JP2011018759A - Shunt resistor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a shunt resistor that prevents the error of a detection voltage and is miniaturized by achieving a high degree of freedom in the connection positions of current terminals in electrodes and allowing an electric current to uniformly flow in a resistor element concerning a large current detection shunt resistor.SOLUTION: The shunt resistor includes: the resistor element 11 formed of a resistance alloy material; a pair of electrodes 12, 12 fixed to both ends of the resistor element; and small width parts 12a formed between the outer edges A and the inner edges B of the respective electrodes along a resistor axial line direction D. The small width parts 12a are recesses 15 arranged on the side surfaces of the electrodes 12 with equal depths. The electrodes 12 are separated into the outer electrodes 12c on the outer side along the resistor axial line direction D and the inner electrodes 12b on the side of the resistor. The surfaces of the current terminals 16 are fixed to ones of the rectangular shape surfaces of the outer electrodes 12c. The recesses 15 being the small width parts are formed on the surfaces L of the electrodes facing a current terminal drawing direction K.

Description

  The present invention relates to a shunt resistor for detecting a large current, and more particularly to a metal resistor in which electrodes made of a metal material are joined to both ends of a resistor made of a resistance alloy material.

  Conventionally, a shunt resistor having the above-described structure (see, for example, Patent Document 1) has been widely used for large current detection applications such as monitoring charging / discharging current of a vehicle-mounted battery. These shunt resistors are provided with a resistor made of a resistance alloy material and a pair of electrodes made of a copper material fixed to both ends thereof, and a current terminal (bus bar) is connected to each electrode, and a pair of electrodes A voltage detection circuit is connected between appropriate locations.

  Therefore, the current flowing from one current terminal flows into the resistor from one electrode and flows out from the other electrode to the other current terminal. A voltage proportional to the current generated between both ends of the resistor is detected by connecting a voltage detection circuit between both electrodes.

  In such a shunt resistor, in the case of detecting a large current of several tens to several hundreds of amperes, the resistor resistance value is required to be a low resistance value of 1 mΩ or less, and the internal resistance distribution of the resistor and electrode material is required. The impact may not be negligible.

  That is, in such a shunt resistor, the current flowing through the resistor is biased due to the internal resistance distribution of the electrode and the resistor due to the current terminal (bus bar) mounting position of the electrode and the tightening condition of the bolt. A detection error may occur in the voltage generated between the electrodes at both ends of the body.

  Regardless of the current terminal (bus bar) mounting position or bolt tightening situation, the current can flow uniformly through the resistor and the detection voltage can be prevented from getting an error. The problem arises that the shunt resistor becomes longer due to the increase in length. As shunt resistors are miniaturized, stress (mechanical load) is likely to be applied to the shunt resistors themselves due to the connection of the current terminals (bus bars) to the electrodes.

Japanese Patent Laid-Open No. 6-224014

  The present invention was made based on the above-described circumstances, and in the shunt resistor for detecting a large current, the degree of freedom of the connection position of the current terminal in the electrode is high, and the current can flow uniformly through the resistor. Accordingly, an object of the present invention is to provide a shunt resistor that does not cause an error in detection voltage and can be miniaturized.

  The shunt resistor of the present invention includes a resistor made of a resistance alloy material, a pair of electrodes fixed to both ends of the resistor, an outer end face along the resistor axial direction of the electrode, A narrow portion formed between the inner end face and the inner end face. The outside of the narrow part of the electrode has a rectangular parallelepiped shape, and the surface of the current terminal is fixed to any surface of the rectangular parallelepiped shape, and the concave part of the narrow part is formed on the surface of the electrode facing the current terminal drawing direction. ing. As a result, the narrow portion has a current rectifying action, and a uniform current can flow through the resistor.

  Further, the shunt resistor of the present invention can be fixed to the base having a fixed piece that fits into the concave portion of the resistor, and the fixed piece fits into the concave portion of the resistor to fix the resistor to the base. it can.

