JP2015021816A - Shunt resistance current sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a shunt resistance type current sensor capable of successfully securing a thermal connection relation between temperature detection means mounted on a circuit board and a bus bar.SOLUTION: A shunt resistance type current sensor 1 includes: a bas bar 10; a circuit board 20 arranged facing the bus bar 10; a connection terminal electrically connecting the bus bar 10 with the circuit board 20 and retaining the circuit board 20 at an interval for the bus bar 10; a voltage detection IC 30 mounted on the circuit board 20 and detecting a voltage value applied to the circuit board 20; and a temperature sensor 35 for detecting a temperature of the bus bar 10 so that the voltage detection IC 30 performs a correction. This bus bar 10 includes a concave part 13 projected toward the circuit board 20 at a position corresponding to the temperature sensor 35.

Description

  The present invention relates to a shunt resistance type current sensor.

  Conventionally, in order to detect a pulse current, a large alternating current, etc., the current to be measured is passed through a shunt resistor having a known resistance value, and the magnitude of the current to be measured is detected by detecting a voltage drop generated in the shunt resistor. A shunt resistance type current sensor has been proposed. For example, in a vehicle such as an automobile, a metal piece called a bus bar is sometimes used for power distribution, and a part of the bus bar corresponding to a current path is used as a shunt resistor. A circuit board is disposed on the bus bar, and the circuit board has a voltage detection IC for detecting a voltage value applied to the shunt resistor unit in order to detect the magnitude of the current to be measured flowing through the bus bar. Installed.

  In addition, in this type of shunt resistance type current sensor, the resistance value of the shunt resistor part may change depending on the temperature. Therefore, the temperature of the shunt resistor part is detected, and the resistance value is corrected according to this temperature. Is going. In particular, when the temperature dependence coefficient related to the shunt resistor portion is large, it is necessary to accurately detect the temperature of the shunt resistor portion. For this reason, a temperature sensor is also mounted on a circuit board on which a voltage detection IC or the like for detecting a voltage drop is mounted (see, for example, Patent Document 1).

JP 2012-78328 A

  By the way, the connection terminals such as the voltage detection terminal and the ground terminal perform not only electrical connection between the circuit board and the bus bar but also mechanical connection, but the connection terminal separates the circuit board from the bus bar. Since it holds, there exists a problem that a space | gap will arise between a circuit board and a bus bar. In this case, the distance between the temperature sensor on the circuit board and the bus bar is also separated by the gap between the bus bar and the circuit board, which may reduce the temperature detection accuracy.

  The present invention has been made in view of such problems, and its purpose is to improve the current detection accuracy by efficiently transmitting the thermal state of the bus bar to the temperature detection means mounted on the circuit board. A shunt resistance type current sensor that can be realized is provided.

  In order to solve such a problem, the present invention electrically connects a substantially flat bus bar, a circuit board disposed facing the bus bar, the bus bar and the circuit board, and the circuit board is connected to the bus bar. A connection terminal that is held apart, a voltage detection means that is mounted on the circuit board and detects a voltage value applied to the bus bar to detect the magnitude of the current to be measured flowing through the bus bar, and is opposed to the bus bar on the circuit board And a temperature detection means for detecting the temperature of the bus bar so that the voltage detection means performs correction, and the bus bar protrudes toward the circuit board at a position corresponding to the temperature detection means. Provided is a shunt resistance type current sensor including a convex portion.

  Here, in the present invention, the connection terminal is formed by bending a strip-like extension piece extending from the edge of the bus bar to the circuit board side, and penetrating the tip region of the extension piece into the circuit board. It is preferable.

  In the present invention, the connection terminal is composed of a base end portion set to the same plate thickness as the bus bar and a tip end portion set to a plate thickness thinner than the bus bar, and a circuit is provided in the middle of the base end portion. It is preferable that the front end portion penetrates the circuit board while being bent toward the substrate side.

  Moreover, in this embodiment, it is preferable to further have a heat conducting member arranged so as to fill a gap between the convex portion and the temperature detecting means.

