JP5918023B2 - Shunt resistance type current sensor - Google Patents

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 voltage detection means for detecting a voltage value is mounted on the circuit board in order to detect the magnitude of the current to be measured flowing through the bus bar. The bus bar and the circuit board are electrically connected by the connecting member, and the circuit board is supported on the bus bar by the connecting member, but the connection is made depending on the difference in the thermal expansion coefficient between the bus bar and the circuit board. There is concern that stress will act on the part, leading to a decrease in durability.

  For example, Patent Document 1 discloses a current measuring device. This current measuring device includes a bus bar interposed in a current path to be measured, and a circuit board in which a circuit for current measurement is incorporated. The bus bar and the circuit board are connected in a linear pin shape. They are electrically and mechanically connected via members. In this case, the shift in the shape change based on the difference in thermal expansion coefficient between the bus bar and the circuit board is absorbed through the elastic action due to the inclination of the pin-like connecting member, thereby relaxing the stress acting on the connecting portion. .

JP 2005-188873 A

  By the way, in the method disclosed in Patent Document 1, one end of the pin-shaped connecting member connected to the bus bar is formed in a so-called press-fit terminal shape, and the one end is press-fitted into a connection hole formed in the bus bar. Thus, the pin-shaped connecting member and the bus bar are connected and fixed. In addition, a through hole is formed in the circuit board, and a land is formed around the through hole. When the other end of the pin-shaped connecting member is inserted into the through hole, the land is connected to the land using solder. The member is connected and fixed.

  In such a configuration, the elastic action by the pin-like connecting member is obtained from the portion connecting the bus bar and the circuit board. However, since the pin-like connecting member has a linear shape, the elastic action is obtained. The portion can be obtained only with a length corresponding to the distance between the bus bar and the circuit board, and there is a problem that the relaxation of stress is limited.

  The present invention has been made in view of such problems, and an object thereof is to effectively relieve stress acting on a connection portion between a bus bar and a circuit board in a shunt resistance type current sensor.

  In order to solve such a problem, the present invention electrically connects a substantially flat bus bar, a circuit board disposed on the bus bar, the bus bar and the circuit board, and supports the circuit board on the bus bar. A shunt resistance type having a connection member and a voltage detection means for detecting a voltage value applied to the circuit board via the connection member for detecting the magnitude of the current to be measured that is mounted on the circuit board and flows through the bus bar A current sensor is provided. In this case, the connecting member is connected to the lower surface side not facing the circuit board in the bus bar, and extends outward from the edge of the bus bar, and extends in the thickness direction when bent in the thickness direction of the bus bar. Connected to the circuit board.

  Here, in the present invention, when the connection member extends from the edge portion of the bus bar, it is preferable that the connection member is bent in the thickness direction of the bus bar via a folded portion having a meander shape.

  In the present invention, the folded portion is preferably formed with a meander shape in a plane perpendicular to the bus bar.

  In the present invention, the folded portion is preferably formed with a meander shape in a plane parallel to the bus bar.

  According to the present invention, since the connecting member is connected to the lower surface side of the bus bar, the length of the connecting member includes the thickness of the bus bar in addition to the distance between the bus bar and the circuit board. It becomes. As a result, the portion (length) for obtaining the elastic action in the connecting member is expanded beyond the distance between the bus bar and the circuit board, so that the elastic action can be obtained effectively. As a result, the stress acting on the connection portion between the bus bar and the circuit board can be effectively reduced.

The top 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. The top view which shows typically the bus bar in the shunt resistance type current sensor shown in FIG. Explanatory drawing which shows the use condition of a shunt resistance type current sensor typically Explanatory drawing which shows the other use of a connection member typically The side view which shows typically the shunt resistance type current sensor which concerns on 2nd Embodiment The top view which shows typically the bus bar in the shunt resistance type current sensor shown in FIG.

(First embodiment)
FIG. 1 is a top view schematically showing the shunt resistance type current sensor 1 according to the present embodiment, and FIG. 2 is a side view schematically showing the shunt resistance type current sensor 1 shown in FIG. FIG. 3 is a top view schematically showing the bus bar 10 in the shunt resistance type current sensor 1 shown in FIG. The shunt resistance type current sensor 1 according to the present embodiment is used as, for example, a battery terminal, and includes a bus bar 10, a circuit board 20, and a voltage detection IC 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 interposed in a current path to be measured so that a current to be measured flows. In the present embodiment, the bus bar 10 includes a shunt resistor SR in a part thereof.

  The bus bar 10 is formed into a desired shape by press molding from a flat steel material. The bus bar 10 is formed in, for example, a substantially L shape, and through holes 11 and 12 are formed at respective tip portions. One through hole 11 functions as a hole for a battery post, and the other through hole 12 functions as a hole for a wire harness fixing screw.

