Shunt resistor module having screw coupling structure

A shunt resistor module which is coupled to a printed circuit board to be used for current measurement, includes: a resistor portion configured to have predetermined resistance; at least two terminal portions configured to extend from opposite ends of the resistor portion; lead pins fixed to first sides of the terminal portions to protrude to be electrically connected to the printed circuit board; and an exterior member formed to at least partially cover first surfaces of the terminal portions and to have pin holes opened to expose the lead pins and screw holes formed to be screwed to the printed circuit board.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a national phase entry under 35 U.S.C. § 371 of International Application No. PCT/KR2019/017393 filed Dec. 10, 2019, published in Korean, which claims priority from Korean Patent Application No. 10-2018-0164125 filed Dec. 18, 2018, all of which are incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to a shunt resistor module, and more particularly, to a shunt resistor module used to measure a current by detecting a current generated depending on a voltage drop across a resistor.

BACKGROUND ART

A rechargeable battery has high applicability according to a product line and has electrical characteristics such as high energy density, and thus it is widely used in electric vehicles or hybrid vehicles driven by electric driving sources, power storage devices, and the like, as well as portable devices. Such a rechargeable battery is attracting attention as a new energy source for eco-friendliness and energy efficiency enhancement thanks to not only a primary advantage of significantly reducing use of fossil fuels but also by-products that are not generated from the use of energy at all.

A power supply system of a battery pack using a rechargeable battery is generally equipped with a current sensor for measuring a current. The current sensor monitors a state of the battery pack by measuring the current flowing in a charging and discharging path of the battery pack, and detects an overcurrent flowing in the battery pack. In addition, the current measured through the current sensor may be used as information for calculating a state of charge (SOC), or may be used as a basis for determining whether a charging and discharging process is normally performed.

However, when the current sensor is not normally operated due to a failure or the like, it is impossible to properly sense a current flowing through the battery pack. As a result, even when an abnormal situation such as an overcurrent flow occurs, it may not be properly blocked, which may cause serious problems such as a failure or an explosion of the battery pack.

A shunt resistor is widely used to measure a current of a battery pack. A conventional shunt resistor has a terminal portion at opposite ends of a resistor portion, and lead pins protruding from these terminal portions may be physically and electrically connected to a printed circuit board through soldering. However, the lead pins may not only be broken in a process of assembling a bus bar in a state where the shunt resistor is poorly mounted, but may also be broken due to vibration or shock while being mounted on an electric vehicle or the like to be driven.

When the lead pins of the shunt resistor are broken, the current flowing through the battery pack is not properly sensed, and thus, even in an abnormal situation such as an overcurrent flow, it cannot be blocked and a malfunction or explosion of the entire battery pack may occur.

SUMMARY

Technical Problem

The present invention has been made in an effort to provide a shunt resistor module configured to enable screw fastening on a printed circuit board by coupling an injection material having a screw fastening hole to a shunt resistor.

However, the problems to be solved by the exemplary embodiments of the present invention are not limited to the above-described problems, and can be variously extended within the scope of the technical spirit included in the present invention.

Technical Solution

An exemplary embodiment of the present invention provides a shunt resistor module coupled to a printed circuit board, including: a resistor portion configured to have predetermined resistance; at least two terminal portions extending laterally from opposite ends of the resistor portion, each terminal portion having a respective first surface; lead pins fixed to and protruding from the respective first surfaces of the terminal portions, wherein the lead pins are configured to be electrically connected to the printed circuit board; and an exterior member adapted to at least partially cover the first surfaces of the terminal portions, wherein the exterior member includes: respective pin holes configured to receive the lead pins, wherein the lead pins are configured to protrude through the respective pin holes; and respective screw holes configured to be screwed to the printed circuit board.

The screw holes may be positioned in a first surface of the exterior member configured to cover the respective first surfaces of the terminal portions.

At least two screw holes may be symmetrically disposed at opposite sides of the exterior member with respect to the resistor portion.

The screw holes and the lead pins may be spaced apart from each other by a creepage amount or more.

A depth of the screw holes in the exterior member may be smaller than a height from the first surface of the exterior member to the respective first surfaces of the terminal portions.

The screw holes may be positioned laterally farther than the pin holes from the resistor portion.

The screw holes may be outwardly positioned farther than the pin holes with respect to the printed circuit board.

The exterior member may be made of a resin injection material.

Each of the terminal portions may be a plate-shaped terminal portion having fastening holes positioned therein, and the exterior member may be adapted to cover peripheries of the lead pins between the fastening holes.

The lead pins may protrude from first surfaces of the respective terminal portions, and the pin holes may be independent of each other and are configured to separately receive each of the lead pins.

