Abstract:
A battery pack housing forms a container that receives battery modules. The battery pack housing includes container portion and a cover that closes an open end of the container portion. The container portion includes a base, sidewalls that surround the base, and parallel rails that protrude from the base inner surface. The rails have longitudinally-spaced slots that open facing the cover. In addition, an inner surface of the cover portion includes parallel rails having longitudinally spaced slots that open facing the base. The slots are configured to receive and retain pins provided on side surfaces of the battery module housing. The cooperation between the pins of the battery module housing and the slots of the container portion and cover portion permit modules to be easily and securely located within the battery pack housing, and to be quickly removed from the battery pack housing during maintenance.

Description:
BACKGROUND 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates a battery pack assembly including structures for locating and securely retaining a battery module within a battery pack housing, and, more particularly, to complimentary structures formed on the battery pack housing and battery module that locate the battery module relative to the battery pack housing, and permit quick connection and disconnection of the battery module from the battery pack housing. 
         [0003]    2. Description of the Related Art 
         [0004]    Battery packs provide power for various technologies ranging from portable electronics to renewable power systems and environmentally friendly vehicles. For example, hybrid electric vehicles (HEV) use a battery pack and an electric motor in conjunction with a combustion engine to increase fuel efficiency. Battery packs are formed of a plurality of battery modules, where each battery module includes several electrochemical cells. The cells are arranged in stacks and are electrically connected in series or in parallel. Likewise, the battery modules within a battery pack are electrically connected in series or in parallel. In some conventional battery packs, the battery modules are installed and retained within the battery pack housing using bolts to locate the battery module relative to the housing and nuts to retain the battery module on the bolts. In some conventional battery packs, holes of the battery module are aligned with corresponding holes of the battery pack housing, and a fastener is passed through the holes and retained using a nut. These methods are difficult to use due to space constraints within the battery pack housing which also lead to difficulty visualizing the holes and fasteners. In addition, use of nut and bolt fasteners is labor intensive and time consuming. 
       SUMMARY 
       [0005]    In some aspects, a battery pack includes a battery pack housing and a battery module disposed in the battery pack housing. The battery pack housing includes a first side, and a second side that is parallel to the first side, where an inner surface of the first side faces and is spaced apart from an inner surface of the second side. The battery pack housing includes a first rail that protrudes from the inner surface of the first side, the first rail including a first surface feature. The battery pack housing also includes a second rail that protrudes from the inner surface of the second side, the second rail including a second surface feature. The battery module is disposed in the battery pack housing so as to reside between the first side and the second side. The battery module includes a module housing, and an outer surface of the module housing includes a third surface feature and a fourth surface feature. The battery module also includes electrochemical cells disposed within the module housing. The first surface feature and the second surface feature comprise one of a protrusion and a slot, the third surface feature and the fourth surface feature comprise the other of the protrusion and the slot, and the slot is shaped and dimensioned to receive and support the protrusion. In addition, the protrusion is disposed in the slot, and the module housing is located and retained relative to the battery pack housing via engagement of the first surface feature with the third surface feature, and engagement of the second surface feature with the fourth surface feature. 
