Patent Publication Number: US-2021175481-A1

Title: Battery pack

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     Korean Patent Application No. 10-2019-0159720, filed on Dec. 4, 2019, in the Korean Intellectual Property Office, and entitled: “Battery Pack,” is incorporated by reference herein in its entirety. 
     BACKGROUND 
     1. Field 
     Embodiments relate to a battery pack. 
     2. Description of the Related Art 
     An electronic device, such as a notebook computer, a mini notebook computer, a net-book, a mobile computer, an ultra-mobile personal computer (UMPC) or a portable multimedia player (PMP), may employ a battery pack in which a plurality of batteries connected in series and/or parallel are used as a portable power supply. The battery pack may include a protective circuit module (PCM) for protecting the battery cells from over-charge, over-discharge and/or over-current. The battery cells and the protective circuit module may be embedded in the battery pack with a case. 
     The above information disclosed in this Background section is only for enhancement of understanding of the background of the described technology and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art. 
     SUMMARY 
     The embodiments may be realized by providing a battery pack including a main frame supporting a battery cell, the main frame including a hook hole and a reinforcer adjacent to the hook hole; and a main cover coupled to the main frame, the main cover including a hook inserted into and retained in engagement with the hook hole, wherein the reinforcer faces the hook hole with the hook therebetween to support the hook. 
     The main frame may include a mounting surface configured to support a surface of the battery cell, and a sidewall portion extending along edges of the mounting surface, and the reinforcer may include a first rib parallel with the sidewall portion, extending from the mounting surface, and being between the battery cell and the sidewall portion, and a connection rib integrally formed with opposite ends of the first rib to connect the opposite ends of the first rib to the sidewall portion. 
     The main frame may further include a sub-frame adjacent to the first rib and parallel with the sidewall portion, the sub-frame extending from the mounting surface, being between the battery cell and the first rib, and being in contact with another surface of the battery cell. 
     The reinforcer further may further include a reinforcement rib integrally formed with the connection rib and extending toward the sub-frame to be connected to the sub-frame. 
     A contact point, at which a top of the reinforcement rib is connected to a top of the sub-frame, may be positioned farther from the mounting surface than a mid-point of the hook hole is from the mounting surface. 
     A height of the reinforcement rib from the mounting surface may be larger than a height of a mid-point of the hook hole from the mounting surface. 
     A length of the first rib may be smaller than a length of the sub-frame. 
     The reinforcement rib may be adjacent to the hook hole. 
     A contact region of the reinforcement rib and the sub-frame may be distal to the hook hole such that the contact region is spaced apart from a region where a contact end of the hook locked into the hook hole contacts the hook hole. 
     A contact point, at which a top of the reinforcement rib is connected to a top of the sub-frame, may be positioned farther from the mounting surface than the contact end is from the mounting surface. 
     The embodiments may be realized by providing a battery pack including a main frame on which a battery cell is supportable, the main frame including a hook hole and a reinforcer adjacent to the hook hole; and a main cover coupled to the main frame, the main cover including a hook inserted into and retained in engagement with the hook hole, wherein the reinforcer faces the hook hole with the hook therebetween to support the hook. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       Features will be apparent to those of skill in the art by describing in detail exemplary embodiments with reference to the attached drawings in which: 
         FIG. 1  is a perspective view of a battery pack according to an embodiment. 
         FIG. 2  is an exploded perspective view of the battery pack shown in  FIG. 1 . 
         FIG. 3  is a perspective view of a main frame of the battery pack shown in  FIGS. 1 and 2 . 
         FIG. 4  is an enlarged perspective view of major parts of the main frame shown in  FIG. 3 . 
         FIG. 5  is an enlarged perspective view of the major parts of the main frame shown in  FIG. 4 , viewed in a different direction. 
         FIG. 6  is a perspective view of a main cover of the battery pack shown in  FIGS. 1 and 2 . 
         FIG. 7  is a perspective view of a coupled portion of the main frame and a main cover. 
