Abstract:
A thermal management system for an energy storage system that controls the temperature of an array of electrochemical cells of the energy storage system. Fluid channels or pathways are provided around outer side regions of an array of electrochemical cells. Fluid flow is directed along one pathway to a next subsequent pathway, absorbing thermal energy generated by the array of electrochemical cells along the way. The fluid flow is eventually discharged from the energy storage system by the thermal management system, thereby removing thermal energy from the energy storage system.

Description:
BACKGROUND 
       [0001]    1. Technical Field 
         [0002]    The subject matter disclosed herein relates to batteries and, more particularly, to a thermal management system for a battery having an array of electrochemical cells. 
         [0003]    2. Discussion of Art 
         [0004]    Multi-celled batteries for storing energy are sensitive to temperature and may operate more effectively at a particular temperature or within a particular temperature range. Current methods of thermally managing multi-celled batteries often employ an excessive amount of material within the battery, for example in the form of cooling panels between rows of electrochemical cells which have to be tied together using manifolds. Such methods can add significant cost and weight to the battery. 
         [0005]    It would therefore be desirable to develop a battery with thermal management features and characteristics that differ from those of batteries that are currently available. 
       BRIEF DESCRIPTION 
       [0006]    In an embodiment, a thermal management system is provided having a first air-flow channel configured to be disposed along a first inner side region of a housing for an array of electrochemical cells, and having a first air inlet end and a first air outlet end. The thermal management system also provides a second air-flow channel configured to be disposed along a second inner side region of the housing that is perpendicular to the first inner side region, and having a second air inlet end configured to be fluidly coupled to the first air outlet end, and having a second air outlet end. The thermal management system further provides a third air-flow channel configured to be disposed along a third inner side region of the housing that is perpendicular to the second inner side region, and having a third air inlet end configured to be fluidly coupled to the second air outlet end, and having a third air outlet end. 
         [0007]    In an embodiment, an energy storage system is provided having an enclosure having a plurality of internal surfaces that define a volume, an array of electrochemical cells disposed within the enclosure volume, and the thermal management system defined above, operable to control a temperature of the array of electrochemical cells in the enclosure. 
         [0008]    In an embodiment, a method is provided including directing an air flow along a first air-flow pathway that is disposed along a first inner side portion of a housing for a plurality of electrochemical cells. The method also includes redirecting at least a portion of the air flow from the first air-flow pathway to a second air-flow pathway that is perpendicular to the first air-flow pathway. The second air-flow pathway is disposed along a second inner side portion of the housing. The method further includes redirecting at least a portion of the air flow from the second air-flow pathway to a third air-flow pathway that is perpendicular to the second air-flow pathway. The third air-flow pathway is disposed along an outer side region adjacent to the plurality of electrochemical cells. 
         [0009]    In an embodiment, a thermal management system for an electrochemical device is provided having means for directing an air flow along a first outer side region adjacent to a plurality of electrochemical cells to remove thermal energy generated, at least in part, by the plurality of electrochemical cells. The thermal management system also has means for redirecting at least a portion of the air flow from along the first outer side region to along a second outer side region adjacent to the plurality of electrochemical cells that is perpendicular to the first outer side region to further remove thermal energy generated, at least in part, by the plurality of electrochemical cells. The thermal management system further has means for redirecting at least a portion of the air flow from along the second outer side region to along a third outer side region adjacent to the plurality of electrochemical cells that is perpendicular to the second outer side region to further remove thermal energy generated, at least in part, by the plurality of electrochemical cells. 