         [0006]    The battery pack may include one or more of the following features: The first surface feature and the second surface feature are aligned in a direction perpendicular to the inner surface of the first side. The first surface feature is a first slot that opens facing the inner surface of the second side, and the second surface feature is a second slot that opens facing the inner surface of the first side. The first slot and the second slot are shaped to conform to the shape of an outer surface of the protrusion. The third surface feature is a protrusion disposed in the first slot, and the fourth surface feature is a protrusion disposed in the second slot. The first rail includes a first support surface that is parallel to and spaced apart from the inner surface of the first side, and the first slot opens at the first support surface. The second rail includes a second support surface that is parallel to and spaced apart from the inner surface of the second side, and the second slot opens at the second support surface. The first slot intersects the first support surface and adjoining side surfaces of the first rail, the adjoining side surfaces extending between the inner surface of the first side and the first support surface. The first slot includes a seat portion and a chamfered guide portion that is disposed between the seat portion and the first support surface. The guide portion is chamfered so as to have a maximum spacing between facing slot surfaces at a location corresponding the intersection of the chamfered portion and the first support surface, and a minimum spacing between facing slot surfaces at a location corresponding to the intersection of the chamfered portion and the seating portion. The seating portion is shaped to conform to the shape of an outer surface of the pin. The module housing includes a module first side that is transverse to the battery pack housing first side, and a module second side opposed to the module first side, and the third surface feature is formed on the module first side and the fourth surface feature is formed on the module second side. The battery pack housing first side includes plural parallel and spaced apart first rails, each first rail including a first surface feature, and the battery pack housing second side includes plural second rails, each second rail aligned with one of said first rails. The battery pack housing includes a detachable cover that includes the first side, and a container portion that includes the second side, and the cover is configured to be supported on the container portion to form a hollow container. The battery pack housing includes a third rail that protrudes from the inner surface of the first side and is spaced apart from the first rail, a fourth rail that protrudes from the inner surface of the second side and is spaced apart from the second rail, wherein the module housing is disposed between the first rail and the third rail, and between the second rail and the fourth rail. 
         [0007]    In some aspects, a housing includes an outer housing and an inner housing disposed in the outer housing. The outer housing includes a first side, and a second side that is parallel to the first side, an inner surface of the first side facing and being spaced apart from an inner surface of the second side. The outer housing includes a first rail that protrudes from the inner surface of the first side, the first rail including a first surface feature. The outer housing also includes a second rail that protrudes from the inner surface of the second side, the second rail including a second surface feature. The inner housing is disposed in the outer housing so as to reside between the first side and the second side, and the inner housing includes a third surface feature and a fourth surface feature. The first surface feature and the second surface feature comprise one of a protrusion and a slot, the third surface feature and the fourth surface feature comprise the other of the protrusion and the slot, and the slot is shaped and dimensioned to receive and support the protrusion. In addition, the protrusion is disposed in the slot, and the inner housing is located and retained relative to the outer housing via engagement of the first surface feature with the third surface feature, and engagement of the second surface feature with the fourth surface feature. 
         [0008]    The housing may include one or more of the following features: The first surface feature is a slot and the third surface feature is a pin. A surface of the slot is shaped to conform to the shape of an outer surface of the pin. The slot is chamfered. The outer housing includes at least two first rails and at least two second rails, each first rail being aligned with a corresponding one of the at least two second rails. Each first rail includes at least two first surface features, and each second rail includes at least two second surface features, each one of the at least two first surface feature being aligned with a corresponding one of the at least two second surface features. 
         [0009]    In some aspects, a battery pack assembly includes structural features for locating and securely retaining a battery module within a battery pack housing. The structural features also permit the battery module to be quickly released from the battery pack housing, for example during maintenance of the battery pack. In some embodiments, the battery pack housing includes container portion and a cover that closes an open end of the container portion to form a hollow container. The container portion includes a base and sidewalls that surround the base. The container portion includes parallel rails that protrude from the base inner surface and have longitudinally-spaced slots that open facing the cover. In addition, an inner surface of the cover portion includes parallel rails having longitudinally spaced slots that open facing the base. The slots are configured to receive and retain pins provided on side surfaces of the battery module housing. The cooperation between the pins of the battery module housing and the slots of the container portion and cover portion permit modules to be easily and securely located within the battery pack housing, and to be quickly removed from the battery pack housing during maintenance. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]      FIG. 1  is an exploded perspective schematic view of a battery pack. 
           [0011]      FIG. 2  is a perspective view of a battery module. 
           [0012]      FIG. 3  is an enlarged view of a portion of the battery module of  FIG. 2 . 
           [0013]      FIG. 4  is an exploded view of the battery pack housing. 
           [0014]      FIG. 5  is an enlarged view of a portion of a base rail illustrating details of a slot. 
           [0015]      FIG. 6  is a perspective view of a module disposed in the container portion of the battery pack housing of  FIG. 4 . 
           [0016]      FIG. 7  is a side view of a module disposed between the cover portion and the container portion of the battery pack housing of  FIG. 4 . 