A voltage drop across the resistor portion may be indicative of a current generated along an electrical path from a battery pack,

Advantageous Effects

According to an exemplary embodiment, a shunt resistor is screwed to a printed circuit board by using a shunt resistor module in which an injection material having a screw fastening hole is coupled to the shunt resistor, thereby preventing the lead pin from being broken even in the case of vibration of a defective lead pin or a device including a battery pack.

In the shunt resistor module according to the exemplary embodiment, vibration shock may be absorbed from an exterior member attached to a shunt resistor, and a stress concentrated on lead pins may be distributed to a screw member, thereby significantly reducing the stress on the lead pins.

DETAILED DESCRIPTION

The present invention will be described more fully hereinafter with reference to the accompanying drawings, in which exemplary embodiments of the invention are shown. As those skilled in the art wherein realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention.

Further, in the specification, the phrase “in a plan view” means when an object portion is viewed from above, and the phrase “in a cross-sectional view” means when a cross-section taken by vertically cutting an object portion is viewed from the side.

FIG. 1illustrates an exploded perspective view of a shunt resistor module100according to an exemplary embodiment of the present invention,FIG. 2illustrates a perspective view of the shunt resistor module100according to an exemplary embodiment of the present invention, andFIG. 3illustrates a bottom perspective view showing the shunt resistor module100illustrated inFIG. 1.

The shunt resistor module100according to the present embodiment includes an exterior member130for covering a shunt resistor110, and may be fastened to a printed circuit board (PCB)50(seeFIG. 4) to be used for measurement.

Referring toFIG. 1, the shunt resistor110includes a resistor portion120having a predetermined resistance value, and at least two terminal portions111and112extending from opposite ends of the resistor portion120. Lead pins121and122are fixed to first surfaces of the terminal portions111and112, and may be protruded to be electrically connected to the printed circuit board50. The terminal portions111and112may formed to have a plate shape, to respectively extend to opposite sides with the resistor portion120at a center thereof, and fastening holes113and114may be respectively formed in the terminal portions111and112.

The exterior member130may be formed to at least partially cover first surfaces of the terminal portions111and112, and as shown inFIG. 2, pin holes131and132opened to expose the lead pins121and122and screw holes141and142for being screwed to the printed circuit board50may be formed. The lead pins121and122protruding from first surfaces of the respective terminal portions111and112may be inserted into corresponding pin holes131and132to be fixed and protected, and in this case, the pin holes131and132may be independent of each other to be formed separately for each of the lead pins121and122.

The exterior member130may include upper surface portions130acovering first surfaces of the terminal portions111and112and having the pin holes131and132and the screw holes141and142, side surface portions130bextending downwardly to surround side surfaces of the terminal portions111and112, and lower surface portions130cextending from the side surface portions130bto second surfaces of the terminal portions111and112and covering them. The upper surface portions130aof the exterior member130may be formed to cover a periphery of the lead pins121and122between the fastening holes113and114of the terminal portions111and112. Referring toFIG. 3, the lower surface portions130cmay partially cover opposite edges of the terminal portions111and112, and may be connected to each other by bridge portions138and139. For example, two bridge portions138and139may be formed. As a result, the exterior member130may be formed to closely wrap a central portion thereof including the resistor portion120of the shunt resistor110from upper, lower, and side surfaces thereof, and the upper surface portions130a, the side surface portions130b, the lower surface portions130c, and the bridge portions138and139may be integrally formed. The exterior member130having a structure as described above may be made of a resin injection material, and the exterior member130and the shunt resistor110that are coupled in this way may be manufactured by an insert molding process to become a shunt resistor module.

As described above, the screw holes141and142may be formed in first surfaces, e.g., the upper surface portions130a, of the exterior member130, which covers first surfaces on which the lead pins121and122protrude from the terminal portions111and112, and the screw holes141and142are formed with screw threads therein, so that screw members10and20(seeFIG. 4) such as screws or bolts may be fastened therewith. At least two screw holes141and142may be symmetrically disposed at opposite sides of the exterior member130with respect to the resistor portion120. Therefore, when fastened to the printed circuit board50through the screw members10and20, they may be symmetrically fixed around the resistor portion120to stably maintain a fixed state.

When viewed in a plane direction that is parallel to first surfaces of the terminal portions111and112, the screw holes141and142may be positioned farther than the pin holes131and132from the resistor portion120, and the screw holes141and142may be outwardly positioned farther than the pin holes131and132with respect to the printed circuit board50. Accordingly, the lead pins121and122inserted into and fixed in the pin holes131and132may be stably fixed from the outside, and even when external vibration or the like occurs, it is possible to prevent fixed portions of the lead pins121and122from being affected. In this case, a distance between the pin holes131and132and the screw holes141and142may be adjusted in proportion to a magnitude of a current and a voltage applied to the shunt resistor110. Accordingly, a distance between the lead pins121and122and the screw members10and20may be controlled.