         FIG. 8  is a perspective view of a battery pack according to another embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Example embodiments will now be described more fully hereinafter with reference to the accompanying drawings; however, they may be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey exemplary implementations to those skilled in the art. 
     In the drawing figures, the dimensions of layers and regions may be exaggerated for clarity of illustration. It will also be understood that when a layer or element is referred to as being “on” another layer or element, it can be directly on the other layer or element, or intervening layers may also be present. In addition, it will also be understood that when a layer is referred to as being “between” two layers, it can be the only layer between the two layers, or one or more intervening layers may also be present. Like reference numerals refer to like elements throughout. 
     As used herein, the terms “or” and “and/or” include any and all combinations of one or more of the associated listed items. In addition, it will be understood that when an element A is referred to as being “connected to” an element B, the element A can be directly connected to the element B or an intervening element C may be present therebetween such that the element A and the element B are indirectly connected to each other. 
     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 are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms that the terms “include,” “including,” “comprise,” and “comprising” when used in this specification, specify the presence of stated features, numbers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, numbers, steps, operations, elements, components, and/or groups thereof. 
     It will be understood that, although the terms first, second, etc. may be used herein to describe various members, elements, regions, layers and/or sections, these members, elements, regions, layers and/or sections should not be limited by these terms. These terms are only used to distinguish one member, element, region, layer and/or section from another. Thus, for example, a first member, a first element, a first region, a first layer and/or a first section discussed below could be termed a second member, a second element, a second region, a second layer and/or a second section without departing from the teachings of the present disclosure. 
     Spatially relative terms, such as “beneath,” “below,” “lower,” “above,” “upper,” and the like, may be used herein for ease of description to describe one element or feature&#39;s relationship to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the element or feature in the figures is turned over, elements described as “below” or “beneath” other elements or features would then be oriented “on” or “above” the other elements or features. Thus, the exemplary term “below” can encompass both an orientation of above and below. 
     For ease of description of major components of the present disclosure, the upper side and the lower side are defined as an upward direction and a downward direction, respectively, on the basis of  FIG. 1 . In addition, on the basis of  FIG. 1 , the longer- and shorter-side directions of a main frame are defined as a lengthwise direction and a widthwise direction, respectively, the direction facing an exterior side of the battery pack is defined as an outward direction, and the direction opposite to the outward direction is defined as an inward direction. Therefore, if directions of the respective components arranged are changed, coupling relations between each of various components are intended to embrace all the concepts varying according to such changes. 
       FIG. 1  is a perspective view of a battery pack according to an embodiment.  FIG. 2  is an exploded perspective view of the battery pack shown in  FIG. 1 .  FIG. 3  is a perspective view of a main frame of the battery pack shown in  FIGS. 1 and 2 .  FIG. 4  is an enlarged perspective view of major parts of the main frame shown in  FIG. 3 .  FIG. 5  is an enlarged perspective view of the major parts of the main frame shown in  FIG. 4 , viewed in a different direction.  FIG. 6  is a perspective view of a main cover of the battery pack shown in  FIGS. 1 and 2 .  FIG. 7  is a perspective view of a coupled portion of the main frame and a main cover.  FIG. 8  is a perspective view of a battery pack according to another embodiment. 
     As illustrated in FIGS .  1  and  2 , the battery pack  10  according to an embodiment may include a battery cell or plurality of battery cells  100 , a protective circuit module  300  electrically connected to the battery cells  100 , a main frame  500  accommodating the battery cells  100  (e.g., in which the removeable battery cells  100  are supportable) and the protective circuit module  300 , and a main cover  700  coupled to the main frame  500 . In an implementation, various other kinds of plates or tapes for protecting the battery cells  100  are not major components of the present disclosure, and thus detailed illustration and descriptions thereof may be omitted. 
