Patent Publication Number: US-2023145706-A1

Title: Bearing Carrier

Description:
TECHNICAL FIELD 
     The present disclosure relates generally to turbochargers and, more particularly, to turbochargers with turbocharger housings configured for efficient assembly and effective bearing of thrust loads and other loading. 
     BACKGROUND 
     Internal combustion engines, for example, diesel engines, gasoline engines, or natural gas engines, employ turbochargers to deliver compressed air for combustion in the engine. A turbocharger compresses air flowing into the engine, helping to force more air into combustion chambers of the engine. The increased supply of air allows for increased fuel combustion in the combustion chambers of the engine, resulting in increased power output from the engine. 
     A typical turbocharger includes a shaft, a turbine wheel connected to one end of the shaft, a compressor impeller (sometimes referred to as a compressor wheel) connected to the other end of the shaft, and bearings to support the shaft. Separate housings connected to each other enclose the compressor impeller, the turbine wheel and the bearings. Exhaust from the engine expands over the turbine wheel and rotates the turbine wheel. The turbine wheel in turn rotates the compressor impeller via the shaft. The compressor impeller receives cool air from the ambient surroundings and forces compressed air into combustion chambers of the engine. 
     Turbocharger bearing systems for the turbocharger shaft, the compressor wheel and the compressor impeller require accurate alignment within surrounding housing components. In previously-known turbochargers, such as that disclosure in U.S. Pat. No. 9,279,343 to Knaack that issued on Mar. 8, 2016 (“the &#39;343 patent”), separate housing and sub-housings are incorporated into turbocharger housings along turbine housing and compressor housings to support the bearings. Adding additional sub-housings to support the bearings creates the potential for added errors in alignment, but can improve the ability to remanufacture the turbocharger. Typically, a bearing carrier or sub-housing used to support the compressor side assemblage requires installation from the compressor side of the primary turbocharger housing. Operating temperatures remain lower than the equivalent turbine side housings, although oftentimes oil supply restrictions in particular require a rather large bearing carrier that remains difficult to machine and integrate into the primary housing. 
     SUMMARY OF THE DISCLOSURE 
     In one aspect of the present disclosure, a bearing carrier for a turbocharger installed within a turbocharger housing between a turbine wheel and a compressor impeller mounted for rotation together on a turbocharger shaft is disclosed. The bearing carrier may include a carrier body, a carrier body bore extending axially through the carrier body and receiving a journal bearing and a corresponding portion of the turbocharger shaft, and a thrust bearing seat on the exterior of the carrier body facing the turbine wheel. The thrust bearing seat may have a complimentary shape to a thrust bearing surface of a thrust bearing disposed between the carrier body and the turbine wheel and engaging the thrust bearing seat. 
     In another aspect of the present disclosure, a bearing assembly for a turbocharger installed within a turbocharger housing between a turbine wheel and a compressor impeller mounted for rotation together on a turbocharger shaft is disclosed. The bearing assembly may include a journal bearing disposed on a corresponding portion of the turbocharger shaft, a thrust bearing having a thrust bearing surface, and a bearing carrier. The bearing carrier may include a carrier body, a carrier body bore extending axially through the carrier body and receiving the journal bearing therein, and a thrust bearing seat on the exterior of the carrier body facing the turbine wheel. The thrust bearing seat may have a complimentary shape to the thrust bearing surface of the thrust bearing, the thrust bearing disposed between the carrier body and the turbine wheel and engaging the thrust bearing seat. 
     In a further aspect of the present disclosure, a turbocharger housing for a turbocharger that includes a turbine wheel and a compressor impeller mounted on a turbocharger shaft for rotation together is disclosed. The turbocharger housing may include a compressor bearing housing with a bearing mounting flange disposed between the turbine wheel and the compressor impeller, and a bearing carrier mounted on the bearing mounting flange. The bearing carrier may include a carrier body, a carrier body bore extending axially through the carrier body and receiving a journal bearing and a corresponding portion of the turbocharger shaft, and a thrust bearing seat on the exterior of the carrier body facing the turbine wheel. The thrust bearing seat may have a complimentary shape to a thrust bearing surface of a thrust bearing disposed between the carrier body and the turbine wheel and engaging the thrust bearing seat, wherein the bearing carrier engages the bearing mounting flange to transmit thrust loads on the turbine wheel in a direction of the compressor impeller to the compressor bearing housing. 
