Shunt resistor

Abstract

To provide a shunt resistor capable of weight reduction.SOLUTION: A shunt resistor 10 includes a plate-shaped resistor 14 containing aluminum as a main component and electrodes 16, 18 bonded to the resistor 14.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a shunt resistor.

Background Art

[0002] Patent Document 1 shows a resistor, which includes a resistor body and a first terminal and a second terminal provided at both ends of the resistor body.

[0003] As the resistor material forming the resistor body of this resistor, a copper-based alloy is generally used. Also, as the electrodes of the resistor, copper electrodes are used.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the shunt resistor as described above, a copper alloy is used as the resistor material. Therefore, the shunt resistor becomes heavy.

[0006] An object of the present invention is to provide a shunt resistor that can be reduced in weight.

Means for Solving the Problems

[0007] According to an aspect of the present invention, a shunt resistor includes a plate-shaped resistor body mainly composed of aluminum and electrodes joined to the resistor body. The resistor contains an alloy of aluminum and magnesium, the magnesium content is 0.7% by mass or more and 5.0% by mass or less, the electrode is mainly composed of aluminum, and is a member different from the resistor.

Effects of the Invention

[0008] According to this aspect, the main component of the plate-shaped resistor body is aluminum, and aluminum has a smaller mass per volume than copper.

[0009] Therefore, the shunt resistor of this embodiment can be reduced in weight as compared with a shunt resistor in which copper is used for the resistor material.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3A

Figure 3B

Figure 4A

Figure 4B

Figure 5

Embodiments for Carrying Out the Invention

[0011] In recent years, for environmental protection, exhaust gas regulations have been strengthened in various countries, and the development of electric vehicles (EVs) has been progressing.

[0012] In electric vehicles, in order to extend the distance that can be traveled on a single charge, weight reduction is required, and the members constituting the parts of electric vehicles are being replaced with aluminum. Examples of parts used in electric vehicles include battery electrodes and electric wires, and replacing the materials of battery electrodes and electric wires with aluminum has been studied.

[0013] In addition, a shunt resistor, which is a resistor for current detection, is used in electric vehicles. The charge and discharge current of the battery of an electric vehicle may exceed 400 A, and a large current flows through the shunt resistor used in the electric vehicle. As the detected current increases in magnitude, the shunt resistor becomes larger in size, and the increase in weight due to the enlargement of the shunt resistor is becoming a problem.

[0014] Generally, the resistor material used for shunt resistors is composed of a copper-based alloy, and copper electrodes are often used. The resistor material using this copper has been one of the factors contributing to the increase in the weight of the shunt resistor.

[0015] Therefore, the inventor has come up with the following embodiments.

[0016] (Embodiment) Hereinafter, an embodiment of the present invention will be described. In this embodiment, a shunt resistor used for detecting the charge and discharge current of a battery of an electric vehicle will be described as an example, but the present invention is not limited thereto. The shunt resistor according to this embodiment can be used as a general shunt resistor for current detection.

[0017] [Shunt Resistor] FIG. 1 is a perspective view showing a shunt resistor 10 according to an embodiment. FIG. 2 is a front view showing a state in which the shunt resistor 10 according to an embodiment is connected to each of the bus bars 40 and 44. In FIGS. 1 and 2, for convenience of explanation, the shunt resistor 10 excluding each plating part 30, 32 (see FIGS. 3A and 3B) described later is shown.

[0018] (Resistor Body) As shown in FIG. 1, the shunt resistor 10 includes a plate-shaped resistor body 14 mainly composed of aluminum (Al). By making aluminum the main component of the resistor body 14, the weight of the shunt resistor 10 including the resistor body 14 is reduced.

[0019] For the convenience of setting the resistance value of the shunt resistor 10, the resistor 14 needs to have a higher specific resistance than each of the electrodes 16 and 18. Also, the resistor 14 needs to exhibit a stable resistance value and have predetermined heat resistance and corrosion resistance.

[0020] And, aluminum, which is used as the main component of the resistor material forming the resistor 14 for weight reduction, generally has difficulty dissolving other elements. For this reason, when the resistor material is composed of an aluminum alloy in which an additive is added to aluminum, the additive element added as an additive forms a compound and precipitates in the aluminum alloy. In this case, the resistance value of the resistor material composed of the aluminum alloy cannot be increased.

[0021] Therefore, while taking aluminum as the main component, a resistor material suitable as the resistor 14 is selected.

[0022] (The first resistor) The selected first resistor 14 contains an alloy (Al-Mg alloy) of aluminum (Al) and magnesium (Mg). In this resistor 14, the content of magnesium is set to 0.7 mass% or more and 5.0 mass% or less with respect to the total mass of the resistor 14.

[0023] This resistor 14 is formed using a resistor material mainly composed of aluminum, which has difficulty dissolving other elements. This resistor material is an alloy in which magnesium is dissolved in aluminum, and while suppressing the precipitation of magnesium as a compound, the amount of magnesium dissolved is increased. Thereby, the adjustment range of the specific resistance is widened and the specific resistance is increased.

