Abstract:
The present teachings provide for a catalytic converter for modifying the composition of exhaust gas of an engine. The catalytic converter includes a housing, a substrate body, and a first layer of catalyst material. The housing can define an inlet for receiving the exhaust gas from the engine, a main chamber in fluid communication with the inlet, and an outlet in fluid communication with the main chamber for exhausting the modified exhaust gas. The substrate body can be disposed within the central chamber and can define a plurality of flow channels. The flow channels can provide fluid communication between the inlet and the outlet. The first layer of catalyst material can provide a first section of the flow channels with a first overall wall thickness that is greater than a second overall wall thickness of a second section of the flow channels.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application is a continuation-in-part of U.S. patent application No. 13/542,796 filed on Jul. 6, 2012, the entire disclosure of which is incorporated herein by reference. 
     
    
     FIELD 
       [0002]    The present disclosure relates to catalytic converter substrates. 
       BACKGROUND 
       [0003]    This section provides background information related to the present disclosure which is not necessarily prior art. 
         [0004]    An internal combustion engine “ICE” (e.g. gasoline or diesel) typically includes a catalytic converter that includes a catalytic substrate having a plurality of small, parallel channels through which exhaust gases can flow. Catalytic substrates can reduce undesirable exhaust emissions (e.g. carbon monoxide “CO”, unburned hydrocarbons “HC”, nitrogen oxides “NOx”) by catalyzing chemical reactions to create more desirable emissions (e.g. carbon dioxide “CO2”, water “H2O”, nitrogen gas “N2”). Catalytic substrates are typically a ceramic (e.g. cordierite) block that is extruded to form the plurality channels through which the exhaust gases flow. The internal walls of the channels are typically coated with a catalyst material that catalyzes the chemical reactions necessary to achieve the more desirable emissions when the exhaust gases contact the catalyst material. 
         [0005]    The exhaust gases can flow through the catalytic substrate such that different channels can receive unequal contact with the exhaust gases. Additionally, flow paths through a particular channel can result in unequal contact of the exhaust gases with the various coated walls of that particular channel. This unequal contact with the exhaust gases can result in inefficient use of the catalyst material. 
       SUMMARY 
       [0006]    This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features. The present teachings provide for a catalytic converter for modifying the composition of exhaust gas of an engine. The present teachings further provide for a method of manufacturing a substrate body of a catalytic converter. Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. 
     
    
     
       DRAWINGS 
         [0007]    The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure. 
           [0008]      FIG. 1  is a schematic illustration of an engine and an exhaust system having a catalytic converter in accordance with the present teachings; 
           [0009]      FIG. 2  is a sectional view of a catalytic converter constructed in accordance with the present teachings; 
           [0010]      FIG. 3  is a perspective view of a catalytic substrate of the catalytic converter of  FIG. 2 , illustrating a flow channel path of a first construction; 
           [0011]      FIG. 4  is a perspective view similar to  FIG. 3 , illustrating a flow channel path of a second construction; 
           [0012]      FIG. 5  is a sectional view illustrating a flow channel cross-sectional shape and catalyst coating of a first construction; 
           [0013]      FIG. 6  is a sectional view similar to  FIG. 5 , illustrating a flow channel cross-sectional shape and catalyst coating of a second construction; 
           [0014]      FIG. 7  is a sectional view similar to  FIG. 5 , illustrating a flow channel cross-sectional shape and catalyst coating of a third construction; 
           [0015]      FIG. 8  is a perspective view of a portion of a catalytic substrate similar to the catalytic substrate of  FIGS. 2 and 3 , illustrating a portion of a three-dimensional printer; and 
           [0016]      FIG. 9  is a sectional view of a portion of a catalytic substrate similar to the catalytic substrate of  FIGS. 3 and 8 , illustrating an interface between a catalytic material and a substrate material. 
       
    
    
       [0017]    Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings. 
       DETAILED DESCRIPTION 
       [0018]    Example embodiments will now be described more fully with reference to the accompanying drawings. 