         [0010]    In an embodiment, a system is provided having a housing with an interior surface that defines a volume, and the interior surface has a base portion that is spaced from a ceiling portion by one or more side surface portions, and the housing has an orientation such that the ceiling portion is relatively above the base portion. The system also has an array of electrochemical cells disposed in the housing volume that are operable to generate heat, each electrochemical cell of the array is elongate and has a first end and a second end, and the first ends are proximate to but spaced from the base portion, and the second ends are proximate to but spaced from the ceiling portion. The system further has a coolant source that is operable to flow a coolant through a first channel that is disposed between the base portion and the first ends, and further operable to flow the coolant subsequently through a third channel that is disposed between the ceiling portion and the second ends. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    Reference is made to the accompanying drawings in which particular embodiments of the invention are illustrated as described in more detail in the description below, in which: 
           [0012]      FIG. 1  illustrates the broad concept of an energy storage system having a thermal management system, in accordance with various embodiments; 
           [0013]      FIG. 2  is an embodiment of an energy storage system having a thermal management system; 
           [0014]      FIG. 3  is an embodiment of a system having the energy storage system of  FIG. 2 , a coolant source, and an outlet bellows; 
           [0015]      FIG. 4  is a first perspective view of an embodiment of a portion of the thermal management system of  FIG. 2 ; 
           [0016]      FIG. 5  is a second perspective view of an embodiment of a portion of the thermal management system of  FIG. 2 ; 
           [0017]      FIG. 6  is a front view of an embodiment of a portion of the thermal management system of  FIG. 2 ; 
           [0018]      FIG. 7  is a side view of an embodiment of a portion of the thermal management system of  FIG. 2 ; 
           [0019]      FIG. 8  is a top view of an embodiment of a portion of the thermal management system of  FIG. 2 ; and 
           [0020]      FIG. 9  is a flowchart of an embodiment of a method of thermally managing the energy storage system of  FIG. 2  using the portion of the thermal management system of  FIGS. 4-8 . 
       
    
    
     DETAILED DESCRIPTION 
       [0021]    Embodiments relate to a thermal management system for an energy storage system. With reference to the drawings, like reference numerals designate identical or corresponding parts throughout the several views. However, the inclusion of like elements in different views does not mean a given embodiment necessarily includes such elements or that all embodiments of the invention include such elements. 
         [0022]      FIG. 1  illustrates the broad concept of an energy storage system  100  having a thermal management system, in accordance with various embodiments. The thermal management system has several elements as is discussed herein. The energy storage system  100  includes a plurality of electrochemical cells  110  for storing energy. The electrochemical cells  110  are arranged adjacent to each other to form an array of electrochemical cells  110 . For example, in accordance with an embodiment, sixty-four electrochemical cells  110  can be arranged as an array of eight cells by eight cells in, for example, a generally cubic (rectangular parallelepiped) configuration. Each electrochemical cell has a first end  111  and a second end  112 , as defined in this example, by the longitudinal axis of the cell. Furthermore, each electrochemical cell includes a negative electrical terminal  113  and a positive electrical terminal  114  on the second end  112 . The electrical terminals of the cells may be connected in series, in parallel, or in some combination of series and parallel connections between adjacent cells, depending on the application. 
         [0023]    Typical embodiments of such electrochemical cells can have dimensions of about 37 mm×27 mm×240 mm, any of which dimensions may vary by up to +/−50%, in accordance with various embodiments. The chemistry of a typical cell is of the sodium-metal-halide type, where NaCl and Ni are converted to Na and NiCl 2  during battery charging. The energy capacity of a cell can range from about 30 amp*hours to about 250 amp*hours. 
         [0024]    An array of cells can be packaged into a housing to form a battery having typical dimensions of about 400 mm×500 mm×300 mm, any of which dimensions may vary by up to +/−50%, in accordance with various embodiments. In accordance with various embodiments, cooling channels are provided within the battery having a height ranging from about 2 mm to about 50 mm. Similarly, the width of a cooling channel can range from about 2 mm to about 50 mm. The operating temperature range of the cells can range between about 270° C. and about 350° C., in accordance with various embodiments. 
         [0025]    The array of electrochemical cells  110  generates heat or thermal energy during operation. In accordance with an embodiment, the build-up of thermal energy and, therefore, the operating temperature of the cells  110  are controlled by providing a thermal management system that facilitates the flow of air (or other coolant) along a first air-flow channel  120  (e.g., under the cells), a second air-flow channel  130  (e.g., up the back of the cells), and a third air-flow channel  140  (e.g., over the top of the cells) along outer side regions defined by the array of cells  110 . The term “channel” refers to a structure that defines a pathway or passageway for the passage of air or other coolant. The flow of air along the pathways of the channels, as indicated by the dashed arrows in  FIG. 1 , serves to remove thermal energy from the energy storage system  100 . A cubic array of cells defines six distinct outer side regions. For example, an array of cells can define a bottom outer side region, a top outer side region, a front outer side region, a back outer side region, a left outer side region, and a right outer side region. 
