Abstract:
A vehicle sub-structure includes an array of electrical power cells, the electrical power cells being ordered into groups of serially connected cells. A switch set provides for selectively interconnecting the plurality of groups of electrical power cells in a selected one of a plurality of possible orders, allowing the first and last cell in the series of cells to be changed. An auxiliary storage element is nested within the electrical power cells and both the auxiliary storage element and the arrays of electrical power cells are housed in a conformal enclosure.

Description:
BACKGROUND 
       [0001]    1. Technical Field 
         [0002]    The technical field relates generally to installation of battery arrays or packs and the storage of fluids and power on motor vehicles. 
         [0003]    2. Description of the Problem 
         [0004]    Packaging arrays of batteries for installation on trucks, particularly where the arrays include a large plurality of batteries or cells, as is common on hybrid vehicles, presents several issues. Battery boxes for conventional trucks can be hung from the vehicle frame rails toward the outside of the vehicle. Their location there allows them covered by a tractor side skirt to protect the batteries, streamline the vehicle and meet styling expectations, while still being accessible for service. The battery arrays designed to meet the traction voltage used on hybrid vehicles typically include many more cells or batteries than are used on non-hybrid vehicles. In order to provide a 345 volt traction power supply up to 96 lithium-ion cells may be used. Hybrid vehicle battery arrays are, as a result, typically bulkier than the two to four battery arrays used on non-hybrid vehicles. 
         [0005]    Simple expansion of a conventional battery box to handle the bulkier array is difficult to accommodate and can lead to relocation of the box on vehicles where open space is restricted or exposure of the box without the protection of an external skirt. Such a location can also affect the vehicle&#39;s aerodynamics. Location of the batteries also has consequences relating to access to the batteries for maintenance. Any one of several factors, such as battery numbers, their location relative to external connections, or the use of lithium ion batteries in the array, can result in increased generation or retention of battery internal heat during charging or discharging. Prolonged exposure to high levels of retained heat can lead to reduced battery service lives. Prolonged positioning of particular cells at the head or tail of a plurality of cells connected serially contributes to a shortened service life. 
       SUMMARY 
       [0006]    A vehicle sub-structure includes an array of electrical power cells. The electrical power cells are ordered into groups of serially connected cells. A switch set provides for selectively interconnecting the plurality of groups of electrical power cells in a selected one of a plurality of possible orders, allowing the first and last cell in the series of cells to be changed. An auxiliary storage element is nested within the electrical power cells and both the auxiliary storage element and the arrays of electrical power cells are housed in a conformal enclosure. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]      FIG. 1  is a perspective view of a vehicle equipped with a conformal multi-function auxiliary tank. 
           [0008]      FIG. 2  is a side elevation illustrating location of the auxiliary tank of  FIG. 1  on a truck behind a chassis skirt. 
           [0009]      FIG. 3  is a side elevation of an multi-function auxiliary tank. 
           [0010]      FIGS. 4A-B  are end views of the auxiliary tank of  FIG. 3 . 
           [0011]      FIG. 5  is an exploded view of a possible set of elements for the auxiliary tank of  FIG. 3  illustrating positioning of the elements. 
           [0012]      FIG. 6  is a cross sectional view of the auxiliary tank of  FIG. 3  taken lengthwise. 
           [0013]      FIGS. 7A-B  are cross sectional views taken along section line  7 A-B of  FIG. 6 . 
           [0014]      FIG. 8  is a detailed view of a representative battery band assembly. 
           [0015]      FIG. 9  is a cross sectional view taken along section line  9  of  FIG. 6 . 
       
    
    
     DETAILED DESCRIPTION 
       [0016]    In the following detailed description, like reference numerals and characters may be used to designate identical, corresponding, or similar components in differing drawing figures. Furthermore, example sizes/models/values/ranges may be given with respect to specific embodiments but are not to be considered generally limiting. In circuit diagrams well-known power and ground connections, and similar well-known elements, may be omitted for the sake of simplicity of illustration. 
         [0017]      FIG. 1  shows a truck  90  supported from front wheels  95  and rear wheels  94 . Truck  90  is built on a frame which includes a side frame rail  91  which is parallel to the longitudinal center line of the vehicle. Frame rail  91  carries a cylindrical fuel tank  93  hung from the frame rail toward the outside of the vehicle. A similar tank may be hung from a passenger side frame rail (not shown). Also hung from the frame rail  91  behind the fuel tank  93  and forward from the rear wheels  94  is a multi-function or auxiliary tank  92 . Multi-function tank  92  may be built to conform in cross sectional shape and dimensions (width and breadth) to the fuel tank  93 , though it can readily vary in length. Multi-function tank  92  can operate as an enclosure for any two or more of a plurality of storage elements, such as electrical power storage elements, pressurized fluid storage tanks, liquid storage tanks, etc. A gap may be left between the fuel tank  93  and the multi-function tank  92  to allow access to the ends of the tank for maintenance procedures, as explained below. As illustrated here both the fuel tank  93  and the multi-function tank  92  are cylinders. 