     As illustrated in  FIG. 2 , the battery cell  100  may have a general structure including an electrode assembly including a positive electrode plate, a negative electrode plate, a separator therebetween, a case accommodating the electrode assembly and an electrolyte solution, and positive and negative electrode tabs drawn out from the positive and negative electrode plates, respectively. When a battery cell is a prismatic or pouch-type battery cell, the battery pack may also be applied to the battery cell  100  of the present disclosure. In the present disclosure, as to a specific configuration of the battery cell, a suitable technique can be applied, and thus a detailed description thereof may not be given. 
     As illustrated in  FIG. 2 , the protective circuit module (PCM)  300  may include a circuit board  310  electrically connected to the positive and negative electrode tabs of the battery cell  100  and a connector  330  for electrically connecting the PCM  300  to external equipment. 
     A plurality of protection devices electrically connected to the circuit board  310  through wiring patterns may be provided in the circuit board  310 , and the positive and negative electrode tabs are electrically connected to the wiring patterns through tab connectors. The plurality of battery cells  100  may be electrically connected in series or in parallel by the wiring patterns formed in the circuit board  310 . The wiring patterns of the circuit board  310  may be electrically connected to external equipment through the connector  330 , thereby controlling charging and discharging of the battery cells  100 . 
     As to a specific configuration of the protective circuit module, a suitable technique can be applied, and thus a detailed description thereof may not be given. 
     In a state in which the battery cells  100  and the protective circuit module  300  are mounted on the main frame  500 , the main cover  700  may be coupled to the main frame  500 . 
     As illustrated in  FIGS. 2 to 5 , the main frame  500  may have a rectangular ring shape having open top and bottom surfaces. The main cover  700  may be coupled to the open top surface of the main frame  500 . 
     The main frame  500  may be made of SUS material (e.g., stainless steel). When the main frame  500  is made of SUS material, the battery pack  10  may have an excellent mechanical strength and a reduced thickness, as compared to when the main frame  500  is made of a material other than the SUS material. When the main frame  500  is made of SUS material, and the main cover  700  described below is made of a material such as a plastic, a coupling force of a coupling portion between the main frame  500  and the main cover  700  may be weakened due to a difference in the characteristic and strength between the materials used for the main frame  500  and the main cover  700 , as compared to when the same material is used in the coupling portion between the main frame  500  and the main cover  700 . 
     The main frame  500  may include a sidewall portion  510  forming an accommodating space, a mounting surface  520  (which is integrally formed with the sidewall portion  510  and on which the battery cells  100  are mounted), and a circuit mounting portion  530  (in or on which the protective circuit module  300  is mounted). In an implementation, the main frame  500  may further include an auxiliary sidewall  540  (partitioning the accommodating space in a widthwise direction inside the sidewall portion  510 ) and a connecting surface  550  according to the mounting location shape of a product in which the battery pack  10  is mounted. 
     In an implementation, the main frame  500  may further include a cover coupling frame  560  to be coupled to the main cover  700 , a sub-frame or plurality of sub-frames  570  supporting one-side edges of the battery cells  100 , and reinforcement units or reinforcers  580  reinforcing the coupling portion of the main frame  500  with the main cover  700 . To address the possibility of weakened coupling force of the coupling portion, the battery pack  10  may include the reinforcers  580 . 
     The sidewall portion  510  is a portion forming the rectangular ring-shaped edge of the main frame  500 . A height of the sidewall portion  510  may be larger than that (e.g., a thickness) of each of the battery cells  100 . For brevity, the sidewall portion  510  may include first to fourth sidewalls  511  to  517 . The first to fourth sidewalls  511  to  517  may define the edge of the main frame  500 , which has a substantially rectangular ring-shape. 
     The first sidewall  511  and the third sidewall  515  may be short sides of the main frame  500 , which face each other. The second sidewall  513  and the fourth sidewall  517  may be long sides of the main frame  500 , which may face each other. In an implementation, for the purpose of forming or accommodating the circuit mounting portion  530 , the fourth sidewall  517  may be shorter than the second sidewall  513 . 
