Patent Publication Number: US-2023145111-A1

Title: Cell insulation defect detection system

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
     This application claims, under 35 U.S.C. § 119(a) the benefit of Korean Patent Application No. 10-2021-0152313, filed on Nov. 8, 2021, the disclosure of which is incorporated herein by reference in its entirety. 
     BACKGROUND 
     Technical Field 
     Embodiments of the present disclosure relate to a battery cell and, more particularly, to a cell insulation defect detection system configured to detect insulation defects of individual cells forming a battery. 
     Background 
     Eco-friendly vehicles, such as electric vehicles, hybrid electric vehicles, and fuel cell vehicles, partially or entirely receive driving force from a motor. Recently, these eco-friendly vehicles have drawn a great deal of attention. 
     The motor is driven by receiving energy stored in a battery provided in a vehicle. Particularly, a battery module or a battery pack comprising a plurality of unit cells electrically connected to each other is applied to a machine requiring high output and large capacity, such as the vehicle. Specifically, the battery module is made by a plurality of unit cells, and the battery pack is obtained by assembling several battery modules. 
     A certain number of unit cells are joined to each other to produce a module with a target capacity where each cell is inserted into a cell housing to be fixed therein. In addition, as shown in  FIG.  1   , each cell  10  may comprise a side surface insulated by a tubing  12  to be insulated from adjacent cells. 
     The above information disclosed in this Background section is only for enhancement of understanding of the background of the present disclosure and therefore it may contain information that does not form the existing technologies that is already known in this country to a person of ordinary skill in the art. 
     SUMMARY 
     The present disclosure has been made in an effort to solve the above-described problems associated with existing technologies, and it is an object of the present disclosure to provide a cell insulation defect detection system capable of detecting insulation defects of individual cells in advance. 
     The object of the present disclosure is not limited to the above-mentioned object, and other objects not yet mentioned will be clearly understood by those of ordinary skill in the art to which the present disclosure pertains from the following descriptions (hereinafter referred to as “those skilled in the art”). 
     In order to achieve the object of the present disclosure as described above and to perform the characteristic functions of the present disclosure to be described later, the characteristics of the present disclosure are described as follows. 
     In one aspect, the present disclosure provides a cell insulation defect detection system including a contact unit including a conductive roller to contact a battery cell to be inspected, the battery cell being rotatably housed therein, and a measurement unit configured to measure insulation resistance between the roller and the cell in contact with each other. 
     Other aspects and preferred embodiments of the disclosure are discussed infra. 
     The above and other features of the disclosure are discussed infra. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other features of the present disclosure will now be described in detail with reference to certain exemplary embodiments thereof illustrated in the accompanying drawings which are given hereinbelow by way of illustration only, and thus are not limitative of the present disclosure, and wherein: 
         FIG.  1    shows an example of an individual cell forming a battery module or a battery pack; 
         FIG.  2    is a schematic view of an insulation test for an enclosure of the battery module; 
         FIG.  3    shows an internal state of the battery module including a plurality of cells connected to each other; 
         FIG.  4    shows a cell insulation defect detection system according to an exemplary embodiment of the present disclosure; 
         FIG.  5    is a partially enlarged view of  FIG.  4   ; 
         FIG.  6    is a partially enlarged view of  FIG.  5   ; 
         FIG.  7 A  is a front view of  FIG.  6   ; 
         FIG.  7 B  is a partial excerpt of a contact unit; 
         FIG.  8    shows a state of the contact unit before the insulation test is performed; 
         FIG.  9    shows a state of the contact unit when the insulation test is performed; 
         FIG.  10    is a plan view of  FIG.  9   ; 
         FIG.  11    is a schematic view of the insulation test performed according to the present disclosure; 
         FIGS.  12 A to  12 H  show an inspection process of the cell insulation defect detection system according to the present disclosure; and 
         FIGS.  13  and  14    show a method of identifying a defective cell from a normal cell during the insulation test performed according to the present disclosure. 
