JP2012177656A - Shunt resistance type current sensor - Google Patents

Abstract

A shunt resistance type current sensor capable of improving the problem of durability due to a difference in thermal expansion and improving the cost is also provided.
A shunt resistance type current sensor (1) includes a substantially flat bus bar (10), a wiring board (20) installed on the bus bar (10), a magnitude of a current to be measured that is installed on the wiring board (20) and flows through the bus bar (10). And a voltage detection IC 30 for detecting a voltage value applied to the wiring board 20. The bus bar 10 has four connection terminal portions 11 that are partly raised from the flat plate portion and are cantilevered. The wiring board is mounted on the free end side of the connection terminal portion 11. Are electrically connected.
[Selection] Figure 2

Description

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

  Conventionally, in order to measure a pulse current, a large alternating current, and the like, a shunt resistance type current sensor has been proposed in which a current to be measured is passed through a shunt resistor having a known resistance value and a voltage drop generated in the shunt resistor is measured. When such a shunt resistance type current sensor measures a voltage drop, it is necessary to connect a wiring board on which a voltage detection IC or the like for measuring the voltage drop is mounted and a shunt resistor. Therefore, when the shunt resistor is a bus bar, it is necessary to connect the bus bar and the wiring board.

  However, since the bus bar and the wiring board have different coefficients of thermal expansion, stress is applied to the bus bar and the wiring board due to the difference in thermal expansion, causing a problem in durability. Therefore, a shunt resistance type current sensor that improves the durability problem due to the difference in thermal expansion has been proposed (see Patent Documents 1 and 2).

JP 2005-188972 A JP 2005-188873 A

  However, the shunt resistance type current sensor described in Patent Documents 1 and 2 uses an expensive flexible wiring board (wiring board) with high flexibility and requires a pin-shaped connecting member, which is costly. There was room for improvement.

  The present invention has been made to solve such conventional problems, and the object of the present invention is to improve the problem of durability due to a difference in thermal expansion and improve the cost. It is to provide a shunt resistance type current sensor.

  The shunt resistance type current sensor of the present invention is a substantially flat bus bar, a wiring board installed on the bus bar, and a magnitude of a current to be measured that is installed on the wiring board and flows through the bus bar. And a voltage detecting means for detecting a voltage value applied to the wiring board, wherein the bus bar has at least two connection terminal portions that are partly raised from the flat plate portion and formed in a cantilever shape. And the wiring board is mounted on and electrically connected to the free end side of the connection terminal portion.

  According to the shunt resistance type current sensor of the present invention, the bus bar has at least two connection terminal portions that are partly raised from the flat plate portion and formed in a cantilever shape. A wiring board is mounted on the end side. For this reason, even if a stress is generated due to a difference in thermal expansion between the bus bar and the wiring board, the stress is relieved by the elastic force of the connection terminal portion formed in a cantilever shape. Therefore, the problem of durability due to the difference in thermal expansion can be improved. In addition, the wiring board does not need to be a flexible and expensive flexible wiring board, and the connection terminal portion is formed by raising a part of the flat portion of the bus bar. There is no need for a connecting member. Therefore, cost can be improved.

  Further, in the shunt resistance type current sensor of the present invention, when the bus bar is viewed in plan, the total area of the at least two connection terminal portions is greater than the total area of the bus bar excluding the at least two connection terminal portions. Also, it is preferable to be small.

  According to the shunt resistance type current sensor, when the bus bar is viewed in plan, the total area of at least two connection terminal portions is smaller than the total area of the portions excluding at least two connection terminal portions of the bus bar. . For this reason, the effective cross-sectional area of the current flowing through the bus bar does not become too small, and the influence on the flow of the current to be measured can be minimized.

  Moreover, in the shunt resistance type current sensor of the present invention, it is preferable that each of the connection terminal portions has a width direction smaller than a length direction.

  According to this shunt resistance type current sensor, each of the connection terminal portions is smaller in the width direction than in the length direction, so that the connection terminal portion is easily bent and stress can be easily relieved. it can.

  Further, in the shunt resistance type current sensor of the present invention, it is preferable that each of the connection terminal portions is cut out to have details that are narrower in the width direction than other portions.