[0024] Also, by forming the resistor 14 from an alloy of aluminum and magnesium that has good workability and excellent weldability, the ease of manufacturing the shunt resistor 10 is enhanced. Further, by forming the resistor 14 from an alloy of aluminum and magnesium that has good corrosion resistance, the corrosion resistance of the resistor 14 is enhanced.

[0025] Then, by setting the magnesium content in the resistor 14 to 0.7 mass% or more and 5.0 mass% or less, the resistivity is increased while suppressing the temperature coefficient of resistance of the resistor 14.

[0026] Specifically, by setting the magnesium content in the resistor 14 to 0.7 mass% or more, the resistivity is increased. Also, by setting the magnesium content in the resistor 14 to 5.0 mass% or less, precipitation of magnesium as a compound is suppressed, and a decrease in resistivity that occurs after precipitation of the compound is suppressed.

[0027] (Second resistor) The selected second resistor 14 contains an alloy (Al-Mn-Mg alloy) of aluminum (Al), manganese (Mn), and magnesium (Mg). In this resistor 14, the magnesium content is 0.7 mass% or more and 5.0 mass% or less, and the manganese content is 0.6 mass% or more and 2.0 mass% or less with respect to the total mass of the resistor 14. Further, in this resistor 14, the combined content of magnesium and manganese is 1.3 mass% or more and 7.0 mass% or less with respect to the total mass of the resistor 14.

[0028] This resistor 14 is formed using a resistor material mainly composed of aluminum in which it is difficult to dissolve other elements. This resistor material is an alloy in which manganese and magnesium are dissolved in aluminum, and while suppressing precipitation of manganese or magnesium as a compound, the amount of manganese or magnesium dissolved is increased. Thereby, the adjustment range of the resistivity is widened and the resistivity can be increased.

[0029] Also, the resistor material of this resistor 14 can dissolve manganese in a state where manganese does not precipitate as a compound even in a state where magnesium is added to aluminum to the maximum extent within a range where magnesium in aluminum does not precipitate as a compound.

[0030] By adding manganese and magnesium to a resistor material mainly composed of aluminum, the total amount of additives that can be added in a solid solution state of aluminum is increased compared to the case where only magnesium is added to the resistor material mainly composed of aluminum. As a result, the adjustment range of the specific resistance of the formed resistor is further widened, and the specific resistance is further increased.

[0031] Also, by forming the resistor 14 from an alloy of aluminum, manganese, and magnesium that has good workability and excellent weldability, the ease of manufacturing the shunt resistor 10 is enhanced. Furthermore, by forming the resistor 14 from an alloy of aluminum, manganese, and magnesium that has good corrosion resistance, the corrosion resistance of the resistor 14 is enhanced.

[0032] And the magnesium content in the resistor 14 is set to be 0.7 mass% or more and 5.0 mass% or less, the manganese content is set to be 0.6 mass% or more and 2.0 mass% or less, and the combined content of magnesium and manganese is set to be 1.3 mass% or more and 7.0 mass% or less. Thereby, while suppressing the temperature coefficient of resistance of the resistor 14, the specific resistance is increased.

[0033] Specifically, by setting the magnesium content in the resistor 14 to be 0.7 mass% or more, the specific resistance is increased. Also, by setting the magnesium content in the resistor 14 to be 5.0 mass% or less, precipitation of magnesium as a compound is suppressed, and a decrease in specific resistance occurring after precipitation of the compound is suppressed.

[0034] Also, by setting the manganese content in the resistor 14 to be 0.6 mass% or more, the specific resistance is increased. Also, by setting the manganese content in the resistor 14 to be 2.0 mass% or less, precipitation of manganese as a compound is suppressed, and a decrease in specific resistance occurring after precipitation of the compound is suppressed.

[0035] And both the resistor 14 made of an alloy of aluminum and magnesium and the resistor 14 made of an alloy of aluminum, manganese, and magnesium are set so that the temperature coefficient of resistance (TCR) is 2000 ppm / °C or less.

[0036] This improves the temperature characteristics of the shunt resistor 10 as compared with the case where the resistor is formed only of aluminum having a resistance temperature coefficient of about 4200 ppm / °C.

[0037] Also, in the resistor 14 formed of an aluminum alloy, it is known that there is a correlation between the resistance temperature coefficient and the specific resistance. Therefore, by increasing the specific resistance of the resistor 14 to be higher than a predetermined value, the resistance temperature coefficient can be made 2000 ppm / °C or less.

[0038] Note that the resistance temperature coefficient of the resistor 14 may be 3000 ppm / °C or less. Further, the resistance temperature coefficient of the resistor 14 may be 4000 ppm / °C or less.