     
    
    
     It should be understood that the appended drawings are not necessarily to scale, presenting a somewhat simplified representation of various preferred features illustrative of the basic principles of the disclosure. The specific design features of the present disclosure as disclosed herein, including, for example, specific dimensions, orientations, locations, and shapes will be determined in part by the particular intended application and use environment. 
     In the figures, reference numbers refer to the same or equivalent parts of the present disclosure throughout the several figures of the drawing. 
     DETAILED DESCRIPTION 
     It is understood that the term “vehicle” or “vehicular” or other similar term as used herein is inclusive of motor vehicles in general such as passenger automobiles including sports utility vehicles (SUV), buses, trucks, various commercial vehicles, watercraft including a variety of boats and ships, aircraft, and the like, and includes hybrid vehicles, electric vehicles, plug-in hybrid electric vehicles, hydrogen-powered vehicles and other alternative fuel vehicles (e.g. fuels derived from resources other than petroleum). As referred to herein, a hybrid vehicle is a vehicle that has two or more sources of power, for example both gasoline-powered and electric-powered vehicles. 
     The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. As used herein, the singular forms “a,” “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. These terms are merely intended to distinguish one component from another component, and the terms do not limit the nature, sequence or order of the constituent components. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. Throughout the specification, unless explicitly described to the contrary, the word “comprise” and variations such as “comprises” or “comprising” will be understood to imply the inclusion of stated elements but not the exclusion of any other elements. In addition, the terms “unit”, “-er”, “-or”, and “module” described in the specification mean units for processing at least one function and operation, and can be implemented by hardware components or software components and combinations thereof. 
     Although exemplary embodiment is described as using a plurality of units to perform the exemplary process, it is understood that the exemplary processes may also be performed by one or plurality of modules. Additionally, it is understood that the term controller/control unit refers to a hardware device that includes a memory and a processor and is specifically programmed to execute the processes described herein. The memory is configured to store the modules and the processor is specifically configured to execute said modules to perform one or more processes which are described further below. 
     Further, the control logic of the present disclosure may be embodied as non-transitory computer readable media on a computer readable medium containing executable program instructions executed by a processor, controller or the like. Examples of computer readable media include, but are not limited to, ROM, RAM, compact disc (CD)-ROMs, magnetic tapes, floppy disks, flash drives, smart cards and optical data storage devices. The computer readable medium can also be distributed in network coupled computer systems so that the computer readable media is stored and executed in a distributed fashion, e.g., by a telematics server or a Controller Area Network (CAN). 
     Unless specifically stated or obvious from context, as used herein, the term “about” is understood as within a range of normal tolerance in the art, for example within 2 standard deviations of the mean. “About” can be understood as within 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, 0.5%, 0.1%, 0.05%, or 0.01% of the stated value. Unless otherwise clear from the context, all numerical values provided herein are modified by the term “about”. 
     Specific structural or functional descriptions in the embodiments of the present disclosure are merely illustrative for the purpose of describing embodiments according to the concept of the present disclosure, and the embodiments according to the concept of the present disclosure may be implemented in various forms. Further, it will be understood that the present description is not intended to limit the disclosure to those embodiments. On the contrary, the disclosure is intended to cover not only the embodiments, but also various alternatives, modifications, equivalents and other embodiments, which may be included within the spirit and scope of the disclosure as defined by the appended claims. 
     Meanwhile, in the present disclosure, terms such as first and/or second may be used to describe various components, but the components are not limited to the terms. The terms are used only for the purpose of distinguishing one component from other components. For example, a first component may be referred as a second component, and similarly, the second component may also be referred to as the first component within the scope not departing from the scope of rights according to the concept of the present disclosure. 
     When one component is referred to as being “connected” or “joined” to the other component, the one component may be directly connected or joined to the other component, but it should be understood that other components may exist therebetween. On the other hand, when the one component is referred to as being “directly connected to” or “directly in contact with” the other component, it should be understood that other components do not exist therebetween. Other expressions for the description of a relationship between components, that is, “between” and “directly between” or “adjacent to” and “directly adjacent to,” should be interpreted in the same manner. 
