JP2014137223A - Shunt resistance type current sensor and fitting structure of shunt resistance type current sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a shunt resistance type current sensor capable of properly suppressing such a situation that liquid water goes into a board, etc. inside a case even when a seal state inside the case by a mold material becomes insufficient and a fitting structure of the same.SOLUTION: A shunt resistance type current sensor 1 has: a bus bar 10; a case 50 which is a box-shaped body with an opened top part and molded by inserting the bus bar 10; a pair of connection terminals 40 which exist in the case 50 and are arranged in the bus bar 10; a circuit board 20 which is connected to the pair of connection terminals 40 in order to detect size of measured current to flow in the bus bar 10; and a sealed part 60 obtained by molding the inside of the case 50 by a mold material. Then, the shunt resistance type current sensor 1 is constituted so that a top part side of the case 50 faces downward at a state that the bus bar 10 is used as a battery terminal and fitted to a battery post 71 arranged in a battery 70.

Description

  The present invention relates to a shunt resistance type current sensor and its mounting structure.

  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. The bus bar is provided with a pair of connection terminals, and a circuit board is connected to the pair of connection terminals in order to detect the magnitude of the current to be measured flowing through the bus bar.

  For example, Patent Literature 1 discloses a battery state detection sensor device. This device includes a shunt resistor electrical connection part, a superelastic alloy lead wire for electrically connecting the electrical connection part of the electronic control board, and a state in which the shunt resistor is held and the electronic control board and the lead wire are accommodated. And a protective case in which the electronic control board and the connection conductor are sealed with the resin mold material filled with the resin mold material and cured by heating.

JP 2010-236981 A

  By the way, according to the method disclosed in Patent Document 1, the top of the case is opened, even though the case is covered with a lid member. Moreover, in the use state which uses a bus bar as a battery terminal, the top part of a case will face upwards. For this reason, in the case of bad weather or car wash, if the sealing state of the mold material is insufficient due to aging or the like, there is a problem that liquid water tends to flow around the substrate in the case.

  The present invention has been made in view of such problems, and the purpose of the present invention is to prevent liquid water from flowing into a substrate or the like inside the case even if the sealing state inside the case by the molding material becomes insufficient. It is to suppress effectively.

  In order to solve the problem, the first invention has a substantially flat-shaped bus bar, a bottom portion and side portions erected on the periphery thereof, the top portion is opened, and the bus bar is insert-molded. And a pair of connection terminals that are present in the case and disposed on the bus bar, and are arranged to face the bus bar and connected to the pair of connection terminals to detect the magnitude of the current to be measured flowing through the bus bar. In the state where the bus bar is used as a battery terminal and is attached to a battery post disposed on the battery, the top side of the case faces downward. A shunt resistance type current sensor is provided.

  Here, in the first invention, it is preferable that the bus bar is integrated with the inside of the bottom portion of the case and has both end portions extended to the outside of the case.

  In the first aspect of the invention, it is desirable that the circuit board is arranged above the battery, and the bus bars are arranged in order above the circuit board.

  Moreover, 2nd invention provides the attachment structure of a shunt resistance type current sensor. This mounting structure includes a battery in which a battery post is disposed, and a shunt resistance type current sensor. Here, the shunt resistance type current sensor has a substantially flat bus bar, a bottom portion and side portions erected around the bottom portion, and a top portion that is open, and a case in which the bus bar is insert-molded; A circuit board which is present in the case and disposed on the bus bar, and is disposed opposite to the bus bar and connected to the pair of connection terminals to detect the magnitude of the current to be measured flowing through the bus bar. And a sealing portion obtained by molding the inside of the case with a molding material. In this case, when the bus bar is used as a battery terminal and is attached to a battery post disposed on the battery, the case is disposed with the top side of the case facing downward.

  According to the present invention, when the shunt resistance type current sensor is mounted, the top side of the case where the sealing portion made of the molding material is exposed faces downward. Since liquid water is difficult to flow in the direction against gravity, even if the sealing condition of the mold material becomes insufficient due to deterioration over time, etc., it is possible to suppress the ingress of liquid water into the case in the mounted state. it can. Thereby, the situation where liquid water wraps around the circuit board inside the case can be effectively suppressed.

The bottom view which shows typically the shunt resistance type current sensor which concerns on this embodiment Side view schematically showing the shunt resistance type current sensor shown in FIG. Explanatory drawing which shows typically the use condition of the shunt resistance type current sensor which concerns on this embodiment Explanatory drawing which shows the manufacturing process of a shunt resistance type current sensor typically Explanatory drawing which shows the manufacturing process of a shunt resistance type current sensor typically Explanatory drawing which shows the manufacturing process of a shunt resistance type current sensor typically Explanatory drawing which shows the manufacturing process of a shunt resistance type current sensor typically

  FIG. 1 is a bottom 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. 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 case 50. In addition, when the shunt resistance type current sensor 1 is used as a battery terminal, the shunt resistance type current sensor 1 itself may function as the battery terminal itself, or may be combined with other members to be a part of the battery terminal. It may function as.

