portion and the recessed portion have a rectangular shape.

[0012] As an example, a method for manufacturing a shunt resistor comprising a resistor and a pair of electrodes connected to both ends of the resistor is provided, wherein a long shunt resistor base material is prepared with the pair of electrodes connected to both ends of the resistor in a first direction, the shunt resistor base material is cut in the first direction and in a convex shape to form a protrusion of the first shunt resistor having a part of the resistor and a part of the pair of electrodes of the first shunt resistor, and the shunt resistor base material is cut in the first direction and in a convex shape at a distance from the protrusion to form a recess of the first shunt resistor and a protrusion of the second shunt resistor extending in the same direction as the protrusion, the protrusion of the second shunt resistor having a part of the resistor and a part of the pair of electrodes of the second shunt resistor.

[0013] In one example, a current detection device is provided comprising the above-mentioned shunt resistor and a current detection circuit board having voltage signal wiring for transmitting a voltage signal from the shunt resistor, wherein the voltage signal wiring is electrically connected to a protruding portion of the shunt resistor.

[0014] In one example, the current detection circuit board further includes voltage terminal pads, which are connected to the protrusions and the voltage signal wiring. In one example, the current detection device further includes an output terminal that outputs a voltage signal from the shunt resistor, and the output terminal is mounted in a recess of the shunt resistor. [Effects of the Invention]

[0015] By positioning the voltage detection unit at a desired location within the detection area of ​​an electrode that constitutes a part of the protruding portion of the current detection device, with a gap between it and the starting end, the desired resistance temperature coefficient can be satisfied. [Brief explanation of the drawing]

[0016] [Figure 1]It is a perspective view showing an embodiment of a shunt resistor. [Figure 2] It is a plan view of the shunt resistor shown in FIG. 1. [Figure 3] It is an enlarged view of the protrusion and the recess. [Figure 4] It is a perspective view showing an embodiment of a current detection device provided with a shunt resistor. [Figure 5] It is a perspective view showing the current detection device when the case of the voltage output device is removed. [Figure 6] It is a schematic diagram showing a state in which a voltage detection terminal is provided in a voltage detection unit. [Figure 7] It is a graph showing the rate of change of the resistance value of the shunt resistor due to temperature change. [Figure 8] It is a plan view showing an embodiment of a shunt resistor having no recess. [Figure 9] It is a graph showing the relationship between the length of the protrusion in the second direction and the rate of change of the resistance value of the shunt resistor. [Figure 10] It is a graph showing the relationship between the length of the protrusion of the shunt resistor and the rate of change of the resistance value of the shunt resistor. [Figure 11] It is a graph showing the rate of change of the resistance value of the shunt resistor. [Figure 12] It is a perspective view showing another embodiment of the shunt resistor. [Figure 13] It is an enlarged view of the protrusion in FIG. 12. [Figure 14] It is a diagram showing an example of a manufacturing process of the shunt resistor. [Figure 15] It is a schematic diagram showing still another embodiment of the shunt resistor. [Figure 16] It is a schematic diagram showing still another embodiment of the shunt resistor. [Figure 17] It is a schematic diagram showing still another embodiment of the shunt resistor. [Figure 18] It is a schematic diagram showing still another embodiment of the shunt resistor. [Figure 19] It is a schematic diagram showing another embodiment of a manufacturing method of the shunt resistor. [Figure 20] This is a schematic diagram illustrating another embodiment of the method for manufacturing a shunt resistor. [Figure 21] This is a perspective view showing another embodiment of the current detection device. [Figure 22] Figure 21 is a side view of the current detection device shown. [Figure 23] This is an enlarged view of the protruding part shown in Figure 21. [Figure 24] This is a schematic diagram illustrating the location of the voltage detection unit. [Figure 25] Figure 24 is a graph showing the change in the resistance value of the shunt resistor due to temperature changes at each detection location. [Figure 26A] This is a schematic diagram showing yet another embodiment of the current detection device. [Figure 26B] This is a schematic diagram showing yet another embodiment of the current detection device. [Figure 27A] This is a schematic diagram showing yet another embodiment of the current detection device. [Figure 27B] This is a schematic diagram showing yet another embodiment of the current detection device. [Figure 28A] This is a diagram illustrating the location of the voltage detection unit. [Figure 28B] This is a diagram illustrating the location of the voltage detection unit. [Figure 29] This is a schematic diagram showing an example where a voltage detection component is connected across a step. [Figure 30] This is a schematic diagram showing another embodiment of the protruding part. [Figure 31] This is a schematic diagram showing another embodiment of the protruding part. [Figure 32] This is a schematic diagram showing yet another embodiment of the current detection device. [Figure 33] This figure shows an example of a conventional shunt resistor. [Figure 34] This figure shows an example of a conventional shunt resistor. [Modes for carrying out the invention]

[0017] Embodiments of the present invention will be described below with reference to the drawings. In the drawings described below, the same or corresponding components are denoted by the same reference numerals, and redundant descriptions are omitted. In the multiple embodiments described below, the configuration of one embodiment that is not specifically described is the same as that of the other embodiments, so redundant descriptions are omitted.

[0018] Figure 1 is a perspective view showing one embodiment of the shunt resistor 1, and Figure 2 is a plan view of the shunt resistor 1 shown in Figure 1. As shown in Figures 1 and 2, the shunt resistor 1 comprises a resistor 5 made of a resistance alloy plate material having a predetermined thickness and width, and a pair of electrodes 6 and 7 made of a highly conductive metal connected to both ends (i.e., both connection surfaces) 5a and 5b of the resistor 5 in a first direction. Electrode 6 has a contact surface 6a that contacts one end (one connection surface) 5a of the resistor 5, and electrode 7 has a contact surface 7a that contacts the other end (the other connection surface) 5b of the resistor 5. Bolt holes 8 and 9 are formed in electrodes 6 and 7, respectively, for fixing the shunt resistor 1 with screws or the like.