  According to the shunt resistance type current sensor, each of the connection terminal portions is partially cut off to form details that are narrower in the width direction than other portions, so that the stress can be more easily relaxed by the details. be able to.

  ADVANTAGE OF THE INVENTION According to this invention, the shunt resistance type current sensor which can aim at the improvement in the cost aspect while improving the problem of durability by a thermal expansion difference can be provided.

It is a side view which shows the shunt resistance type current sensor which concerns on embodiment of this invention. It is a top view which shows the shunt resistance type current sensor which concerns on embodiment of this invention. It is a top view which shows the bus bar which concerns on this embodiment. It is a top view which shows the bus bar which concerns on a modification.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described with reference to the drawings. FIG. 1 is a side view showing a shunt resistance type current sensor according to an embodiment of the present invention, and FIG. 2 is a top view showing the shunt resistance type current sensor according to an embodiment of the present invention. The shunt resistance type current sensor 1 shown in FIG. 1 includes a bus bar 10, a wiring board 20, and a voltage detection IC (voltage detection means) 30.

  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. The bus bar 10 is formed into a desired shape by press molding from a flat steel material. The bus bar 10 serves as a shunt resistor so that a current to be measured flows.

  The wiring board 20 has a predetermined circuit pattern 21 and is configured on the bus bar 10 so that a part of the current to be measured flows through the circuit pattern 21. Further, the wiring board 20 includes four through holes 22a and 22b, and is electrically connected to the bus bar 10 through the through holes 22a and 22b.

  The voltage detection IC 30 is installed on the circuit pattern 21 of the wiring board 20 and detects a voltage value applied to the circuit pattern 21 in order to detect the magnitude of the current to be measured flowing through the bus bar 10. The voltage drop generated in the bus bar 10 is measured by the detection of the voltage value by the voltage detection IC 30.

  Here, the bus bar 10 has four connection terminal portions 11. A part of the connection terminal portion 11 is raised from the flat plate portion of the bus bar 10 and is formed in a cantilever shape. These connection terminal portions 11 are formed at positions corresponding to the four through holes 22a and 22b, and their free ends are electrically connected to the through holes 22a and 22b by soldering or the like.

  In the present embodiment, the number of connection terminal portions 11 is four. That is, it is sufficient that there are at least two of the voltage input 1 side and the input 2 side to the wiring board 20. Further, it is sufficient that at least two through holes 22a and 22b correspond to the connection terminal portion 11.

  In addition, when the bus bar 10 is viewed in plan (that is, when viewed from the top shown in FIG. 2), the total area of the four connection terminal portions 11 is greater than the total area of the portions of the bus bar 10 excluding the four connection terminal portions 11. It is also small. Thereby, the effective cross-sectional area of the current flowing through the bus bar 10 does not become too small, and the influence on the flow of the current to be measured can be suppressed as much as possible. In particular, the size of the connection terminal portion 11 is desirably as small as possible for the above reasons.

  Each of the connection terminal portions 11 has a width direction smaller than a length direction. That is, it is desirable that the connection terminal portion 11 is thin.

  Next, the operation of the shunt resistance type current sensor 1 according to the present embodiment will be described. First, it is assumed that both the bus bar 10 and the wiring board 20 are thermally expanded due to the influence of heat. At this time, since the bus bar 10 and the wiring board 20 are made of different materials, the coefficients of thermal expansion are also different. For this reason, stress is generated due to the difference in expansion coefficient, and the joint portion (that is, the solder portion) that electrically connects the bus bar 10 and the wiring board 20 may be damaged, and the electrical connection may not be established.

  However, the shunt resistance type current sensor 1 according to the present embodiment includes the connection terminal portion 11. Moreover, a part of the connection terminal portion 11 is raised from the flat plate portion of the bus bar 10 to be cantilevered. For this reason, the stress is relieved by the elastic force of the connection terminal portion 11. Thereby, the situation where a junction part will be damaged by stress will be suppressed.

  Further, the wiring board 20 does not need to be a flexible and expensive flexible wiring board. That is, it is not necessary for the wiring board 20 itself to relieve stress. Moreover, since the connection terminal portion 11 is formed by raising a part from the flat plate portion of the bus bar 10, no pin-shaped connection member is required.