     The same reference numerals represent the same components throughout the specification. On the other hand, the terms in the specification are used to describe embodiments and are not intended to limit the present disclosure. In this specification, an expression in a singular form also includes a plural form unless otherwise clearly specified in the phrase. As used herein, expressions such as “comprise” and/or “comprising” do not exclude the presence or addition of one or more other components, steps, operations, and/or elements other than those described. 
     Hereinafter, some embodiments of the present disclosure will be described in detail with reference to the exemplary drawings. In the drawings, the same reference numerals will be used throughout to designate the same or equivalent elements. In addition, a detailed description of well-known features or functions will be ruled out in order not to unnecessarily obscure the gist of the present disclosure. 
     As described above, a module includes a plurality of unit cells connected to each other, and a plurality of modules are assembled to form a battery pack. 
     In a battery module assembly process, insulating capability of the cell may be destroyed by several factors, such as foreign metal materials or other jig burrs. Therefore, an insulation resistance test is usually performed on the assembled module before the module is made into the battery. 
     As shown in  FIG.  2   , in general, the insulation resistance test is performed using an enclosure (for example, a metal enclosure) of a battery module  800 . An inspection jig  810  surrounding the enclosure of the battery module  800  is manufactured, and an insulation resistance measuring device  820  checks whether the battery module  800  has an insulation defect. 
     However, when the tubing  12  of the cell  10  forming the module is damaged and insulation is broken, this type of insulation defect may not be identified by this enclosure inspection method, yet an insulation problem may appear as a field issue. As shown in  FIG.  3   , since a plurality of cells  10  are connected in series in the module and a gap between the cells adjacent to each other is narrow by about 1 to 2 mm, insulation performance may get worsen when a defect occurs in the tubing  12  of the cell  10 . 
     If the insulation defects of individual cells can be identified in advance, costs may be significantly reduced compared to disposal costs incurred due to poor insulation performance detected after the assembly of a module or a pack. Further, it is possible to prevent an insulation problem which may occur in the field. 
     An object of the present disclosure is to provide a highly reliable cell insulation defect detection system capable of detecting a cell insulation defect in an individual cell state prior to the assembly of a battery module. Specifically, according to the present disclosure, an insulation resistance test is performed where a conductive rubber is contacted with a cell tubing surface prior to assembly of the battery module. Here, provided is a contact unit to which a rotation pressurization method is applied, the rotation pressurization method being used for the conductive rubber to approach and contact the cell tubing. The present disclosure allows the conductive rubber to make rolling contact with the tubing surrounding an outside of the cell, thereby performing insulation inspection on a peeled portion of the cell tubing prior to module or cover assembly. 
     As shown in  FIGS.  4  to  6   , a cell insulation defect detection system  1  according to an exemplary embodiment of the present disclosure may be installed on a support  2 . A base  4  may be provided on the support  2 , and a contact unit  20  and a measurement unit  40  may be disposed on the base  4 . 
     The contact unit  20  is disposed on one side of the base  4 , and the measurement unit  40  is disposed on the other side of the base  4  to be spaced apart from the contact unit  20  at a predetermined distance. The rotation unit  60  is disposed at a position spaced apart from the contact unit  20  at a predetermined distance. According to an exemplary embodiment, the rotation unit  60  may be disposed between the contact unit  20  and the measurement unit  40 . According to another embodiment, the contact unit  20  may be disposed between the rotation unit  60  and the measurement unit  40 . According to the present disclosure, the contact unit  20 , the measurement unit  40 , and the rotation unit  60  may be disposed in various ways. 