[0039] And if the resistance temperature coefficient of the resistor 14 is made 1000 ppm / °C or less, the temperature characteristics of the shunt resistor 10 are further improved and the specific resistance further increases, but a selection of the resistor material for forming the resistor 14 is necessary.

[0040] Here, the resistance temperature coefficient (TCR) is obtained based on the change rate of the resistance value and the temperature change amount. For example, when an object showing a first resistance value R1 at a first temperature T1 is changed to a second temperature T2 and the object becomes a second resistance value R2, the resistance temperature coefficient TCR [ppm / °C] is obtained by the following arithmetic expression.

[0041] TCR = [{(R2 - R1) / R1} / (T2 - T1)] × 1000000

[0042] (Electrode) This shunt resistor 10 includes electrodes 16 and 18 joined to the resistor 14. Each of the electrodes 16 and 18 is formed in a plate shape mainly composed of aluminum (Al).

[0043] To have aluminum as the main component means that, from the perspective of reducing the weight of the shunt resistor 10, the content of aluminum is 50% by mass or more with respect to the total mass of each of the electrodes 16 and 18. The content of aluminum is preferably 80% by mass or more, and more preferably 90% by mass or more.

[0044] Examples of the conductive material having aluminum as the main component include pure aluminum with a purity of 99% or more, or an aluminum alloy.

[0045] Here, when different types of metals are joined, due to the difference in the standard electrode potential between the metals, a local battery is formed at the joined portion, and there is a risk of galvanic corrosion occurring at the joined portion due to the presence of moisture or the like. This galvanic corrosion also appears when aluminum is used as the metal.

[0046] In the present embodiment, in order to reduce the weight of the shunt resistor 10, the resistor 14 is formed of a resistor material having aluminum, which is a light metal, as the main component.

[0047] When each of the electrodes 16 and 18 is formed of a conductive material having aluminum as the main component, if the resistor 14 is formed of a resistor material having a large potential difference from the standard electrode potential of aluminum, galvanic corrosion due to contact between dissimilar metals may occur at the joined portions between the resistor 14 and each of the electrodes 16 and 18. Examples of the resistor material that causes galvanic corrosion between the electrodes 16 and 18 having aluminum as the main component include copper, chromium, and iron.

[0048] Therefore, in the shunt resistor 10 according to the present embodiment, each of the electrodes 16 and 18 is formed of a conductive material having aluminum as the main component. By using aluminum for the resistor material and the electrode material, the shunt resistor 10 of the present embodiment can suppress galvanic corrosion at the joined portions between the resistor 14 and each of the electrodes 16 and 18 while achieving weight reduction.

[0049] The electrodes of the shunt resistor 10 include a first electrode 16 joined to one end of the resistor 14 and a second electrode 18 joined to the other end of the resistor 14.

[0050] As shown in FIGS. 1 and 2, the first electrode 16 is formed with a first hole 16a through which a bolt 42 is inserted when connecting the first electrode 16 to the bus bar 40. Also, the second electrode 18 is formed with a second hole 18a through which a bolt 46 is inserted when connecting the second electrode 18 to the bus bar 44.

[0051] A first joint portion 20 is formed at the joint portion between the resistor 14 and the first electrode 16. A second joint portion 22 is formed at the joint portion between the resistor 14 and the second electrode 18.

[0052] Examples of methods for joining the resistor 14 to the respective electrodes 16 and 18 include welding, which joins the materials to be joined by melting them, and pressure welding, which joins the materials to be welded by diffusion of metal atoms. Also, an example of a method for joining the resistor 14 to the respective electrodes 16 and 18 is brazing, which joins the materials to be welded with a brazing material.

[0053] In the present embodiment, the resistor 14 and the respective electrodes 16 and 18 are joined by welding or pressure welding without using a brazing material. Examples of welding include laser welding or electron beam welding.

[0054] By joining in this way, in the present embodiment, since no brazing material is interposed between the resistor 14 and the respective electrodes 16 and 18, the resistance characteristics of the shunt resistor 10 can be improved.

[0055] The resistor 14 is in the shape of a rectangular plate. The respective electrodes 16 and 18 are also in the shape of rectangular plates. The widths of the resistor 14 and the respective electrodes 16 and 18 are set to be substantially the same size. Thereby, the shunt resistor 10 in which the resistor 14 is joined to the respective electrodes 16 and 18 becomes a rectangle that is long in the arrangement direction NH of the respective electrodes 16 and 18 and the resistor 14.

[0056] (Plated portion) It is assumed that each bus bar 40, 44 or harness etc. connected to the respective electrodes 16, 18 mainly composed of aluminum is formed of a copper (Cu)-based member.

[0057] Here, the standard electrode potential of aluminum is -1.68 V, and the standard electrode potential of copper is +0.34 V. Therefore, between each electrode 16, 18 mainly composed of aluminum and each bus bar 40, 44, etc. formed of a copper-based member, a local battery is formed at the contact portion, and corrosion can occur if moisture or the like is present at the contact portion. For this reason, it is conceivable to provide a moisture-proof and waterproof structure so that moisture or the like does not penetrate into the contact portions between each electrode 16, 18 and each bus bar 40, 44, etc.