         [0019]    The present teachings are directed to a catalytic converter and a method of manufacturing a catalytic converter. A substrate of the catalytic converter defines a plurality of channels through which exhaust gas can flow. The channels are lined with a catalyst material. The thickness of the catalyst lining varies with location in the channels. The substrate and the catalyst lining can be three-dimensionally printed together such that the channels can follow a generally curved path through the substrate and such that the catalyst lining can be thicker in any desirable location within the substrate. 
         [0020]    With reference to  FIG. 1 , an example of an engine assembly  10  including a powertrain  12  and an exhaust system  14 . The powertrain  12  and exhaust system  14  of the present teachings can be used in any suitable device, such as a motor vehicle, stationary machinery, or a generator for example. The powertrain  12  includes an internal combustion engine  16  and a drivetrain  18  that are configured to generate and output rotational power. 
         [0021]    The internal combustion engine  16  can include an air intake system  22  and the exhaust system  14 . The exhaust system  14  can include a catalytic converter  24 , an exhaust manifold  26 , and a tail pipe  28 . The catalytic converter  24  can be configured to treat exhaust gases of the engine  16 . More specifically, the catalytic converter  24  can be configured to reduce the amount of undesirable exhaust emissions (e.g. carbon monoxide “CO”, unburned hydrocarbons “HC”, nitrogen oxides “NOx”) in the exhaust gases by catalyzing chemical reactions of the combustion products to create more desirable emissions (e.g. carbon dioxide “CO2”, water “H2O”, nitrogen gas “N2”). The catalytic converter  24  can be fluidly coupled to the exhaust manifold  26  to receive exhaust gases from the exhaust manifold  26  and can be fluidly coupled to the tail pipe  28  to discharge the treated gases. 
         [0022]    With additional reference to  FIG. 2 , a first exemplary construction of the catalytic converter  24  is illustrated in greater detail. The catalytic converter  24  can include an elongated housing  50  that can be fabricated from any type of material suitable for use with hot exhaust gases. The housing  50  can include multiple sections which may be fixed (i.e., welded or riveted) together. The housing  50  can include a shell  52 , an inlet end cone  54  and an outlet end cone  56 . In the example shown, the shell  52  is generally cylindrical in shape and has a generally circular cross-section, though the shell  52  can have other cross-sectional shapes (e.g. generally rectangular, square or oval). 
         [0023]    Shell  52  can define an internal central chamber  58 . The inlet and outlet end cones  54  and  56  can be generally conical in shape and can have a generally circular cross-section of varying diameters, though the end cones  54  and  56  can have other cross-sectional shapes. Each of the end cones  54  and  56  can taper from a first larger edge perimeter  60  to a second smaller edge perimeter  62 . A portion of each end cone  54 ,  56  adjacent to the first larger edge perimeter  60  can be rigidly attached to a peripheral edge of the elongated shell  52  in a suitable manner (e.g. welding). The second smaller edge perimeter  62  of the inlet end cone  54  can be coupled to a portion of the exhaust system  14  ( FIG. 1 ) to fluidly couple the inlet end cone  54  to the exhaust manifold  26  ( FIG. 1 ). The second smaller edge perimeter  62  of the outlet end cone  56  can be coupled to a portion of the exhaust system  14  ( FIG. 1 ) to fluidly couple the outlet end cone  54  to the tail pipe  28  ( FIG. 1 ). Thus exhaust gases can enter the housing  50  at the second smaller edge perimeter  62  of the inlet end cone  54  and exit the housing  50  at the second smaller edge perimeter  62  of the outlet end cone  56 . 
         [0024]    A catalyst-coated substrate  70  can be located within the internal chamber  58  of the elongated housing  50 . The catalytic substrate  70  can be formed from a ceramic material (e.g. cordierite) impregnated or loaded with a catalyst material as described in greater detail below. The catalyst material can perform the catalytic function in any suitable manner when exhaust gases contact the catalyst material while passing through the catalytic substrate  70 . In the example provided, the catalytic substrate  70  is generally cylindrical in shape and has a generally circular cross-section, though the catalytic substrate  70  can have other cross-sectional shapes (e.g. generally rectangular, square, or oval). In the example provided, the catalytic substrate  70  and the housing  50  share a common central axis  76 , though other configurations can be used. 