     The contact unit  20  includes a fixed frame  120  and a rotation frame  220 . The fixed frame  120  is a non-movable part and may be supported by the base  4 . The rotation frame  220  is disposed coaxially with the fixed frame  120  and is disposed at an outside of the fixed frame  120  to surround the fixed frame  120 . The rotation frame  220  is disposed at the outside of the fixed frame  120  to be rotatable at least at a predetermined angle with respect to the fixed frame  120 . The rotation frame  220  is configured to be rotatable bidirectionally with respect to the fixed frame  120 , that is, clockwise or counterclockwise. According to an exemplary embodiment, a predetermined distance may be provided between the fixed frame  120  and the rotation frame  220  for the rotation of the rotation frame  220 . 
     As shown in  FIGS.  7 A and  7 B , the mounting unit  140  is provided at the center of the contact unit  20 . The mounting unit  140  is disposed inside of the fixed frame  120  or the rotation frame  220 . More specifically, the mounting unit  140  may be disposed at the center of the fixed frame  120  or the rotation frame  220 , and the cell  10  to be inspected may be disposed at the mounting unit  140 . The cell  10  includes the tubing  12  for insulation, and the tubing  12  surrounds an outer circumferential surface of the cell  10 . The cell  10  is preferably cylindrical. However, the cell  10  may comprise other shapes, such as a square column, an elliptical column, and the like. 
     The mounting unit  140  is configured to be rotatable within the contact unit  20 . The mounting unit  140  is disposed in the contact unit  20  to be rotatable by a driving unit. As a non-limiting example, the driving unit may be a motor. According to an exemplary embodiment of the present disclosure, the cell  10  may be configured to receive rotational force from a mounting motor  320  disposed below the base  4 . The mounting unit motor  320  is mounted to rotate the mounting unit  140 , and a terminal of the cell  10  is in close contact with the mounting unit  140  and placed thereon. 
     The mounting unit  140  is configured to allow the conduction of electricity. As will be described later, the mounting unit  140  functions as a detecting terminal of one electrode of the cell  10  to be inspected. 
     Referring to  FIGS.  8  to  10   , one or more rollers  420  are disposed around the mounting unit  140  in the contact unit  20 . According to an exemplary embodiment of the present disclosure, the rollers  420  are disposed at a predetermined distance along an inner surface of the fixed frame  120  and are configured to be movable at least a certain distance inside of the fixed frame  120  so as to cause the roller(s)  420  to contact the cell  10  or cease the contact with the cell  10 . As will be described later, one roller  420  may be configured to determine the insulation defect of the cell  10  rotated by the mounting unit  140  in the contact unit  20 , but as the number of rollers  420  increases, the accuracy of inspection may increase. 
     According to an exemplary embodiment of the present disclosure, the roller  420  is provided in a cylindrical shape. However, as long as the roller  420  can contact the cell  10 , depending on a shape of the cell  10 , the roller  420  may be provided in a different shape. The roller  420  includes a sleeve  422  mounted therearound and a roller terminal  424  extending in a longitudinal direction of the roller  420 . The sleeve  422  is preferably made of a conductive material and may be a conductive rubber. The roller terminals  424  may protrude from opposing ends of the sleeve  422 . 
     A plurality of links  520  connecting the fixed frame  120 , the rotation frame  220 , and the roller  420  are provided. In an exemplary embodiment, the link  520  may be disposed at each roller terminal  424  with respect to one roller  420 . In an exemplary embodiment, the number of the link  520  may correspond to the number of rollers  420 . 
     Opposite sides of the link  520  are connected to the roller  420  and the rotation frame  220 , respectively. The fixed frame  120  is connected between the opposite sides of the link  520 . According to an exemplary embodiment of the present disclosure, the link  520  includes an outer connection part  522 , a pivot part  524 , and an inner connection part  526 . 
     The inner connection part  526  of the link  520  is provided on one side of the link  520 . The inner connection part  526  is connected to the roller  420 . Particularly, the roller terminal  424  of the roller  420  may be inserted into the inner connection part  526 , and the inner connection part  526  may be supported by a surface of the roller  420 . 