[0058] As a moisture-proof and waterproof structure, a structure in which the contact portions between each electrode 16, 18 and each bus bar 40, 44, etc. are covered with a plastic cover is generally known.

[0059] However, there is a risk that moisture may seep in from the contact interface between the metal and the plastic of each bus bar 40, 44, etc. Further, since plastic is easily melted at high temperatures, when covering the contact portion with a plastic cover, deformation at high temperatures is a concern.

[0060] In addition, after connecting each bus bar 40, 44, etc. to each electrode 16, 18, it is necessary for the user to cover the contact portions between each electrode 16, 18 and each bus bar 40, 44, etc. with a plastic cover, and there is a concern about poor usability.

[0061] Therefore, each electrode 16, 18 in the present embodiment has a plating containing nickel (Ni) or zinc (Zn).

[0062] The standard electrode potential of nickel is -0.26 V. Compared with copper having a standard electrode potential of +0.34 V, the difference from the standard electrode potential of aluminum is small, and galvanic corrosion hardly occurs.

[0063] Also, the standard electrode potential of zinc is -0.76 V. Compared with copper having a standard electrode potential of +0.34 V, the difference from the standard electrode potential of aluminum is small, and galvanic corrosion hardly occurs.

[0064] FIG. 3A is a plan view showing a state in which plating portions 30 and 32 are formed on respective electrodes 16 and 18 of a shunt resistor 10 according to an embodiment. FIG. 3B is a front view showing a state in which plating portions 30 and 32 are formed on respective electrodes 16 and 18 of a shunt resistor 10 according to an embodiment.

[0065] As shown in FIGS. 3A and 3B, in the first electrode 16, a region including the outer peripheral portion of the first hole 16a is covered with the first plating portion 30. Further, in the second electrode 18, a region including the outer peripheral portion of the second hole 18a is covered with the second plating portion 32. Each of the plating portions 30 and 32 is formed of a plating containing nickel (Ni) or zinc (Zn).

[0066] The first plating portion 30 covers the front surface 16b, the back surface 16c, both side surfaces 16d and 16e, one end surface 16f of the first electrode 16, and the inner peripheral surface of the first hole 16a. The second plating portion 32 covers the front surface 18b, the back surface 18c, both side surfaces 18d and 18e, the other end surface 18f of the second electrode 18, and the inner peripheral surface of the second hole 18a.

[0067] Thereby, as shown in FIG. 2, when the bus bars 40 and 44 are overlapped and connected to the respective electrodes 16 and 18 of the shunt resistor 10, direct contact between the respective electrodes 16 and 18 and the bus bars 40 and 44 is suppressed. Further, direct contact between the bolts 42 and 46 that pass through the holes 16a and 18a of the respective electrodes 16 and 18 to fix the respective electrodes 16 and 18 and the bus bars 40 and 44 is suppressed.

[0068] Here, in the present embodiment, as shown in FIGS. 3A and 3B, the shunt resistor 10 in which a part of the first electrode 16 is covered with the first plating portion 30 and a part of the second electrode 18 is covered with the second plating portion 32 is shown, but the present invention is not limited thereto.

[0069] For example, the shunt resistor 10 may be configured as in the following modified example.

[0070] (Modified example) Here, a modified example of the present embodiment will be described.

[0071] FIG. 4A is a plan view showing a shunt resistor according to a modification. FIG. 4B is a plan view showing a shunt resistor according to a modification. This shunt resistor 50 is a modification of the aforementioned shunt resistor 10, and the ranges of the respective plating portions 30 and 33 formed on the respective electrodes 16 and 18 are different as compared with the aforementioned shunt resistor 10.

[0072] As shown in FIGS. 4A and 4B, the first plating portion 30 formed on the first electrode 16 reaches the first joint portion 20 which is the joint portion between the first electrode 16 and the resistor body 14, and the entire surface of the first electrode 16 is covered with the first plating portion 30. The second plating portion 32 formed on the second electrode 18 reaches the second joint portion 22 which is the joint portion between the second electrode 18 and the resistor body 14, and the entire surface of the second electrode 18 is covered with the second plating portion 32.

[0073] Thereby, as shown in FIG. 2, when the respective bus bars 40 and 44 are overlapped and connected to the respective electrodes 16 and 18 of the shunt resistor 50, direct contact between the respective electrodes 16 and 18 and the respective bus bars 40 and 44 is suppressed. Further, direct contact between the bolts 42 and 46 inserted through the respective holes 16a and 18a of the respective electrodes 16 and 18 and the respective electrodes 16 and 18 is suppressed.