     Additional aspects are defined by the claims of this patent. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a schematic illustration of an exemplary internal combustion engine and a turbocharger in accordance with the present disclosure; 
         FIG.  2    is a perspective view of an exemplary configuration of the turbocharger of  FIG.  1   ; 
         FIG.  3    is a cross-sectional view of an exemplary configuration of the turbocharger of  FIG.  2   ; and 
         FIG.  4    is an enlarged cross-sectional view of a bearing assembly in accordance with the present disclosure and adjacent components of a turbocharger shaft of the turbocharger of  FIG.  2   . 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIG.  1   , an internal combustion engine  10  having an integrated turbocharger  12  in accordance with the present disclosure is illustrated schematically. The engine  10  may find applications in mobile machines (not shown) such as, but not limited to, vehicles, heavy mechanical equipment, large tractors, on-road vehicles, off-road vehicles, marine vessels and the like, and in stationary machines such as generator sets and pumps. The engine  10  may include a crankcase  14  that forms a plurality of compression cylinders  16 . While six compression cylinders  16  are shown in an inline arrangement for illustration purposes, fewer or more compression cylinders  16  arranged in inline or alternative configurations within the crankcase  14 , for example in a V-configuration, may be used. Each compression cylinder  16  may include a reciprocating piston (not shown) connected to a common engine output shaft  18 . In the engine  10 , the combustion of a fuel and air mixture in the compression cylinders  16  generates motive power that rotates the engine output shaft  18 , and a resultant mixture of exhaust gas is produced as is known in the art. 
     The engine  10  may include an air intake manifold  20  that is selectively in fluid communication with each compression cylinder  16  and provides compressed intake air to the compression cylinders  16 . Air may be provided to air intake manifold  20  by an air induction system  22  that draws air from the ambient atmosphere surrounding the engine  10  and the machine in which the engine  10  is implemented. The engine  10  may include a fuel tank (not shown) to store suitable fuel for combustion in the compression cylinders  16  of the engine  10 . In various embodiments, the engine  10  may be configured to combust gasoline, diesel fuel, natural gas (liquefied or compressed) or other combustible energy sources, and the fuel tank will be configured as appropriate to store the fuel and provide the fuel to the engine  10  as required and known in the art. Compressed air from the air intake manifold  20  along with the fuel from the fuel tank provided to the compression cylinders  16  forms a combustible mixture that ignites when compressed or in the presence of a spark. Combustion byproducts are evacuated from each compression cylinder  16  through exhaust valves (not shown) to an exhaust manifold  24  that collects the exhaust gas from each compression cylinder  16 , and at least a portion of the exhaust gases may be transmitted to an exhaust system  26  for after treatment prior to being released back into the atmosphere. In the engine  10 , the intake air in the air intake manifold  20  as well as the exhaust gas released to the exhaust manifold  24  are under pressure. 
     In the illustrated embodiment, the turbocharger  12  is integrated with the engine  10  to provide compressed air with greater pressure to the air intake manifold  20 . As schematically illustrated in  FIG.  1   , the turbocharger  12  may be fluidly connected to the exhaust manifold  24  and arranged to receive pressurized exhaust gas therefrom via a high pressure exhaust gas line  28 . A turbocharger housing  30  of the turbocharger  12  is configured so that the pressurized exhaust gas from the high pressure exhaust gas line  28  acts on a turbine wheel  32  mounted on a turbocharger shaft  34  within the turbocharger housing  30 . The turbocharger  12  may further include a compressor impeller  36  mounted via a compressor stud  35  ( FIG.  3   ) that is coupled to the turbocharger shaft  34  for rotation with the turbocharger shaft  34  and the turbine wheel  32 . The pressurized exhaust gas from the high pressure exhaust gas line  28  is directed at the turbine wheel  32  to create exhaust torque on the turbocharger shaft  34 . When the exhaust gas temperature and pressure are sufficient, the exhaust torque causes the turbine wheel  32  to rotate the turbocharger shaft  34 , the compressor stud  35  and the compressor impeller  36 . A compressor stage  62  ( FIGS.  2  and  3   ) of the turbocharger  12  in which the compressor impeller  36  is disposed may receive air from the air induction system  22  via a low pressure air line  38 . The rotating compressor impeller  36  compresses the air from the air induction system  22  and outputs compressed air to the air intake manifold  20  via a high pressure air line  40  for addition to the air coming directly from the air induction system  22  and the fuel from the fuel tank. After powering the turbine wheel  32 , the spent exhaust gas is discharged to the exhaust system  26  via a low pressure exhaust gas return line  42 . 