     A hook hole or plurality of hook holes  519  may be formed on or in the first to fourth sidewalls  511  to  517 , e.g., penetrating the first to fourth sidewalls  511  to  517 . Positions of the hook holes  519  may correspond to those of hooks  732   a  of the main cover  700  to be described below. 
     The mounting surface  520  may be integrally formed with the bottom end of the sidewall portion  510 . The auxiliary sidewall  540  and the connecting surface  550  may be between the second sidewall  513  and the fourth sidewall  517  in a widthwise direction. 
     The mounting surface  520  may vertically extend from the bottom end of the sidewall portion  510  to support one surface of the battery cell  100 . The mounting surface  520  may form the bottom surface of the main frame  500  and may have a width that may help prevent the battery cell  100  from deviating therefrom, rather than a width enough to entirely occupy the bottom surface of the main frame  500 . In an implementation, the mounting surface  520  may have a shape adapted to support bottom edges of each of the battery cells  100  according to the number of the battery cells  100 . 
     In an implementation, if the number of battery cells  100  included in the battery pack  10  is three, the mounting surface  520  may form planes corresponding to bottom edges of each of the three battery cells  100 . Open holes may be in regions other than the bottom edges of the battery cells  100 . In an implementation, the mounting surface  520  may be configured such that holes having a smaller size than the battery cells  100  are formed on a substantially rectangular plate. 
     As illustrated in  FIGS. 2 and 3 , the circuit mounting portion  530  may be a portion where the protective circuit module of the battery cells  100  is mounted. The circuit mounting portion  530  may outwardly protrude further than the fourth sidewall  517 . In an implementation, the circuit mounting portion  530  may be covered by the protection cover  534  shown in  FIG. 2 . In addition, a connector withdrawal part  532   a  (through which the connector  330  is exposed) may be formed in the circuit mounting portion  530 . 
     The protection cover  534  may surround the mounting surface  532  from the upper side, e.g., as illustrated in  FIG. 1 . In an implementation, the protection cover  534  may cover the protective circuit module  300  on the mounting surface  532  by adopting one of the aforementioned structures. In an implementation, the protective circuit module  300  may be blocked or covered by the protection cover  534  so as not to be exposed. In an implementation, the protection cover  534  may be separately provided to then be coupled to the or may integrally formed with the main cover  700  to then be coupled to the main cover  700 . 
     In an implementation, the accommodating space (in which the battery cells  100  are accommodated) may be formed by the sidewall portion  510  and the mounting surface  520 , and the accommodating space may be divided into multiple spaces, as desired. 
     As illustrated in  FIGS. 2 and 3 , the auxiliary sidewall  540  may be arranged (e.g., may extend lengthwise) in the direction in which the second sidewall  513  and the fourth sidewall  517  are connected. In an implementation, the auxiliary sidewall  540  may be arranged to partition the accommodating space in or relative to the lengthwise direction of the main frame  500 . The auxiliary sidewall  540  may be integrally formed with the second sidewall  513  and the fourth sidewall  517  by connecting opposite ends thereof to the second sidewall  513  and the fourth sidewall  517  or by connecting at least one end thereof to the second sidewall  513  or the fourth sidewall  517 . 
     The auxiliary sidewall  540  may include a pair of auxiliary sidewalls provided according to the shape of a region where the battery pack  10  is installed, and a connecting surface  550  connecting the pair of auxiliary sidewalls  540  may be formed. In some cases, interference could occur between the battery pack and a peripheral component according to the location of a product in which the battery pack is mounted. Therefore, when the battery cells  100  are not arranged in a line to install the battery pack  10  so as to be kept away from the peripheral component, the auxiliary sidewall  540  and the connecting surface  550  may be provided. A through-hole formed in the connecting surface  550  may be used for separating the connecting surface  550  from a mold which is not a feature of this application, and a detailed description thereof may be omitted. 