[0019] The first direction described above is the longitudinal direction of the resistor 5, which corresponds to the longitudinal direction of the shunt resistor 1. The longitudinal direction of the shunt resistor 1 is the direction in which the electrodes 6, resistor 5, and electrode 7 are arranged in that order. The direction perpendicular to this first direction is the second direction. The second direction is the width direction of the shunt resistor 1. As shown in Figures 1 and 2, electrodes 6 and 7 have the same structure and are arranged symmetrically with respect to the resistor 5.

[0020] Each of the ends 5a and 5b of the resistor 5 is connected (joined) to the electrodes 6 and 7 by means of welding (for example, electron beam welding, laser beam welding, or brazing). An example of the material of the resistor 5 is a low-resistance alloy material such as a Cu-Mn alloy. An example of the material of the electrodes 6 and 7 is copper (Cu).

[0021] The shunt resistor 1 has a projection 11 formed on its side surface 1a and a recess 12 formed on its side surface 1b. The projection 11 extends outward from the side surface 1a, and the recess 12 extends inward from the side surface 1b (towards the center of the shunt resistor 1). Both the projection 11 and the recess 12 extend in the same direction (second direction). When viewed from above (from a direction perpendicular to both the first and second directions), the projection 11 and the recess 12 have a rectangular shape.

[0022] Side surface 1a is the surface of the shunt resistor 1 parallel to the first direction and has side surface 6c of electrode 6 and side surface 7c of electrode 7. Side surface 1b is the surface of the shunt resistor 1 parallel to the first direction and is the surface opposite side surface 1a. Side surface 1b has side surface 6b of electrode 6 and side surface 7b of electrode 7. Side surfaces 6b and 7b are surfaces parallel to side surfaces 6c and 7c.

[0023] Figure 3 is an enlarged view of the protrusion 11 and recess 12. The protrusion 11 has a part of the resistor 5 and a part of the electrodes 6 and 7. Specifically, the protrusion 11 has a portion 14 which is a part of the resistor 5 and voltage detection units 20 and 21 for measuring the voltage generated at both ends 5a and 5b of the resistor 5. The length of the portion 14 in the second direction is represented by the length t1 (the length t1 of the protrusion 11 in the second direction), which is the distance from the sides 6c and 7c of the electrodes 6 and 7 to the side 5c of the resistor 5.

[0024] The voltage detection units 20 and 21 are parts of electrodes 6 and 7, respectively. That is, electrode 6 has the voltage detection unit 20, and electrode 7 has the voltage detection unit 21. The voltage detection unit 20 extends outward from the side surface 6c of electrode 6, and the voltage detection unit 21 extends outward from the side surface 7c of electrode 7. The voltage detection units 20 and 21 are connected to both ends 5a and 5b of the resistor 5, respectively. The voltage detection units 20 and 21 are arranged symmetrically with respect to part 14. The length of the voltage detection units 20 and 21 in the second direction is also represented by length t1.

[0025] The recess 12 has a side surface 5d of the resistor 5 parallel to the first direction. Specifically, in this embodiment, the side surface 12c of the recess 12 in the first direction (see Figure 2) is composed of the side surface 6d of the electrode 6, the side surface 5d of the resistor 5, and the side surface 7d of the electrode 7. In this embodiment, the width W1 of the protrusion 11 (length of the protrusion 11 in the first direction) and the width W2 of the recess 12 (length of the recess 12 in the first direction) are the same, and the length t1 of the protrusion 11 in the second direction (i.e., the width direction of the shunt resistor 1) and the length t2 of the recess 12 in the second direction are the same. The position of the protrusion 11 in the first direction and the position of the recess 12 in the first direction are the same. That is, the side surface 11a of the protrusion 11 is located on the extension of the side surface 12a of the recess 12, and the side surface 11b of the protrusion 11 is located on the extension of the side surface 12b of the recess 12.

[0026] Figure 4 is a perspective view showing one embodiment of a current detection device 30 equipped with a shunt resistor 1. The current detection device 30 further includes a voltage output device 31 that outputs the voltage of the resistor 5 (the voltage generated across both ends 5a and 5b of the resistor 5) to the outside. The voltage output device 31 is connected to the shunt resistor 1. The voltage output device 31 includes a non-conductive case 32 that covers the resistor 5 and an output terminal 35 (output connector 35) for outputting a voltage signal from the shunt resistor 1 (voltage of the resistor 5). The output connector 35 includes a first terminal, a second terminal, and a ground terminal, which are not shown.

[0027] Figure 5 is a perspective view showing the current detection device 30 with the case 32 of the voltage output device 31 removed. As shown in Figure 5, the voltage output device 31 further comprises a current detection circuit board 34. The current detection circuit board 34 has voltage signal wiring 46, 47 that transmits the voltage signal (voltage across resistor 5) from the shunt resistor 1 to the output terminal 35, and a ground wiring 50. The current detection circuit board 34 is positioned on the shunt resistor 1, and the output terminal 35 is mounted in the recess 12.

[0028] The current detection circuit board 34 further has voltage terminal pads 36, 37 (copper foil portions 36, 37). One end of the voltage signal wiring 46 is connected to the voltage terminal pad 36, and the other end is connected to the first terminal of the output connector 35. One end of the voltage signal wiring 47 is connected to the voltage terminal pad 37, and the other end is connected to the second terminal of the output connector 35. The voltage signal wirings 46, 47 are bent and routed above the protruding portion 11 from the second direction (see Figure 2) to the first direction (see Figure 2). One end of the ground wiring 50 is connected to the voltage terminal pad 36, and the other end is connected to the ground terminal of the output connector 35. The voltage signal wirings 46, 47, the ground wiring 50, and the voltage terminal pads 36, 37 are formed from a highly conductive metal (copper in this embodiment).