  According to the present invention, since the height on the surface of the bus bar is partially raised due to the presence of the convex portion, the bus bar can be brought close to the temperature detecting means on the circuit board. Thereby, the thermal state of the bus bar can be efficiently transmitted to the temperature detecting means, and the current detection accuracy can be improved.

The top view which shows typically the shunt resistance type current sensor which concerns on 1st Embodiment The bottom view which shows typically the shunt resistance type current sensor which concerns on 1st Embodiment Side view schematically showing the shunt resistance type current sensor shown in FIG. Sectional drawing which shows a bus bar typically Explanatory drawing which shows the use condition of a shunt resistance type current sensor typically Explanatory drawing which shows typically the shunt resistance type current sensor which concerns on 2nd Embodiment.

  FIG. 1 is a top view schematically showing a shunt resistance type current sensor 1 according to this embodiment, and FIG. 2 is a bottom view schematically showing the shunt resistance type current sensor 1 according to this embodiment. FIG. 3 is a side view schematically showing the shunt resistance type current sensor 1 shown in FIG. 1, and shows a state in which the shunt resistance type current sensor 1 shown in FIG. 1 is viewed from the lower side with respect to the paper surface. The shunt resistance type current sensor 1 according to the present embodiment is used as a battery terminal, and mainly includes a bus bar 10 and a circuit board 20.

  The bus bar 10 is a substantially flat conductive member, and is made of, for example, a copper manganese alloy or a copper nickel alloy. A part of the bus bar 10 can function as a shunt resistor SR, and when a current flows through the bus bar 10, a current to be measured flows through the shunt resistor SR. The bus bar 10 is formed into a desired shape by press molding from a flat steel material.

  In this embodiment, the bus bar 10 is formed in, for example, a substantially U shape, and through holes 11 and 12 are formed on both sides of the shunt resistor portion SR located in the center. One through hole 11 functions as a battery post hole, and the other through hole 12 functions as a wire harness fixing hole.

  The shunt resistance type current sensor 1 includes a pair of voltage detection terminals 41 and 42 corresponding to the positive electrode and the negative electrode. The individual voltage detection terminals 41 and 42 electrically connect the circuit board 20 and the bus bar 10 and hold the circuit board 20 with respect to the bus bar 10. When the shunt resistance type current sensor 1 is used as a battery terminal and attached to the battery post on the negative electrode side of the battery, one voltage detection terminal 41 corresponds to a voltage detection terminal on the positive electrode side, and the other voltage detection terminal 42 is a negative electrode. This corresponds to the voltage detection terminal on the side. The voltage detection terminals 41 and 42 are provided at positions corresponding to both ends of the shunt resistor SR.

  In the present embodiment, each of the voltage detection terminals 41 and 42 is configured as a strip-like extension piece extending from the edge of the bus bar 10. The individual voltage detection terminals 41 and 42 are extended in an alternating direction from the edge portions facing each other, and are arranged in parallel. In the present embodiment, these voltage detection terminals 41 and 42 are formed integrally with the bus bar 10, and are formed simultaneously with the bus bar 10 by, for example, pressing a flat plate steel material. The individual voltage detection terminals 41 and 42 have forms corresponding to each other, and the voltage detection terminal 42 will be described as an example.

  FIG. 4 is an explanatory view schematically showing an AA section of the bus bar 10 shown in FIG. The voltage detection terminal 42 is formed in a substantially L shape, that is, a shape that extends from the edge of the bus bar 10 and then is bent toward the circuit board 20 side. A portion of the voltage detection terminal 42 on the tip side of the bending position extends linearly, and the tip region penetrates the circuit board 20 (see FIG. 2).

  The voltage detection terminal 42 includes a proximal end portion 42a connected to the bus bar 10 and a distal end portion 42b positioned on the distal end side of the proximal end portion 42a. The base end portion 42a is set to the same plate thickness as the bus bar 10, and is bent toward the circuit board 20 in the middle thereof. On the other hand, the tip 42b is set to be thinner and narrower than the bus bar, and penetrates the circuit board 20. The tip end portion 42b is formed by, for example, a thickness reducing process that reduces the plate thickness. This thickness reduction process is a pre-process for realizing penetration of the circuit board 20 with a small hole, and is performed prior to the bending process at the base end part 42a.