  The bus bar 10 is a substantially flat conductive member, and is formed 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, and a current to be measured flows. The bus bar 10 is formed into a desired shape by press molding from a flat steel material. A through hole is formed at each tip (not shown) of the bus bar 10. One through hole functions as a hole for a battery post, and the other through hole functions as a hole for a wire harness fixing screw.

  The case 50 is a resin box-like body having a bottom portion 50a and side portions 50b erected around the bottom portion 50a and having a top portion opened. As for this case 50, the bus bar 10 is integrated with the inner surface side of the bottom part 50a by insert molding. As a result, the central portion of the bus bar 10 is covered with the case 50, and both ends thereof extend to the outside of the case 50.

  The circuit board 20 is spaced apart from the bus bar 10 by a predetermined space. As shown in FIG. 2, the circuit board 20 is laid out below the bus bar 10 when the shunt resistance type current sensor 1 is in use. On the circuit board 20, a voltage detection IC (not shown) is mounted. In order to detect the magnitude of the current to be measured flowing through the bus bar 10, the voltage detection IC applies a voltage value applied to the circuit board 20 via a pair of connection terminals 40 described later, that is, a shunt resistor portion of the bus bar 10. The applied voltage value is detected. As a result, the voltage detection IC detects a voltage drop that occurs in the shunt resistor portion 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 bus bar 10 and the circuit board 20 are electrically connected via a pair of connection terminals 40. Each connection terminal 40 is formed of, for example, a pin-shaped conductive member, and is erected in a central portion of the bus bar 10, that is, in an area included in the case 50. The standing position of each connection terminal 40 may be anywhere as long as the voltage drop of the current to be measured can be measured, and is arranged at a predetermined distance in the flow direction of the current to be measured. That is, the connection terminals 40 are respectively connected to both end portions of the shunt resistor portion of the bus bar 10. The other end of each connection terminal 40 is connected to the circuit board 20.

  In such a configuration, the bus bar 10 and the circuit board 20 are hierarchically accommodated inside the case 50, and these elements are sealed by the sealing portion 60. The sealing part 60 is configured by molding the inside of the case 50 with a molding material such as a resin, whereby a state in which the periphery of the circuit board 20 is covered with the sealing part 60 is formed.

  FIG. 3 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, one through hole of the bus bar 10 is connected to a battery post 71 on the negative electrode side of the battery 70, and a terminal 75 a of the battery cable 75 is connected to the other through hole via a bolt 72 and a nut 73. Yes.

  In such a use state, the shunt resistance type current sensor 1 is configured such that the top side of the case 50 faces downward. In the present embodiment, the battery post 71 is formed on the upper surface portion of the battery 70, and the shunt resistance type current sensor 1 has the top side of the case 50 facing the upper surface portion of the battery 70. That is, the shunt resistance type current sensor 1 is configured such that the circuit board 20 is arranged above the battery 70 and the bus bar 10 is arranged above the battery 70 on the basis of the use state.

  4-7 is explanatory drawing which shows typically the manufacturing process of the shunt resistance type current sensor 1. FIG. Hereinafter, the manufacturing method of the shunt resistance type current sensor 1 will be described by using the bus bar 10 of the shunt resistance type current sensor 1 as a battery terminal.

  As a first step, a box-shaped case 50 is insert-molded with a predetermined resin material using a desired mold according to the shape of the case 50 using the bus bar 10 as an insert part. As a result, as shown in FIGS. 4 and 5, the bus bar 10 is configured to be integrated with the bottom 50 a of the case 50 and to extend both ends to the outside of the case 50.

  As shown in the figure, a pair of connection terminals 40 are erected in the center of the bus bar 10, that is, in a region corresponding to the inside of the case 50. The connection terminal 40 may be formed integrally with the bus bar 10 as a part of the insert part or separately, or may be formed on a corresponding portion of the bus bar 10 after the insert molding. The bus bar 10 and the connection terminal 40 can be connected by a known method such as soldering, welding, thermocompression bonding, or the like.

  As a second step, the circuit board 20 is assembled from the opening side (top side) of the case 50, and the circuit board 20 is connected to the pair of connection terminals 40 erected on the bus bar 10. The connection between the circuit board 20 and the connection terminal 40 is made by passing the other end side of the connection terminal 40 through a pair of through holes formed at predetermined positions of the circuit board 20, soldering, welding, The connection can be made by a known method such as thermocompression bonding.

