WO2020008845A1 - Shunt device - Google Patents

Abstract

The present invention provides a shunt device having improved current-detection precision, in which large-width metal frame terminals are connected to a shunt resistor. A shunt device (1), comprises: a shunt resistor (2), provided with a resistance element (5) made of a resistance alloy, and a pair of electrodes (6, 7) made of a highly electroconductive metal and joined to both ends of the resistance element (5); and a pair of large-width metal frame terminals (3, 4) connected to the shunt resistor (2). The electrodes (6, 7) comprise steps (12, 13) demarcating a voltage detection part (10, 11). The frame terminals (3, 4) are connected to the voltage detection parts (10, 11) located between the steps (12, 13) and the resistance element (5).

Description

Shunt device

The present invention relates to a shunt resistor for current detection, and in particular, to a shunt resistor in which electrodes made of metal are joined to both ends of a resistor made of a resistance alloy, and an extraction terminal for detecting a voltage generated at both ends of the resistor. And a shunt device connected to the shunt device.

Shunt resistors have been widely used for large current detection applications, such as monitoring the charge / discharge current of onboard batteries. Such a shunt resistor includes a resistor made of a resistance alloy plate and electrodes made of a copper material fixed to both ends thereof.A detection electrode portion is provided at an appropriate place of the electrode, and for example, an aluminum wire is provided there. , The voltage generated at both ends of the resistor is detected (see JP-A-2016-054224, JP-A-2015-184206, JP-A-2017-00419, JP-A-2001-118701). .

Such a shunt resistor has excellent detection accuracy for a large current, has a small temperature drift, does not generate excessive heat even when a large current is applied, and has a low resistance value of 1 mΩ or less. Is required. In order to detect a voltage generated in a resistor having such a low resistance value with high accuracy, the position of a terminal for detecting a voltage generated at both ends of the resistor is related.

That is, in a resistor having a low resistance value of 1 mΩ or less, the internal resistance of the electrode cannot be ignored, and the voltage measurement result varies depending on the connection position of the voltage detection terminal. There is a problem that accuracy is not stable.

By the way, in recent years, in a current detection resistor used in a large current circuit, a demand has been seen for a wide metal frame terminal as an extraction terminal for detecting a voltage. When such a wide metal frame terminal is used as a lead terminal, unlike a terminal having a small diameter such as wire bonding, the voltage detection value tends to vary depending on the mounting position of the wide metal frame terminal.

The present invention has been made based on the above circumstances, and a shunt device in which a wide metal frame terminal is connected as a voltage detection extraction terminal to a low resistance shunt resistor to improve current detection accuracy. The purpose is to provide.

One embodiment of the present invention provides a shunt resistor including a resistor made of a resistance alloy, and a pair of electrodes made of a high-conductivity metal joined to both ends of the resistor, and a pair of the shunt resistor. A pair of wide metal frame terminals connected to the electrodes, wherein the electrodes have a step for partitioning a voltage detection unit, and the frame terminals are located between the steps and the resistor. A shunt device connected to the voltage detection unit.

Since the electrode has a step, the connection position (fixed position) of the frame terminal to the electrode is specified. By providing the steps, it is possible to suppress a phenomenon in which the variation in the temperature coefficient of resistance increases. In other words, even if the frame terminal is arranged at a specific position adjacent to the resistor, and even if the frame terminal protrudes, it is possible to suppress a phenomenon that the variation of the temperature coefficient of resistance increases. As a result, the shunt device can improve the current detection accuracy.

It is a perspective view showing one embodiment of a shunt device. FIG. 4 is a diagram illustrating a relationship between a connection position of a frame terminal and a voltage detection position of the frame terminal. It is a top view of a shunt device. FIG. 4 is a sectional view taken along line AA of FIG. 3. It is a figure showing other embodiments of a crevice. It is a figure showing other embodiments of a level difference. It is a figure explaining an effect by formation of a level difference. 9 is a graph showing an effect of forming a step. It is a figure showing still another embodiment of a level difference. It is a figure showing still another embodiment of a level difference. It is a figure showing still another embodiment of a level difference. It is a figure which shows the electric current which advances to S-shaped direction.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings described below, the same or corresponding components are denoted by the same reference numerals, and redundant description will be omitted.

FIG. 1 is a perspective view showing an embodiment of the shunt device 1. As shown in FIG. 1, the shunt device 1 includes a shunt resistor 2 and a pair of wide metal frame terminals (lead frame terminals) 3 and 4 fixed to the shunt resistor 2. Hereinafter, in this specification, the shunt resistor 2 may be simply referred to as the resistor 2.