  Here, the inner diameter of the through hole formed in the circuit board 20 corresponds to the outer diameter of the distal end portion 42b, and the base end portion 42a cannot enter the through hole. For this reason, a gap corresponding to the length from the bent position to the tip end portion 42 b exists between the bus bar 10 and the circuit board 20. Thus, the voltage detection terminal 42 holds the circuit board 20 with respect to the bus bar 10.

  The shunt resistance type current sensor 1 further includes a ground terminal 43. The ground terminal 43 electrically connects the bus bar 10 and the circuit board 20 and holds the circuit board 20 with respect to the bus bar 10 like the pair of voltage detection terminals 41 and 42. The ground terminal 43 is disposed outside the pair of voltage detection terminals 41 and 42 with reference to the current path of the current to be measured flowing through the bus bar 10. In other words, the ground terminal 43 is disposed outside the shunt resistor portion SR. In the present embodiment, the ground terminal 43 is provided between the other voltage detection terminal 42 and the through hole 11 for the battery post.

  The ground terminal 43 is configured as a strip-like extension piece that extends from the edge of the bus bar 10, extends from the edge of the bus bar 10, is bent toward the circuit board 20, and has its tip region Penetrates the circuit board 20 (see FIG. 2). Note that the specific form of the ground terminal 43 is the same as that of the voltage detection terminals 41 and 42, and thus detailed description thereof is omitted.

  Referring to FIGS. 1 to 3 again, the circuit board 20 is installed with a predetermined space so as to face the bus bar 10. A pair of circuit patterns (not shown) are formed on the circuit board 20. One end of the pair of circuit patterns is connected to voltage detection terminals 41 and 42 penetrating the circuit board 20, and the other end is connected to a voltage detection IC 30 described later. Further, a ground pattern (not shown) is formed on the circuit board 20. One end of the ground pattern is connected to the ground terminal 43 that penetrates the circuit board 20, and the other end is connected to the voltage detection IC 30. The connection between the individual voltage detection terminals 41 and 42 and the circuit pattern and the connection between the ground terminal 43 and the ground pattern are performed by, for example, soldering.

  The voltage detection IC 30 is mounted on the circuit board 20 and is connected to a circuit pattern and a ground pattern formed on the circuit board 20. As the voltage detection IC 30, a microcomputer mainly composed of a CPU, a ROM, a RAM, and an I / O interface can be used. The voltage detection IC 30 detects a voltage value applied to the circuit board 20 via the pair of voltage detection terminals 41 and 42 in order to detect the magnitude of the current to be measured flowing through the bus bar 10 (voltage detection means). . That is, the voltage detection IC 30 detects a voltage drop that occurs in the shunt resistor SR of the bus bar 10 and detects the magnitude of the current to be measured flowing through the bus bar 10 from the voltage drop.

  The voltage detection IC 30 performs correction according to a detection result by a temperature sensor 35 described later. That is, the voltage detection IC 30 corrects the resistance value in the shunt resistor SR according to the temperature result so as not to detect an erroneous current value due to the influence of the resistance change due to the temperature change.

  The temperature sensor 35 is provided on the surface of the circuit board 20 facing the shunt resistor SR of the bus bar 10. In the present embodiment, the temperature sensor 35 is provided on the surface of the circuit board 20 opposite to the mounting surface of the voltage detection IC 30. It has been. For this reason, the temperature sensor 35 detects the temperature of the bus bar 10 (shunt resistor SR) located at a position facing itself (temperature detection means).

  As one of the features of this embodiment, the bus bar 10 includes a convex portion 13 protruding toward the circuit board 20 at a position corresponding to the temperature sensor 35. This convex part 13 bears the function which improves the thermal connection of the bus bar 10 and the temperature sensor 35 using the height with which it is provided. The protruding height by the convex portion 13 is set so that the convex portion 13 and the temperature sensor 35 are as close as possible based on the distance between the bus bar 10 and the circuit board 20 (temperature sensor 35). .

