Patent Publication Number: US-2023156952-A1

Title: Holding device, current monitoring device, and power supply device

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is based upon and claims the benefit of priority from prior Japanese patent application No. 2021-188078, filed on Nov. 18, 2021, the entire contents of which are incorporated herein by reference. 
     TECHNICAL FIELD 
     The present invention relates to a holding device, a current monitoring device, and a power supply device. 
     BACKGROUND ART 
     There has been proposed a current detection device including a unit metal member through which a current to be measured flows, voltage terminal portions which acquire a voltage signal from the unit metal member, and a holding member that holds a plurality of the unit metal members in parallel (for example, JP-A-2017-15588). In this device, the plurality of unit metal members are sandwiched between the holding member and a substrate on which a wiring pattern is formed, and the voltage terminal portions of the unit metal member are connected to the wiring patterns of the substrate. 
     SUMMARY OF INVENTION 
     Technical Problem 
     When the unit metal member such as a shunt resistor is connected to the wiring pattern of the current detection device, a connection failure may occur. An object of the present invention is to provide a holding structure of a shunt resistor with which a connection portion can be easily recognized. 
     Solution to Problem 
     According to an aspect of the present invention, there is provided a holding device, including: a holding portion configured to hold a shunt resistor; a spacer portion extending from the holding portion and abutting on a front surface of a substrate on which a monitoring unit configured to monitor a current value of a current flowing through the shunt resistor is mounted; and an engaging portion extending from the holding portion and having an engaging claw to be engaged with a back surface of the substrate, in which the spacer portion separates the holding portion and the substrate from each other such that a connection portion which electrically connects the shunt resistor and the monitoring unit is visible. 
     Advantageous Effects of Invention 
     According to the aspect of the present invention, it is possible to provide a holding structure of a shunt resistor with which the connection portion can be easily recognized. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG.  1    is a schematic cross-sectional view of a power supply device including a shunt resistor and a holding device for the shunt resistor. 
         FIG.  2    is an exploded perspective view illustrating an example of a current monitoring device according to a first embodiment. 
         FIG.  3    is a perspective view illustrating an example of the current monitoring device according to the first embodiment. 
         FIG.  4    is a front view illustrating an example of the current monitoring device according to the first embodiment. 
         FIG.  5    is an exploded perspective view illustrating an example of a current monitoring device according to a second embodiment. 
         FIG.  6    is a perspective view illustrating an example of the current monitoring device according to the second embodiment. 
         FIG.  7    is a front view illustrating an example of a current monitoring device according to a third embodiment. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Hereinafter, embodiments of the present invention will be described with reference to the drawings. 
     First Embodiment 
       FIG.  1    is a schematic cross-sectional view of a power supply device including a shunt resistor and a holding device for the shunt resistor. The power supply device (battery)  1  illustrated in  FIG.  1    includes a housing  2 , a lid  3 , a battery pack  4 , a cover  5 , bus bars  6 A,  6 B, a shunt resistor  7 , bosses  8 A,  8 B, bolts  9 A,  9 B, a holding device  10 , and a substrate  11 . The power supply device  1  is, for example, a power supply for supplying electric power to an in-vehicle device such as a navigation device or an audio device, but is not limited to the examples. 
     The housing  2  and the lid  3  are packages that accommodate the battery pack  4 . The battery pack  4  is, for example, a secondary battery such as a lead storage battery, but the power storage method is not particularly limited. The battery pack  4  is formed by connecting a plurality of battery cells so as to obtain a predetermined voltage or capacity, but the voltage, capacity, and the like thereof are not particularly limited. Further, the cover  5  is, for example, a resin cover for a purpose of waterproofing, and covers the battery pack  4  together with the housing  2 . 