     During some operating conditions of the engine  10 , it may be desirable to drive the turbine wheel  32  of the turbocharger  12  even though the temperature and pressure of the exhaust gas in the high pressure exhaust gas line  28  are insufficient to rotate the turbine wheel  32  or to rotate the turbine wheel  32  at a desired speed. For example, at low engine speeds such as when the engine  10  is idling, emissions of pollutants such as nitrous oxides (NOx) can increase and low exhaust temperatures can make exhaust after treatment systems in the exhaust system  26  ineffective. In one exemplary embodiment, to selectively provide direct drive to the turbocharger  12  by the engine  10  when the operating conditions dictate, the engine output shaft  18  may drive the turbocharger shaft  34  when the exhaust gas will not drive the turbine wheel  32 , and may be disengaged when the exhaust gas will create sufficient torque and rotate the turbine wheel  32  and the compressor impeller  36  at sufficient speeds so that direct drive by the engine  10  is unnecessary. 
     In an embodiment, a carrier shaft  52  may be operatively coupled to the turbine wheel  32  and may have a carrier drive gear  54  mounted thereon and rotatable therewith. An operative connection between the engine  10  and the carrier drive shaft may be provided by a turbocharger drive gear  56  connected to a gear train or transmission  58  that is driven by the engine output shaft  18 . The turbocharger drive gear  56  is operatively connected to the carrier drive gear  54  by one or more idler gears  60  so that the carrier shaft  52  will spin at a desired speed and direction relative to the engine output shaft  18 . In other embodiments that utilize a compressor housing  66  ( FIGS.  2  and  3   ) disclosed herein, other appropriate drive mechanisms and arrangements may be utilized to drive the turbine wheel  32  and compressor impeller  36 . 
       FIGS.  2  and  3    illustrate an exemplary embodiment of a turbocharger  12  in accordance with the present disclosure that may be implemented with the engine  10  of  FIG.  1   . As shown in  FIG.  3   , the turbocharger  12  may include the compressor stage  62  and a turbine stage  64  disposed in the turbocharger housing  30  ( FIGS.  2  and  3   ). The turbocharger housing  30  comprises the compressor housing  66  and a turbine housing  72 . The compressor stage  62  may embody a fixed geometry compressor impeller  36  ( FIG.  3   ) attached via the compressor stud  35 , which is coupled to the turbocharger shaft  34 , and configured to compress air received from the air induction system  22  ( FIG.  1   ) before the air enters the engine  10  for combustion. Air may enter the compressor housing  66  via a compressor inlet  68  ( FIG.  2   ) and exit the compressor housing  66  via a compressor outlet  70 . As air moves through the compressor stage  62 , the compressor impeller  36  may increase the pressure of the air that is directed into the engine  10 . 