         [0026]    As shown in  FIG. 1 , the air flow along the first air-flow channel  120  fluidly couples to the second air-flow channel  130  which then fluidly couples to the third air-flow channel  140 . As  FIG. 1  shows a side-view of an array of electrochemical cells  110  along one dimension of the array, it is to be understood that air flow is channeled over the entire depth (i.e., into the page of  FIG. 1 ) of the array of cells  110 , in accordance with various embodiments. By concentrating the flow of air around the outer perimeter (i.e., the outer side regions) of the array of cells  110 , additional elements such as, for example, cooling panels between rows of electrochemical cells (tied together using manifolds) are not employed, helping to reduce weight and cost of the energy storage device  100 . 
         [0027]    The cooling efficiency of the thermal management system of  FIG. 1  may be reduced, compared to a more conventional system employing cooling panels between rows of cells, or other techniques which add weight and cost. This may limit the energy storage system  100  to low discharge rate applications such as uninterruptible power supply (UPS) applications and telecommunications applications, for example. 
         [0028]    However, the cells  110  and the spatial relationship of the cells  110  to each other can be configured to allow gaps  150  to exist between the cells  110 , for example, at the corners of the cells  110 . As a result, a portion of the air flow can be directed upward between the cells directly from the first air-flow channel  120  toward the third air-flow channel  140  without the use of additional material or panels. Such inter-cell air flow can help to improve the cooling efficiency of the thermal management system of the energy storage system  100 . 
         [0029]      FIG. 2  illustrates an embodiment of an energy storage system  200  having the cells  110  of  FIG. 1  and a thermal management system, including the air flow channels  120 ,  130 ,  140  of  FIG. 1 . Furthermore, the thermal management system includes an inlet air manifold  210 . 
         [0030]    The first air-flow channel  120  has an air inlet end  121  and an air outlet end  122 . The second air-flow channel  130  has an air inlet end  131  and an air outlet end  132 . The third air-flow channel  140  has an air inlet end  141  and an air outlet end  142 . In general, during operation, the path of air flow (see dashed arrows in  FIG. 2 ) is into the inlet air manifold  210  and downward toward the air inlet end  121 , across the first air-flow channel  120  toward the air inlet end  131 , upward along the second air-flow channel  130  toward the air inlet end  141 , and across the third air-flow channel  140  toward the air outlet end  142 . In accordance with an embodiment, the first air-flow channel  120  is a corrugated structure, allowing air to effectively flow above and below the channel  120  (as indicated in  FIG. 2 ).  FIGS. 4 ,  5 , and  8  illustrate the corrugated nature of the channel  120 . 
         [0031]    As air flows from channel to channel, more thermal energy is absorbed by the air, raising the temperature of the air as the air flows. Therefore, in general, the temperature of the air through the third air-flow channel  140  will be higher than the temperature of the air through the first air-flow channel  120 . 
         [0032]    In accordance with an embodiment, the third air-flow channel  140  is a sheet of mica material resting upon vertical mica sheets (not shown) residing between the cells  110  and extending upward just above the cell terminals  113  and  114 , or resting upon a cranked portion (not shown) of one of the terminals of each of the cells, or resting on strips of mica (not shown) supported by flat intercell connectors on the cells, for example. During operation, air flows along the third air-flow channel  140  across the upper portions of the cells  110 . 
         [0033]    In accordance with an embodiment, the thermal management system of the energy storage system  200  further includes a heating element  220  adjacent to the third air-flow channel  140 . The heating element  220  serves to input thermal energy (heat) into the energy storage system  200  to raise the temperature of the electrochemical cells  110  toward a desired operating temperature. Control of the heating element  220  and the air flow along the air-flow channels  120 ,  130 ,  140  provides overall thermal management of the energy storage system  200 . 