           [0017]      FIG. 8  is a cross sectional view of a portion of the battery pack as seen along a plane parallel to the base  23  and passing through a pair of pins disposed in a single slot. 
           [0018]      FIG. 9  is an enlarged view of a portion of a base rail illustrating details of an alternative slot. 
       
    
    
     DETAILED DESCRIPTION 
       [0019]    Referring to  FIGS. 1 and 2 , a battery pack  10  used to provide electrical power includes electrochemical cells  20  that are electrically interconnected and stored in an organized manner within a battery pack housing  12 . The cells  20  are prismatic lithium-ion cells that include an electrode assembly (not shown) that is sealed within a cell housing  22  along with an electrolyte to form a power generation and storage unit. The electrode assembly may be, but is not limited to, a “jelly roll” electrode assembly that includes a positive electrode, a negative electrode and an intermediate separator provided in a stacked and rolled arrangement. An array of cells  20  are bundled together within a module housing  14  to form a battery module  16 . Within the battery module  16 , the array of cells  20  are electrically connected in series or in parallel, and within the battery pack housing  12 , the battery modules  16  are electrically connected in series or in parallel. The battery pack housing  12  and the battery module housings  14  include structural features that cooperatively engage to permit blind installation of the battery modules  16  within the battery pack housing  12 , and that securely retain the battery module housing  14  in a fixed position relative to the battery pack housing  12  once the battery pack  10  has been assembled, as discussed further below. 
         [0020]    Referring to  FIGS. 2 and 3 , the module housing  14  of each battery module  16  has a rectangular shape and includes a first end  60 , an opposed second end  61 , and four sides that extend between, and join, the first end  60  to the second end  61 . That is, the four sides of the module housing  14  include a first side  62 , a second side  63  adjoining the first side  62 , a third side  64  opposed to the first side  62 , and a fourth side  65  opposed to the second side  63 . For purposes of description, the distance between the first end  60  and the second end  61  corresponds to a height dimension of the module housing  14 , the distance between the first side  62  and the third side  64  corresponds to a length dimension of the module housing  14 , and the distance between the second side  63  and the fourth side  65  corresponds to a width dimension of the module housing  14 . In the illustrated embodiment, the length of the module housing  14  is greater than its width, and the width of the module housing  14  is greater than its height. 
         [0021]    In some embodiments, the module housing  14  may include a first restraint  66  in the form of a metal strap that is disposed adjacent the first end  60  and surrounds a circumference of the module housing  14  defined by the four sides  62 ,  63 ,  64 ,  65 . An edge  70  of the first restraint  66  is folded over a periphery of the first end  60 . In addition, the module housing  14  may include a second restraint  67  in the form of a metal strap that is disposed adjacent the second end  61  and surrounds the circumference of the module housing  14 . An edge  72  of the second restraint  67  is folded over a periphery of the second end  61 . 
         [0022]    Opposed second and fourth sides  63 ,  65  of the module housing  14  are provided with outwardly protruding pins  68 . That is, the pins  68  protrude in the width direction of the module housing  14 . The pins  68  are structural features of the module housing  14  that cooperatively engage with slots  36  formed on the battery pack housing  12  to facilitate installation and retention of the module housing  14  within the battery pack housing  12 . The slots  36  are described below. 
         [0023]    The pins  68  provided on the fourth side  65  are identical to, and have the same arrangement as, the pins  68  provided on the second side  63 , and thus only the pins  68  on the second side  63  will be described. Each pin  68  is circular in cross-sectional shape when viewed facing the housing side  63 , and has the appearance of a thin disc. For example, the pin  68  has a width w p  that is less than a diameter d of the pin cross-section, where the pin width is aligned with a width of the module housing  14 . In some embodiments, the pin  68  has a width that is in a range of about 10 to 25 percent of the diameter of the pin cross section. 