     Referring to  FIG.  3   , the turbine stage  64  may include a turbine housing  72  and the turbine wheel  32  that may be operably connected to the turbocharger shaft  34  (which may comprise one or more shafts operably coupled). Exhaust gases exiting the engine  10  may enter a turbine scroll  73  via a turbine inlet  74  and flow toward a turbine exhaust duct  76 . The exhaust gases exit the turbine housing  72  via the turbine exhaust duct  76 . As the hot exhaust gases move through the turbine housing  72  and expand against the blades  80  of the turbine wheel  32 , the turbine wheel  32  may rotate the compressor impeller  36  via the operable connection of the turbocharger shaft  34  and the compressor stud  35 . The hot exhaust gases may also heat the turbine housing  72 , which in turn may heat the compressor housing  66  and other components of the turbocharger  12  attached to or located near the turbine housing  72 . As the compressor impeller  36  is rotated by the turbine wheel  32 , air may be drawn axially inward through the compressor inlet  68  toward a center of the compressor impeller  36 . Compressor blades  82  of the compressor impeller  36  may then push the air radially outward in a spiraling fashion into the compressor outlet  70  and to the air intake manifold  20 . 
     The compressor stage  62  as illustrated is formed by a series of components including the compressor housing  66  that encloses the compressor impeller  36  and defines the airflow channels fluidly connecting the compressor inlet  68  to the compressor outlet  70 . The compressor housing  66  may include, among other elements, an outer volute  90 , an inner volute  92 , an impeller cover  94 , a compressor diffuser  96 , an insert  98  and a compressor cover  100 . The outer volute  90  in the illustrated embodiment includes a back wall  102  that separates the compressor housing  66  from a compressor bearing housing  120 , and has the turbocharger shaft  34  extending therethrough. A curved airflow passageway wall  104  may extend generally radially outward from the back wall  102  and wrap around to form a radially outer portion of an airflow passageway  106  that is fluidly connected to the compressor outlet  70 . The outer volute  90  may further include an annular outer volute flange  108  with an outer volute inner surface  110  that receives the inner volute  92 , the impeller cover  94 , the compressor diffuser  96 , and the insert  98  therethrough. The inner volute  92  may include a curved bridge wall  112  that combines with an outer end wall  114  of the impeller cover  94  to form a radially inner portion of the airflow passageway  106 . The compressor diffuser  96  may be positioned adjacent to and abut the back wall  102  of the outer volute  90 , and the outer end wall  114  of the impeller cover  94  may be disposed between the compressor diffuser  96  and the curved bridge wall  112  of the inner volute  92 . The impeller cover  94  and the insert  98  may define a compressor cavity  116  around the compressor impeller  36  such that the compressor cavity  116 , the compressor diffuser  96  and the airflow passageway  106  define a continuous fluid passage connecting the compressor inlet  68  to the compressor outlet  70 . 
     The turbine housing  72  may be configured for efficient assembly and effective bearing of loads on the turbocharger shaft  34  and the compressor stud  35  that are created by the turbine wheel  32  and the compressor impeller  36 . The turbine housing  72  may include the compressor bearing housing  120  mounted to the main turbocharger housing  30  on the turbine side of the back wall  102  of the outer volute  90 . The compressor bearing housing  120  may be disposed between the turbine wheel  32  and the compressor impeller  36 , and surround and support the corresponding portion of the turbocharger shaft  34  after the turbocharger  12  is assembled. The compressor bearing housing  120  may include a turbine seal mounting flange  122  extending toward and terminating proximate the turbine wheel  32 , and a bearing mounting flange  124  extending toward the turbine wheel  32  and terminating at a location between the compressor impeller  36  and the turbine seal mounting flange  122 . A turbine seal  126  is mounted to the turbine seal mounting flange  122 , and a bearing assembly  128  is mounted to the bearing mounting flange  124 . The portion of the turbocharger shaft  34  between the turbine wheel  32  and the compressor impeller  36  passes through the turbine seal  126 , the bearing assembly  128  and a compressor seal  130  that is mounted to the back wall  102  of the outer volute  90 . 
     The area between the turbine wheel  32  and the compressor impeller  36  is shown in greater detail in the enlarged cross-section of  FIG.  4   . In the illustrated embodiment, the turbocharger shaft  34  is assembled from multiple components to facilitate assembly of the turbocharger  12  and effective operation of the turbocharger  12  after assembly. The turbocharger shaft  34  extends toward the compressor impeller  36 , and includes a bore that receives an end of the compressor stud  35 . A shaft insert  144  surrounds the interface between the turbocharger shaft  34  and the compressor stud  35 , and an impeller collar  146  encircles portions of the turbocharger shaft  34 , the compressor stud  35  and the shaft insert  144 , and the components are secured together so that the turbine wheel  32  and the compressor impeller  36  rotate together. The illustrated composition and arrangement of the components is exemplary, and alternative constructions that interact with the bearing assembly  128  as described hereinafter are contemplated by the inventor. 
