Current detection device

Abstract

Current detection device comprising: a first wiring member (11) made of a highly conductive material, a second wiring member (12) made of a highly conductive material, and a resistance body (13) made of a metal material having a lower temperature coefficient of resistance than that of the highly conductive materials used in the wiring members (11, 12), wherein the first wiring member (11) and the second wiring member (12) are welded to the resistance body (13), the second wiring member (12) being longer than the first wiring member (11), wherein the second wiring member (12) has a plurality of bent parts (16, 17, 18), and wherein the plurality of bent parts comprises horizontally bent parts (16) and vertically bent parts (17, 18).

Description

Technical field

[0001] The present invention relates to a current detection device, and more particularly, it relates to a device capable of measuring a large current with a high degree of accuracy while the device is used as wiring for supplying a current. Technical background

[0002] Current detectors are suitable for detecting charging and discharging currents in batteries, detecting motor currents for driving electric and hybrid vehicles, and detecting currents in electrical devices such as air conditioners, solar panels, and the like. Current is detected by measuring the voltage between both ends of a shunt resistor, which is caused by the current flowing through the resistor.

[0003] Bus bars are selected as a route for supplying current from a power source, such as a battery, to an electrical device. A shunt resistor can be connected to the bus bar to detect current flowing through the bus bar. In these cases, the bus bar and the shunt resistor can be connected by a screw stop or by soldering (see JP 2011-3694 A and JP H6-224014 A).

[0004] However, these connection methods enlarge the connection parts, which becomes a factor in heat generation. These methods can cause problems in ensuring connection reliability. Therefore, a current detection device that can detect a large current with high reliability during use is desired.

[0005] Forming a shunt resistor at a part inside a bus bar is proposed by forming an elongated hole at that position (see JP 2001-349907 A). However, for the bus bar, a low-resistivity metal such as copper is generally used. Metals such as copper have a high temperature coefficient of resistance, making it difficult to detect current with high accuracy. Therefore, high-accuracy current detection is difficult when forming a shunt resistor part inside the bus bar using a metal material such as copper for this part.

[0006] Furthermore, DE 10 2007 027 916 A1, DE 10 2008 006 042 A1, and DE 10 2007 034 757 A1 each show shunts with connecting elements and a shunt resistance element accommodated between them, which can be welded to the connecting elements. The connecting elements can have different lengths and are sometimes bent out of the plane. Summary of the inventionTechnical problem

[0007] The invention was made based on the above-mentioned circumstances. Therefore, an object of the invention is to provide a current detection device that can measure a current flowing through a bus bar with high accuracy and high reliability. Solution to the problem

[0008] According to the invention, a current detection device according to claim 1 is provided. Further embodiments of the invention emerge, inter alia, from the dependent claim. The current detection device provides a first wiring member made of a highly conductive material, a second wiring member made of highly conductive material, and a resistance body made of a metal material with a lower temperature coefficient of resistance than the highly conductive materials used in the wiring members, wherein the first wiring member and the second wiring member are welded to the resistance body, and wherein the second wiring member is longer than the first wiring member. The second wiring member has a plurality of bent parts with both horizontally and vertically bent parts.

[0009] According to the invention, the function of the bus bar can be integrated with the function of the shunt resistor because both ends of the resistor body are firmly attached to the wiring members, eliminating the need for connections. Therefore, the number of parts can be reduced and the reliability of the connection can be improved. Because the resistor body, made of a metal material with a small temperature coefficient of resistance, is incorporated into the bus bar, high-accuracy detection of large currents is possible, just like with the shunt resistor. Thus, the above-mentioned problems are solved.