     In an implementation, a wire for electrical connection of the battery pack  10  may be provided at a lower side of the connecting surface  550  shown in  FIG. 3 . Here, in order to avoid interference with the wire, the auxiliary sidewall  540  and the connecting surface  550  may be formed for the purpose of partitioning the main frame  500  to accommodate the battery cells  100 . However, as shown in  FIG. 8 , the coupling structure of the main frame  500  and the main cover  700  according to the present disclosure may also be applied to a general battery cell accommodating structure in which the accommodating space is not partitioned. 
     Next, a coupling structure for coupling the main cover  700  will be described in further detail. 
     As illustrated in  FIGS. 3 and 4 , the cover coupling frame  560  may be inside the sidewall portion  510  (e.g., on an inner side of the sidewall portion  510 ) positioned toward the battery cells  100 , and may extend upwardly from the mounting surface  520  so as to face the sidewall portion  510 . In coupling the main cover  700 , the main cover  700  may be inserted between the sidewall portion  510  and the cover coupling frame  560 . Referring to  FIG. 4 , the main cover  700  may be coupled to a gap between the second sidewall  513  and the cover coupling frame  560 . Such a coupling structure may be commonly applied to all of the first to fourth sidewalls  511  to  517  defining the sidewall portion  510 . A distance between the cover coupling frame  560  and the sidewall portion  510  corresponds to a thickness of a portion into which the main cover  700  is inserted in coupling the main cover  700 . In an implementation, the distance between the cover coupling frame  560  and the sidewall portion  510  may correspond to a distance in which the hooks  732   a  (to be described below) may be inserted. 
     The cover coupling frame  560  may have a height equal to or slightly smaller than that of the sidewall portion  510 . In an implementation, the cover coupling frame  560  may be formed at each of the second sidewall  513  and the fourth sidewall  517 . The sub-frames  570  may be formed at the first sidewall  511  and the third sidewall  515 . 
     As illustrated in  FIGS. 3 to 5 , each of the sub-frames  570  may be formed inside the first sidewall  511  and the third sidewall  515 , respectively, and may extend upwardly from the mounting surface  520 . Ends of the sub-frame  570  may be connected to the cover coupling frame  560  or may be formed separately from the cover coupling frame  560 . When the battery cells  100  are mounted on the mounting surface  520 , the sub-frame  570  may support one side of each of the battery cells  100 , thereby preventing movement of the battery cells  100 . Therefore, when the battery cells  100  are mounted, the sub-frames  570  may be at locations where they closely contact the battery cells  100 . The sub-frames  570  may have a size that helps prevent movement of the battery cells  100  while not being interfered with the main cover  700  in coupling the main cover  700 . 
     The reinforcers  580  may be between the sub-frame  570  and each of the first sidewall  511  and the third sidewall  515  to help protect the battery cells  100  and protective circuit module  300  from external impacts and to help prevent separation of the main cover  700 . 
     As illustrated in  FIGS. 4 to 7 , each of the reinforcers  580  may include a first rib  582  (e.g., a plurality of first ribs  582 ) supporting the coupling portion of the main cover  700 , a connection rib  584  connecting the first rib  582  and the sidewall portion  510 , and a reinforcement rib  586  between the connection rib  584  and the sub-frame  570 . 
     In an implementation, the first rib  582  may include a plurality of first ribs each disposed to be parallel with the first sidewall  511  and between the first sidewall  511  and the sub-frame  570 . In an implementation, the plurality of first ribs  582  may be parallel with the third sidewall  515  and between the third sidewall  515  and the sub-frames  570 . The first rib  582  may be at a region where each of the hook holes  519  is formed and may have a length sufficient to cover the region where the hook hole  519  is formed. In an implementation, the length of the first rib  582  may be smaller than that of the sub-frame  570 . 