     The bearing assembly  128  is configured to support the turbocharger shaft  34  and acts as an intermediary to transfer loads from the turbine wheel  32 , the turbocharger shaft  34  and the compressor impeller  36  to the turbine housing  72  via the compressor bearing housing  120 . The bearing assembly  128  is disposed around the turbocharger shaft  34  between the turbine wheel  32  and the compressor impeller  36 . In particular, in the illustrated embodiment, the bearing assembly  128  is disposed on the impeller collar  146 . The bearing assembly  128  includes a bearing carrier  150  configured to support a journal bearing  152 , a thrust bearing  154  and one or more anti-thrust bearings  156 . The bearing carrier  150  has a carrier body  158  with an annular shape and a carrier body bore  160  dimensioned to receive the journal bearing  152  therein. A floating anti-rotation pin  162  may be inserted in a radial anti-rotation pin bore and into engagement with the journal bearing  152  to prevent axial translation and circumferential rotation of the journal bearing  152  relative to the bearing carrier  150 . The journal bearing  152  is dimensioned to receive the impeller collar  146  during assembly for support of the turbocharger shaft  34 . 
     A thrust bearing seat  164  of the bearing carrier  150  is oriented facing the turbine wheel  32  when installed as shown. The thrust bearing  154  has a thrust bearing surface  166  with a complimentary shape to the thrust bearing seat  164  to substantially limit radial movement of the thrust bearing  154  relative to the bearing carrier  150 . The thrust bearing  154  is positioned against the thrust bearing seat  164  by a thrust washer  168  that is disposed between the thrust bearing  154  and the turbine seal  126  and a thrust shoulder  170  of the turbocharger shaft  34 . In the illustrated embodiment, the conical or spherical thrust bearing seat  164  and thrust bearing surface  166  limit pure radial movement of the thrust bearing  154  while allowing for angular variations experienced by the rotary components. In alternative embodiments, the thrust bearing seat  164  and the thrust bearing surface  166  may have other complimentary shapes and connectivity at their interface that facilitate load transfer and constrain or control movement of the thrust bearing  154  relative to the bearing carrier  150 . For example, the thrust bearing seat  164  and the thrust bearing surface  166  may be planar and use a pilot or dual pin alignment to prevent radial movement while allowing a degree of relative angular movement. Additional complimentary shapes are contemplated by the inventor that facilitate compact designs of the bearing carrier  150  and support of the bearings  152 ,  154 ,  156  for installation from the turbine side and ensure direct load paths to the structural components of the turbocharger housing  30 . 
     On the opposite side of the bearing carrier  150  from the thrust bearing seat  164 , an anti-thrust bearing surface  172  faces the compressor impeller  36 . The anti-thrust bearing surface  172  may have one or more anti-thrust bearings  156  mounted thereto by anti-thrust mounting bolts  174  or other appropriate attachment mechanisms. A collar flange  176  extends radially outward from the impeller collar  146  and is disposed between the compressor seal  130  and the bearing carrier  150 . The collar flange  176  includes an anti-thrust shoulder  178  that faces the anti-thrust bearings  156  after installation as shown. Those skilled in the art will understand that the anti-thrust bearings  156  may be omitted in some turbocharger implementations with low anti-thrust loads. In such implementations, the anti-thrust shoulder  178  may face and engage the anti-thrust bearing surface  172  to during anti-thrust loading. 