  As a third step, the periphery of the circuit board 20 in the case 50 is molded with a molding material such as resin. As a result, a sealing portion 60 made of a molding material is formed in the internal space of the case 50.

  When the shunt resistance type current sensor 1 manufactured in this way is attached to the battery post 71 provided in the battery 70 using the bus bar 10 as a battery terminal, the top side of the case 50 faces downward. Deploy. With this mounting structure, the shunt resistance type current sensor 1 corresponding to the use state as shown in FIG. 3 can be obtained.

  As described above, the shunt resistance type current sensor 1 according to the present embodiment exists in the bus bar 10, the case 50 in which the bus bar 10 is insert-molded, and the box-shaped case 50 in which the top portion is opened. A pair of connection terminals 40 disposed on the bus bar 10, a circuit board 20 connected to the pair of connection terminals 40 for detecting the magnitude of the current to be measured flowing through the bus bar 10, and the case 50 with a molding material And a molded sealing portion 60. In the shunt resistance type current sensor 1, the top side of the case 50 faces downward when the bus bar 10 is used as a battery terminal and is attached to a battery post 71 disposed in the battery 70.

  According to this configuration, when the shunt resistance type current sensor 1 is mounted, the top portion side of the case 50 where the sealing portion 60 made of the molding material is exposed faces downward. Since the liquid water is difficult to flow in the direction against the gravity, the liquid water can be prevented from entering the case 50 in the attached state. Thereby, even if the sealing state of the molding material becomes insufficient due to aging or the like, it is possible to effectively suppress a situation in which liquid water wraps around the circuit board 20 inside the case 50.

  In the present embodiment, the bus bar 10 is configured to be integrated inside the bottom 50 a of the case 50 and to extend both ends to the outside of the case 50.

  According to this configuration, connection to the battery 70 (battery post 71) or the like can be performed at both ends of the bus bar 10. Moreover, since the sealing property of the extension site | part of the bus bar 10 can be ensured by using insert molding, the situation where liquid water approachs in the case 50 can be suppressed.

  In the present embodiment, the shunt resistance type current sensor 1 is configured such that the circuit board 20 is arranged above the battery 70 and the bus bar 10 is arranged above the circuit board 20 in order.

  According to this configuration, the circuit board 20 is sandwiched between the battery 70 and the bus bar 10. Therefore, the emission of electrical noise from the circuit board 20 can be suppressed.

  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. In addition, in the present invention, not only the shunt resistance type current sensor itself but also the above-described mounting structure of the shunt resistance type current sensor functions as a part of the present invention.

DESCRIPTION OF SYMBOLS 1 Shunt resistance type current sensor 10 Bus bar 20 Circuit board 40 Connection terminal 50 Case 50a Bottom part 50b Side part 60 Sealing part 70 Battery 71 Battery post 72 Bolt 73 Nut 75 Battery cable 75a Terminal

Claims (4)

A substantially flat bus bar;
A case in which the top portion is opened with a bottom portion and side portions erected around the bottom portion, and the bus bar is insert-molded,
A pair of connection terminals present in the case and disposed on the bus bar;
A circuit board disposed opposite to the bus bar and connected to the pair of connection terminals to detect the magnitude of the current to be measured flowing through the bus bar;
A sealing portion molded with a molding material in the case,
A shunt resistance type current sensor characterized in that the top side of the case faces downward when the bus bar is used as a battery terminal and is attached to a battery post disposed on the battery.   2. The shunt resistance type current sensor according to claim 1, wherein the bus bar is integrated with an inner side of a bottom portion of the case and has both end portions extended to the outer side of the case.   3. The shunt resistance type current sensor according to claim 1, wherein a circuit board is arranged above the battery, and a bus bar is arranged above the circuit board in order. In the mounting structure of the shunt resistance type current sensor,
A battery provided with a battery post;
The shunt resistance type current sensor,
The shunt resistance type current sensor is
A substantially flat bus bar;
A case in which the top portion is opened with a bottom portion and side portions erected around the bottom portion, and the bus bar is insert-molded,
A pair of connection terminals present in the case and disposed on the bus bar;
A circuit board disposed opposite to the bus bar and connected to the pair of connection terminals to detect the magnitude of the current to be measured flowing through the bus bar;
A sealing portion molded with a molding material in the case,
When the bus bar is used as a battery terminal and attached to a battery post disposed on the battery, the shunt resistance type current sensor mounting structure is characterized in that the case is disposed with the top side facing downward.

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