     The bus bars  6 A,  6 B are provided in an output current path of the battery pack  4 , and are connected between the battery pack  4  and a load. The shunt resistor  7  is connected between the bus bars  6 A,  6 B. The shunt resistor  7  is connected to the substrate  11  via the holding device  10 . The holding device  10  is a member provided for fixing the shunt resistor  7  to the substrate  11 . The substrate  11  is, for example, a circuit substrate on which a monitoring unit (not shown) including a current sense amplifier and a microcomputer is mounted, and the monitoring unit is connected to the shunt resistor  7  via two lead pins. The current sense amplifier amplifies a voltage between two points of the shunt resistor corresponding to a value of a current flowing through the load, and outputs the amplified voltage to the microcomputer. The microcomputer monitors the current value based on a potential difference between the two points of the shunt resistor  7  amplified by the current sense amplifier. That is, the microcomputer performs A/D conversion on the received potential difference and performs processing according to a magnitude of the voltage after the conversion. In the present embodiment, the housing  2  for the battery pack  4  is also used as a housing for the substrate  11  and the shunt resistor  7 , instead of providing a dedicated housing incorporating the substrate  11  and the shunt resistor  7  together with the housing  2  for the battery pack  4 . As a result, the cost may be reduced. 
       FIG.  2    is an exploded perspective view illustrating an example of a current monitoring device according to a first embodiment.  FIG.  3    is a perspective view illustrating an example of the current monitoring device according to the first embodiment.  FIG.  4    is a front view illustrating an example of the current monitoring device according to the first embodiment. A direction in which a tongue piece portion  114  protrudes from a main body portion  113  of the substrate  11  to be described later, is referred to as front for the sake of convenience, and the description will be made based on front, rear, left, right directions illustrated in  FIG.  2   . A current monitoring device  12  includes the shunt resistor  7 , the holding device  10 , and the substrate  11 . The shunt resistor  7  has through holes  71  into which the bolts  9 A,  9 B (not shown) for connecting the bus bars  6 A,  6 B (not shown) and the bosses  8 A,  8 b (not shown) can be inserted. A female screw may be provided inside the through hole  71 . As shown in  FIG.  4   , the shunt resistor  7  includes two lead pins  72  protruding toward the substrate  11 . The lead pins  72  are fixed to the substrate  11  by, for example, soldering. In  FIG.  4   , the lead pins  72  of the shunt resistor  7  are connected to the substrate  11  by solder portions  73  formed on front and back surfaces of the substrate  11 . 
     The holding device  10  is formed of, for example, a resin, and includes a holding portion  101  for holding the shunt resistor  7 , and spacer portions  102  and engaging portions  103  for fixing the holding portion  101  to the substrate  11 . The holding portion  101  holds the shunt resistor  7  such that front and back sides of the shunt resistor  7  are sandwiched. In the present embodiment, the metal shunt resistor  7  and the holding device  10  are integrally formed by, for example, insert molding. The spacer portions  102  protrude from the holding portion  101  toward the substrate  11  and are abutted with the substrate  11 . The engaging portions  103  protrude from four corners of the holding portion  101  toward the substrate  11 . An engaging claw  1031  for engaging with an edge of the substrate  11  is provided on a front end side of the engaging portion  103 . Further, the holding portion  101  has an opening portion (exposed portion)  104  through which a part of a surface (upper surface) of the shunt resistor  7  that is opposite to a surface (lower surface) facing the substrate  11  is exposed. 
     The substrate  11  has through holes  111  into which bolts for connecting to bosses (not shown) can be inserted. A monitoring unit  112  including, for example, a current sense amplifier and a microcomputer is mounted on the front surface or the back surface of the substrate  11 . The current sense amplifier of the monitoring unit  112  is electrically connected to the shunt resistor  7 . Further, the substrate  11  includes the main body portion  113  on which the monitoring unit  112  and the like are mainly mounted, and the tongue piece portion  114  which is a small piece protruding from the main body portion  113  to one side (front side in the example of  FIG.  2   ). Two through holes  115  for inserting of the lead pins  72  of the shunt resistor  7  are formed in the tongue piece portion  114 . The lead pins  72  of the shunt resistor  7  are inserted into the through holes  115 , and are connected to the substrate  11  by the solder portions  73 . Then, the shunt resistor  7  is electrically connected to the monitoring unit  112  mounted on the substrate  11 . Notches  116  are formed at four corners of the tongue piece portion  114 . The notches  116  are engaged with the engaging claws  1031  of the holding device  10 , and the holding device  10  is connected to the substrate  11 . 