  The circuit board 20 is disposed on the bus bar 10 and is disposed so as to face the upper surface 10a of the bus bar 10 at a predetermined distance. The circuit board 20 is supported on the bus bar 10 by a connecting member 40 described later. A circuit pattern 21 is formed on the circuit board 20, and a connection portion 22 in the circuit pattern 21 is electrically connected to the bus bar 10 via a connection member 40.

  The voltage detection IC 30 is mounted on the circuit pattern 21 formed on the circuit board 20. The voltage detection IC 30 detects the voltage value applied to the circuit board 20 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 the voltage applied to the shunt resistor SR of the bus bar 10 via the circuit pattern 21 and the connection member 40. As a result, 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 that flows to the bus bar 10 from the voltage drop.

  Note that a temperature sensor may be mounted on the surface of the circuit board 20 facing the bus bar 10, and the voltage detection IC 30 may perform correction according to the detection result of the temperature sensor. That is, the voltage detection IC 30 may correct 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 bus bar 10 and the circuit board 20 are electrically connected via a pair of connection members 40. The connecting member 40 is a linear member having conductivity, and is formed of, for example, copper or a copper alloy and has a predetermined shape as described later.

  In the connection member 40, one end is connected to the connection portion 22 in the circuit board 20. For example, a through hole is formed in the circuit board 20 corresponding to the connection portion 22, and one end portion of the connection member 40 is inserted into the through hole and soldered. As a result, the connection member 40 is electrically connected to the circuit board 20 (circuit pattern 21) via the connection portion 22 and mechanically connected to the circuit board 20.

  Further, the other end of the connection member 40 is connected to a predetermined position of the bus bar 10, whereby the pair of connection members 40 are connected to both end portions of the shunt resistor SR. In addition, the connection position of the connection member 40 with respect to the bus bar 10 may be anywhere as long as a voltage drop with respect to the shunt resistor SR can be measured. The connection method between the bus bar 10 and the other end of the connection member 40 can be widely applied as long as it enables electrical connection with the bus bar 10 such as welding or press fitting.

  As one of the features of this embodiment, each connection member 40 is connected to the lower surface 10 b side of the bus bar 10, that is, the surface side that does not face the circuit board 20. The connection member 40 extends from the edge of the bus bar 10 to the outside, and when bent in the thickness direction of the bus bar 10, the connection member 40 extends in the thickness direction and is connected to the circuit board 20.

  Further, in the present embodiment, the individual connection members 40 are not simply bent after extending outward from the edge of the bus bar 10, but are bent in the thickness direction of the bus bar 10 through the folded portion 41 having a meander shape. It has been. The folded portion 41 is formed in a meander shape in a plane perpendicular to the bus bar 10, and as a result, the entire shape of the connection member 40 is also configured in a two-dimensional shape included in the plane.

  FIG. 4 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. For example, the through hole 11 of the bus bar 10 is connected to the battery post 71 on the negative electrode side of the battery 70, and the other through hole 12 is connected to the wire harness W via the wire harness fixing screw 72.

  Thus, the shunt resistance type current sensor 1 of the present embodiment includes the connection member 40 that electrically connects the bus bar 10 and the circuit board 20. The connecting member 40 is connected to the lower surface 10b side of the bus bar 10, extends outward from the edge of the bus bar 10, and extends in the thickness direction when the bus bar 10 is bent in the thickness direction. It is connected to the.

  According to such a configuration, since the connection member 40 is connected to the lower surface 10b side of the bus bar 10, the thickness of the bus bar 10 is added to the connection member 40 in addition to the distance between the bus bar 10 and the circuit board 20. It will be included in the length. As a result, the portion (length) for obtaining the elastic action in the connecting member 40 is expanded beyond the distance between the bus bar 10 and the circuit board 20, so that the elastic action can be obtained effectively. . As a result, the stress acting on the connection portion between the bus bar 10 and the circuit board 20 can be effectively reduced.

  Here, assuming that the connecting member 40 is connected to the upper surface 10a side of the bus bar 10, the distance between the bus bar 10 and the circuit board 20 needs to be equally expanded in order to obtain the same elastic action as in the present embodiment. Can lead to an increase in the size of the apparatus. In this regard, according to the present embodiment, the connection member 40 is connected to the lower surface 10 b side of the bus bar 10, whereby the extension of the length of the connection member 40 can be achieved using the thickness of the bus bar 10. it can. Thereby, the stress which acts on the connection part of the bus bar 10 and the circuit board 20 can be relieve | moderated effectively, obtaining the merit of size reduction of an apparatus.