         [0018]    Some trucks a equipped with chassis skirts for reasons of styling and streamlining. An example of a truck  90  equipped with a chassis skirt  70  with a multi-function tank  92  hung from the frame rail  91  and extending just past the end of the chassis skirt  70  is shown in  FIG. 2 . 
         [0019]      FIG. 3  shows the exterior of one side of a multi-function tank  92 . Multi-function tank  92  is cylindrical and closed at each end by end caps  53 ,  54 . Tank outlet ports  51 ,  57  are provided at each end for the connection of conduits through which cables may be run to the tank or fluids introduced or withdrawn. Heat exchanger fluid ports  12  may be located along the side of the multi-function tank  92 . The contents of multi-function tank  92  may be cooled or heated depending upon the application. 
         [0020]    Multi-function tank  92  is employed as a storage vessel for fluids or components used for the storage of electrical energy, usually capacitors or battery cells. Multi-function tank  92  may be used as the location for batteries and capacitors, and for the storage of fluids including compressed gases such as air or propane, liquefied natural gas, engine coolant, hydraulic oil, engine oil, deicer, urea, diesel fuel or other substances. 
         [0021]      FIGS. 4A-B  show opposite ends of multi-function tank  92 . Multi-function tank  92 , when cylindrical may be suspended from a frame rail by conventional tank straps  14  as used with cylindrical fuel tanks. Conduits  56 ,  58  are shown connected to tank outlet ports  51 ,  57 . Removable end caps  53 ,  54  are aligned on the tank  92  by alignment studs  13 . Conventional fasteners may be used to secure the end caps  53 ,  54  on the tank  92 . 
         [0022]    Where tank  92  is used for locating a plurality of batteries, particularly an array of lithium-ion cells connected in series for a hybrid vehicle, end cap  54  may be modified to incorporate a battery rotation plate indicator dial  11 . As described below, on hybrid vehicles, the traction battery cells are typically connected in series to build a battery having an operational voltage of approximately 345 volts. If the order of the cells in the series is left unchanged, the cells at the beginning and end of the chain tend to exhibit premature failure, potentially leading to a cascade failure of all the cells in the chain resulting in the expensive replacement of the cells. Battery rotation plate indicator dial is used to change the order of the cells in the chain to alter which cells are at the beginning and end of the chain. 
         [0023]    As illustrated, an operator can select any of three cells (here out of 36 or 48 cells) for location at the head of the chain and three cells for location at the tail of the chain. This does not involve actual physical repositioning of the batteries, but a change in wiring implemented with rotation of the indicator dial  11  in the direction indicated by the letter A. A handle (not shown) may be added to the face of indicator dial  11  to ease lifting and rotation of the indicator dial. Three stops of the indicator dial are associated with the set point markers  84 A, B and C, marked as J, M and S. The letters used are associated with the months of January, May and September, which may be used as recommended times of the year for changing the battery cell order. The particular start dates for operating periods are arbitrary, and there is no particular significance to January, May and September. Selection of a particular order for the cells is done by positioning one of the set point markers  84 A, B or C proximate to a battery rotation plate service alignment indicator  16 . 
         [0024]    Referring to  FIG. 5 , an exploded view of the contents of a multi-function tank  92  used for battery storage of electrical power for a hybrid vehicle. A secondary tank  40  is located centered within four radial battery bands  17 ,  18 ,  19  and  20 . Secondary tank  40  may be used for storage of a large variety of liquids or gases, or could be a capacitor. Tank  40  has a threaded tank connector  82  for connection to tank outlet port  51 . 
         [0025]    A typical arrangement of cells  31  for location in multi-function tank  92  are in four radial groups of twelve cells each. This arrangement works for lithium ion cells having a nominal output voltage of about 3.6 volts. Ninety six cells may be used to build a traction battery having a nominal output voltage of 345 volts. With 48 cells per multi-function tank  92 , and two multi-function tanks, 96 cells may be connected in series to provide a theoretical output voltage of 345.6 volts, disregarding resistance losses. Each cell has a positive terminal  39  and a negative terminal  38 . 