         [0024]    In the illustrated embodiment, the second module housing side  63  includes four pins as follows: The second module housing side  63  includes first pair of pins corresponding to two longitudinally spaced-apart pins  68   a,    68   b  that protrude from the first restraint  66 , and a second pair of pins corresponding to two longitudinally spaced-apart pins  68   c,    68   d  that protrude from the second restraint  67 . Of the four pins, two pins  68   a,    68   c  are adjacent the first side  62  (e.g., closer to the first side  62  than a mid-length  69  of the module housing  14 ), and are aligned in the height direction. The other two pins  68   b,    68   d  are adjacent the third side  64  (e.g., closer to the third side  64  than the mid-length  69  of the module housing  14 ) and are aligned in the height direction. In some embodiments, the pins  68   a,    68   b,    68   c,    68   d  may be formed separately from the restraints  66 ,  67 , and then rigidly secured thereto for example by welding or using a fastener. In other embodiments, the pins  68   a,    68   b,    68   c,    68   d  are integrally formed with the restraints  66 ,  67 , for example by molding, punching or machining 
         [0025]    Referring to  FIG. 4 , the battery pack housing  12  includes a container portion  22  and a cover portion  40  that covers an open end of the container portion  22 . The container portion  22  has the shape of an open-ended box, and includes a rectangular base  23 . A sidewall  24  is connected to and surrounds a periphery of the base  23 . The sidewall  24  includes two longitudinal sidewall portions  25 ,  27  that are parallel to a longitudinal axis  29  of the battery pack housing  12  and define a length dimension of the battery pack housing  12 . The sidewall  24  also includes two transverse sidewall portions  26 ,  28  that extend transverse to the longitudinal sidewall portions  25 ,  27  and join opposed ends of the longitudinal sidewall portions  25 ,  27 . The transverse sidewall portions  26 ,  28  define a width dimension of the battery pack housing  12 . A height dimension of the battery pack housing  12  corresponds to a distance between the container portion  22  and the cover portion  40  when the cover portion  40  is assembled thereon. The length dimension of the battery pack housing  12  is greater than its width dimension, and the width dimension of the battery pack housing is greater than its height dimension. 
         [0026]    The cover portion  40  has the shape of a generally flat, rectangular plate having the same dimensions as the base  23 . The cover portion  40  is formed separately from the container portion  22 , and is detachably secured over the open end of the container portion  22  via conventional fastening means. For example, in the illustrated embodiment, the cover portion  40  is secured to the sidewall  24  via screws (not shown). 
         [0027]    The container portion  22  further includes base rails  32  that protrude inward from an inner surface  31  of the base  23 . In addition, the cover portion  40  includes cover rails  42  that protrude inward from an inner surface  41  of the cover portion  40 . The base rails  32  and cover rails  42  are elongated, rectangular in cross-section and extend longitudinally between opposed transverse sidewall portions  26 ,  28 . The number of base rails  32  provided corresponds to the number of cover rails  42  provided, and each base rail  32  is aligned with a corresponding one of the cover rails  42 . The base rails  32  and cover rails  42  may be formed integrally with the respective container portion  22  and cover portion  40 , or may be rigidly fixed thereto. Outer base rails  32   o  and outer cover rails  42   o  are provided adjoining each longitudinal sidewall portion  25 ,  27 . Intermediate base rails  32   i  and intermediate cover rails  42   i  are disposed between the respective outer base rails  32   o  and outer cover rails  42   o.  For example, in the illustrated embodiment, two intermediate base rails  32   i  are disposed between the outer base rails  32   o  and two intermediate cover rails  42   i  are disposed between the outer cover rails  42   o.    
         [0028]    The transverse spacing S t  between adjacent base rails  32  corresponds to a width dimension of the battery module housing  14 . The transverse spacing S t  between adjacent cover rails  42  is the same as the transverse spacing between adjacent base rails  32 . 