[0074] Further, in the shunt resistor 50 according to this modification, the entire surfaces of the respective electrodes 16 and 18 are covered with the respective plating portions 30 and 32. For this reason, corrosion of the respective electrodes 16 and 18 is suppressed over the entire surface.

[0075] (Operation and Effect) Next, the operation and effect of the first embodiment will be described.

[0076] The shunt resistors 10 and 50 of the present embodiment include a plate-shaped resistor body 14 mainly composed of aluminum, and the respective electrodes 16 and 18 joined to the resistor body 14.

[0077] In this configuration, the main component of the resistor body 14 is aluminum, and aluminum has a smaller mass per volume as compared with copper.

[0078] Therefore, the shunt resistors 10 and 50 can be made lighter than a shunt resistor in which a resistive material uses copper.

[0079] Also, in the shunt resistors 10 and 50 of the present embodiment, the electrodes 16 and 18 are plate-shaped with aluminum as a main component.

[0080] In this configuration, the main component of each of the electrodes 16 and 18 is also aluminum, and aluminum has a smaller mass per volume than copper.

[0081] Therefore, the shunt resistors 10 and 50 can be made even lighter than a shunt resistor in which copper is used for each of the electrodes 16 and 18.

[0082] Here, weight reduction will be specifically described.

[0083] FIG. 5 is an explanatory diagram showing a comparison between the shunt resistors 10 and 50 according to one embodiment and a shunt resistor 100 according to a comparative example.

[0084] FIG. 5 shows a shunt resistor 100 according to a comparative example having a resistive body 114 and electrodes 116 and 118 mainly made of copper, and the shunt resistors 10 and 50 according to the present embodiment having a resistive body 14 and electrodes 16 and 18 mainly made of aluminum.

[0085] The shunt resistor 100 according to the comparative example has a length L of 80.0 mm, a width W of 80.0 mm, and a thickness T of 2.0 mm, and the weight of the shunt resistor 100 according to the comparative example is about 25.6 g.

[0086] With the dimensions of the shunt resistor 100 according to this comparative example maintained, the shunt resistors 10 and 50 according to the present embodiment are formed using a resistive body 14 mainly made of aluminum and electrodes 16 and 18 mainly made of aluminum.

[0087] In this case, the specific gravity of aluminum is 2.7 g / cm 3Therefore, the weights of the formed shunt resistors 10 and 50 are about 7.8 g, and the weight can be reduced by about 70% compared to the shunt resistor 100 according to the comparative example.

[0088] Here, aluminum has a higher specific resistance than copper. For this reason, in order to pass the same current through the shunt resistors 10 and 50 mainly composed of aluminum as through the shunt resistor 100 mainly composed of copper, it is necessary to increase the cross-sectional area of the resistor body 14. Then, the volume of the resistor body 14 of the shunt resistors 10 and 50 increases, and the volumes of the respective electrodes 16 and 18 also increase.

[0089] Specifically, the specific resistance of copper is 1.7×10 -8 Ω·m, and the specific resistance of aluminum is 2.7×10 -8 Ω·m. The specific resistance of aluminum is about 1.6 times that of copper. For this reason, in order to pass the same current through the shunt resistors 10 and 50 mainly composed of aluminum as through the shunt resistor 100 mainly composed of copper, it is necessary to make the thickness T of the shunt resistors 10 and 50 about 1.6 times that of the shunt resistor 10 mainly composed of copper.

[0090] For this reason, the thickness T of the shunt resistors 10 and 50 according to the present embodiment mainly composed of aluminum is about 3.2 mm, and the weight is about 12.5 g. As a result, compared with the shunt resistor 100 according to the comparative example having a weight of about 25.6 g, the weight of the shunt resistors 10 and 50 according to the present embodiment can be reduced by about 51%.

[0091] Also, the weight unit price of aluminum is generally about 1 / 3 of that of copper. And the weight of aluminum is about 1 / 2 of the weight of copper. Considering these, the material cost of the resistor body 14 and the respective electrodes 16 and 18 can be suppressed to about 1 / 6.

[0092] As a result, the shunt resistors 10 and 50 according to the present embodiment can suppress the material cost compared with the shunt resistor 100 according to the comparative example.

[0093] Further, the resistors 14 and the electrodes 16 and 18 constituting the shunt resistors 10 and 50 are mainly composed of aluminum. Therefore, galvanic corrosion that may occur when the resistor 14 and the electrodes 16 and 18 are formed of different types of metals can be suppressed.

[0094] Furthermore, the resistor 14 and the electrodes 16 and 18 forming the shunt resistors 10 and 50 are plate-shaped. Therefore, the shunt resistors 10 and 50 can be formed in a plate shape as a whole.

[0095] As a result, compared with a shunt resistor in which the electrode connected to the end face of the resistor 14 is formed in a rectangular parallelepiped shape and a part of the electrode protrudes downward from the resistor 14, the entire shunt resistors 10 and 50 can be made thinner.

[0096] Also, in the shunt resistors 10 and 50 of the present embodiment, the resistor 14 contains an alloy of aluminum and magnesium.