[0010] Because the second wiring link is longer, it becomes possible to form the wiring link into a complex curved shape. This means that the structure of the wiring link can be customized to the user's specifications. The first wiring link is shorter and can be standardized as a semi-machined product with the resistor body. Therefore, a part including the first wiring link and the resistor body has the capability of mass production, and a part including the second wiring link has improved adaptability to a customer's design. This enables the coexistence of mass production capability with the capability of customization to customer design.Furthermore, it becomes possible to reduce the concentration of stress on welded parts of the resistance body and the wiring member by forming a plurality of bent parts in the second wiring member. Short description of the drawings Fig. 1 shows a perspective view of a current detection device of the first embodiment of the invention. Fig. 2 shows in the upper part a top view of the Fig. 1, Fig. 2 shows in the lower left part a front view of the Fig. 1 and Fig. 2 shows in the lower right part a side view of the Fig. 1. Fig. 3 shows a perspective view of a current detection device of a second embodiment of the invention. Fig. 4 shows in the upper part a top view of the Fig. 3, and Fig. 4 shows in the lower part a front view of the Fig. 3. Fig. 5 shows a perspective view of a current detection device of a third embodiment of the invention. Fig. 6 shows a perspective view of a current detection device of the fourth embodiment of the invention. Fig. 7 shows a perspective view of a current detection device of a fifth embodiment of the invention. Fig. 8 shows a perspective view of voltage detection terminals of another embodiment of the invention. Description of the embodiments

[0011] Embodiments of the invention are described below with reference to Fig. 1 to Fig. 8. Identical or corresponding parts or elements are designated and explained by the same reference numerals throughout the views.

[0012] The Fig. 1 and Fig. 2 shows a current detection device of a first embodiment that measures a current flowing through the bus bar. A resistance body 13 is welded and fixed between the first wiring member 11 and the second wiring member 12, which is longer than the first wiring member 11. That is, the current detection device is formed in the shunt resistor 13 (resistance body) between the wiring members 11, 12. Furthermore, the entire structure of the current detection device consists of a bus bar.

[0013] The first and second wiring members 11, 12 are made of strip-shaped (bus bar-shaped) highly conductive metal material, which is made of copper, a copper system alloy, or aluminum, etc. "Highly conductive" means that the electrical conductivity is high, and the conductivity of wiring members is higher than the conductivity of the resistance body 13. The resistance body 13 is made of a metal resistance alloy material, such as a Cu-Mn system alloy, a Cu-Ni system alloy, or a Ni-Cr system alloy, which has an extremely low temperature coefficient of resistance compared to metal materials such as copper, etc.

[0014] Both end faces of the resistor body 13 are welded to the end surfaces of the wiring members 11, 12, forming strongly bonded surfaces. The welding process may use electron beam welding, laser beam welding, brazing, or soldering, etc. Furthermore, pressure bonding may be used by bringing the end surfaces of the resistor body and the wiring members into contact and pressing them together to form a bond.

[0015] A pair of voltage detection terminals 14, 15 are installed in the wiring member 11, 12 near the resistor body 13. The current flowing through the wiring member 11, 12 flows through the resistor body 13, and the voltage generated at both ends of the resistor body 13 is detected by the voltage detection terminals 14, 15. Therefore, the structure of the resistor body 13 and its circumference are similar to ordinary shunt resistors (for example, Japanese Laid-Open Patent Publication H6-224014), and high-precision current detection similar to ordinary shunt resistors can be achieved.

[0016] That is, because the wiring elements perform the function of the electrodes or terminals of the shunt resistors, the function of the shunt resistors can be integrated with the function of the bus bar. This eliminates the need for a connection part between a shunt resistor and a bus bar, and the number of parts can be reduced. Thus, the current flowing through the bus bar can be measured with high accuracy and high reliability.

[0017] The second wiring member 12 is longer than the first wiring member 11. The second wiring member 12 has a plurality of bent parts as shown in Fig. 1. A bent portion 16 is bent in a horizontal plane, and a bent portion 17 is bent from a horizontal plane to a vertical plane. Furthermore, a bent portion 18 is bent from a vertical plane to a horizontal plane.

[0018] Because a longer wiring member 12 is provided with a plurality of bent portions 16, 17, 18, the wiring member 12 can be shaped to suit a custom design with bent shapes according to a user's specifications. Thus, the device in which the wiring member 12 is installed can be made small and compact. By forming a plurality of bent portions in the wiring member, stress applied to the bus bar can be further dispersed. Furthermore, stress applied to the joint surfaces between the resistor body 13 and the wiring members 11, 12 can be reduced.

[0019] Because both ends of the wiring members 11, 12 have holes 19, 20, both ends of the bus bar with the shunt resistance function can be connected between the connecting devices with screw fixation, etc. Furthermore, both ends of the bus bar with the shunt resistance function, which do not have the holes 19, 20, can be connected between the connecting devices with welds, etc.