     According to the spacer portions  102  of the holding device  10 , the holding portion  101  and the front surface of the substrate  11  can be separated from each other such that connection portions (the lead pins  72  and the solder portions  73 ) that electrically connect the shunt resistor  7  and the monitoring unit  112  is visible. In the example of  FIG.  4   , the lead pins  72  and the solder portions  73  are visible without being blocked by the spacer portion  102  and the engaging portions  103  in a front view. In particular, the solder portions  73  formed on the front surface (upper surface) of the substrate  11  can be recognized through an opening  1021  formed between two spacer portions  102  in a front view. Specifically, since the opening  1021  is formed by the holding portion  101 , the two spacer portions  102 , and the substrate  11  in a front view, the solder portions  73  can be checked. The spacer portion  102  may be one or more columnar protruding portions, or may be, for example, a wall-shaped protruding portion extending in a predetermined direction such as a front-rear direction. That is, the spacer portion  102  is a protruding portion at least a part of which is opened such that the connection portions between the shunt resistor  7  and the monitoring unit  112  can be visually recognized. According to such spacer portions  102 , the work of checking the connection failure is facilitated, and improvement of the quality may be expected. 
     According to the spacer portions  102  of the holding device  10 , the substrate  11  and the shunt resistor  7  can be separated from each other, and transfer of heat from the shunt resistor  7  to the substrate  11  can be reduced. Further, according to the opening portion  104  of the holding device  10 , the heat from the shunt resistor  7  can be efficiently dissipated. That is, breakage of the substrate or mounted components due to heat generation can be prevented. A shape of the opening portion  104  is not limited to a window-shaped hole that is surrounded by the periphery as long as the exposed portion through which at least a part of an upper side of the shunt resistor  7  is exposed is provided. By engaging the engaging claws  1031  with the notches  116  of the tongue piece portion  114 , the holding device  10  facilitates positioning of an installation location of the shunt resistor  7 , and the assembly of the shunt resistor  7 . Further, the holding device  10  is fixed not to the main body portion  113  but to the tongue piece portion  114  of the substrate  11 . In other words, the holding device  10  and the shunt resistor  7  are not mounted on the main body portion  113  on which components are mounted. Accordingly, components that are mounted on the main body portion  113  are not below the holding device  10  and the shunt resistor  7 , and the degree of freedom of component arrangement in the main body portion  113  is increased. 
     Second Embodiment 
       FIG.  5    is an exploded perspective view illustrating an example of a current monitoring device according to a second embodiment.  FIG.  6    is a perspective view illustrating an example of the current monitoring device according to the second embodiment. In the present embodiment, the same components as those of the above-described embodiment are denoted by the same reference numerals, and the description thereof will be omitted. A current monitoring device  12 A includes the shunt resistor  7 , a holding device  10 A, and the substrate  11 . The shunt resistor  7  and the holding device  10 A according to the present embodiment are not integrally formed, but are formed by combining different members. 
     The holding device  10 A according to the present embodiment includes a holding portion  101 A whose upper surface is opened and on which the shunt resistor  7  can be placed, and the spacer portions  102  and the engaging portions  103  for fixing the holding portion  101 A to the substrate  11 . As in the above-described embodiment, the spacer portions  102  protrude from the holding portion  101 A toward the substrate  11  and are abutted with the substrate  11 . The engaging portions  103  are connected to the holding portion  101 A via wall portions  105  and horizontal portions  106 , and protrude from four corners of the horizontal portions  106  toward the substrate  11 . The wall portions  105  are formed at front and rear of the holding portion  101 A, respectively, and are erected upward. The horizontal portions  106  are formed at ends of the wall portions  105  respectively, and extend in a left-right direction. Then, the engaging portions  103  protrude downward from left and right end portions of each of the horizontal portions  106 . An engaging claw  1031  for engaging with the edge of the substrate  11  is formed on a lower end side of the engaging portion  103 . Further, the holding portion  101 A includes locking portions  107  that protrude from four corners of the holding portion  101 A in a direction (upward) opposite to the substrate  11  and that lock the shunt resistor  7 . A locking claw  1071  for locking an edge of the shunt resistor  7  is formed on an upper end side of the locking portion  107 . Further, the holding portion  101 A has opening portions  108 , through which the lead pins  72  of the shunt resistor  7  passes, at positions corresponding to the through holes  115  of the substrate  11  on a surface (lower surface) of the holding portion  101 A facing the substrate  11 . 