     The outer connection part  522  is provided on an opposite side of the inner connection part  526 . The outer connection part  522  is connected to the rotation frame  220  or placed thereon. According to an exemplary embodiment, the rotation frame  220  includes a plurality of pin members  222  provided thereon. The pin members  222  are disposed to be spaced apart from each other at a predetermined distance along the circumference of the rotation frame  220 . In an exemplary embodiment, the outer connection part  522  may be inserted into the pin member  222 . The outer connection part  522  is formed to be larger than a diameter/cross-section or size of the pin member  222 , and the pin member  222  is configured to be movable within the outer connection part  522 . 
     The link  520  is coupled to the fixed frame  120  by the pivot part  524 . The pivot part  524  is provided between the inner connection part  526  and the outer connection part  522 , and the link  520  is configured to be rotatable around the pivot part  524 . According to an exemplary embodiment, the pivot part  524  is arranged at a center portion of the link  520 . According to another embodiment, the pivot part  524  is provided at a location closer to the outer connection part  522  than the central portion of the link  520 . In addition, in still another embodiment, the pivot part  524  is provided at a location closer to the inner connection part  526  than the central portion of the link  520 . 
     According to some embodiments of the present disclosure, an extension terminal  620  is further provided. The extension terminal  620  may further comprise a roller extension terminal  622  and a cell extension terminal  624 . Here, the roller extension terminal  622  and the cell extension terminal  624  may have the same shape or may have different shapes. Different terms are being used for the roller extension terminal  622  and the cell extension terminal  624  to indicate that the roller extension terminal  622  is a terminal connected to the roller  420  and that the cell extension terminal  624  is a terminal connected to the mounting unit  140  or the cell  10 . 
     The roller extension terminal  622  may be connected to the roller terminal  424  and extend outwards in a radial direction of the contact unit  20 . For example, one side of the roller extension terminal  622  may be in contact with the roller terminal  424 , and the other side of the roller extension terminal  622  may be placed on the fixed frame  120 . Particularly, the presence of the roller extension terminal  622  may facilitate measurement such as when the roller extension terminal  622  is connected to the measurement unit  40 . 
     The cell extension terminal  624  may be connected to the cell  10  or the mounting unit  140 . The cell extension terminal  624  is disposed to extend radially outward from the side of the mounting unit  140 . The cell extension terminal  624  also improves convenience in measurement, similarly to the roller extension terminal  622 . 
     Referring back to  FIG.  7 A , the rotation unit  60  provides rotational force to the rotation frame  220 . The rotation unit  60  is disposed on the base  4  to be rotatable by a driving unit. In an exemplary embodiment, the rotation unit  60  is configured to be rotatable by a rotation unit motor  62  installed below the base  4 . 
     The rotation unit  60  and the rotation frame  220  are connected to each other by a belt  64 . The belt  64  is disposed to surround the rotation unit  60  and the rotation frame  220 . Accordingly, when the rotation unit  60  rotates, the rotation frame  220  is configured to rotate together therewith. 
     Referring to  FIG.  11   , the measurement unit  40  is configured to perform the insulation test. Specifically, the measurement unit  40  is configured to measure an insulation resistance value in a circuit set up by the roller  420  and the cell  10 . The roller terminal  424  or the roller extension terminal  622  is connected to the measurement unit  40  by a first wire  42 , and the mounting unit  140  or the cell extension terminal  624  is connected to the measurement unit  40  by a second wire  44 . 
     Referring back to  FIG.  5   , according to an exemplary embodiment of the present disclosure, a holder unit  80  is further provided. The holder unit  80  supports the cell  10  placed on the mounting unit  140  during the inspection performed by the present system. In an exemplary embodiment, the holder unit  80  is configured to be movable upwards and downwards. The holder unit  80  descends after the cell  10  is inserted into the mounting unit  140  to press the cell  10  with a certain force. The certain force is a force pressing the cell  10  to be rotatable, and a magnitude of the force may be preset. In an exemplary embodiment, the holder unit  80  is supported by the base  4 . In another embodiment, the holder unit  80  is supported by the contact unit  20 . 