         [0025]    With additional reference to  FIG. 3 , the catalytic substrate  70  is illustrated in greater detail. The catalytic substrate  70  can include a body section  96  disposed within the internal chamber  58  ( FIG. 2 ). The body section  96  can be cylindrical and can have a generally circular cross-section, though other configurations can be used. The body section  96  can include a planar inlet face  98  and a planar outlet face  100 . 
         [0026]    The body section  96  can define a plurality of flow channels  102  that are formed in the catalytic substrate  70  and extend between the inlet face  98  and the outlet face  100 . The untreated exhaust gases, received from the engine  16  ( FIG. 1 ) through the inlet end cone  54  ( FIG. 2 ), can initially contact the inlet face  98  and be directed into an inlet  104  of each of the flow channels  102 . As the exhaust gas flows through the flow channels  102 , it can contact the catalyst-treated side-walls of the flow channels  102  before being discharged through an outlet  106  of each of the flow channels  102  to exit the housing through the outlet end cone  56  ( FIG. 2 ). The treated gases can be discharged through the outlet end cone  56  ( FIG. 2 ) to the tail pipe  30  ( FIG. 1 ). 
         [0027]    In the example provided, the flow channels  102  can be formed to be non-linear between their respective inlets  104  and outlets  106 . In particular, the term “skewed” will hereafter be used to describe and define the non-linear properties of the flow channels  102  and is intended to encompass configurations of the flow channels  102  that are rotated, indexed, clocked, twisted, slanted, obliquely-aligned and/or angulated, either partially or completely, along their length and which have a central flow axis that is not parallel to and/or concentric with the central axis  76  of the catalytic converter  24 . The skewed flow channels  102  can generate stronger turbulence and a more controlled exhaust flow by spinning the exhaust gases. 
         [0028]    In the example provided, at least one flow channel  102  follows a skewed path between its corresponding inlet  104  and outlet  106 . While  FIG. 3  illustrates the path of a single one of the flow channels  102 , it is understood that a plurality of the inlets  104  are associated with the inlet face  98  and communicate with a plurality of outlets  106  associated with the outlet face  100  via a series of flow channels. While not specifically shown, those skilled in the art will appreciate that these additional flow channels can also be skewed and may, for example, be similarly configured to the single exemplary flow channel  102  shown. It is also understood that these additional flow channels  102  can alternatively follow dissimilar paths between their respective inlets  104  and outlets  106 . 
         [0029]    In the example provided, the flow channel  102  follows a generally curved (e.g. arcuate or helical) path about the central axis  76  of the catalytic substrate  70 , though other configurations can be used.  FIG. 3  illustrates the walls  110 , and more specifically an outer wall  114   a,    114   b,    114   c,    114   d,  of the flow channel  102  at four locations between its inlet  104  and outlet  106 . The first location (e.g. at inlet face  98 ) is indicated by reference numeral  102   a.  The second location is indicated by reference numeral  102   b.  The third location is indicated by reference numeral  102   c.  The fourth location (e.g. at outlet face  100 ) is indicated by reference numeral  102   d.  The outer wall  114   a,    114   b,    114   c,    114   d  can remain radially outward of the other walls of the flow channel  102  as the flow channel  102  rotates or curves about the axis  76 . While the flow channel  102  is illustrated as having a generally rectangular cross-section, it is understood that other shapes can be used (e.g. polygonal, circular, ovoid). 
         [0030]      FIG. 3  also includes a clock face to clearly illustrate the indexing or rotation of the flow channel  102  between the inlet face  98  and the outlet face  100 . In the example provided, the flow channel  102  follows along a continuous arcuate or helical path to define a rotational clocking of 90° between the inlet  104  and the outlet  106 , though other rotational clocking magnitudes can be used. In an alternative construction, not specifically shown, the flow channel  102  can be rotationally indexed through different angular ranges along different longitudinal segments of the catalytic substrate  70  to provide distinct arcuate segments which can facilitate greater turbulence in a particular location along the catalytic substrate  70 . According to another alternate construction, not specifically shown, a portion of the flow channel  102  can be linear along a longitudinal segment of the catalytic substrate  70  and can be interconnected with the rotationally indexed portions of the flow channel  102 . 