         [0034]    The energy storage system  200  of  FIG. 2  includes a battery base  230  (e.g., a mica sheet) upon which the cells  110  sit. In accordance with an embodiment, the first air-flow channel  120  acts as a sump to support the cells on the battery base  230  while providing a region for air to flow beneath the battery base  230  and, therefore, beneath the cells  110 . In this embodiment, the battery base  230  is made of a mica material and has a plurality of holes  231  therethrough. The plurality of holes  231  allow air to flow from the first air-flow channel  120 , through the holes  231 , and upward between the cells  110  (i.e., through the gaps  150 ) directly from the first air-flow channel  120  toward the third air-flow channel  140  without the use of additional material or panels. Such inter-cell air flow can help to improve the cooling efficiency of the thermal management system of the energy storage system  200 . In accordance with an embodiment, a mica panel, stainless steel panel, and/or other panel can be positioned directly adjacent to each of the four sides of the array of cells  110  providing electrically insulating protection for the cells  110 . 
         [0035]    The energy storage system  200  also includes a housing or enclosure  240  (e.g., inner battery box) surrounding the electrochemical cells  110  and the various elements  120 ,  130 ,  140  and  210 ,  220 ,  230  of the thermal management system. The housing  240  defines an enclosed volume and has inner side regions (interior surfaces) and outer side regions (exterior surfaces). In accordance with an embodiment, the surfaces of the housing  240  define a base portion  243  that is spaced from a ceiling portion  244  by one or more side portions  245 , where the ceiling portion  244  is relatively above the base portion  243 . The housing  240  includes an input port  241  for the intake of air, and an output port  242  to remove air from the energy storage system  200 . 
         [0036]      FIG. 3  is an embodiment of a system having the energy storage system  200  of  FIG. 2 , a coolant source  310 , and an outlet bellows  320 . In accordance with an embodiment, air flow is provided to the input port  241  from the coolant source  310  (e.g., an air blower or fan), and air is exited from the output port  242  via the outlet bellows  320 . The outlet bellows  320  is made of stainless steel and/or mild steel. However, other materials can be used. The outlet bellows  320  connects between the inner battery box  240  and an outer battery housing  330 , a portion of which is shown in  FIG. 3 . In accordance with an embodiment, a vacuum is pulled between the inner battery box  240  and the outer battery housing  330  to form an insulating space between them. 
         [0037]    In accordance with an alternative embodiment, the thermal management system of the energy storage system  200  may be configured to use some other coolant instead of air such as, for example, an inert gas (e.g., argon or neon) or a liquid fluid (e.g., a water or an alcohol solution). In such an alternative embodiment, the flow of the fluid is still around the perimeter of the electrochemical cells  110  (e.g., along the bottom of the cells, then upward along the back of the cells, then across the top of the cells). In the case of a liquid fluid, the coolant source  310  can include a pump and the outlet bellows  320  can be replaced with a suction reservoir. 
         [0038]      FIG. 4  is a first perspective view of an embodiment of a portion of the thermal management system of  FIG. 2  including the inlet air manifold  210 , the first air-flow channel  120 , and the second air-flow channel  130 . Similarly,  FIG. 5  is a second perspective view of an embodiment of a portion of the thermal management system of  FIG. 2 . As shown in  FIG. 4 , the bottom end of the inlet air manifold  210  fits to the air inlet end  121  of the first air-flow channel  120 . The inlet air manifold  210  is perpendicular to the first air-flow channel  120 . Similarly, the air outlet end  122  of the first air-flow channel  120  fits to the air inlet end  131  of the second air-flow channel  130 . The second air-flow channel  130  is perpendicular to the first air-flow channel  120  and parallel to the inlet air manifold  210 . The corrugated nature of the first air-flow channel  120 , in accordance with an embodiment, allows air to flow through the troughs  450  and peaks  430  formed by the corrugation such that air effectively flows above and below the channel  120  as shown in  FIG. 2 . The first air-flow channel  120  is made of stainless steel in accordance with an embodiment; however, other materials can be used. 
         [0039]    An embodiment relates to a thermal management system. The system comprises means (see structure shown at least in  FIGS. 2 ,  3 ,  4 ,  5 , and  7 ) for directing an air flow along a first outer side region adjacent to a plurality of electrochemical cells to remove thermal energy generated, at least in part, by the plurality of electrochemical cells. The system also comprises means (see structure shown at least in  FIGS. 2 ,  3 ,  4 ,  5 , and  7 ) for redirecting at least a portion of the air flow from along the first outer side region to along a second outer side region adjacent to the plurality of electrochemical cells that is perpendicular to the first outer side region to further remove thermal energy generated, at least in part, by the plurality of electrochemical cells. The system further comprises means (see structure shown at least in  FIGS. 2 and 3 ) for redirecting at least a portion of the air flow from along the second outer side region to along a third outer side region adjacent to the plurality of electrochemical cells that is perpendicular to the second outer side region to further remove thermal energy generated, at least in part, by the plurality of electrochemical cells. 