  Further, since the connecting terminal portion 11 is smaller in size in the width direction than in the length direction, the shape becomes thinner, the stress can be more easily relaxed, and damage to the joint portion can be further prevented. .

  In addition, since the connection terminal portion 11 is made higher than the flat portion of the bus bar 10, contact between the bus bar 10 and the wiring board 20 is also avoided.

  Thus, according to the shunt resistance type current sensor 1 according to the present embodiment, the bus bar 10 includes four connection terminal portions 11 that are partly raised from the flat plate portion and formed in a cantilever shape. The wiring board 20 is mounted on the free end side of the connection terminal portion 11. For this reason, even if a stress occurs due to a difference in thermal expansion between the bus bar 10 and the wiring board 20, the stress is relieved by the elastic force of the connection terminal portion 11 formed in a cantilever shape. Therefore, the problem of durability due to the difference in thermal expansion can be improved. Further, the wiring board 20 does not need to be a flexible and expensive flexible wiring board or the like, and the connection terminal portion 11 is formed by raising a part thereof from the flat plate portion of the bus bar 10. There is no need for a pin-shaped connecting member. Therefore, cost can be improved.

  Further, when the bus bar 10 is viewed in plan, the total area of the four connection terminal portions 11 is smaller than the total area of the portions of the bus bar 10 excluding the four connection terminal portions 11. For this reason, the effective cross-sectional area of the current flowing through the bus bar 10 does not become too small, and the influence on the flow of the current to be measured can be minimized.

  In addition, since each of the connection terminal portions 11 is smaller in the width direction than in the length direction, the connection terminal portions 11 are easily bent and stress can be easily relaxed.

  In addition, since the wiring board 20 has a plurality of voltage input 1 sides (through holes 22a) and a plurality of voltage input 2 sides (through holes 22b), even if the joints are damaged by stress, Thus, the joint portion functions, and the measurement can be continued.

  As described above, the present invention has been described based on the embodiment, but the present invention is not limited to the above embodiment, and may be modified without departing from the gist of the present invention.

  For example, in the shunt resistance type current sensor 1 according to this embodiment, the connection terminal portion 11 is not limited to the shape according to the above embodiment. FIG. 3 is a top view showing the bus bar 10 according to the present embodiment, and FIG. 4 is a top view showing the bus bar 10 according to a modification.

  As shown in FIG. 3, in the above embodiment, the connection terminal portion 11 is raised from the bus bar 10 and formed in a cantilever shape. However, it may be as shown in FIG. That is, the connection terminal portion 12 may have a detail 12a that is raised from the bus bar 10 and formed in a cantilever shape, and then part of the connection terminal portion 12 is cut off and made smaller in the width direction than other portions. This is because stress can be more easily relaxed.

  In the example shown in FIG. 4, the details 12a are formed by being cut into a substantially semicircular shape from both sides of the connection terminal portion 12, but are not particularly limited to a substantially semicircular shape, and other shapes such as a substantially rectangular shape and a substantially square shape. May be cut off.

DESCRIPTION OF SYMBOLS 1 ... Shunt resistance type current sensor 10 ... Bus bar 11, 12 ... Connection terminal part 12a ... Detail 20 ... Wiring board 21 ... Circuit pattern 22 ... Through hole 30 ... Voltage detection IC (voltage detection means)

Claims (4)

A substantially flat bus bar;
A wiring board installed on the bus bar;
Voltage detecting means installed on the wiring board and detecting a voltage value applied to the wiring board in order to detect the magnitude of the current to be measured flowing through the bus bar,
The bus bar has at least two connection terminal portions that are partly raised from the flat plate portion and formed in a cantilever shape, and the wiring board is mounted on the free end side of the connection terminal portion to electrically A shunt resistance type current sensor characterized by being connected. When the bus bar is viewed in plan, a total area of the at least two connection terminal portions is smaller than a total area of a portion of the bus bar excluding the at least two connection terminal portions. Item 2. The shunt resistance type current sensor according to Item 1. The shunt resistance type current sensor according to claim 1, wherein each of the connection terminal portions has a width direction smaller than a length direction. 4. The connection terminal portion according to claim 1, wherein a part of the connection terminal portion is cut out to be narrower in the width direction than the other portion. Shunt resistance type current sensor.

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