         [0031]    With additional reference to  FIG. 4 , a second example of a catalytic substrate  70 ′ is illustrated. The catalytic substrate  70 ′ can be similar to the catalytic substrate  70  ( FIGS. 2 and 3 ), except as otherwise shown or described herein. Accordingly similar reference numerals denote similar elements as those described above with reference to the catalytic substrate  70  ( FIGS. 2 and 3 ). In the example shown in  FIG. 4 , at least one of the flow channels  102 ′ can follow a curved (e.g. arcuate or helical) path about an axis  410  that is not coaxial with the central axis  76 ′ of the catalytic substrate  70 ′. In the example provided, the axis  410  is parallel to and offset from the central axis  76 ′, though other configurations can be used. In an alternative construction, not specifically shown, at least one of the flow channels  102 ′ can follow an irregularly curved path, such as a path that does not curve continuously at a constant radius about a single axis for example. 
         [0032]    With additional reference to  FIG. 5 , a cross-sectional view of one of the flow channels  102  is illustrated. The walls  110  can include an outer wall  114  (e.g.  114   a,    114   b,    114   c,  or  114   d ), an inner wall  118 , and a pair of side walls  122 . A first layer  130  of catalyst material can be affixed to the outer wall  114  to line the flow channel  102  along the outer wall  114 . A second layer  134  of catalyst material can be affixed to the inner wall  118  to line the flow channel  102  along the inner wall  118 . A third layer  138  of catalyst material can be affixed to one side wall  122 , and a fourth layer  142  of catalyst material can be affixed to the other side wall  122  to line the flow channel  102  along the side walls  122 . The catalyst material can be any suitable material configured to catalyze reactions between the combustion products in the untreated exhaust gases to produce more desirable emissions. 
         [0033]    In the example provided, the first layer  130  can be thicker than the second layer  134 , and the thickness of the third and fourth layers  138 ,  142  can transition from the thickness of the first layer  130  to the thickness of the second layer  134 . In operation, as exhaust gases flow through the curved path of the flow channel  102 , centrifugal force results in more exhaust gas contacting the outer wall  114  than the inner wall  118 . Thus, the first layer  130  is thicker and can have more catalyst material to contact the greater amount of exhaust gas located proximate to the outer wall  114 . The thicknesses of the first, second, third, and fourth layers  130 ,  134 ,  138 ,  142  can also optionally vary with axial position along the length of the flow channel  102 . 
         [0034]    With additional reference to  FIG. 6 , a cross-sectional view of a flow channel  602  of a second construction is illustrated. The flow channel  602  can be similar to the flow channels  102  ( FIG. 3 ) except as otherwise shown or described herein. In the example provided, the flow channel  602  can be defined by a wall  610  that has a generally circular shaped cross-section, though other configurations can be used (e.g. ovoid). The wall  610  can be similar to the walls  110  ( FIG. 3 ) except as otherwise shown or described herein. The wall  610  can have an outer wall portion  614 , an inner wall portion  618 , and a pair of side wall portions  622 . In the example provided, these wall portions  614 ,  618 ,  622  are generally quadrants of the flow channel  602 , though other configurations can be used. 
         [0035]    A first layer  630  of catalyst material can be affixed to the outer wall portion  614  to line the flow channel  602  along the outer wall portion  614 . A second layer  634  of catalyst material can be affixed to the inner wall portion  618  to line the flow channel  602  along the inner wall portion  618 . A third layer  638  of catalyst material can be affixed to one side wall portion  622 , and a fourth layer  642  of catalyst material can be affixed to the other side wall portion  622  to line the flow channel  602  along the side wall portions  622 . 
         [0036]    In the example provided, the first layer  630  can be thicker than the second layer  634 , and the thickness of the third and fourth layers  638 ,  642  can transition from the thickness of the first layer  630  to the thickness of the second layer  634 . The thicknesses of the first, second, third, and fourth layers  630 ,  634 ,  638 ,  642  can also optionally vary with axial position along the length of the flow channel  602 . 