  Further, in the present embodiment, when the connection member 40 extends from the edge of the bus bar 10, the connection member 40 is bent in the thickness direction of the bus bar 10 via a folded portion 41 having a meander shape.

  According to this configuration, in addition to the distance between the bus bar 10 and the circuit board 20, a distance corresponding to the thickness of the bus bar 10 is included, so that a space for forming the folded portion 41 in the connection member 40 can be generated. . In the case where the connecting member 40 is configured only by a simple linear shape, a certain amount of limit may occur in the stress relaxation due to the inclination. However, since the folded portion 41 is included, an elastic action can be further obtained. The stress acting on the connection portion between the circuit board 20 and the circuit board 20 can be effectively relaxed. Further, even if the connection member 40 has a meander-shaped folded portion 41, such a shape can be included by using the thickness of the bus bar 10, which effectively reduces the size of the device. Can be planned.

  In the embodiment described above, the shape of the folded portion 41 of the connection member 40 is set in a range that does not contact the circuit board 20. However, as shown in FIG. 5, by attaching the circuit board 20 so as to be in contact with the folded portion 41 of the connection member 40, the height of the circuit board 20 with respect to the bus bar 10 can be set using the folded portion 41 of the connection member 40. May be adjusted.

(Second Embodiment)
FIG. 6 is a side view schematically showing the shunt resistance type current sensor 1 according to the second embodiment, and FIG. 7 is a top view schematically showing the bus bar 10 in the shunt resistance type current sensor 1 shown in FIG. FIG. The point where the shunt resistance type current sensor 1 according to the present embodiment is different from that of the first embodiment is the form of the connection member 40. Hereinafter, the description of the same configuration as that of the first embodiment will be omitted, and the description will focus on the differences.

  The individual connection members 40 are connected to the lower surface 10b side of the bus bar 10 as in the first embodiment. The connecting member 40 is formed with a folded portion 42 having a meander shape after extending outward from the edge of the bus bar 10. Then, when the connection member 40 passes through the folded portion 42 and is bent in the thickness direction of the bus bar 10, the connection member 40 extends in the thickness direction and is connected to the circuit board 20.

  Here, the folded portion 42 according to the present embodiment has a meander shape in a plane parallel to the bus bar 10, and as a result, the entire shape of the connecting member 40 is parallel to the bus bar 10 and the bus bar 10. 10 and a three-dimensional shape included in a vertical plane.

  As described above, according to the present embodiment, since the connection member 40 includes the folded portion 42, the elastic action can be effectively obtained as in the first embodiment. Therefore, the bus bar 10, the circuit board 20, and the like. It is possible to effectively relieve the stress acting on the connecting portion. Further, since the folded portion 42 that ensures the elastic action is formed in a plane parallel to the bus bar 10, it is not necessary to obtain the formation space of the folded portion 42 in the thickness direction of the bus bar 10. Since the length of the connection member 40 after being bent in the thickness direction can be reduced, it is possible to effectively reduce the size of the apparatus.

  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. For example, the bus bar is configured to include a part of the bus bar as the shunt resistance unit, but the bus bar is not limited thereto, and the whole may be used as the shunt resistance unit.

DESCRIPTION OF SYMBOLS 1 Shunt resistance type current sensor 10 Bus bar 11, 12 Through-hole 20 Circuit board 21 Circuit pattern 22 Connection part 30 Voltage detection IC
40 Connection member 41, 42 Folded part 70 Battery 71 Battery post 72 Fixing screw SR Shunt resistance part W Wire harness

Claims (4)

A substantially flat bus bar;
A circuit board disposed on the bus bar;
A connection member for electrically connecting the bus bar and the circuit board and supporting the circuit board on the bus bar;
Voltage detecting means mounted on the circuit board and detecting a voltage value applied to the circuit board via the connection member in order to detect the magnitude of the current to be measured flowing through the bus bar;
The connecting member is connected to a lower surface side of the bus bar that does not face the circuit board, and extends outward from an edge of the bus bar and extends in the thickness direction when bent in the thickness direction of the bus bar. And a shunt resistor type current sensor connected to the circuit board.   2. The shunt resistance type current sensor according to claim 1, wherein when the connection member extends from an edge of the bus bar, the connection member is bent in a thickness direction of the bus bar through a folded portion having a meander shape. .   The shunt resistance type current sensor according to claim 2, wherein the folded portion is formed with a meander shape in a plane perpendicular to the bus bar.   The shunt resistance type current sensor according to claim 2, wherein the folded portion is formed with a meander shape in a plane parallel to the bus bar.

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