         [0040]    In accordance with an embodiment, the first air-flow channel  120 , the second air-flow channel  130 , and the inlet air manifold  210  form an integrated structure  400  configured to be installed in the housing  240  as a single assembly. Alternatively, the first air-flow channel  120 , the second air-flow channel  130 , and the inlet air manifold  210  are configured to each be separately positioned into the housing  240 . For example, the first air-flow channel  120  can be placed in the housing  240  first, followed by the second air-flow channel  130  where the inlet air end  131  is fit with the outlet air end  122 , then followed by the inlet air manifold  210  where the bottom portion of the inlet air manifold  210  is fit with the inlet air end  121 . 
         [0041]    In accordance with an embodiment, air enters the inlet air manifold  210  at the inlet port  410  at the front of the energy storage system  200  and is directed downward toward the air inlet end  121  of the first air-flow channel  120  by a triangular section  420  of the inlet air manifold  210 . As air enters the inlet port  410  at a top corner of the triangular section  420 , the air is efficiently directed downward by the triangular section  420 . The thickness of the inlet air manifold is about 10 millimeters, in accordance with an embodiment. The inlet air manifold  210  is made of mild steel, in accordance with an embodiment; however, other materials can be used. 
         [0042]    In accordance with an embodiment, the second air-flow channel  130  includes a plurality of parallel spacer elements  440  running from the air inlet end  131  to the air outlet end  132 . The spacer elements  440  provide an offset (e.g., about 10 millimeters) from the cells  110  at the back of the energy storage system  200 , providing a space for air to flow upward along the second air-flow channel  130 . The spacer elements  440  are attached to a side plate  460  of the second air-flow channel  130 , or can be an integral part of the side plate  460 . The second air-flow channel  130  is made of mild steel, in accordance with an embodiment; however, other materials can be used. 
         [0043]      FIG. 6  is a front view of an embodiment of a portion of the thermal management system of  FIG. 2 . As can be seen in  FIG. 6 , the height of the inlet air manifold  210  is about two-thirds the height of the second air-flow channel  130 , in accordance with an embodiment.  FIG. 7  is a side view of an embodiment of a portion of the thermal management system of  FIG. 2 , and  FIG. 8  is a top view of an embodiment of a portion of the thermal management system of  FIG. 2 . 
         [0044]      FIG. 9  is a flowchart of an embodiment of a method  900  of thermally managing the energy storage system  200  of  FIG. 2  using the portion of the thermal management system of  FIGS. 4-8 . In step  910  of the method  900 , air flow is directed along a first air-flow pathway  120  that is disposed along a first inner side portion of a housing  240  for a plurality of electrochemical cells  110 . In step  920 , at least a portion of the air flow is redirected from the first air-flow pathway  120  to a second air-flow pathway  130  that is perpendicular to the first air-flow pathway  120 . The second air-flow pathway  130  is disposed along a second inner side portion of the housing  240 . In step  930 , at least a portion of the air flow is redirected from the second air-flow pathway  130  to a third air-flow pathway  140  that is perpendicular to the second air-flow pathway  130 . The third air-flow pathway  140  is disposed along an outer side region adjacent to the plurality of electrochemical cells  110 . 
         [0045]    Referring to  FIG. 3 , in accordance with an embodiment, the air flow into the energy storage system  200  can be cycled on and off by the cooling source  310  according to a determined duty cycle. The duty cycle is controlled by the cooling source  310  to minimize temperature gradients across the energy storage system  200  while achieving cooling in a given time period, so as not to overcool the front of the energy storage system  200  with respect to the back of the energy storage system  200 , for example. 
         [0046]    During the manufacturing process of the electrochemical cells, the cells are heated as part of the manufacturing process. Before being shipped as a final energy storage product, the cells are put through a cool-down period to reduce the temperature of the cells. The thermal management system discussed herein can be used to cool down the cells, thus reducing the normal cool-down period, saving time and money, even if the end-user of the energy storage system (having the thermal management system) does not use the thermal management portion of the energy storage system in the field (e.g., in a low power telecommunications application). 