     A distance between the first rib  582  and each of the first sidewall  511  and the third sidewall  515  may be larger than the thickness of an insertion portion  732  of the main cover  700  and smaller than the thickness of the hook  732   a  (h of  FIG. 7 ). The first rib  582  may provide a reaction force for preventing the hook  732   a  from deviating from a state in which the hook  732   a  is engaged with (e.g., in an interengaging relationship with) the hook hole  519  (e.g., may help prevent the hook  732   a  from decoupling or detaching from the main frame  500 ). If the distance between the first rib  582  and each of the first sidewall  511  and the third sidewall  515  were to be excessively large, it could be difficult for the first rib  582  to sufficiently provide the reaction force against the external force applied to the hook  732   a.  In an implementation, the distance between the first rib  582  and each of the first sidewall  511  and the third sidewall  515  may be smaller than a width h of the hook  732   a.    
     In coupling the main cover  700  with the main frame  500 , the first rib  582  may have a smaller height than that of the first sidewall  511  and the third sidewall  515 , so as to allow the main cover  700  to closely contact the main frame  500 . In addition, one of opposite ends of the first rib  582  may be connected to the first sidewall  511  or the third sidewall  515  by the connection rib  584  having a smaller height than the first rib  582 , and the other of the opposite ends of the first rib  582  may be connected to the sub-frame  570  by the reinforcement rib  586  having a smaller height than the first rib  582  to then be supported. 
     In an implementation, a portion of the first rib  582 , which is not supported by the connection rib  584  and the reinforcement rib  586 , may be temporarily deformable, and the hook  732   a  may be inserted into the hook hole  519 , even if the distance between the first rib  582  and the sidewall portion  510  is smaller than the width h of the hook  732   a.  For example, the portion of the first rib  582 , which is not supported by the connection rib  584  and the reinforcement rib  586 , may exhibit elasticity (e.g., may be elastically biased toward the insertion portion  732 ), and may help prevent the hook  732   a  of the insertion portion  732  from coming out of the hook hole  519 . 
     The connection rib  584  may be integrally formed with the opposite end of the first rib  582  and may be connected to the first sidewall  511  or the third sidewall  515 . The connection rib  584  may have a height ranging from a point corresponding to half of the height of the hook hole  519   a  to a top end height of the hook hole  519 . The term “height” used herein means a distance measured upwardly from the mounting surface  520 , on the basis of  FIG. 7 . 
     The reinforcement rib  586  may face the connection rib  584  and may be integrally formed with the opposite ends of the first rib  582  to then be connected to the sub-frame  570 . The reinforcement rib  586  may be shaped to have a height gradually decreasing from the top end of the first rib  582  in a streamlined manner, unlike the connection rib  584 . In an implementation, the reinforcement rib  586  may have a streamlined shape so as to get closer to the mounting surface  520  away from the top end of the first rib  582 . 
     The reinforcement rib  586  may be integrally formed with the connection rib  584  to form a plane (e.g., a continuous flat surface). In an implementation, the first rib  582  may be configured such that opposite ends thereof are supported by the connection rib  584  and the reinforcement rib  586 . The reinforcement rib  586  may be located adjacent to the hook hole  519  and the hook  732   a  to support the hook  732   a  so as not to be disengaged from the hook hole  519 . To this end, the length and location of the first rib  582  may be set in consideration of the location of the reinforcement rib  586 . 
     In an implementation, on the basis of  FIG. 7 , the reinforcement rib  586  may be opposite to the hook hole  519  with the hook  732   a  interposed therebetween. The hook hole  519  and the reinforcement rib  586  may not be arranged in a line but may be arranged to be opposite to each other, and thus the reinforcement rib  586  may help support the hook  732   a.    
     A point where the reinforcement rib  586  and the top end of the first rib  582  meet may be defined as a topmost point of the reinforcement rib  586 , and a point where the reinforcement rib  586  and the mounting surface  520  meet (also a point where the reinforcement rib and the bottom end of the sub-frame meet) may be defined as a bottommost point of the reinforcement rib  586 . A top end of a point where the reinforcement rib  586  and the top end of the sub-frame  570  meet may be defined as a contact point H 0 . 