[0020] By making the first wiring member 11 shorter, the first wiring member 11 including the resistor body 13 can be standardized, simplifying the manufacturing process for mass production. By making the second wiring member 12 longer, it becomes possible to make the second wiring member have a complex curved shape. That is, it becomes possible to customize the structure of the second wiring member to meet user specifications. Thus, for the bus bar with current detection function, the coexistence of mass production productivity and customer customization is made possible.

[0021] The Fig. 3 and Fig. 4 shows a current detection device according to the second embodiment, which measures a current flowing through the bus bar. As in the first embodiment, the resistance body 13 is welded and connected between the first wiring member 11 and the second wiring member 12. In this embodiment, the wiring member 12 is designed to bend downward by providing bent parts 21, 22, 23, 24 according to a user's specifications, although a straight wiring member can connect from the hole 19 to the hole 20. Therefore, a small and compact design of the device becomes possible for users, and the number of parts can be reduced.

[0022] Fig. 5 shows a current detection device according to the third embodiment, which measures a current flowing through the bus bar. In this embodiment, the wiring member 12 is made to bend on one side in the horizontal plane by providing bent parts 25, 26, 27, 28 according to a user's specifications. Therefore, a small and compact design of the device becomes possible for users, and the number of parts can be reduced.

[0023] Fig. 6 shows a current detection device according to the fourth embodiment, which measures a current flowing through the bus bar. In this embodiment, bent parts 29, 30, 31, 32, and 33 are installed. The wiring member 12 is bent vertically downward at part 29 from the resistance body 13 side in the horizontal plane, thereby performing a downward deflection. The wiring member 12 is bent horizontally at part 30, bent vertically in a horizontal plane, thereby performing a deflection to one side in the horizontal plane at part 31, bent vertically in the vertical plane at part 32, and bent horizontally at part 33. Therefore, a small and compact device design is possible for users, and the number of parts can be reduced.

[0024] Fig. 7 shows a current detection device according to the fifth embodiment, which measures a current flowing through the bus bar. The entire surfaces of the wiring members 11, 12 and the resistance bodies 13 are covered with a protective film 35, except for holes 19, 20 and their edges. Only the voltage detection terminals 14, 15 protrude from the protective film 35. The peripheral portions of the holes 19, 20 not covered with the protective film are treated with a plating film 36, 37, such as Sn or Ni, etc. The entire bus bar can be prevented from oxidation by coating the protective film 35 and the plating films 36, 37. As for the protective film 35, a coating film of inorganic material such as glass or ceramic, etc., or a non-conductive oxide film formed by alumite treatment or anodizing may be used.

[0025] According to the above embodiments, voltage detection terminals protrude vertically upward on a surface of the wiring member. However, the voltage detection terminals 14, 15 only need to be installed in the vicinity of the connection surface with the resistor body on the wiring members, and then Fig. 8 shown constructions are possible. That is, the left view in Fig. Figure 8 shows that the voltage detection terminals 14a, 15a protrude horizontally from the side surfaces of the wiring members. Furthermore, the right view of the Fig. 8, that installation cuts or slots 38, 39 in the vicinity of the connecting surfaces with the resistor body on the wiring members and parts between the cut and the connecting surface are used as voltage detection terminals 14b, 15b.

[0026] Although embodiments of the invention have been explained, the invention is not limited to the above embodiments, and various changes and modifications can be made within the scope of the technical concepts of the invention. Industrial applicability

[0027] The invention can be suitably used for current detection devices that measure large currents flowing through wiring members. 36979

Claims

[1] Current detection device comprising: a first wiring member (11) made of a highly conductive material, a second wiring member (12) made of a highly conductive material, and a resistance body (13) made of a metal material having a lower temperature coefficient of resistance than that of the highly conductive materials used in the wiring members (11, 12), wherein the first wiring member (11) and the second wiring member (12) are welded to the resistance body (13), the second wiring member (12) being longer than the first wiring member (11), wherein the second wiring member (12) has a plurality of bent parts (16, 17, 18), and wherein the plurality of bent parts comprises horizontally bent parts (16) and vertically bent parts (17, 18). [2] The device according to claim 1, wherein voltage detection terminals (14, 15) are formed in the vicinity of the resistance body (13) on the first (11) and second (12) wiring members.

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