         [0037]    With additional reference to  FIG. 7 , a cross-sectional view of a flow channel  702  of a third construction is illustrated. The flow channel  702  can be similar to the flow channels  102  ( FIG. 3 ) except as otherwise shown or described herein. The flow channel  702  can be defined by walls  710  that can define a generally polygonal shaped cross-section (e.g. triangular, rectangular, pentagonal, etc.). In the example provided, the walls  710  define a generally hexagonal cross-section, though other configurations can be used. The walls  710  can be similar to the walls  110  ( FIG. 3 ) except as otherwise shown or described herein. The walls  710  can have an outer wall  714 , an inner wall  718 , a pair of first side walls  722 , and a pair of second side walls  724 . 
         [0038]    A first layer  730  of catalyst material can be affixed to the outer wall  714  to line the flow channel  702  along the outer wall  714 . A second layer  734  of catalyst material can be affixed to the inner wall  718  to line the flow channel  702  along the inner wall  718 . A third layer  738  of catalyst material can be affixed to one of the first side walls  722 , and a fourth layer  742  of catalyst material can be affixed to the other one of the first side walls  722  to line the flow channel  702  along the first side walls  722 . A fifth layer  746  of catalyst material can be affixed to one of the second side walls  724 , and a sixth layer  750  of catalyst material can be affixed to the other one of the second side walls  724  to line the flow channel  702  along the second side walls  724 . 
         [0039]    In the example provided, the first layer  730  can be thicker than the second layer  734 , and the thickness of the third, fourth, fifth, and sixth layers  738 ,  742 ,  746 ,  750  can transition from the thickness of the first layer  730  to the thickness of the second layer  734 . The thicknesses of the first, second, third, and fourth layers  730 ,  734 ,  738 ,  742 ,  746 ,  750  can also optionally vary with axial position along the length of the flow channel  702 . 
         [0040]    With additional reference to  FIG. 8 , a portion of a catalytic substrate  70 ″ is illustrated. The catalytic substrate  70 ″ can be similar to the catalytic substrates  70 , or  70 ′ ( FIG. 3  or  4 ) except as otherwise shown or described herein. In  FIG. 8 , a portion of a three-dimensional printer  810  is also illustrated. The walls  110 ″ can define the flow channels  102 ″ of the catalytic substrate  70 ″ similar to the flow channels  102 ,  102 ′ ( FIGS. 2-5 ), the flow channels  602  ( FIG. 6 ), or the flow channels  702  ( FIG. 7 ). The flow channels  102 ″ can be lined with layers  814  of catalyst material that can be similar to the layers  130 ,  134 ,  138 ,  142  ( FIG. 5 ), the layers  630 ,  634 ,  638 ,  642  ( FIG. 6 ), or the layers  730 ,  734 ,  738 ,  742 ,  746 ,  750  ( FIG. 7 ), respectively. 
         [0041]    The catalytic substrate  70 ″ and layers  814  can be “printed” three-dimensionally by the three-dimensional printer  810 . The three-dimensional printer  810  can selectively deposit substrate particles (e.g. cordierite particles) that make up the body section  96 ″ of the catalytic substrate  70 ″ and walls  110 ″. The three-dimensional printer  810  can deposit these substrate particles layer by layer (e.g. shown as layers  818 ). The substrate particles can be mixed with a bonding agent (e.g. an adhesive) to bond the individual substrate particles together and to preceding layers  818  in order to form each subsequent layer  818 . 
         [0042]    The three-dimensional printer  810  can selectively deposit catalytic material particles that make up the layers  814  of catalyst material. The three-dimensional printer  810  can deposit these catalytic material particles layer by layer (e.g. layers  818 ) and adjacent to the walls  110 ″ on the interior of the flow channels  102 ″ to form the layers  814  of catalyst material. The three-dimensional printer  810  can deposit the catalytic material particles such that the layers  814  of catalyst material can have any suitable thicknesses along the walls  110 ″, such as those shown in  FIGS. 5-7  for example. 