     In an implementation, as shown in  FIG. 7 , a contact point height H 1  of the reinforcement rib  586  may be higher than a height H 2 . The contact point height H 1  of the reinforcement rib  586  may be higher than a height H 3 . 
     The term “height” used herein means a distance (length) ranging or measured from (e.g., in a vertical direction) the mounting surface  520  on the basis of  FIG. 7  in which the mounting surface  520  of the main frame  500  faces downward. Reference symbol H 1  means a distance from the mounting surface  520  to the contact point H 0  of the reinforcement rib  586 . Reference symbol H 2  means a distance from the mounting surface  520  to a contact end  732   a′  of the hook  732   a.  Reference symbol H 3  means a distance from the mounting surface  520  to a point corresponding to half or mid-point of the hook hole  519  to the top end height of the hook hole  519 . 
     The contact point height H 1  of the reinforcement rib  586  refers to a height at which a reaction force against the external force applied to the hook  732   a  in coupling the main cover  700 , which will be described below. 
     As illustrated in  FIG. 6 , the main cover  700  may include a main plate  710  and a cover side surface  730  at edges of the main plate  710 . The main cover  700  may be formed by injection-molding an insulating material such as a plastic for the purpose of insulating. 
     The main plate  710  may cover the open top surface of the main frame  500  and may have a size sufficient to entirely cover the battery cells  100 . The cover side surface  730  may extend downwardly from the edges of the main plate  710 . 
     The cover side surface  730  extending downwardly from the edges of the main plate  710  may be inserted between the sidewall portion  510  and the cover coupling frame  560 . The cover side surface  730  may have a width that is smaller than that of the insertion portion  732 , and an insertion portion or a plurality of insertion portions  732  may extend downward therefrom. The term “width” used herein means an extending length ranging or measured from (e.g., downwardly from) the edges of the main plate  710 . The cover side surface  730  may have a smaller width than the insertion portion  732  to avoid interference between the cover side surface  730  and a peripheral structure, such as the connection rib  584 , when the main cover  700  is coupled to the main frame  500 . 
     The insertion portion  732  may extend downwardly from the bottom end of the cover side surface  730 . At least one hook  732   a  may be on the insertion portion  732 . The entire width of the cover side surface  730  including the insertion portion  732  may be equal to or slightly smaller than the width of the sidewall portion  510 . In an implementation, a position of the hook  732   a  may correspond to or be aligned with the hook hole  519  of the sidewall portion  510 . 
     As illustrated in  FIGS. 6 and 7 , the hook  732   a  may slantingly protrude outwardly from the plane of the insertion portion  732 . The top end of the protruding hook  732   a  may form the contact end  732   a′,  which may come into contact with the top end (e.g., inner top side) of the hook hole  519 . The hook  732   a  may be configured such that it becomes farther away from the insertion portion  732  in an upward direction from its lower side toward the contact end  732   a′.  The contact end  732   a′  (at the top end of the hook  732   a ) may have a predetermined width h. The contact end  732   a′  may be locked into the hook hole  519 , and the main cover  700  may be retained coupled to the main frame  500 . 
     In the battery pack  10  having the aforementioned configuration according to an embodiment, when the main frame  500  made of SUS material and the main cover  700  made of a plastic material, there is a possibility of the hook  732   a  being disengaged from the hook hole  519  due to an external force. 
     Referring to  FIG. 7 , the possibility of the hook  732   a  being disengaged from the hook hole  519  could be increased when an external force is applied to the top end of the hook  732   a,  e.g., the contact end  732   a′,  as compared to when the external force is applied to the bottom end the hook  732   a.  In order to help reduce or prevent disengagement of the hook  732   a  by providing a reaction, pressing, or elastic force against the external force applied to the hook  732   a  (in a direction indicated by the left arrow of  FIG. 7 ), the hook  732   a  may be supported in a direction opposite to the direction of the external force applied to the hook  732   a  (in a direction indicated by the right arrow of  FIG. 7 ). To this end, the reinforcement rib  586  may be provided. In an implementation, the reinforcement rib  586  may be located adjacent to the hook hole  519 . 