[0097] In this configuration, even in a resistor material mainly composed of aluminum in which other elements are difficult to dissolve, it is possible to increase the solid solution amount of magnesium while suppressing the precipitation of magnesium as a compound. As a result, the adjustment range of the specific resistance can be widened and the specific resistance can be increased as compared with the case where an additive whose solid solution amount in aluminum is limited is dissolved.

[0098] Also, the resistor 14 having such a high specific resistance can be formed of an aluminum alloy. Therefore, it is possible to form the resistor 14 having a thickness as compared with a case where a resistor has to be formed by forming a mixture of aluminum and other elements due to the structure of forming a resistor using an element whose solid solution amount in aluminum is limited.

[0099] And by increasing the thickness of the resistor 14, the current passing through the resistor 14 can be increased. As a result, the shunt resistors 10 and 50 can be used in a circuit through which a large current flows, and detection of a large current becomes possible.

[0100] In addition, an alloy of aluminum and magnesium has good workability and excellent weldability. Therefore, the manufacturability of the shunt resistors 10 and 50 can be improved. Furthermore, an alloy of aluminum and magnesium has good corrosion resistance. Therefore, the corrosion resistance of the resistor body 14 can be improved.

[0101] Also, in the shunt resistors 10 and 50 of the present embodiment, the resistor body 14 has a magnesium content of 0.7% by mass or more and 5.0% by mass or less.

[0102] In this configuration, by setting the magnesium content in the resistor body 14 to 0.7% by mass or more and 5.0% by mass or less, the specific resistance can be increased while suppressing the resistance temperature coefficient of the resistor body 14.

[0103] Also, in the shunt resistors 10 and 50 of the present embodiment, the resistor body 14 contains an alloy of aluminum, manganese, and magnesium.

[0104] In this configuration, even in a resistor body material mainly composed of aluminum, in which it is difficult to dissolve other elements, it is possible to increase the solid solution amounts of manganese and magnesium while suppressing the precipitation of manganese or magnesium as a compound.

[0105] As a result, the adjustment range of the specific resistance can be widened and the specific resistance can be increased as compared with the case of dissolving an additive whose solid solution amount in aluminum is limited.

[0106] Also, even if the maximum amount of magnesium is added within the range where magnesium does not precipitate as a compound in a resistor body material mainly composed of aluminum, manganese can be dissolved in a state where manganese does not precipitate as a compound.

[0107] As a result, the amount of the additive added to the resistor material mainly composed of aluminum can be increased, so that the adjustment range of the specific resistance of the formed resistor 14 can be further widened, and the specific resistance can be further increased.

[0108] In addition, the resistor 14 having a high specific resistance can be formed of an alloy in this way. Therefore, in a structure in which a resistor is formed using an element whose solid solution amount in aluminum is limited, compared with a case where a mixture of aluminum and other elements has to be formed to form a resistor, it becomes possible to form the resistor 14 having a thickness.

[0109] And by increasing the thickness of the resistor 14, the current passing through the resistor 14 can be increased. As a result, the shunt resistors 10 and 50 can be used in a circuit through which a large current flows, and detection of a large current becomes possible.

[0110] In addition, an alloy of aluminum, manganese, and magnesium has good workability and excellent weldability. Therefore, the ease of manufacturing the shunt resistors 10 and 50 can be improved. Furthermore, an alloy of aluminum, manganese, and magnesium has good corrosion resistance. Therefore, the corrosion resistance of the resistor 14 can be improved.

[0111] In the shunt resistors 10 and 50 of the present embodiment, the resistor 14 has a magnesium content of 0.7 mass% or more and 5.0 mass% or less, and a manganese content of 0.6 mass% or more and 2.0 mass% or less. And the combined content of magnesium and manganese in the resistor 14 is 1.3 mass% or more and 7.0 mass% or less.

[0112] In this configuration, the specific resistance can be increased while suppressing the resistance temperature coefficient of the resistor 14.

[0113] In the shunt resistors 10 and 50 of the present embodiment, the resistor 14 is an aluminum alloy having a resistance temperature coefficient of 2000 ppm / °C or less.

[0114] In this configuration, the temperature characteristics of the shunt resistors 10 and 50 can be improved as compared with the case where the resistor body is formed only of aluminum having a resistance temperature coefficient of about 4200 ppm / °C.

[0115] Also, in the resistor body 14 formed of an aluminum alloy, it is known that there is a correlation between the resistance temperature coefficient and the specific resistance. Therefore, by increasing the specific resistance of the resistor body 14, the resistance temperature coefficient can be made 2000 ppm / °C or less.

[0116] Further, in the shunt resistors 10 and 50 of the present embodiment, the respective electrodes 16 and 18 have a plating containing nickel or zinc.