         [0043]    With additional reference to  FIG. 9  as well as  FIG. 8 , an example of an interface between one of the layers  814  of catalyst material and one of the walls  110 ″ is illustrated. The wall  110 ″ can be printed by the three-dimensional printer  810  to have a key slot  910  and the layer  814  can be printed to have a key  914  disposed within the key slot  910 . In the example provided, the key slot  910  can have a narrow opening  918  at an inner surface  922  of the wall  110 ″ that opens into the flow channel  102 ″. The key slot  910  can widen from the narrow opening  918  to a back face  926  of the key slot  910 , though other configurations can be used. The key  914  can be printed to have a complementary shape to fill the key slot  910  and extend out of the narrow opening  918 . The key  914  can be printed to be coupled with the portion of the layer  814  of the catalyst material that lines the inner surface  922  of the wall  110 ″. In this way, the layer  814  of catalyst material can be securely coupled to the wall  110 ″. 
         [0044]    The three-dimensional printer can manufacture the catalytic substrate  70 ″ by way of a method that includes first depositing a first one of the layers  818  of the catalytic substrate  70 ″, then depositing a second one of the layers  818 , followed by depositing sequential ones of the layers  818  until the entire catalytic substrate  70 ″ is formed (e.g. from the planar inlet face  98 ″ to the planar outlet face  100 ″). The step of depositing the first layer of the catalytic substrate  70 ″ can include depositing a first layer of substrate particles and a first layer of catalytic material particles in predetermined discrete locations (e.g. corresponding to walls  110 ″ and layers  814 ). 
         [0045]    The step of depositing the second layer of the catalytic substrate  70 ″ can include depositing a second layer of substrate particles and a second layer of catalytic material particles in predetermined discrete locations (e.g. corresponding to walls  110 ″ and layers  814 ). Then subsequent layers of the catalytic substrate  70 ″ can be deposited similar to the first and second layers  818 . The layers  818  of substrate particles can cooperate to define the walls  110 ″ and flow channels  102 ″. The layers  818  of the catalytic material particles can cooperate to define the layers  814  of catalytic material. 
         [0046]    While the three-dimensional printer  810  is illustrated as printing the layers  818  sequentially along the flow axis  76 ″ (i.e. printing the layers  818  sequentially from the planar inlet face  98 ″ to the planar outlet face  100 ″), it is understood that the three-dimensional printer  810  could print layers  818  sequentially in other orientations. For example, the layers  818  could be printed sequentially transverse to the flow axis  76 ″ such that each layer  818  spans from the planar inlet face  98 ″ to the planar outlet face  100 ″. 
         [0047]    The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure. 
         [0048]    Example embodiments are provided so that this disclosure will be thorough, and will fully convey the scope to those who are skilled in the art. Numerous specific details are set forth such as examples of specific components, devices, and methods, to provide a thorough understanding of embodiments of the present disclosure. It will be apparent to those skilled in the art that specific details need not be employed, that example embodiments may be embodied in many different forms and that neither should be construed to limit the scope of the disclosure. In some example embodiments, well-known processes, well-known device structures, and well-known technologies are not described in detail. 
         [0049]    The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting. As used herein, the singular forms “a,” “an,” and “the” may be intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms “comprises,” “comprising,” “including,” and “having,” are inclusive and therefore specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. The method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order discussed or illustrated, unless specifically identified as an order of performance. It is also to be understood that additional or alternative steps may be employed. 
         [0050]    When an element or layer is referred to as being “on,” “engaged to,” “connected to,” or “coupled to” another element or layer, it may be directly on, engaged, connected or coupled to the other element or layer, or intervening elements or layers may be present. In contrast, when an element is referred to as being “directly on,” “directly engaged to,” “directly connected to,” or “directly coupled to” another element or layer, there may be no intervening elements or layers present. Other words used to describe the relationship between elements should be interpreted in a like fashion (e.g., “between” versus “directly between,” “adjacent” versus “directly adjacent,” etc.). As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. 
         [0051]    Although the terms first, second, third, etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms may be only used to distinguish one element, component, region, layer or section from another region, layer or section. Terms such as “first,” “second,” and other numerical terms when used herein do not imply a sequence or order unless clearly indicated by the context. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the example embodiments. 
         [0052]    Spatially relative terms, such as “inner,” “outer,” “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. Spatially relative terms may be 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 device in the figures is turned over, elements described as “below” or “beneath” other elements or features would then be oriented “above” the other elements or features. Thus, the example term “below” can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.