     As described above, the contact point height H 1  of the reinforcement rib  586  may be higher than the height H 2  of the contact end  732   a′  of the hook  732   a.  In an implementation, the contact point height H 1  of the reinforcement rib  586  may be higher than the height H 3  of the point corresponding to at least a half of the length of the hook hole  519  to provide a sufficient reaction force. 
     In an implementation, the contact point of the reinforcement rib  586  may be far away from (e.g., distal to) the hook hole  519  and may be spaced apart from a contact portion of the contact end  732   a′  of the hook  732   a  and the hook hole  519 . In an implementation, the reinforcement rib  586  may be formed such that a length ranging from one end of the reinforcement rib  586 , which is connected to the mounting surface  520 , to the other end which extends from the one end, is larger than a length ranging from the mounting surface  520  to the center of the hook hole  519 . 
     The aforementioned battery pack  10  according to an embodiment may be configured such that a plurality of battery cells  100  are arranged in a line, and an accommodating space of the battery cells  100  may be partially partitioned so that some of the battery cells  100  are separated from one another. In an implementation, a battery pack  10 ′ may be configured such that a plurality of battery cells  100  are mounted to be adjacent to one another without partitioning an accommodating space. The battery pack  10 ′ according to another embodiment is shown in  FIG. 8 . 
     As illustrated in  FIG. 8 , the battery pack  10 ′ according to another embodiment may include a plurality of battery cells  100 ′, a protective circuit module  300 ′ electrically connected to the battery cells  100 ′ and electrically connected to an external circuit by a connector  330 ′, a main frame  500 ′ accommodating the battery cells  100 ′ and the protective circuit module  300 ′, and an upper cover  700   a′  and a lower cover  700   b′  coupled to the main frame  500 ′. 
     The battery pack  10 ′ may have the same coupling structure as described above with reference to  FIGS. 1 to 7  and may be configured such that the main frame  500 ′ accommodating the battery cells  100 ′ is not provided with the auxiliary sidewall  540  and the connecting surface  550  of the battery pack  10  according to an embodiment. In addition, the battery pack  10 ′ may be configured such that a circuit mounting portion  530 ′ does not protrude outwardly from the main frame  500 ′. Therefore, a repeated description will not be given. 
     As described in the foregoing embodiments, the battery pack coupling structure may also be applied to a battery pack having prismatic or pouch-type battery cells. In addition, the coupling structure may also be applied to a battery pack having cylindrical battery cells as long as the main frame  500 ,  500 ′ and the main cover  700  (or the upper cover  700   a′  and the lower cover  700   b′ ) are coupled to each other with a hook mechanism. 
     One or more embodiments may provide a battery pack that can support coupling portions to help prevent a case from being separated as the coupling portions are disengaged due to external impacts. 
     In the battery pack according to an embodiment, the reinforcement ribs may be adjacent to coupling portions of the hooks and the hook holes. Accordingly, the reinforcement ribs may help support the hooks and help prevent the hooks from being inadvertently pushed away to disengaged positions due to, e.g., external impacts. Therefore, the hooks may be firmly retained coupled to the hook holes without being separated from the hook holes by an external force. 
     Example embodiments have been disclosed herein, and although specific terms are employed, they are used and are to be interpreted in a generic and descriptive sense only and not for purpose of limitation. In some instances, as would be apparent to one of ordinary skill in the art as of the filing of the present application, features, characteristics, and/or elements described in connection with a particular embodiment may be used singly or in combination with features, characteristics, and/or elements described in connection with other embodiments unless otherwise specifically indicated. Accordingly, it will be understood by those of skill in the art that various changes in form and details may be made without departing from the spirit and scope of the present invention as set forth in the following claims.