         [0047]    Another embodiment relates to an energy storage system having a thermal management system. The energy storage system includes a plurality of electrochemical cells for storing energy, which are arranged into an array. (Dimensional and other aspects of the cells may be as described above.) The array is defined by six sides: a first pair (front, rear), a second pair (left, right), and a third pair (top, bottom). The sides of each pair are parallel to one another. Also, the sides of each pair are perpendicular and contiguous with the sides of the other pairs. The thermal management system includes a first channel that defines a first air flow region along the bottom side of the array. The thermal management system also includes a second channel that defines a second air flow region along the rear side of the array. The thermal management system also includes a third channel that defines a third air flow region along the top side of the array. (Dimensional aspects of the channels may be as described above.) The first air flow region is fluidly coupled with the second air flow region (and perpendicular thereto), and the second air flow region is fluidly coupled with the third air flow region (and perpendicular thereto). In operation, when air is urged through the first channel towards the rear side, the air flows through the first air flow region, is turned to flow through the second air flow region, and is turned to flow through the third air flow region, i.e., under, up the back, and back over the top of the array. There are no substantial air flow regions up the left and right sides, meaning there may be incidental gaps or spaces, but for a given flow rate through the first, second, and third channels, an incidental flow rate past the left and right sides is no more than 5%. In another embodiment, the thermal management system additionally includes an inlet member. The inlet member defines an air inlet, and is configured and positioned by the front side of the array to establish a fourth air flow region at the front side. The fourth air flow region is perpendicular and fluidly coupled to the first air flow region, such that when air is urged through the air inlet into the fourth air flow region, the air travels down the front of the front side of the air, and is turned for passing into the first air flow region. The inlet member is coupled to at least the first channel, and the channels are coupled to one another, as applicable, such that substantially all (at least 95%) of the air urged through the air inlet is directed through the fourth air flow region, then through the first, second, and third air flow regions in that order. 
         [0048]    In any of the embodiments herein where elements are perpendicular, such elements may be generally perpendicular, meaning 90 degrees plus or minus 3 degrees, to account for relatively minor manufacturing variances/tolerances. Similarly, in any of the embodiments herein where elements are parallel, such elements may be generally parallel, meaning 0 degrees plus or minus 3 degrees, to account for relatively minor manufacturing variances/tolerances. 
         [0049]    In the appended claims, the terms “including” and “having” are used as the plain language equivalents of the term “comprising”; the term “in which” is equivalent to “wherein.” Moreover, in the following claims, the terms “first,” “second,” “third,” “upper,” “lower,” “bottom,” “top,” etc. are used merely as labels, and are not intended to impose numerical or positional requirements on their objects. Further, the limitations of the following claims are not written in means-plus-function format and are not intended to be interpreted based on 35 U.S.C. §112, sixth paragraph, unless and until such claim limitations expressly use the phrase “means for” followed by a statement of function void of further structure. As used herein, an element or step recited in the singular and proceeded with the word “a” or “an” should be understood as not excluding plural of said elements or steps, unless such exclusion is explicitly stated. Furthermore, references to “one embodiment” of the present invention are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features. Moreover, unless explicitly stated to the contrary, embodiments “comprising,” “including,” or “having” an element or a plurality of elements having a particular property may include additional such elements not having that property. Moreover, certain embodiments may be shown as having like or similar elements, however, this is merely for illustration purposes, and such embodiments need not necessarily have the same elements unless specified in the claims. 
         [0050]    As used herein, the terms “may” and “may be” indicate a possibility of an occurrence within a set of circumstances; a possession of a specified property, characteristic or function; and/or qualify another verb by expressing one or more of an ability, capability, or possibility associated with the qualified verb. Accordingly, usage of “may” and “may be” indicates that a modified term is apparently appropriate, capable, or suitable for an indicated capacity, function, or usage, while taking into account that in some circumstances the modified term may sometimes not be appropriate, capable, or suitable. For example, in some circumstances an event or capacity can be expected, while in other circumstances the event or capacity cannot occur—this distinction is captured by the terms “may” and “may be.” 
         [0051]    This written description uses examples to disclose the invention, including the best mode, and also to enable one of ordinary skill in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differentiate from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.