     In the present embodiment, when the holding device  10  is molded, it is not necessary to perform insert molding in combination with the shunt resistor  7 . As compared with the first embodiment, an upper portion of the shunt resistor  7  is more largely exposed, and the heat dissipation efficiency is improved. Further, since the engaging portion  103  is provided on the holding portion  101 A via the wall portion  105  and the horizontal portion  106 , the engaging portion  103  is formed longer in the upper-lower direction and can be easily deformed, and the wall portion  105  and the horizontal portion  106  can also be deformed, so that a stress generated in the mounted component can be released. 
     In the present embodiment, according to the spacer portions  102  of the holding device  10 A, the holding portion  101 A and the front surface of the substrate  11  can also be separated such that the connection portions (the lead pins  72  and the solder portions  73 ) that electrically connect the shunt resistor  7  and the monitoring unit  112  can be visually recognized. According to the spacer portions  102  of the holding device  10 A, the substrate  11  and the shunt resistor  7  can be separated from each other, and the transfer of heat from the shunt resistor  7  to the substrate  11  can be reduced. Further, the holding device  10 A facilitates positioning of the installation location of the shunt resistor  7  by engaging the engaging claws  1031  with the notches  116  of the substrate  11 . 
     Third Embodiment 
       FIG.  7    is a front view illustrating an example of a current monitoring device according to a third embodiment. In the present embodiment, the same components as those of the above-described embodiments are also denoted by the same reference numerals, and the description thereof will be omitted. A current monitoring device  12 B includes the shunt resistor  7 , a holding device  10 B, and the substrate  11 . In the holding device  10 B according to the present embodiment, a shape of an engaging claw  1031 B is different from those of the above-described embodiments. The shunt resistor  7  and the holding device  10 B according to the present embodiment may be integrally molded, or may not be integrally molded. 
     The engaging claw  1031 B of an engaging portion  103 B includes a first inclined portion  1032  whose thickness increases toward an extending direction (lower side) in which the engaging portion  103 B extends, and a second inclined portion  1033  which is located below the first inclined portion  1032  and whose thickness decreases toward the lower side. The first inclined portion  1032  can urge the holding device  10 B in a direction, in which the holding device  10 B is brought into close contact with the substrate  11 , and can reliably fix the holding device  10 B and the substrate  11 . That is, in a state where the holding device  10 B and the substrate  11  are engaged with each other, for example, when an external force such as vibration is applied to the substrate  11 , a load can be reduced by a reaction force generated by the engaging claws  1031 B, and particularly, the connection portions of the lead pins  72  between the holding device  10 B and the substrate  11  can be protected. 
     In the present embodiment, according to the spacer portions  102  of the holding device  10 B, the holding portion  101  and front surface of the substrate  11  can also be separated such that the connection portions (the lead pins  72  and the solder portions  73 ) that electrically connect the shunt resistor  7  and the monitoring unit  112  can be visually recognized. According to the spacer portions  102  of the holding device  10 B, the substrate  11  and the shunt resistor  7  can be separated from each other, and the transfer of heat from the shunt resistor  7  to the substrate  11  can be reduced. Further, the holding device  10 B facilitates positioning of the installation location of the shunt resistor  7  by engaging the engaging claws  1031 B with the notches  116  of the substrate  11 .