  The convex portion 13 may be formed simultaneously with the molding of the bus bar 10 by pressing, or may be additionally formed after the bus bar 10 is molded. Further, the convex portion 13 may be formed not only integrally with the bus bar 10 but also by an independent member. The convex portion 13 is for enhancing the thermal connection between the temperature sensor 35 and the bus bar 10, and preferably has a thermal conductivity equal to or higher than that of the bus bar 10.

  FIG. 6 is an explanatory diagram schematically showing a usage state of the shunt resistance type current sensor 1 according to the present embodiment. The bus bar 10 of the shunt resistance type current sensor 1 according to the present embodiment is used as a battery terminal that can be used for the battery 70. For example, one through hole 11 of the bus bar 10 is connected to the negative electrode side of the battery post 71 using a bolt 14 and a nut 15 (see FIG. 1). The other through-hole 12 is connected to the wire harness W via a wire harness fixing screw 73.

  As described above, in the present embodiment, the shunt resistance type current sensor 1 electrically connects the bus bar 10, the circuit board 20 disposed to face the bus bar 10, the bus bar 10 and the circuit board 20, and is connected to the bus bar 10. On the other hand, a connection terminal that holds the circuit board 20 at a distance, and a voltage detection that detects a voltage value applied to the bus bar 10 in order to detect the magnitude of the current to be measured that is mounted on the circuit board 20 and flows through the bus bar 10. The IC 30 includes a temperature sensor 35 that is mounted on a surface of the circuit board 20 facing the bus bar 10 and detects the temperature of the bus bar 10 so that the voltage detection IC 30 performs correction. Protrusions 13 protruding toward the circuit board 20 are provided at positions corresponding to the bus bar 10 and the temperature sensor 35. In the present embodiment, the pair of voltage detection terminals 41 and 42 and the ground terminal 43 correspond to connection terminals, respectively.

  Since the height on the surface of the bus bar 10 is partially raised due to the presence of the convex portion 13, the bus bar 10 and the temperature sensor 35 on the circuit board 20 can be brought close to each other. Thereby, the current detection accuracy can be improved by efficiently transmitting the thermal state of the bus bar 10 to the temperature sensor mounted on the circuit board 20.

  Further, by simultaneously forming the convex portion 13 by deforming the shape of the bus bar 10 itself through press working, it is possible to improve the production efficiency together with the above-described effects.

  In the present embodiment, the connection terminal is formed by bending a strip-like extension piece extending from the edge of the bus bar 10 toward the circuit board 10, and the tip region of the extension piece is formed on the circuit board 20. It penetrates.

  According to this configuration, a gap is generated between the bus bar 10 and the circuit board 20 according to the length between the bending position of the connection terminal and the holding position of the circuit board 20. Even when such a form is adopted for the connection terminal, the height on the surface of the bus bar 10 is partially raised due to the presence of the convex portion 13, so the bus bar 10 and the circuit board 20 The temperature sensor 35 can be brought close to. Thereby, the current detection accuracy can be improved by efficiently transmitting the thermal state of the bus bar 10 to the temperature sensor mounted on the circuit board 20.

  Moreover, in this embodiment, the connection terminal is comprised by the base end part set to the same board thickness as the bus bar 10, and the front-end | tip part set to plate | board thickness thinner than a bus bar, The middle of a base end part In this configuration, the circuit board 20 is bent and the tip portion penetrates the circuit board 20.

  When the distal end portion is formed by performing the thickness reducing process, it is preferable to bend the connection terminal at the proximal end portion in consideration of the effect of work hardening occurring at the distal end portion. Since only the front end penetrates the circuit board 20, a gap corresponding to the length from the bent position to the front end exists between the bus bar 10 and the circuit board 20. That is, when the connection terminal has a two-stage configuration of the base end portion and the tip end portion, a gap is inevitably generated between the bus bar 10 and the circuit board 20. However, according to this embodiment, the height on the surface of the bus bar 10 is partially raised due to the presence of the convex portion 13, so that the bus bar 10 and the temperature sensor 35 on the circuit board 20 are brought close to each other. Can do. Thereby, the current detection accuracy can be improved by efficiently transmitting the thermal state of the bus bar 10 to the temperature sensor mounted on the circuit board 20.