(A) is a perspective view which shows the shunt resistor of one Example of this invention, (b) is a top view which shows the electric current path | route. It is a figure which shows an example of an electric current path | route, (a) shows a prior art example, (b) shows the example of this invention. It is arrow sectional drawing along CC line in FIG.1 (b) which shows the structural example of various narrow parts, and the part of hatching in a figure is a narrow part cross section. It is a perspective view which shows the example of a connection structure of various electrodes and an electric current terminal. It is a figure which shows the mounting state which accommodated the shunt resistor of this invention in the housing | casing. It is a perspective view which shows the example of fixation structure to the base of the shunt resistor of this invention. It is a perspective view which shows the example of a manufacturing process of the shunt resistor of this invention. It is a perspective view which shows the other example of a manufacturing process of the shunt resistor of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to 8. In addition, in each figure, the same code | symbol is attached | subjected and demonstrated to the same or equivalent member or element.

  As shown in FIG. 1A, this shunt resistor includes a resistor 11 made of a resistance alloy material such as a rectangular parallelepiped Cu—Mn alloy, Ni—Cr alloy, Cu—Ni alloy, and the resistance. And a pair of electrodes 12 and 12 made of a rectangular parallelepiped Cu material fixed to both ends of the body. Each of the pair of electrodes 12 and 12 includes a narrow portion 12a formed between an outer end surface A and an inner end surface B along the resistor axial direction D of the electrode, and the electrode 12 is provided on the inner side. The electrode 12b and the outer electrode 12c are separated.

  Here, the narrow portion 12 a is provided with a recess (groove) 15 having a uniform width and depth on the side surface of the electrode 12. For example, if the cross section of the electrode 12 is 5 mm × 5 mm, the depth and width of the recess 15 are each preferably about 1 mm.

  For fixing the resistor 11 and the electrodes 12 and 12, electron beam welding, pulse energization joining, thermocompression bonding, cold welding, resistance welding, brazing material such as copper or silver, soldering, etc. can be applied. However, it is preferable to use diffusion bonding using pulse current bonding, thermocompression bonding, or the like, from the stability of characteristics such as bonding state and resistance value.

  FIG. 1B shows the current path of this shunt resistor. A current terminal (not shown) is fixed to any surface of the outer electrode 12c, and current flows in and out of the fixed surface. However, the current flow direction is rectified by the narrow portion 12a, and the wide inner electrode 12b and the resistor 11 are rectified. In the inner electrode 12b on the opposite side, the current is uniformly distributed in the cross section and flows in the resistor axial direction D, and after passing through the narrow portion 12a on the opposite side, toward the fixed surface of the current terminal of the outer electrode 12c. Thus, a current path is formed.

  That is, in a resistor having a low resistance value of 1 mΩ or less, the current path bias caused by the resistance distribution inside the electrode cannot be ignored. FIG. 2A shows a conventional example that does not include the narrow portion 12a. In this example, the current terminal (bus bar) 16 is fixed to the outer end face of the electrode 12 and is drawn upward (in the direction indicated by the arrow K in the figure) perpendicular to the axial direction D of the resistor.

  The current terminal 16 and the electrode 12 are fixed by welding or the like along the outer peripheral surface of the outer end surface of the electrode 12, the internal resistance becomes low near the corner indicated by the symbol E, and the current concentrates in this portion. It becomes biased near the corner E. For this reason, in the resistor 11, the current does not flow evenly distributed in the cross section, the current density becomes high near the corner E in the figure, and the current path I in the resistor 11 is the upper side in the figure. It will be biased to.

  In such a state, the voltage generated at both ends of the resistor 11 is detected at the central portion in the width direction in the immediate vicinity of the resistor of the electrodes 12 and 12 (see FIG. 5), so that the apparent resistance value becomes high and the detected voltage and An error occurs in the TCR.