The resistor 2 includes a resistor 5 made of a resistance alloy having a predetermined thickness and width, and a pair of electrodes 6 and 7 made of a high conductivity metal joined to both ends of the resistor 5. Both end faces of the resistor 5 are joined to end faces of the electrodes 6 and 7 by means of welding (for example, electron beam welding, laser beam welding, or brazing).

と し て As an example of the material of the resistor 5, a low-resistance alloy such as a Cu—Mg—Ni-based alloy can be given. An example of the material of the electrodes 6 and 7 is copper (Cu). Examples of the material of the frame terminals 3 and 4 include copper (Cu) plated with tin (Sn) or unplated copper.

Generally, in a resistor having a low resistance value of 1 mΩ or less, the potential distribution generated by the resistance component inside the electrode cannot be ignored. Copper (Cu), which is a material of the electrodes 6 and 7, has a high temperature coefficient of resistance (TCR). Therefore, as the connection positions of the frame terminals 3 and 4 are further away from the resistor 5, the temperature coefficient of resistance (TCR) indicating the rate of change in resistance value due to temperature increases. As a result, the current cannot be accurately detected. Therefore, it is ideal that the two detection terminals detect voltages at positions closer to the resistor and at substantially equal distances from the resistor.

In the case of the shunt device described above, the variation caused by the connection of the frame terminals being displaced has a large effect on the current detection accuracy, and as a result, the current detection accuracy varies. FIG. 2 is a diagram illustrating the relationship between the connection positions of the frame terminals and the voltage detection positions of the frame terminals.

When the wide frame terminals 3 and 4 are connected to the electrodes 6 and 7, the substantial voltage detection position is at the center of the contact surface of the frame terminal with the electrode, as shown by the black circle X in FIG. (A = A '). Therefore, when the connection positions of the frame terminals are not clearly determined, the distance between the resistor and the frame terminals on both sides thereof may be different. In the example shown in FIG. 2, the distance B between the resistor and the detection position of the frame terminal 4 is smaller than the distance B 'between the resistor and the detection position of the frame terminal 3 (B <B').

Unlike the case of connecting a terminal having a small diameter such as a bonding wire (for example, see Patent Document 1), it is generally difficult to clearly specify the connection position of the frame terminal. Tends to vary. In particular, when welding the frame terminals to the electrodes, it is difficult to accurately determine the connection positions of the frame terminals, and the influence of the variation is likely to occur significantly.

Therefore, in the present invention, in order to improve current detection accuracy, the shunt device 1 includes a structure for specifying the connection position of the frame terminals 3 and 4. Hereinafter, the detailed structure of the shunt device 1 will be described with reference to the drawings.

FIG. 3 is a plan view of the shunt device 1. FIG. 4 is a sectional view taken along line AA of FIG. In FIG. 3, white arrows indicate the current direction. As shown in FIG. 1, FIG. 3, and FIG. 4, the electrodes 6, 7 are provided with steps 12, 13, which partition the voltage detectors 10, 11 extending in a direction perpendicular to the current direction.

The voltage detector 10 is a part of the electrode 6 adjacent to the resistor 5, and is a part between the resistor 5 and the step 12. The frame terminal 3 is disposed on the voltage detection unit 10 and is connected to the voltage detection unit 10. The frame terminal 4 is disposed on the voltage detection unit 11 and is connected to the voltage detection unit 11. In other words, each of the voltage detection units 10 and 11 forms a voltage detection area.

In the present embodiment, the electrode 6 has the concave groove 22 formed on the surface thereof, and the electrode 7 has the concave groove 23 formed on the surface thereof. The step 12 constitutes a part of the groove 22 (more specifically, the wall on the resistor side), and the step 13 constitutes a part of the groove 23 (more specifically, the wall on the resistor side). are doing. Each of the steps 12, 13 forms a hollow part (space) SP at an adjacent position.

FIG. 5 is a view showing another embodiment of the concave grooves 22 and 23. As shown in FIG. 5, the concave groove 22 may extend to the outer end face 6a of the electrode 6, and the concave groove 23 may extend to the outer end face 7a of the electrode 7.

An example of the dimensions of the shunt device 1 will be described with reference to FIGS. 3 and 4, some of the components of the shunt device 1 are exaggerated for the sake of clarity. As shown in FIG. 3, the length L1 in the longitudinal direction of the resistor 2 is 40 mm, and the length W1 in the width direction of the resistor 2 is 15 mm. The distance D1 between the resistor 5 and the step 12 (that is, the length in the width direction of the voltage detection unit 10) is 2 mm.