On the other hand, the shunt resistance module according to another exemplary embodiment may be formed in the exterior member, so that one pin hole may be formed to expose the lead pins. Thus, the pin hole may be formed as a single integrated hole rather than being independently and individually formed for each of the lead pins. In addition, the exterior member according to another exemplary embodiment may be formed to have one or three or more bridge portions on a bottom surface thereof, or may be formed to cover lower surfaces of the terminal portions as much as the upper surface thereof without forming the bridge portion.

In addition, the shunt resistance module according to another exemplary embodiment may form a screw hole near each corner of the upper surface. That is, four screw holes may be formed.

FIG. 4illustrates a perspective view showing a state in which the shunt resistor module100is connected to the printed circuit board50according to an example of the present invention, andFIG. 5illustrates a cross-sectional view taken along a line V-V ofFIG. 4.

As illustrated inFIG. 4, the printed circuit board50has a protrusion corresponding to the exterior member130of the shunt resistor module100, and the upper surface portions130aof the exterior member130are superimposed on the protrusion to come into contact therewith. Soldering holes are positioned in the printed circuit board50to correspond to the lead pins121and122of the shunt resistor module100to be electrically connected thereto through soldering. Similarly, openings may be formed to correspond to the screw holes141and142of the exterior member130in the printed circuit board50, and the screw members10and20may be screwed into the screw holes141and142of the exterior member130through the openings of the printed circuit board50. For example, a fastening member having a thread on the outside, such as a bolt or a screw, may be applied as the screw members10and20.

The screw holes141and142to which the screw members10and20are fastened and the lead pins121and122of the shunt resistor module100need to be spaced from each other by greater than a creepage amount depending on a voltage magnitude of a system, i.e., a minimum insulation distance. That is, a distance “1” measured along a surface of the printed circuit board50between the screw members10and20and the lead pins121and122may be set in proportion to magnitudes of a current and a voltage across the shunt resistor, and may be designed to a certain level or more in consideration of the creepage.

Meanwhile, referring toFIG. 5, a depth of the screw holes141and142formed in the exterior member130may be formed to be smaller than a thickness from a surface of the exterior member130to the first surface of the shunt resistor110. Furthermore, a thickness of the exterior member130may be set in consideration of the required creepage between the screw members10and20and the shunt resistor110and may be determined in consideration of a distance d1between the screw hole142and the shunt resistor110as illustrated inFIG. 5, and the length of the screw member20and the thickness of the exterior member130may be determined in consideration of a distance d2between the screw member20and the shunt resistor110. Even when the screw members10and20are added by forming it in consideration of the creepage in this way, a current flow is not affected. In addition, it is possible to prevent dangers such as short circuits that may occur due to a short creepage.

With regard to setting of the creepage, a distance may be calculated in compliance with the specifications depending on requirements of the device or field to which the shunt resistor module according to the present exemplary embodiment is applied. For example, the creepage may be set in consideration of an international electrotechnical commission (IEC) standard, an Underwriters Laboratories Inc. (UL) standard, a Verde Deutscher Elektrotrchniker (VDE) standard, or a Japanese standard.

FIG. 6is a cross-sectional view showing a state in which a shunt resistor12is connected to the printed circuit board50according to a comparative example of the present invention.

Referring toFIG. 6, unlike the shunt resistor module100according to the example, the shunt resistor12of the comparative example may be adhered to the printed circuit board50without including a separate external member around lead pins21and22. That is, the shunt resistor12of the comparative example may have terminal portions at opposite ends of the resistor portion, and the lead pins21and22protruding from these terminal portions may be physically and electrically connected to the printed circuit board50through soldering. However, the lead pins21and22may not only be broken in a process of assembling a bus bar in a state where the shunt resistor12is poorly mounted, but may also be broken due to vibration or shock while being mounted on an electric vehicle or the like to be driven.

That is, the lead pins21and22were performing not only the electrical connection of the printed circuit board50but also the physical fixation function in the shunt resistor12of the comparative example, but according to the example, vibration shock is absorbed from the exterior member130attached to the shunt resistor110, and a stress concentrated on the lead pins121and122is distributed to the screw members10and20in the shunt resistor module100. Since the shock absorber is absorbed once from the exterior member130made of an injection material and the shunt resistor110is firmly fixed to the printed circuit board50by using the screw members10and20, the stress of the lead pins121and122of the shunt resistor110may be significantly reduced.