[0029] The voltage terminal pad 36 is connected to the voltage detection position 16 (see Figure 3) of the voltage detection unit 20 of the protrusion 11 via internal wiring (not shown) of the current detection circuit board 34. Similarly, the voltage terminal pad 37 is connected to the voltage detection position 17 (see Figure 3) of the voltage detection unit 21 of the protrusion 11 via internal wiring (not shown). In other words, the voltage signal wirings 46 and 47 are electrically connected to the voltage detection units 20 and 21 of the protrusion 11, respectively. The internal wiring and the voltage detection units 20 and 21 are connected by a method such as soldering. The operator connects a cable equipped with a connector that fits into the output terminal 35 and measures the voltage generated across both ends 5a and 5b of the resistor 5. With this configuration, the voltage of the resistor 5 can be easily measured. In one embodiment, an operational amplifier (amplifier), an A / D converter, and / or a temperature sensor may be mounted on the current detection circuit board 34 to amplify the voltage signal from the shunt resistor 1.

[0030] In one embodiment, as shown in Figure 6, voltage detection terminals 38 and 39 may be provided on the voltage detection units 20 and 21, respectively. The voltage detection terminals 38 and 39 are conductive pins that extend perpendicularly from the surfaces of the voltage detection units 20 and 21, respectively. Specifically, the voltage detection terminals 38 and 39 are connected to the voltage detection positions 16 and 17 of the voltage detection units 20 and 21, respectively, by methods such as soldering. The voltage generated across the resistor 5 can be measured by connecting a conductor (e.g., aluminum wire) to each of the voltage detection terminals 38 and 39, or by inserting the voltage detection terminals 38 and 39 through holes formed in the circuit board and making a conductive connection with the wiring formed in the circuit board. With this configuration, the voltage of the resistor 5 can be measured with a simple configuration.

[0031] Figure 7 is a graph showing the rate of change in the resistance value of the shunt resistor 1 due to temperature changes. The horizontal axis of Figure 7 represents the temperature of the shunt resistor 1, and the vertical axis represents the rate of change in the resistance value of the shunt resistor 1. The solid line curve shows the rate of change in the resistance value of the shunt resistor 1 in this embodiment, and the dotted line curve shows the rate of change in the resistance value of a conventional shunt resistor (shunt resistor 100 shown in Figure 33). Figure 7 shows the results when a copper-manganese alloy is used as the resistor 5.

[0032] As is clear from a comparison of the range of variation in the resistance rate of the shunt resistor 1 of this embodiment with the range of variation in the resistance rate of a conventional shunt resistor, the shunt resistor 1 of this embodiment can reduce the range of variation in the resistance rate due to temperature changes. In other words, the results in Figure 7 show that the shunt resistor 1 can reduce the temperature coefficient of resistance (TCR). By forming a protrusion 11 having a part of the resistor 5 and a part of the electrodes 6 and 7 as described above, the equipotential lines are distorted, and as a result, the temperature coefficient of resistance of the shunt resistor 1 can be reduced.

[0033] Figure 8 is a plan view showing one embodiment of a shunt resistor 200 without a recess 12. The configuration of the shunt resistor 200 is the same as that of the shunt resistor 1, except that it does not have a recess 12. That is, the shunt resistor 200 comprises a resistor 205 corresponding to the resistor 5 of the shunt resistor 1, and a pair of electrodes 206 and 207 connected to both ends of the resistor 205. Electrodes 206 and 207 correspond to electrodes 6 and 7 of the shunt resistor 1. The shunt resistor 200 has a protrusion 211 corresponding to the protrusion 11 of the shunt resistor 1, and the protrusion 211 comprises a part of the resistor 205 and a part of the electrodes 206 and 207. The protrusion 211 comprises voltage detection sections 220 and 221, which are parts of the electrodes 206 and 207 arranged symmetrically with respect to the resistor 205.

[0034] Figure 9 is a graph showing the relationship between the length t3 of the protrusion 211 in the second direction and the rate of change of resistance of the shunt resistor 200. Figure 9 shows the results when a copper-manganese alloy is used as the resistor 205 for the shunt resistor shape shown in Figure 8. The vertical axis of Figure 9 shows the rate of change of resistance when the temperature of the shunt resistor 200 rises from 25°C to 100°C. The results in Figure 9 show that the rate of change of resistance of the shunt resistor 200 depends on the length t3. More specifically, the rate of change of resistance decreases as the length t3 increases.

[0035] Figure 10 is a graph showing the relationship between the length t1 of the protrusion 11 of the shunt resistor 1 and the rate of change of the resistance value of the shunt resistor 1. Figure 10 shows the results when a copper-manganese alloy is used as the resistor 5 for the shape of the shunt resistor shown in Figure 2. The length t2 of the recess 12 is the same as the length t1. The vertical axis of Figure 10 shows the rate of change of resistance when the temperature of the shunt resistor 1 rises from 25°C to 100°C. The results in Figure 10, similar to the results in Figure 9, show that the rate of change of resistance value of the shunt resistor 1 depends on the length t1, and the rate of change of resistance value decreases as the length t1 increases. For example, when the length t1 is 2 mm, the rate of change of resistance value of the shunt resistor 1 is approximately 0%.

[0036] Furthermore, as shown in Figure 10, the rate at which the resistance change rate of shunt resistor 1 decreases is the same as the rate at which the resistance change rate of shunt resistor 200 decreases, as shown in Figure 9. In other words, the results in Figure 10 indicate that the temperature-dependent resistance change rate of shunt resistor 1 depends on the length t1 of the protrusion 11, not on the recess 12. Therefore, the results in Figure 10 indicate that the temperature coefficient of resistance of shunt resistor 1 can be corrected and reduced by adjusting the length t1.