の 長 The length W2 of the concave groove 22 in the width direction is 1 mm. As shown in FIG. 4, the depth Dp of the concave groove 22 (that is, the height of the step 12) is 0.5 mm. The thickness t1 of the resistor 2 is 2 mm, and the thickness t2 of the frame terminal 3 is 0.6 mm. The dimensions of the shunt device 1 are not limited to the embodiment shown in FIGS.

The concave grooves 22 and 23 are symmetrically arranged with respect to the resistor 5. Therefore, although not shown, the distance between the resistor 5 and the step 13 is the same as the distance D1, the horizontal length of the step 13 is the same as the length L2, and the length of the concave groove 23 in the width direction. The length is the same as the length W2, and the depth of the concave groove 23 is the same as the depth Dp.

In the present embodiment, the length L2 of the concave groove is smaller than the length W1, and the step 12 is formed in a part of the electrode 6 in the width direction of the resistor 2. FIG. 6 is a view showing another embodiment of the step 12. In FIG. 6, illustration of the frame terminals 3 and 4 is omitted for easy viewing of the drawing. As shown in FIG. 6, the length L2 may be the same as the length W1. In this case, the step 12 is formed on the entire electrode 6 in the width direction of the resistor 2.

As shown in FIG. 1, the frame terminal 3 includes a contact portion 3a that contacts the voltage detection portion 10 of the electrode 6, a vertical portion 3b perpendicular to the contact portion 3a, a vertical portion 3b, and a contact portion 3a. And a bent portion 3c that is parallel to the above. The frame terminals 3 and 4 have the same structure. That is, similarly to the frame terminal 3, the frame terminal 4 includes the contact portion 4a, the vertical portion 4b, and the bent portion 4c. The contact portions 3 a and 4 a of the frame terminals 3 and 4 are connected to the electrodes 6 and 7 on both sides of the resistor 5 so as to be adjacent to the resistor 5.

The user can arrange the frame terminal 3 in the voltage detection unit 10 based on the step 12. More specifically, it is preferable that the user connects the frame terminal 3 to the voltage detection unit 10 so that the step-side end face 3d of the contact portion 3a of the frame terminal 3 is located on the same plane as the step 12. As will be described later, there is no problem even if the connection is made so as to extend over the step 12 and protrude into the hollow portion SP and cover a part of the hollow portion SP. The connection method of the frame terminal 4 to the voltage detection unit 11 is the same as the connection method of the frame terminal 3. It is preferable that the end surface 4 d on the step side of the contact portion 4 a of the frame terminal 4 be located on the same plane as the step 13. According to the present embodiment, since the electrodes 6 and 7 have the steps 12 and 13, the user can specify the connection position (arrangement position) of the frame terminals 3 and 4.

シ ャ ン The shunt device 1 having the steps 12, 13 can provide the following effects. Hereinafter, the effect of the formation of the step 12 will be described with reference to FIG. As described above, the step 12 forms the hollow portion SP at an adjacent position. In the above-described embodiment, the frame terminal 3 is preferably connected to the voltage detection unit 10 such that the end surface 3d on the step side of the contact portion 3a is arranged in the same plane as the step 12. A part of 3 may be disposed so as to extend over the step 12 and protrude into the hollow part SP.

FIG. 7 is a diagram for explaining the effect of the formation of the step 12. When the step 12 is not provided, the voltage detection position P1 is at the center of the contact surface of the frame terminal 3 with the electrode 6. On the other hand, as shown in FIG. 7, when the step 12 is formed, a part of the frame terminal 3 is arranged so as to protrude from the step 12. The voltage detection position P2 is the center of the contact surface of the frame terminal 3 with the electrode 6. Therefore, the distance Da between the resistor 5 and the voltage detection position P2 is smaller than the distance Db between the resistor 5 and the voltage detection position P1.

As described above, the step 12 can limit the contact surface of the frame terminal 3 with the electrode 6 to the inside of the step 12 (that is, the resistor 5 side). Therefore, even if the frame terminal 3 is arranged apart from the resistor 5, the voltage is detected at a position closer to the resistor 5, and the variation occurring at the connection position of the frame terminals 3 and 4 is reduced. Therefore, the shunt device 1 can improve the current detection accuracy.

FIG. 8 is a graph showing the effect of forming the step 12. 8, the horizontal axis represents the relative position of the frame terminal 3 to the electrode 6, and the vertical axis represents the temperature coefficient of resistance.