  On the other hand, in the embodiment of the present invention shown in FIG. 2 (b), since the concave portion 15 having a narrow width is formed on the surface L of the electrode 12 facing the lead-out direction K of the current terminal 16, its rectifying action is achieved. As a result, the current path I is pushed downward in the figure, and a uniform current distribution is obtained by the inner electrode 12b, the resistor 11, and the inner electrode 12b on the opposite side. Therefore, by providing the recess 15 on the surface of the electrode 12 in the lead-out direction K of the current terminal 16, the current path I in the inner electrode 12b, the resistor 11, and the inner electrode 12b on the opposite side can be moved to the center inside the resistor. A uniform current distribution can be formed, and the occurrence of errors in the detection voltage and TCR can be suppressed.

  3A to 3E show examples of various cross-sectional shapes of the narrow portion 12a. In the figure, the hatched portion shows a narrow section. In addition, x mark shows the center position of an electrode cross section. In order to pass the current path through the central portion of the electrode 12, the concave portion does not reach the central portion in the cross section of the resistor CC (see FIG. 1B). In which part the concave portion is formed is determined in relation to the lead-out direction of the current terminal 16 connected to the outer electrode 12c.

  FIG. 3A is an example in which concave portions are provided on the left and right sides of the electrode shown in FIGS. 1A and 1B, and the current terminal 16 can be pulled out in two left and right directions (of course, the vertical direction can be changed by changing the direction). become). FIG. 3B shows an example in which a recess is provided on one side surface of the electrode, and the current terminal 16 can be drawn out in one direction (left side in the drawing). FIG. 3C shows an example in which concave portions are provided on the left side and upper side of the electrode, and the current terminal 16 can be drawn out in two directions (left and upper in the drawing). FIG. 3D shows an example in which concave portions are provided on the left and right side surfaces and the upper side surface of the electrode, and the current terminal 16 can be drawn out in three directions (left, upper and right in the drawing). FIG. 3E shows an example in which concave portions are provided on the left and right side surfaces and the upper and lower side surfaces of the electrode, and the current terminal 16 can be drawn in four directions (left, top, right, and bottom in the drawing).

  4A to 4C show various connection structure examples of the resistor and the current terminal according to the present invention. That is, each of the pair of electrodes 12 and 12 of the resistor has a rectangular parallelepiped shape, a concave portion 15 having a uniform depth is provided on the side surface of the electrode, and a narrow portion 12a is formed on the electrode. It is separated into an outer electrode 12c on the outer side along the instrument axis direction D and an inner electrode 12b on the resistor side, and the surface of the current terminal 16 is fixed to one of the surfaces of the outer electrode 12c. A narrow recess 15 is formed on the surface L of the electrode 12 facing the electrode.

  In FIG. 4A, the side surface of the current terminal 16 is fixed to the end surface of the outer electrode 12 c, and a narrow recess 15 is formed on the surface L of the electrode 12 facing the lead-out direction K of the current terminal 16. In FIG. 4B, the recess 15 is provided on both side surfaces of the electrode 12. For this reason, the end face of the current terminal 16 is fixed to the respective side surfaces of the one outer electrode and the other outer electrode, but the lead-out direction K of the current terminal 16 can be arranged in the opposite direction. Further, as shown in FIG. 4C, the drawing direction K of the current terminal 16 can be the same direction.

  In any of these examples, the current can be made to flow uniformly through the resistor 11 by the rectifying action of the narrow portion 12a, and errors in the detection voltage and TCR can be suppressed. While suppressing, one surface of the current terminal 16 can be fixed to any one of the five surfaces of the external electrode 12c, and the degree of freedom of the extraction direction and the like can be expanded.

  FIG. 5 is a diagram showing a mounted state in which the shunt resistor is accommodated in the housing. As shown in FIG. 5B, the resistor having a pair of electrodes 12 and 12 fixed to both ends of the resistor 11 includes a recess 15 and a housing (base) 21 formed of an insulating resin. Includes a fixing piece 21a, and the concave portion 15 of the resistor and the fixing piece 21a of the casing are fitted to fix the resistor to the casing. The side surface of the current terminal 16 is fixed to the end surface of the outer electrode 12 c by tightening the bolt 19. The current terminal 16 is a bus bar and is connected to a cable 17 through which a current to be measured flows.