[0037] Figure 11 is a graph showing the rate of change in resistance values ​​for shunt resistor 1 and shunt resistor 200, respectively. Figure 11 shows the rate of change in resistance values ​​of shunt resistors 1 and 200 due to changes in the lengths t1 and t3 of the protrusions 11 and 211 at a predetermined temperature (constant temperature). The length t2 of the recess 12 is the same as the length t1. The results in Figure 11 show that in shunt resistor 200, which does not have a recess 12, the resistance value changes significantly depending on the length t3 of the protrusion 211. For example, the resistance value of shunt resistor 200 when the length t3 is 1.5 mm is about 8% lower than the resistance value when the length t3 is 0 mm. This is because forming the protrusion 211 increases the length of the resistor 205 in the second direction, and the resistance value of the resistor 205 changes.

[0038] As shown in Figure 11, in the shunt resistor 1 having the recess 12, the change in the resistance value of the shunt resistor 1 due to a change in length t1 is suppressed. This is because the length of the resistor 5 in the second direction is kept constant by forming the recess 12 which has a side surface 5d of the resistor 5. In other words, by forming the recess 12, it is possible to suppress the change in the resistance value of the shunt resistor 1 due to the formation of the protrusion 11.

[0039] Therefore, by adjusting the length t1 of the protrusion 11 and the length t2 of the recess 12 of the shunt resistor 1 according to the size and shape of the shunt resistor 1, it is possible to satisfy the desired TCR while maintaining the desired resistance value. Accordingly, according to this embodiment, it is possible to reduce the temperature coefficient of resistance of the shunt resistor 1 while maintaining the desired resistance value with a simple structure in which a protrusion 11 having a part of the resistor 5 and a part of the electrodes 6 and 7 is formed on the side surface 1a of the shunt resistor 1, and a recess 12 having the side surface 5d of the resistor 5 is formed on the side surface 1b of the shunt resistor 1.

[0040] Figure 12 is a perspective view showing another embodiment of the shunt resistor 1, and Figure 13 is an enlarged view of the protrusion 11 of Figure 12. The configuration of this embodiment, which is not specifically described, is the same as that of the embodiment described with reference to Figures 1 to 3, so the redundant description is omitted. The resistor 5 of this embodiment has a notch 25. The notch 25 extends parallel to the end faces 5a and 5b (in the second direction shown in Figure 2). The notch 25 has a slit-like shape that extends in a straight line. The notch 25 is formed on the side surface 5c of the resistor 5 and extends in a straight line from the side surface 5c toward the inside of the shunt resistor 1 (towards the center of the shunt resistor 1).

[0041] By forming such a notch 25 in the resistor 5, the resistance value of the shunt resistor can be adjusted, and in addition, the TCR of the shunt resistor 1 can be finely adjusted. Specifically, the narrower the width W3 in the first direction of the notch 25 and the larger the length t4 in the second direction, the larger the TCR can be. In this embodiment as well, the current detection device 30 described with reference to Figures 4 and 5 and the voltage detection terminals 38, 39 described with reference to Figure 6 can be applied.

[0042] Next, the manufacturing method of the shunt resistor 1 will be described. Figures 14(a) to 14(f) show an example of the manufacturing process of the shunt resistor 1. In Figures 14(a) to 14(f), bolt holes 8 and 9 are omitted.

[0043] First, as shown in Figure 14(a), a long (strip-shaped) shunt resistor base material 60 (metal plate) is prepared with electrodes 6 and 7 connected to both ends of the resistor 5 in the first direction. Next, as shown in Figure 14(b), the shunt resistor base material 60 is cut in the direction in which the electrodes 6, resistor 5, and electrode 7 are aligned (i.e., the first direction). Specifically, the shunt resistor base material 60 is cut in the first direction and in a convex shape. This convex shape corresponds to the shape of the protruding portion 11 of the shunt resistor 1. By cutting the shunt resistor base material 60 in the first direction and in a convex shape, the side surface 1a and the protruding portion 11 of the shunt resistor 1 (first shunt resistor 1A) are formed (Figure 14(c)).

[0044] Next, as shown in Figure 14(c), the shunt resistor base material 60 is cut in a convex shape in the first direction, similar to Figure 14(b), leaving a gap in the second direction from the protrusion 11 and the side surface 1a. As a result, the first shunt resistor 1A is separated from the shunt resistor base material 60, and the side surface 1b of the first shunt resistor 1A, the recess 12 of the first shunt resistor 1A, the protrusion 11 of the other shunt resistor 1 (second shunt resistor 1B), and the side surface 1a of the second shunt resistor 1B are formed (Figure 14(d)).

[0045] Next, as shown in Figures 14(e) and 14(f), similar to Figures 14(c) and 14(d), the shunt resistor base material 60 is cut in a convex shape in the first direction, leaving a gap in the second direction from the protrusion 11 and side surface 1a of the second shunt resistor 1B. As a result, the second shunt resistor 1B is separated from the shunt resistor base material 60, and the side surface 1b and recess 12 of the second shunt resistor 1B are formed. Multiple shunt resistors 1 are manufactured by repeating the process shown in Figures 14(c) to 14(f).

[0046] The manufacturing method shown in Figures 14(a) to 14(f) allows for the simple production of the shunt resistor 1 and enables the efficient use of the shunt resistor base material 60. As a result, costs can be reduced.