(Second Embodiment)
FIG. 6 is an explanatory diagram schematically showing the shunt resistance type current sensor 1 according to the present embodiment. The shunt resistance type current sensor 1 according to the second embodiment is different from the first embodiment in that the thermal connection between the bus bar 10 and the temperature sensor 35 is further improved. In addition, the description about the structure which overlaps with 1st Embodiment shall be abbreviate | omitted, and it demonstrates focusing on difference below.

  By providing the convex portion 13, the bus bar 10 and the temperature sensor 35 can be brought close to each other. However, a gap may be generated between the convex portion 13 and the temperature sensor 35 according to the processing accuracy of parts and individual differences. Conceivable. Therefore, in the present embodiment, this is solved by providing the heat conducting member 36. That is, the shunt resistance type current sensor 1 according to the present embodiment further includes a heat conducting member 36 disposed so as to fill a gap between the convex portion 13 and the temperature sensor 35. As the heat conductive member 36, for example, a heat conductive resin or a high heat conductive resin obtained by adding a highly heat conductive filler to a resin can be used.

  As a result, the temperature of the bus bar 10 quickly conducts heat to the temperature sensor 40 via the high thermal conductive member 36, so even when a gap is formed between the convex portion 13 and the temperature sensor 35, The thermal connection relationship with 10 can be ensured satisfactorily.

  Moreover, according to this embodiment, on the assumption that the convex part 13 exists, the heat conductive member 36 is arrange | positioned in the state where the distance with the temperature sensor 35 became short. For this reason, if there is no gap between the convex portion 13 and the temperature sensor 35 according to the processing accuracy of the component and individual differences, the heat conducting member 36 can be omitted, and this can be arranged. Even if it is provided, it is possible to reduce the amount of the heat conducting member 36 used or to improve the work efficiency for providing it.

  The shunt resistance type current sensor according to the present embodiment has been described above, but the present invention is not limited to this embodiment, and various modifications can be made within the scope of the present invention.

DESCRIPTION OF SYMBOLS 1 Shunt resistance type current sensor 10 Bus bar 13 Convex part 20 Circuit board 30 Voltage detection IC
35 Temperature Sensor 36 Heat Conducting Member 41 Voltage Detection Terminal 42 Voltage Detection Terminal 42a Base End 42b Tip 43 Ground Terminal 70 Battery 71 Battery Post SR Shunt Resistor W Wire Harness

Claims (4)

A substantially flat bus bar;
A circuit board disposed facing the bus bar;
A connection terminal for electrically connecting the bus bar and the circuit board, and holding the circuit board with respect to the bus bar.
Voltage detection means mounted on the circuit board for detecting a voltage value applied to the bus bar in order to detect the magnitude of the current to be measured flowing through the bus bar;
Temperature detection means mounted on a surface of the circuit board facing the bus bar and detecting the temperature of the bus bar so that the voltage detection means performs correction,
The bus bar includes a projecting portion protruding toward the circuit board at a position corresponding to the temperature detecting means.   The connection terminal is formed by bending a strip-like extension piece extending from the edge of the bus bar to the circuit board side, and a leading end region of the extension piece passes through the circuit board. The shunt resistance type current sensor according to claim 1. The connection terminal is
A base end set to the same thickness as the bus bar;
It consists of a tip part set to a plate thickness thinner than the bus bar,
3. The shunt resistance type current sensor according to claim 1, wherein the shunt resistance current sensor is bent toward the circuit board in the middle of the base end portion, and the tip end portion penetrates the circuit board.   The shunt resistance type current sensor according to any one of claims 1 to 3, further comprising a heat conducting member disposed so as to fill a gap between the convex portion and the temperature detecting means.

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