  One end of a bonding wire 18, 18 that is a voltage detection terminal is connected to the center of the inner electrode 12 b from the resistor 11, the other end is connected to the voltage detection IC 20, and the voltage detected at both ends of the resistor 11. Are processed by the IC 20 and output from the connector portions 23 and 23. The case lid 22 shown in FIG. 5A covers the resistor and the voltage detection circuit portion, thereby protecting them and firmly fixing the resistor to the housing.

  As described above, the resistor includes the recess 15 on the electrode side surface, and the fixing piece 21a of the housing (base) is fitted to the resistor to fix the resistor, so that the resistor can be stably supported. And a load (mechanical stress) applied to the resistor can be reduced.

  FIGS. 6A and 6B show another embodiment of a structure for fixing a resistor to a base. 6A includes a pair of fixing members 26, 26 on the upper surface of the base 25, and the fixing pieces 26a are fitted to the recesses 15 provided on both side surfaces of the resistor electrode 20, so that the resistor is mounted on the base. 25 is fixed. FIG. 6B shows a structure in which a claw 26b is further provided on the fixed piece 26a in addition to the above structure to restrain the upward movement of the resistor.

  Next, an embodiment of a method for manufacturing a shunt resistor according to the present invention will be described with reference to FIG. First, as shown in FIG. 7A, a plate-like resistance alloy material 31 and a plate-like Cu electrode material 32 are prepared. Then, as shown in FIG. 7B, the plate-like Cu electrode material 32, the plate-like resistance alloy material 31, and the plate-like Cu electrode material 32 are stacked and diffusion bonded to each interface by thermocompression bonding. The layer is formed to form a block-shaped laminate 34. At this time, the thickness of the Cu electrode material 32a is the length in the resistor axial direction of the electrode 12 at the product stage, and the thickness of the resistance alloy material 31a is the length in the resistor axial direction of the resistor 11 at the product stage.

  Next, it slices by dicing along the line X, and forms the plate-shaped laminated body 35 as shown in FIG.7 (c). At this time, the slice width of the plate-shaped laminated body 35 is set to the height of the electrode 12 and the resistor 11 in the product stage. Next, as shown in FIG.7 (d), the groove | channel 15m is formed in the Cu electrode material 32a of the sliced surface of the plate-shaped laminated body 35 by cutting. At this time, the groove width and depth are the same as the width and depth of the recess 15 in the product stage. Then, by cutting out (dicing) along the line Y to obtain individual products, the shunt resistor of the present invention shown in FIG. 7E is completed. At this time, the dicing width is the same as the width of the resistor in the product stage.

  According to the above manufacturing process, the shunt resistor of the present invention can be formed from a large plate material by cutting including thermocompression bonding and dicing (slicing).

  Next, another embodiment of the manufacturing method of the shunt resistor of the present invention will be described with reference to FIG. A square-piece-shaped resistor 11m is cut out from a square-bar-shaped resistance alloy material, a square-piece-shaped electrode body 12m is cut out from a square-bar-shaped Cu material, and a groove 15m is formed by cutting as shown in FIG. To do. And as shown in FIG.8 (b), by joining these by methods, such as an electron beam welding, pulse electric current joining, thermocompression bonding, cold pressure welding, resistance welding, the electrode 12, Thus, the shunt resistor of the present invention in which the narrow portion 12a is formed by providing the concave portion 15 on the side of the electrode and fixing the concave portion 15 is obtained.

  The groove 15m may be formed after the square-piece-shaped resistor 11m and the square-piece-shaped electrode body 12m are joined. At this time, the resistor element bodies obtained by joining the square-piece-shaped resistor 11m and the square-piece-shaped electrode body 12m may be arranged in parallel to the jig, and grooves 15m may be simultaneously formed in a number of resistor elements. .