         [0029]    The base rails  32  and cover rails  42  provide structural stiffness to the container portion  22 , and also include structural features (e.g., slots  36 ) that cooperatively engage with the pins  68  of the module housing to facilitate installation and retention of the module housing  14  within the battery pack housing  12 . In particular, each base rail  32  includes a cover-facing surface  34 , and adjoining side surfaces  33 ,  35  that extending between the inner surface  31  of the base  23  and the cover-facing surface  34 . The cover-facing surface  34  of each base rail  32  is formed having the slots  36  that open facing the cover portion  40  and extend across a width (e.g., the distance between the adjoining sides surfaces  33 ,  35 ) of each base rail  32 . Similarly, each cover rail  42  includes a cover-facing surface  44 , and adjoining side surfaces  43 ,  45  that extending between the inner surface  41  of the cover  40  and the base-facing surface  44 . The base-facing surface  44  of each cover rail  42  is formed having slots  36  that open facing the base  23  and extend across a width (e.g., the distance between the adjoining sides surfaces  43 ,  45 ) of each cover rail  42 . 
         [0030]    Each base rail  32  is aligned in the height direction (e.g. in a direction perpendicular to the inner surface  21  of the base  23 ) with a corresponding cover rail  42 . In addition, each slot  36  formed in the base rail  32  is aligned in the height direction, with a corresponding slot  36  formed in cover rail  32 . The slots  36  are longitudinally spaced apart. In particular, the slots  36  are formed in pairs in which the longitudinal spacing of the slots  36  of the pair corresponds to the spacing of the pins  68  on a side of the module housing  14 . Longitudinal spacing between adjacent pairs of slots  36  is relatively short to provide close packing of module housings  14  within the battery pack  10 . 
         [0031]    Referring to  FIG. 5 , the slots  36  formed in the base rails  32  and cover rails  42  are identical, so only the slots  36  of the base rails  32  will be described in detail. The slots  36  are shaped and dimensioned to receive and support a corresponding one of the pins  68  formed on an outer surface of the module housing  14 . To that end, the slots  36  each include a seat portion  37  and a guide portion  38  that is disposed between the seat portion  37  and the corresponding base-facing, or cover-facing, surface  34 ,  44 . The guide portion  38  is chamfered so as to have a maximum spacing S 1  between facing slot surfaces at a location corresponding the intersection of the guide portion  38  and the cover-facing, surface  34 , and a minimum spacing S 2  between facing slot surfaces at a location corresponding to the intersection of the guide portion  38  and the seat portion  37 . The chamfered guide portion  38  provides a lead-in that directs the pin  68  to the seat portion  37 , which facilitates blind location during assembly. 
         [0032]    In addition, the seat portion  37  is shaped and dimensioned to conform to the shape of an outer surface of the pin  68 . For example, in the illustrated embodiment, the seat portion  37  is circular to correspond to the circular cross-sectional shape of the pin  68 , and is sized to receive the pin  68  in a clearance fit. 
         [0033]    In some embodiments, the seat portion  37  of each slot is provided with a compressible, resilient pad (not shown) that accommodates differences in tolerances between the seat portion  37  and the pin  68  and reduces vibration and its associated noise. 
         [0034]    Referring to  FIGS. 1 and 6-7 , in some embodiments, the battery pack housing  12  includes four base rails  32 , and four cover rails  42 , each cover rail  42  in alignment with one of the base rails  32 . A row of battery modules  16  is supported between each pair of adjacent base rails  32 , and thus three rows of battery modules  16  are supported with the battery pack housing  12 . In addition, each base rail  42  and each cover rail  42  includes six slots  36  corresponding to three slot pairs. Each battery module includes the first pair of pins  68   a,    68   b  arranged to engage a corresponding slot pair of the cover rail  42 , and the second pair of pins  68   c,    68   d  arranged to engage a corresponding slot pair of the base rail  32 . Thus, each row of battery modules  16  may include up to three battery modules  16 . In some embodiments, the battery module controller (BMS)  18  is disposed within the battery pack housing in the place of one of the battery modules  16 , whereby the number of battery modules  16  within the battery pack  10  is reduced by one to make space for the BMS. Thus, in the illustrated embodiment, the battery pack housing contains eight battery modules  16  and the BMS. 