     An operation of the system according to the present disclosure will be described with reference to  FIGS.  12 A to  12 H . 
     As shown in  FIG.  12 A , the cell insulation defect detection system  1  according to the present disclosure is in a standby state. For inspection, the cell  10  is inserted into the mounting unit  140  from above the contact unit  20  as shown in  FIG.  12 B . When the cell  10  is inserted thereinto, arrangement as shown in  FIG.  12 C  is achieved. In this case, the roller  420  is positioned adjacent to an inner circumferential surface of the fixed frame  120 , and the link  520  is disposed not in the radial direction of the contact unit  20  but at an angle relative to the radial direction thereof. Next, when the cell  10  is completely mounted in the mounting unit  140 , the holder unit  80  descends to press an upper portion of the cell  10  ( FIG.  12 D ). When the cell  10  is pressed by the holder unit  80 , the rotation unit  60  is rotated. For example, the rotation unit  60  is rotated counterclockwise so that the rotation frame  220  is also rotated counterclockwise. When the rotation frame  220  rotates, the link  520  connected to the rotation frame  220  also rotates with respect to the pivot part  524 . Then the link  520  is aligned with the radial direction of the contact unit  20  as shown in  FIG.  12 E  (refer to an arrow in  FIG.  9   ). Put differently, all the links  520  are oriented toward the cell  10 . As the link  520  is aligned with the radial direction of the contact unit  20 , the roller  420  connected to the inner connection part  526  moves radially inward. Accordingly, at the present position, the roller  420  moves further away from the fixed frame  120  and comes into close contact with the cell  10  mounted in the mounting unit  140 . Here, the respective roller  420  in close contact with the cell  10  maintains a predetermined distance from each other. As described above, in the state in which the roller  420  is in contact with the cell  10 , the mounting unit motor  320  is driven to rotate the mounting unit  140 . The cell  10  is rotated by the rotation of the mounting unit  140 , and insulation resistance measurement of the cell  10  starts ( FIG.  12 F ). While the cell  10  rotates, the cell  10  is checked whether the tubing  12  is damaged. As shown in  FIGS.  13  and  14   , the insulation resistance test may be determined based on a measurement value of the measurement unit  40 .  FIG.  13    shows a case of the non-defective cell  10 , and  FIG.  14    shows a case of the defective cell  10 . When there is no defect in the tubing  12  of the cell  10 , the cell  10  and the roller  420  are insulated from each other even when the conductive roller  420  and the cell  10  are in contact with each other (a dotted line in  FIG.  13    indicates an insulation state), and a measured resistance value becomes a large value. For example, when the insulation of the cell  10  is normal, about 100 megaohms may be measured. On the other hand, as in case of  FIG.  14   , when there is a damaged portion D on the tubing  12  of the cell  10 , the cell  10  and the roller  420  are electrically connected to each other through the damaged portion D, and a resistance value much smaller than that of the case of  FIG.  13    is measured. For example, when the insulation is broken, about  10  milliohms may be measured. When the inspection is performed in this manner and completed, the holder unit  80  is moved upwards as shown in  FIG.  12 G  and the cell  10  is removed from the contact unit  20  ( FIG.  12 H ). 
     According to the present disclosure, insulation defects of individual cells can be detected prior to assembly of a battery module, thereby reducing costs and improving reliability. 
     As is apparent from the above description, the present disclosure provides a cell insulation defect detection system capable of detecting insulation defects of individual cells in advance. 
     The effect of the present disclosure is not limited to the above-mentioned effect, and other effects not mentioned will be clearly understood by those skilled in the art from detailed descriptions in the embodiments. 
     The disclosure has been described in detail with reference to preferred embodiments thereof. However, it will be appreciated by those skilled in the art that changes may be made in these embodiments without departing from the principles and spirit of the disclosure, the scope of which is defined in the appended claims and their equivalents.