[0047] Figures 15 to 18 are schematic diagrams showing yet another embodiment of the shunt resistor 1. The configuration of this embodiment, which is not specifically described, is the same as that of the embodiment described with reference to Figures 1 to 3, so the redundant description is omitted. In Figures 15 to 18, the bolt holes 8 and 9 are not shown. In the embodiments shown in Figures 15 to 18, the current detection device 30 described with reference to Figures 4 and 5 and the voltage detection terminals 38 and 39 described with reference to Figure 6 can also be applied.

[0048] In one embodiment, as shown in Figure 15, the sides 11a, 11b of the protrusion 11 and the sides 12a, 12b of the recess 12 may be formed obliquely with respect to the second direction (see Figure 2). In the example shown in Figure 15, the sides 11a, 11b extend away from the resistor 5. Side 12a is formed parallel to side 11a, and side 12b is formed parallel to side 11b.

[0049] In one embodiment, as shown in Figure 16, the voltage detection units 20 and 21 may each have notches 20a and 21a extending from the sides 11a and 11b toward the resistor 5. Furthermore, in one embodiment, as shown in Figure 17, the width W2 of the recess 12 may be greater than the width W1 of the protrusion 11, and as shown in Figure 18, the width W2 may be smaller than the width W1.

[0050] Figure 19 is a schematic diagram showing another embodiment of the manufacturing method of the shunt resistor 1. As shown in Figure 19, the shunt resistor 1 may be manufactured by punching out the outer shape of the shunt resistor 1 from the shunt resistor base material 60. As shown in Figure 20, the shunt resistor 1 of the embodiment shown in Figure 17 may be manufactured by a method similar to the method described with reference to Figure 19.

[0051] Figure 21 is a perspective view showing another embodiment of the current detection device 30, and Figure 22 is a side view of the current detection device 30 shown in Figure 21. The current detection device 30 of this embodiment includes a shunt resistor 1. In other words, the current detection device 30 of this embodiment is the shunt resistor 1 itself. The shunt resistor 1 shown in Figures 21 and 22 shows another embodiment of the shunt resistor 1 described with reference to Figures 1 to 7 and Figures 10 to 20. The configuration of the shunt resistor 1 of this embodiment, which is not specifically described, is the same as that of the embodiment described with reference to Figures 1 to 3, so a redundant explanation is omitted.

[0052] In this embodiment, electrodes 6 and 7 have first wall portions 66b and 67b along a first direction that form part of the protrusion 11, and second wall portions 66a and 67a along a second direction that form part of the protrusion 11. The first wall portions 66b and 67b are formed on the same plane as the side surface 5c of the resistor 5. The second wall portions 66a and 67a correspond to the aforementioned side surfaces 11a and 11b. In this embodiment, the first wall portion 66b and the first wall portion 67b are of the same length, and the second wall portion 66a and the second wall portion 67a are of the same length.

[0053] The electrode 6 has a detection area 66 defined by a first wall portion 66b, a second wall portion 66a, a starting end portion 66c which is the boundary line between the protrusion 11 and the main body 6f of the electrode 6, and a contact surface 6a which at least a part of which contacts the resistor 5. The electrode 7 has a detection area 67 defined by a first wall portion 67b, a second wall portion 67a, a starting end portion 67c which is the boundary line between the protrusion 11 and the main body 7f of the electrode 7, and a contact surface 7a which at least a part of which contacts the resistor 5.

[0054] The main bodies 6f and 7f are the parts of electrodes 6 and 7 other than the parts that form the protruding portions 11. In other words, the main bodies 6f and 7f are the parts that form the main current path. The main current is the primary flow of current. Current flows through the protruding portions 11 as well, but mainly through the main body 6f, the main body of the resistor 5 (the part of the resistor 5 other than the part 14), and the main body 7f. The starting point is an imaginary straight line extending from the sides 6c and 7c of electrodes 6 and 7 (main bodies 6f and 7f) toward the resistor 5.

[0055] As shown in Figures 21 and 22, in this embodiment, the thickness of electrodes 6 and 7 is greater than the thickness of the resistor 5. As shown in Figure 22, the back surfaces of electrodes 6 and 7 and the back surface of the resistor 5 are on the same plane, and the surfaces 6e and 7e of electrodes 6 and 7 are higher than the surface 5e of the resistor 5. A step 18 is formed by the surface 6e of electrode 6, the contact surface 6a, and the surface 5e of resistor 5, and a step 19 is formed by the surface 7e of electrode 7, the contact surface 7a, and the surface 5e of resistor 5. A space SP is formed by the steps 18 and 19 and the surface 5e.

[0056] In other words, the detection regions 66 and 67 protrude beyond the resistor 5 in the thickness direction of the current detection device 30 (the thickness direction of the shunt resistor 1). The thickness direction of the current detection device 30 (shunt resistor 1) is the direction perpendicular to both the first and second directions. With this structure of the shunt resistor 1, when a substrate such as a current detection circuit board 34 is placed on the surface of the shunt resistor 1, an air gap (space SP) can be formed between the resistor 5 and the substrate. This prevents the heat generated by the resistor 5 from being directly transmitted to the substrate. It also becomes possible to place wiring for voltage detection (for example, voltage signal wiring 46 and 47) on the space SP. The resistor 5 does not exist between the detection regions 66 and 67. Therefore, the current flowing through the shunt resistor 1 avoids the surfaces of the detection regions 66 and 67, enabling stable voltage detection. In one embodiment, the electrodes 6 and 7 and the resistor 5 may be of the same thickness. Furthermore, in one embodiment, the shunt resistor 1 may not have a recess 12.

[0057] Figure 23 is an enlarged view of the protruding portion 11 in Figure 21. In the embodiments described with reference to Figures 1 to 3, the voltage detection units 20 and 21 comprise the entire portion forming the protruding portion 11 of the electrodes 6 and 7. However, in this embodiment, the voltage detection units 20 and 21 are arranged in the detection regions 66 and 67 with a gap between them and the starting ends 66c and 67c. The position and shape of the voltage detection units 20 and 21 are not limited to those shown in Figure 23.