         [0035]    When the battery modules  16  are disposed in the battery pack  12 , and the cover portion  40  is secured to the container portion  22 , each battery module  16  is placed between a pair of base rails  32  and corresponding pair of cover rails  42  such that the length dimension of the battery module is parallel to the longitudinal axis  29  of the battery pack housing  12 . Since the spacing between adjacent base rails  32  and between adjacent cover rails  42  corresponds to a width of the battery module housing  14 , each battery module  16  is constrained from transverse movement by the rails  32 ,  42 . In addition, the first pair of pins  68   a,    68   b  of the opposed sides  63 ,  65  of the battery module  16  are received within a corresponding pairs of slots  36  of adjacent cover rails  42 , and the second pair of pins  68   c,    68   d  of the opposed sides  63 ,  65  of the battery module  16  are received within a corresponding pairs of slots  36  of adjacent base rails  36 , whereby each battery module  16  is constrained from both longitudinal movement and movement in the height direction. 
         [0036]    Referring to  FIG. 8 , the slots  36  have a slot width w s  that is sufficient to receive and support two pins  68  aligned in a transverse direction. In particular, each slot  36  can receive a first pin  68 ( 1 ) from a first module  16 ( 1 ) disposed along a first adjoining side surface  33  of the base rail  30 , and a second pin  68 ( 2 ) from a second module  16 ( 2 ) disposed along a second adjoining side surface  35  of the base rail  30 . 
         [0037]    In the illustrated embodiment, the pins  68  and the seat portion  37  of the slots  36  are formed having a circular shape. However, other the pins  68  and the slots  36  may be formed having other shapes. For example, in some embodiments and as shown in  FIG. 9 , an alternative slot  36 ′ may include a chamfered guide portion  38 ′ and a flat seat portion  37 ′. A corresponding alternative pin  68 ′ may have a trapezoidal cross sectional shape, including angled sides  74  and a flat base  76 , that is shaped and dimensioned to correspond to the shape of the alternative slot  36 ′. 
         [0038]    In the illustrated embodiment, the cover portion  40  includes four cover rails  42  and the base  23  of the container portion  22  includes the corresponding four base rails  32 . However, the number of cover rails  42  and base rails  32  is not limited to four, and can be changed to permit fewer or greater numbers of battery modules  16  to be store within the battery pack  10 . 
         [0039]    Although the battery pack  10  is described as including a set of slotted rails  32 ,  42  provided on the battery pack housing  12  and corresponding pins  68  provided on the battery module housing  14 , an alternative embodiment is contemplated in which the battery module housing  14  is formed having slots that are configured to cooperatively engage with pins formed on the battery pack housing  12 . 
         [0040]    Although the module housing  14  is described as including restraints  66 ,  67 , the module housing  14  is not limited to this configuration. For example, in some embodiments, the module housing  14  is formed without restraints  66 ,  67 , and the pins  68  are formed on an outer surface of the restraint-free module housing. 
         [0041]    Although the cells  20  that make up the battery module  16  are described herein as having a prismatic shape, the cells  20  are not limited to this shape. For example, the cells  20  may have a circular, elliptical, pouch or other shape. 
         [0042]    Although the cells that make up the battery module  16  are described herein as being a lithium-ion cell, the cells are not limited to this type. For example, the cells  20  may be alkaline, aluminum-ion, nickel metal hydride, nickel cadmium or other type of cell. 
         [0043]    The cooperative engagement between the pins  68  on the outer surface of the module housing  14  and the slots  36  on an inner surface of the battery pack housing  12  provide a locating and restraint system for mounting module housings  14  within the battery pack housing  12 . It is contemplated that a similar locating and restraint system can be used to secure individual cells within a module housing  14 , by providing one of pins or slots on the outer surface of the cell housings, and the other of pins or slots on the interior surface of the module housing  14 . 
         [0044]    Selective illustrative embodiments of the battery pack are described above in some detail. It should be understood that only structures considered necessary for clarifying the battery pack have been described herein. Other conventional structures, and those of ancillary and auxiliary components of the battery pack, are assumed to be known and understood by those skilled in the art. Moreover, while working examples of the battery pack have described above, the battery pack is not limited to the working examples described above, but various design alterations may be carried out without departing from the device as set forth in the claims.