In FIG. 8, the reference (zero) on the horizontal axis is the position of the frame terminal 3 when the end face of the frame terminal 3 (that is, the end face 3 d on the step side) is located on the same plane as the step 12. When the frame terminal 3 is arranged at a position separated from the resistor 5, the numerical value indicating the position of the frame terminal 3 becomes a positive number. When the frame terminal 3 is arranged at a position close to the resistor 5, the numerical value indicating the position of the frame terminal 3 becomes a negative number.

As shown in FIG. 8, when the step 12 is provided, and the frame terminal 3 is arranged at a position separated from the resistor 5, the frame terminal 3 protrudes from the step 12. The resistance temperature coefficient in this case is smaller than the resistance temperature coefficient when the step 12 is not provided.

The change in the temperature coefficient of resistance when the frame terminal 3 is arranged at a position close to the resistor 5 is as follows. The temperature coefficient of resistance when the step 12 is provided is closer to zero than the temperature coefficient of resistance when the step 12 is not provided (see FIG. 8). The reason is that the potential distribution generated by the formation of the step 12 is different from the potential distribution generated when the step 12 is not formed, and the amount of change in the resistance temperature coefficient with respect to the displacement of the connection position of the frame terminal 3 is This is because it differs depending on the presence or absence. In the present embodiment, as can be seen from FIG. 8, by providing the step 12, it is possible to suppress a phenomenon in which the variation in the temperature coefficient of resistance increases.

In the present embodiment, the steps 12, 13 are formed linearly when viewed from above. More specifically, the steps 12, 13 extend in parallel with the width direction of the resistor 2 (see FIG. 3). However, the shapes of the steps 12, 13 are not limited to the present embodiment.

FIGS. 9 to 11 are views showing still another embodiment of the steps 12 and 13. FIG. 9 to 11, illustration of the frame terminals 3 and 4 is omitted to make the drawings easy to see.

段 As shown in FIG. 9, the steps 12, 13 may be formed in an arc shape when viewed from above. In the embodiment shown in FIG. 9, each of the steps 12 and 13 has a shape curved in a direction away from the resistor 5. The voltage detector 10 is formed between the step 12 and the resistor 5, and the voltage detector 11 is formed between the step 13 and the resistor 5.

As shown in FIG. 10, the steps 12, 13 may be formed in a U-shape when viewed from above. In the embodiment shown in FIG. 10, each of the steps 12 and 13 has a shape protruding in a direction away from the resistor 5. The voltage detector 10 is formed between the step 12 and the resistor 5, and the voltage detector 11 is formed between the step 13 and the resistor 5.

As shown in FIG. 11, the steps 12, 13 may be arranged diagonally across the resistor 5 when viewed from above. In the embodiment shown in FIGS. 1, 3, and 4, the steps 12, 13 are opposed to each other with the resistor 5 interposed therebetween, but in the embodiment shown in FIG. 11, the steps 12, 13 are 5 are arranged diagonally. This arrangement is suitably applied when the current I flows in the S-shaped direction as shown in FIG. As described above, by determining the formation positions of the steps 12 and 13 according to the current direction, the shunt device 1 can improve the current detection accuracy.

Although one embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment, and it goes without saying that the present invention may be implemented in various forms within the scope of the technical idea.

INDUSTRIAL APPLICABILITY The present invention can be suitably used for a shunt device in which a shunt resistor in which electrodes made of metal are joined to both ends of a resistor made of a resistance alloy and a lead terminal for detecting a voltage generated at both ends of the resistor is connected. is there.

Claims (6)

1. A shunt resistor including a resistor made of a resistance alloy and a pair of electrodes made of a high conductivity metal joined to both ends of the resistor,
   A pair of wide metal frame terminals connected to the shunt resistor,
   The electrode includes a step that partitions a voltage detection unit,
   The shunt device, wherein the frame terminal is connected to the voltage detection unit located between the step and the resistor.
2. The shunt device according to claim 1, wherein a length of the step is shorter than a length of the electrode in a width direction.
3. The shunt device according to claim 1, wherein the step is formed in a linear shape, an arc shape, or a U-shape.
4. 2. The shunt device according to claim 1, wherein a part of the frame terminal extends over the step and protrudes into a space formed by the step. 3.
5. The shunt device according to claim 1, wherein one end face of the frame terminal is located on the same plane as the step.
6. The voltage detector is adjacent to the resistor,
   The shunt device according to claim 1, wherein a distance between the resistor and the step is longer than a length of the frame terminal in a width direction.

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