[0058] Figure 24 is a schematic diagram illustrating the positions of the voltage detection units 20 and 21, and Figure 25 is a graph showing the change in the resistance value of the shunt resistor 1 due to temperature changes at each detection position shown in Figure 24. Figure 25 shows the simulation results of the temperature characteristics of the resistance value of the shunt resistor 1 when the voltage detection units 20 and 21 are placed at detection positions A to D in Figure 24. In the simulation, the voltage drop across the shunt resistor 1 (voltage across the resistor 5) was measured from the voltage detection units 20 and 21 at each of the detection positions A to D, and the resistance value of the shunt resistor 1 was calculated from the measured voltage. In the simulation, the material of the resistor 5 was assumed to be a Ni-Cr alloy. In addition, in the simulation, the lengths t1 of the second walls 66a and 67a and the lengths PW of the first walls 66b and 67b were both set to 2 mm.

[0059] For example, if the voltage detection units 20 and 21 are placed at the starting ends 66c and 67c, that is, on the main current side (the main body 6f and 7f side), the temperature characteristics of the resistance value of the shunt resistor 1 obtained from the voltage detection units 20 and 21 will approximate the temperature characteristics of the resistor 5 itself. Therefore, since the detection position D is close to the starting ends 66c and 67c, the temperature characteristics of the shunt resistor 1 when the voltage detection units 20 and 21 are placed at the detection position D will be similar to the temperature characteristics of the resistor 5.

[0060] On the other hand, as shown in Figure 25, the further the voltage detection units 20 and 21 are from the starting ends 66c and 67c and closer to the ending ends (first wall portions 66b and 67b), the more clockwise the slope of the temperature characteristic becomes (the slope of the temperature characteristic becomes smaller). For example, the temperature characteristic at detection unit D has a positive slope, and the slope is relatively large, but by arranging the voltage detection units 20 and 21 at detection positions A and C, the slope of the temperature characteristic becomes smaller. It is also possible to have a negative temperature characteristic (negative temperature characteristic) as at detection positions A and B. In this way, the temperature characteristic of the resistance value of the shunt resistor 1 changes depending on the position of the voltage detection units 20 and 21 in the second direction within the detection regions 66 and 67.

[0061] In particular, between detection position B and detection position C, there exists a region where the slope of the temperature characteristic of the resistance value of the shunt resistor 1 (i.e., TCR) is almost zero over a wide temperature range. Detection unit C is located 0.5 mm away from the starting ends 66c and 67c, and detection position B is located 1.0 mm away from the starting ends 66c and 67c. Therefore, good TCR characteristics can be obtained by positioning the voltage detection units 20 and 21 at a distance of 0.5 mm or more from the starting ends 66c and 67c. Preferably, the distance from the starting ends 66c and 67c to where the voltage detection units 20 and 21 are located is between 0.5 mm and 1.0 mm.

[0062] As described above, since the TCR changes depending on the position of the voltage detection units 20 and 21, it is possible to compensate for variations in the characteristics of the resistive material (the material of the resistor 5) itself and variations in the processing of the resistive material by adjusting the position of the voltage detection units 20 and 21 during the design and manufacturing process of the shunt resistor 1.

[0063] For example, the reference positions of the voltage detection units 20 and 21 are set according to the temperature characteristics of a predetermined resistive material. If the actual temperature characteristics of the resistive material are observed to be more positive than expected, the voltage detection units 20 and 21 are adjusted closer to the end (first wall portion 66b, 67b) than the reference position. Conversely, if the temperature characteristics of the resistive material are observed to be more negative than expected, the voltage detection units 20 and 21 are adjusted closer to the starting end portion 66c, 67c. In this way, variations in the characteristics of the resistive material can be corrected by adjusting the position of the voltage detection units 20 and 21.

[0064] As described above, in this embodiment, the desired temperature coefficient of resistance can be satisfied by arranging the voltage detection units 20 and 21 at a desired position in the detection regions 66 and 67 of the electrodes 6 and 7, which constitute a part of the protruding portion 11 of the current detection device 30, with a gap between them and the starting ends 66c and 67c.

[0065] Figures 26A and 26B are schematic diagrams showing yet another embodiment of the current detection device 30. The configuration of this embodiment, which is not specifically described, is the same as that of the embodiment described with reference to Figures 21 to 25, so the redundant description is omitted. As shown in Figures 26A and 26B, the current detection device 30 of this embodiment comprises a shunt resistor 1 and a wiring board 33. The wiring board 33 is provided with detection pads 33a and 33b. Wiring (not shown) is formed on the wiring board 33 for transmitting a voltage signal (voltage of the resistor 5) from the shunt resistor 1, and the detection pads 33a and 33b are connected to the above-mentioned wiring (not shown).

[0066] The detection pads 33a and 33b are thin metallic films and are connected to voltage detection units 20 and 21 (not shown in Figures 26A and 26B). Figure 26B shows the state in which the position of the wiring board 33 is shifted in a second direction (see Figure 23) from Figure 26A and the wiring board 33 is connected to the detection regions 66 and 67. In this embodiment, the portions on the detection regions 66 and 67 connected to the detection pads 33a and 33b become the voltage detection units 20 and 21.

[0067] As shown in Figures 26A and 26B, the positions of the detection pads 33a and 33b connected to the detection regions 66 and 67 can be adjusted by adjusting the relative position of the shunt resistor 1 and the wiring board 33. In other words, the positions of the voltage detection units 20 and 21 can be adjusted by adjusting the relative position of the shunt resistor 1 and the wiring board 33. Therefore, the TCR characteristics can be corrected by adjusting the relative position of the shunt resistor 1 and the wiring board 33. The width of the detection pads 33a and 33b in the second direction is smaller than t1, and is a size that allows for position adjustment. The smaller the width of the detection pads 33a and 33b, the better the temperature characteristics of the shunt resistor 1 tend to be, but the size of the detection pads 33a and 33b should be set considering the bonding strength and the risk of disconnection. Furthermore, by adjusting the position of the detection pads 33a and 33b, it is possible to change the resistance value of the current detection device 30, and this can also be applied to the resistance value correction function.