         [0026]    Cells  31  are arranged in radial bands circumscribing tank  40 . The number of bands is variable with four bands  17 ,  18 ,  19  and  20  of twelve cells  31  each shown. Alternatively two or three bands may be used with differing numbers of cells. Each band includes heat exchanger lines  22 , which connect to one another between bands and from band to the heat exchanger outlet ports  12 . Typically the concern is for cooling of the batteries, and the heat exchanger lines  22  may be connected to an external heat sink (not shown) and coolant circulated through the lines by a pump (also not shown) and in theory can be used to transfer heat in or out of the system. Under some circumstances the cells may be warmed by circulated heated coolant through the lines  22 . 
         [0027]    Attached behind end cap  54  between the end cap and battery band  20  is a battery control electrical assembly  21  which includes a battery rotation switch assembly  24 . Battery control electrical assembly  21  is aligned on band  20  using battery switch plate alignment elements  23 . Battery rotation switch assembly  24 , except during rotation of one of the plates of the battery rotation switch assembly  24 , holds electrical contacts  26 ,  27 ,  28  in electrical contact. Assembly  24  is held in mechanical linkage to indicator dial  11  by threaded fasteners  25 . Electrical cables (described below) from each of the bands  17 ,  18 ,  19  and  20  are connected to selected electrical contacts  27 ,  28  in the switch assembly  24  allowing selection of which band includes the cell  31  to be at the base of the chain of cells  31  and which band is to include the cell at the head of the chain. 
         [0028]      FIG. 6  illustrates in cross section the assembled multi-function tank with cells circumscribing auxiliary tank  40 . The location and direction of cross-sectional views illustrating electrical connection of the cells  31  in  FIGS. 7A ,  7 B and  9  is shown. The battery assembly and tank  40  are enclosed within the tank wall  83  of the multi-function tank  92 . 
         [0029]    Referring to  FIGS. 7A and 7B  a rotation plate  29  and a fixed plate  30  of the battery rotation switch assembly  24  are shown. Rotation plate  29  and fixed plate  30  face one another in the assembly  24  to contact pads  26  of the rotation plate  29  and the fixed plate negative contacts  27 A,  27 B,  27 C and fixed plate positive contacts  28 A,  28 B,  28 C. Rotation plate  29  and fixed plate  30  are set up with three sets of electrical contacts for three groups or “bands” of cells and to allow selection of which band will include the base cell  31  and which band will include the head cell  31  of the series. Rotation plate  29  may be mechanically linked to indicator dial  11  to indicate the relative rotational relationship between plates  28  and  29 . Three rotational relationships between plates  29  and  30  are defined by tongue and groove system locks  87 ,  88 . The plates  29 ,  30  may be urged together by a spring, but can come together for electrical contact only if the tongues  87  are aligned with the grooves  88 . It is arbitrary which plate carries the tongues and which carries the grooves. 
         [0030]    Two sets of contacts  26 C and  26 D are electrically shorted using jumpers  46 . Contacts  26 C and  26 D provide electrical connection between bands or groups of cells. Contacts  26 A and  26 B define the base and head cell  31  of the series by not being jumped to one another but instead being connected to positive and negative main output cables  44  and  45 . 
         [0031]    Fixed plate  30  has three positive contacts  27 A, B and C and three negative contacts  28 A, B and C. Electrical cables  34 A, B and C are connected from a positive terminal on a cell in one each of the bands to a positive contact  27  on the fixed plate  30 . Electrical cables  35 A, B and C are connected between a negative terminal on a cell in one of the bands and one of the negative contacts  28 . 
         [0032]      FIGS. 8 and 9  illustrate pass through of cable sets  34 B,  35 B and  34 C,  35 C from lower bands of an array via pass through wiring pass through holes  32  through a cell frame  43  for connection to the fixed plate  30 . Cable set  34 A,  35 A may be directly connected to the fixed plate  30  without pass through.  FIG. 8  shows the distribution of some of the cells  31  within the exterior surface  33  of a battery band assembly. 
         [0033]      FIG. 9  illustrates electrical connections within a representative band, here the band adjacent the fixed plate  30 . Each cell  31  has a positive and negative terminal  39 ,  38 . Eleven cell cable connectors  41  are provided between positive and negative terminals  39 ,  38  of adjacent cells  31 . One pair of adjacent cells  31  is missing a cell cable connector, with the respective positive and negative terminals being connected to positive and negative cables out  34 A,  35 A. Depending upon the relative alignments of plates  29  and  30  in the battery switch rotation assembly  24 , either the cell  31  connected to cable out  34 A will be the last battery in the series connection of cells from band to band, or the cell connected to cable out  35 A will be the first or base cell in the series, although if there is more than one band they will never be concurrently in these positions. Battery switch rotation assembly  24  allows the electrical sequence of the bands to be changed. 
         [0034]    Signal wires  36 ,  37  are provided from the cells  31  to an external battery management system.