[0117] In this configuration, even when bus bars 40, 44, etc. made of a metal different in type from the respective electrodes 16 and 18 are connected to the respective electrodes 16 and 18, it is possible to suppress galvanic corrosion that may occur at the contact portion.

[0118] Note that, in the present embodiment, the rectangular plate-shaped shunt resistors 10 and 50 have been described as an example, but the shunt resistors 10 and 50 are not limited to this shape.

[0119] For example, the shunt resistors 10 and 50 may have a shape in which the respective electrodes 16 and 18 are provided on the lower surface of the resistor body 14, or a shape in which L-shaped electrodes 16 and 18 are provided on the end surface of the resistor body 14. Further, the shunt resistors 10 and 50 may have a shape in which the electrodes 16 and 18 provided on the end surface of the resistor body 14 protrude downward from the resistor body 14.

[0120] As described above, the embodiments of the present invention have been described, but the above embodiments merely show a part of the application examples of the present invention, and are not intended to limit the technical scope of the present invention to the specific configurations of the above embodiments.

Examples

[0121] Next, the composition of the resistor material forming the resistors 14 of the shunt resistors 10 and 50 according to each embodiment will be described.

[0122] For the convenience of setting the resistance values of the shunt resistors 10 and 50, the resistor 14 needs to have a higher specific resistance than each of the electrodes 16 and 18. Further, the resistor 14 needs to exhibit a stable resistance value and have predetermined heat resistance and corrosion resistance.

[0123] And aluminum, which is used as the main component of the resistor material forming the resistor 14 for weight reduction, generally has difficulty in dissolving other elements. For this reason, when the resistor material is composed of an aluminum alloy in which an additive is added to aluminum, the additive element added as an additive forms a compound and precipitates in the aluminum alloy. In this case, the resistance value of the resistor material composed of the aluminum alloy cannot be increased.

[0124] Therefore, in order to select a resistor material suitable as the resistors 14 of the shunt resistors 10 and 50 while using aluminum as the main component, a plurality of alloys having each composition in which the following elements are added in a predetermined amount were prepared. Then, for each alloy composition, the specific resistance (ρ) and the temperature coefficient of resistance (TCR) were measured.

[0125] The elements added to aluminum are manganese (Mn), magnesium (Mg), chromium (Cr), copper (Cu), and silicon (Si), and aluminum contains other components as impurities.

[0126] An alloy of aluminum (Al) and magnesium (Mg) (Al-Mg alloy) is known to have good workability, excellent weldability, and good corrosion resistance. For this reason, this Al-Mg alloy can be expected as a resistor material. Magnesium is known to be able to increase the amount of solid solution in aluminum, and the Al-Mg alloy can be expected to improve the specific resistance.

[0127] In addition, an alloy of aluminum (Al) and manganese (Mn) (Al-Mn alloy) is known to have excellent corrosion resistance and good weldability. Therefore, this Al-Mn alloy can be expected as a resistor material.

[0128] And manganese is known to be able to increase the solid solubility amount in aluminum. Therefore, by using manganese as an additive to aluminum, an improvement in specific resistance can be expected.

[0129] Also, manganese is an additive that is often added together with magnesium. By dissolving manganese and magnesium in aluminum, an Al-Mn-Mg alloy can be formed.

[0130] Table 1 shows the composition of the alloy constituting the resistor material and the measurement results of the specific resistance (ρ) and the temperature coefficient of resistance (TCR) of the resistor material composed of the alloy of each composition.

[0131]

Table 1

[0132] In this Table 1, the resistor materials composed of the alloys of each composition are listed in rank, and each rank of the resistor material is determined based on the specific resistance (ρ) and the temperature coefficient of resistance (TCR) of the resistor material.

[0133] Specifically, the higher the specific resistance (ρ), the more suitable the resistor material, and the higher the rank. Also, the smaller the temperature coefficient of resistance (TCR), the more suitable the resistor material, and the higher the rank.

[0134] The ranks described in the rank column indicate that the resistor materials are suitable in the order of "C", "B", "A", "S".

[0135] From this Table 1, the alloy having a composition corresponding to the "S" rank is the most suitable as the resistor material, and it is desirable to use the alloy having a composition corresponding to the "A" rank or higher as the resistor material. Also, it is preferable to use an alloy having a composition corresponding to "B" rank or higher as the resistor material, and it is also possible to use an alloy having a composition corresponding to "C" rank or higher as the resistor material.

[0136] Also, from Table 1, it can be seen that an Al-Mn-Mg alloy containing aluminum, manganese, and magnesium, or an Al-Mg alloy containing aluminum and magnesium is suitable as the resistor material. In particular, an Al-Mn-Mg alloy containing aluminum, manganese, and magnesium is suitable as the resistor material.

[0137] Next, the composition of the alloy constituting each resistor material will be described.