[0068] The method for aligning the wiring board 33 and the shunt resistor 1 is as follows. First, in the initial flow, the inherent temperature characteristics of the shunt resistor 1 are measured by using a detection probe to measure the resistance value of the shunt resistor 1 at predetermined detection positions at two points (or more points) at a reference temperature of 25°C (or 20°C) and a predetermined temperature (e.g., 125°C). This determines the connection position of the wiring board 33. Alignment of the wiring board 33 and the shunt resistor 1 can be performed by image detection or by providing reference pins on the shunt resistor 1 or the jig to vary its position. In this way, a mechanism that can relatively control the initial characteristics and the voltage detection lead value can be configured within the process.

[0069] Figures 27A and 27B are schematic diagrams showing yet another embodiment of the current detection device 30. The configuration of this embodiment, which is not specifically described, is the same as that of the embodiment described with reference to Figures 21 to 25, so redundant descriptions are omitted. As shown in Figures 27A and 27B, the current detection device 30 of this embodiment includes a shunt resistor 1 and detection members 72 and 73. The detection members 72 and 73 are connected to voltage detection units 20 and 21 (not shown in Figures 27A and 27B) of detection regions 66 and 67.

[0070] Figure 27B shows the state in which the positions of the detection members 72 and 73 are shifted in a second direction from Figure 27A and connected to the detection regions 66 and 67. In this embodiment, the portions on the detection regions 66 and 67 connected to the detection members 72 and 73 become the voltage detection units 20 and 21. Examples of detection members 72 and 73 include pads made of solder or other metals, pin terminals, lead frames, etc.

[0071] As shown in Figures 27A and 27B, the position of the voltage detection units 20 and 21 (not shown in Figures 27A and 27B) can be adjusted by adjusting the connection position of the detection members 72 and 73. Therefore, the TCR characteristics can be corrected by adjusting the position of the detection members 72 and 73. The width of the detection members 72 and 73 in the second direction is smaller than t1, and is small enough to allow for position adjustment. The smaller the width of the detection members 72 and 73, the better the temperature characteristics of the shunt resistor 1 tend to be, but the size of the detection members 72 and 73 should be set considering the connection quality and the risk of disconnection. Furthermore, by adjusting the position of the detection members 72 and 73, it is possible to change the resistance value of the current detection device 30, and this can also be applied to the resistance value correction function.

[0072] Figures 28A and 28B illustrate the positions of the voltage detection units 20 and 21. As described above, if the voltage detection units 20 and 21 are placed at the starting ends 66c and 67c, the temperature characteristics of the resistance value of the shunt resistor 1 obtained from the voltage detection units 20 and 21 approximate the temperature characteristics of the resistor 5 itself. Therefore, in this embodiment, the voltage detection units 20 and 21 are placed within the detection regions 66 and 67, avoiding the starting ends 66c and 67c.

[0073] In one embodiment, the voltage detection unit 20 is located in the region 75 shown by the diagonal lines in Figure 28A. Although not shown, the voltage detection unit 21 is located symmetrically to the voltage detection unit 20 with respect to the resistor 5. Specifically, the voltage detection units 20 and 21 are located in the terminating 3 / 4 of the detection regions 66 and 67 (on the first wall portion 66b and 67b side) in the second direction.

[0074] While Cu is generally used as the material for electrodes 6 and 7, in order to minimize the influence of the temperature characteristics of the resistance value of this electrode material, in one embodiment, as shown in Figure 28B, the voltage detection units 20 and 21 may be positioned closer to the resistor 5 than the center (center line CL) of the detection regions 66 and 67 in the first direction. Specifically, the voltage detection unit 20 may be positioned in the region 75 shown by the diagonal lines in Figure 28B. Although not shown, the voltage detection unit 21 is positioned symmetrically to the voltage detection unit 20 with respect to the resistor 5. Region 75 in Figure 28B is the terminating 3 / 4 (first wall portion 66b, 67b side) of the detection regions 66 and 67 in the second direction, and the resistor 5 side 1 / 2 of the detection regions 66 and 67 in the first direction.

[0075] As described above, in this embodiment, the shunt resistor 1 has steps 18 and 19. Therefore, in one embodiment, a voltage detection member for detecting the voltage of the resistor 5 may be connected across the steps 18 and 19 (covering the contact surfaces 6a and 7a). This reduces the influence of the temperature characteristics of the resistance values ​​of the electrode materials 6 and 7, and allows for more accurate measurement of the voltage generated at both ends 5a and 5b of the resistor 5. In addition, the steps 18 and 19 prevent the voltage detection member from coming into contact with the resistor 5.

[0076] Figure 29 is a schematic diagram showing an example in which the voltage detection member is connected across steps 18 and 19. In this embodiment, the current detection device 30 comprises a wiring board 33 and a shunt resistor 1. The wiring board 33 is equipped with detection pads 33a and 33b as voltage detection members. The detection pads 33a and 33b are connected to voltage signal wiring 48 and 49 via via holes 52 and 53. The detection pads 33a and 33b are connected to detection areas 66 and 67, spanning across steps 18 and 19 (covering the contact surfaces 6a and 7a). With this configuration, the voltage detection units 20 and 21 (not shown in Figure 29) can be positioned further inside the electrodes 6 and 7, allowing the voltage of the resistor 5 to be measured without being affected by the characteristics of the electrodes 6 and 7. As a result, in this embodiment, the voltage generated at both ends 5a and 5b of the resistor 5 can be measured with greater accuracy.