  Although this embodiment shows an example in which concave portions are formed on both sides in the width direction of the resistor, the concave portions may be formed only on one side or may be formed by cutting in four directions.

  In the above embodiment, the resistor and the electrode have been described as having a rectangular parallelepiped shape. However, the electrode narrow portion of the present invention can be applied to a resistor having a columnar resistor and an electrode.

  Although one embodiment of the present invention has been described so far, it is needless to say that the present invention is not limited to the above-described embodiment, and 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 resistor particularly for high current applications in which electrodes made of a Cu material are disposed at both ends of a resistance alloy material.

Claims (11)

A resistor made of a resistance alloy material;
A pair of electrodes fixed to both ends of the resistor;
Each of the electrodes includes a narrow portion formed between an outer end surface and an inner end surface along the resistor axial direction of the electrode.   The resistor according to claim 1, wherein the electrode has a rectangular parallelepiped shape.   2. The resistor according to claim 1, wherein the narrow portion is provided with a concave portion having a uniform depth on a side surface of the electrode.   2. The resistor according to claim 1, wherein an outer side of the narrow portion of the electrode has a rectangular parallelepiped shape, and a surface of the current terminal is fixed to any surface of the rectangular parallelepiped shape.   5. The resistor according to claim 4, wherein a concave portion of the narrow portion is formed on a surface of the electrode facing the drawing direction of the current terminal. A structure in which a current terminal is connected to the electrode of a resistor including a resistor made of a resistance alloy material and a pair of electrodes fixed to both ends of the resistor,
A concave portion having a uniform depth is provided on the side surface of the electrode to form a narrow portion in the electrode, and the electrode is separated into an outer outer electrode along the resistor axial direction and an inner electrode on the resistor side,
The outer electrode has a rectangular parallelepiped shape, and the surface of the current terminal is fixed to any surface thereof,
A connection structure between a resistor and a current terminal, in which a concave portion of the narrow portion is formed on a surface of the electrode facing the drawing direction of the current terminal.   The resistor and current terminal connection structure according to claim 6, wherein a side surface of the current terminal is fixed to an end surface of the outer electrode.   The resistor and current terminal connection structure according to claim 6, wherein an end face of the current terminal is fixed to a side surface of the outer electrode. A resistor comprising a resistor made of a resistance alloy material and a pair of electrodes fixed to both ends of the resistor is fixed to the base,
The resistor is provided with a concave portion having a uniform depth on the side surface of the electrode to form a narrow portion in the electrode, and the electrode includes an outer outer electrode along the resistor axial direction and an inner electrode on the resistor side. Separated by the recess,
The base includes a fixing piece that fits into the concave portion of the resistor, and the fixing piece fits into the concave portion of the resistor to fix the resistor to the base. Construction. A plate-shaped electrode material, a plate-shaped resistance alloy material, and a plate-shaped electrode material are overlapped to form a block-shaped laminate by pressure bonding, and the thickness of the electrode material is the resistance of the electrode in the product stage The axial length, and the thickness of the resistance alloy material is the axial length of the resistor of the product stage resistor,
The block-like laminate is sliced with a predetermined width to form a plate-like laminate, and the slice width of the plate-like laminate is the height of the electrode and resistor in the product stage,
In the electrode material of the sliced surface of the plate-shaped laminate, a recess having a predetermined width and depth is formed in parallel to the resistance alloy material,
A method of manufacturing a resistor, wherein the plate-shaped laminate is cut out with a predetermined width to form individual resistors, the predetermined width being the same as the width of the resistor at the product stage. Cut out a square piece resistor from a square rod-shaped resistance alloy material, cut out a square piece electrode body from a square rod-shaped Cu material,
By joining them, a resistor with electrodes fixed at both ends of the resistor is formed,
A method for manufacturing a resistor, wherein a concave portion is provided on a side surface of the electrode to form a narrow portion.

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