[0138] (Alloy containing aluminum and magnesium) In an Al-Mg alloy containing aluminum and magnesium, the Al-1Mg alloy has a specific resistance (ρ) of 3.4×10 -8 Ω·m and a temperature coefficient of resistance (TCR) of 3155 ppm / °C. The Al-2.6Mg alloy has a specific resistance (ρ) of 5.0×10 -8 Ω·m and a temperature coefficient of resistance (TCR) of 2206 ppm / °C. The Al-4.4Mg alloy has a specific resistance (ρ) of 6.0×10 -8 Ω·m and a temperature coefficient of resistance (TCR) of 1809 ppm / °C.

[0139] When the content of magnesium exceeds 5.0% by mass with respect to the total mass of the resistor material, the grain boundary precipitation of magnesium compounds increases. For this reason, in a resistor material in which the content of magnesium exceeds 5.0% by mass, the decreasing tendency of the temperature coefficient of resistance becomes smaller, and in a storage test in which it is left in an environment of 175°C, the change amount of the resistance value becomes larger.

[0140] Specifically, the Al-1.3Mn-5.0Mg-0.3Cr alloy has a specific resistance (ρ) of 6.9×10 -8Ω·m, and the temperature coefficient of resistance (TCR) is 1760 ppm / °C. Thus, it can be seen that as the magnesium addition amount approaches 5.0% by mass, the decrease in the temperature coefficient of resistance (TCR) becomes smaller.

[0141] Therefore, in order to make the temperature coefficient of resistance 2500 ppm / °C or less, it is preferable that the magnesium addition amount be 0.7% by mass or more and 5.0% by mass or less with respect to the total mass of the resistor material.

[0142] (Alloy containing aluminum, manganese, and magnesium) In an Al-Mn-Mg alloy containing aluminum, manganese, and magnesium, the Al-1Mn-0.3Mg alloy has a specific resistance (ρ) of 3.9×10 -8 Ω·m, and the temperature coefficient of resistance (TCR) is 2878 ppm / °C. The Al-1Mn-1Mg alloy has a specific resistance (ρ) of 4.4×10 -8 Ω·m, and the temperature coefficient of resistance (TCR) is 2406 ppm / °C.

[0143] Also, the Al-1.8Mn-1Mg alloy has a specific resistance (ρ) of 8.4×10 -8 Ω·m, and the temperature coefficient of resistance (TCR) is 938 ppm / °C. The Al-2Mn-1Mg alloy has a specific resistance (ρ) of 9.5×10 -8 Ω·m, and the temperature coefficient of resistance (TCR) is 824 ppm / °C.

[0144] In the case of an alloy containing aluminum, manganese, and magnesium, taking A grade or above as an index of good products, with respect to the total mass of the resistor material, the magnesium content is 0.7% by mass or more and 5.0% by mass or less, and the manganese content is 0.6% by mass or more and 2.0% by mass or less. And in an alloy containing aluminum, manganese, and magnesium, by making the combined content of magnesium and manganese 1.3% by mass or more and 7.0% by mass or less, good resistance characteristics can be obtained.

[0145] In particular, in the case of an Al-Mn-Mg alloy, by setting the manganese content to 1.8% by mass or more and 2.0% by mass or less and the magnesium content to 1.0% by mass with respect to the total mass of the resistor material, the resistance characteristics become good. This is worthy of an S rank.

[0146] Also, in the case of an Al-Mn-Mg alloy, simply setting the manganese content within the normal solid solution range cannot particularly improve the resistance characteristics. However, it can be said that the resistance characteristics can be improved by setting the combined content of magnesium and manganese to 1.3% by mass or more and 7.0% by mass or less, from the minimum and maximum values of manganese and magnesium in the A rank to the S rank.

Explanation of symbols

[0147] 10, 50 shunt resistors 14 resistor 16 first electrode 18 second electrode 30 first plating part 32 second plating part TCR resistance temperature coefficient

Claims

1. A plate-shaped resistor mainly composed of aluminum, and an electrode joined to the resistor, The resistor contains an alloy of aluminum and magnesium, The magnesium content is 0.7% by mass or more and 5.0% by mass or less, The electrode is mainly composed of aluminum and is a member different from the resistor, A shunt resistor.

2. The shunt resistor according to claim 1, The resistor contains an alloy of aluminum, manganese, and magnesium, A shunt resistor.

3. The shunt resistor according to claim 2, The resistor has a manganese content of 0.6% by mass or more and 2.0% by mass or less, and the combined content of magnesium and manganese is 1.3% by mass or more and 7.0% by mass or less, A shunt resistor.

4. The shunt resistor according to any one of claims 1 to 3, The resistor is an aluminum alloy with a temperature coefficient of resistance of 2000 ppm / °C or less, A shunt resistor.

5. The shunt resistor according to any one of claims 1 to 3, The temperature coefficient of resistance of the resistor is an aluminum alloy of 1000 ppm / °C or less, A shunt resistor.

6. The shunt resistor according to any one of claims 1 to 5, The electrode has a plating containing nickel or zinc, A shunt resistor.

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