[0077] As described above, the resistor 5 is connected to the electrodes 6 and 7 by means of welding (for example, electron beam welding, laser beam welding, or brazing). Therefore, irregularities are created at the joint between the resistor 5 and the electrodes 6 and 7 due to welding marks. However, in this embodiment, since the shunt resistor 1 has steps 18 and 19, the voltage detection member can be connected across the steps 18 and 19 without being affected by the welding marks.

[0078] Figure 30 is a schematic diagram showing another embodiment of the protrusion 11. In some cases, it is not necessary to make the temperature characteristic of the resistance value of the shunt resistor 1 have a negative slope. In this case, the length t1 of the second wall portions 66a and 67a does not need to be longer than necessary. Shortening the length t1 of the second wall portions 66a and 67a can contribute to miniaturization and cost reduction of the shunt resistor 1. In one embodiment, as shown in Figure 30, the length PW of the first wall portions 66b and 67b may be longer than the length t1 of the second wall portions 66a and 67a. For example, PW:t1 may be 4:3, or PW:t1 may be 3:2.

[0079] Furthermore, in one embodiment, the corners of the protruding portion 11 may be rounded, as shown in Figure 31. In this embodiment as well, the ratio of the lengths of t1 and PW may be the same as in the embodiment of Figure 30. Furthermore, in one embodiment, the corners of the protruding portion 11 may be chamfered. In this case as well, the ratio of the lengths of t1 and PW may be the same as in the embodiment of Figure 30.

[0080] Figure 32 is a schematic diagram showing yet another embodiment of the current detection device 30. The configuration of this embodiment, which is not specifically described, is the same as that of the embodiment described with reference to Figures 21 to 31, so the redundant description is omitted. In this embodiment as well, the current detection device 30 is equipped with a shunt resistor 1. In other words, the current detection device 30 of this embodiment is the shunt resistor 1 itself. In this embodiment, slits 76 and 77 are formed in the electrodes 6 and 7. Also, in this embodiment, the shunt resistor 1 does not have a recess 12. Specifically, the slits 76 and 77 extend from the sides 6c and 7c toward the inside of the electrodes 6 and 7 (extending in the second direction (see Figure 21)). In this embodiment, the slits 76 and 77 form a protrusion 11. In this embodiment as well, the embodiments of Figures 26A to 31 can be applied, and the effects described with reference to Figures 21 to 31 can be achieved.

[0081] The embodiments described above are intended to enable persons with ordinary skill in the art to implement the present invention. Various modifications of the above embodiments can be made naturally by those skilled in the art, and the technical idea of ​​the present invention can be applied to other embodiments as well. Therefore, the present invention is not limited to the embodiments described, but is to be interpreted in the broadest sense according to the technical idea defined by the claims. [Industrial applicability]

[0082] The present invention is applicable to current detection devices, particularly current detection devices using shunt resistors. [Explanation of symbols]

[0083] 1. Shunt resistor 1A First shunt resistor 1B Second shunt resistor 1a,1b side 5 Resistors 5a, 5b Both ends (connecting surfaces on both sides) 5c,5d side 5e surface 6,7 electrodes 6a,7a Contact surface 6b,6c,6d Side 7b,7c,7d Side 6e,7e surface 6f, 7f main unit 8,9 Bolt holes 11 Protrusion 11a,11b Side 12 recesses 12a,12b,12c side 14 parts 16,17 Voltage detection position 18, 19 steps 20,21 Voltage detection unit 20a, 21a Notches 25 Notch 30 Current detection device 31 Voltage output device 32 cases 33 Wiring board 33a, 33b detection pads 34 Current detection circuit board 35 Output terminals 36,37 Voltage terminal pads 38,39 Voltage detection terminals 46,47 Voltage signal wiring 48,49 Voltage signal wiring 50 Ground wiring 52, 53 Beer Hall 60 Shunt resistor base material 66,67 Detection area 66a,67a 2nd wall part 66b,67b 1st wall part 66c,67c Starting end 72,73 Detection members 75 areas 76,77 Slits 100 Shunt Resistors 105 Resistor 106,107 electrode 108,109 bolt holes 120,121 Voltage detection unit 200 Shunt Resistors 205 Resistor 206,207 electrode 211 Protrusion 220,221 Voltage detection unit

Claims

1. A current detection device used for current detection, A resistor and The resistor comprises a pair of electrodes connected to both ends in the first direction, The current detection device is It has a protrusion that extends in a second direction, The protruding portion has a part of the resistor and a part of the pair of electrodes, The first direction is the direction in which the pair of electrodes are arranged, and the second direction is the direction perpendicular to the first direction. Each electrode has a first wall portion along the first direction that forms a part of the protrusion, and a second wall portion along the second direction that forms a part of the protrusion. Each electrode has a detection area defined by the first wall, the second wall, the starting end which is the boundary between the protruding portion and the body of the electrode, and a contact surface which at least a part of it contacts the resistor. Each electrode has a voltage detection unit positioned in the detection region at a distance of 0.5 mm or more from the starting end. The current detection device further comprises a wiring board, The current detection device comprises a wiring board that overlaps the protruding portion, is connected to the voltage detection unit, and has voltage signal wiring spaced apart from each of the electrodes.

2. The current detection device according to claim 1, wherein the voltage detection unit is located closer to the resistor than the center of the detection area.

3. The current detection device according to claim 1 or 2, wherein the detection region protrudes more than the resistor in the thickness direction of the current detection device.

4. The current detection device according to any one of claims 1 to 3, wherein the length of the first wall portion is longer than the length of the second wall portion.

Images