     The bearing carrier  150  is mounted to the bearing mounting flange  124  to support the bearing carrier  150  in the axial and the radial directions. The bearing mounting flange  124  may include an axial support ring  180  having an annular shape and extending radially inward toward the turbocharger shaft  34 . The bearing carrier  150  is disposed on the turbine side of the axial support ring  180  and has an axial support surface  182  that faces and engages the axial support ring  180 . A carrier mounting bolt  184  or bolts or other appropriate attachment mechanisms threaded through the axial support ring  180  and into the bearing carrier  150  to secure the bearing carrier  150  to the axial support ring  180 . The bearing mounting flange  124  further includes a carrier housing  186  having a hollow cylindrical shape and extending axially in the direction of the turbine wheel  32 . The carrier housing  186  has a carrier housing inner surface  188  that receives the bearing carrier  150  and faces and engages a bearing carrier outer surface  190 . The carrier housing inner surface  188  and the bearing carrier outer surface  190  are dimensioned so that the bearing carrier  150  may be press fit into the carrier housing  186  to substantially prevent movement of the bearing carrier  150  relative to the bearing mounting flange  124 . 
     INDUSTRIAL APPLICABILITY 
     The bearing assembly  128  in accordance with the present disclosure allows installation on the turbine side of the turbocharger housing  30  with accurate alignment of the bearings  152 ,  154 ,  156  with the turbocharger shaft  34  and other components. The bearing carrier  150  performs the fixity and centering functions for all three of the shaft-related bearings  152 ,  154 ,  156 . At the same time, the bearing carrier  150  effectively transmits loads to the structure of the turbine housing  72  with minimal load transfer to the bolts  184  in the bearing assembly  128 . For example, radial loads on the turbocharger shaft  34  are transmitted through the journal bearing  152  and the bearing carrier  150  into the carrier housing  186  of the bearing mounting flange  124 . Engagement between the surfaces  188 ,  190  results in minimal shear loading on the carrier mounting bolt(s)  184  when the radial loads are experienced. 
     The main thrust loads occur on the turbine wheel  32  in the direction toward the compressor impeller  36 . The main thrust loads cause the thrust shoulder  170  to force the thrust washer  168  and the thrust bearing  154  against the bearing carrier  150 , which in turn transmits the main thrust load to the axial support ring  180  of the bearing mounting flange  124 . The carrier mounting bolt(s)  184  are completely unloaded due to the primary thrust load feeding directly through the bearing carrier  150  to the bearing mounting flange  124  so that this arrangement essentially eliminates significant tensile loads experienced by thrust bearing mounting bolts in previously-known turbocharges with thrust bearings installed from the compressor side of the turbocharger housing. Anti-thrust loads experienced by the compressor impeller  36  in the direction of the turbine wheel  32  are significantly lower than the main thrust loads. When anti-thrust loads occur, the anti-thrust shoulder  178  of the impeller collar  146  presses against the anti-thrust bearings  156 . However, because the anti-thrust loads are smaller than the main thrust loads, the press fit engagement between the surfaces  188 ,  190  may be sufficient to withstand the anti-thrust loads without dislodging the bearing carrier  150  from the housing carrier  186 , and the carrier mounting bolt(s)  184  are not required to absorb anti-thrust loads as was the design in previous turbochargers. 
     Installation of the single bearing carrier  150  that simultaneously supports the journal bearing  152 , the primary thrust bearing  154  and the anti-thrust bearings  156  from the turbine housing  72  in the turbine stage  64  of the main turbocharger housing  30  allows a more compact and cost-effective design with no detriment to the turbine seal  126  installed near the turbine wheel  32 . Bearing carriers in previously-known turbochargers require mounting flanges that are usually too large in diameter to fit through the mount for the turbine seal  126 . Incorporating the three bearings along with integral anti-rotation features of the bearing carrier  150  reduces the overall envelope to not much larger in diameter than the largest bearing element, which in the present design is the thrust bearing  154 . By placing the bearing mounting flange  124  on the turbine side, the main thrust loads from the turbine wheel  32  in the direction of the compressor impeller  36  react directly into the turbocharger housing  30  rather than creating tension in the carrier mounting bolt(s)  184  and the oil supply feeds to the three bearings  152 ,  154 ,  156  than in previous turbochargers where the bearings are mounted on the compressor side of the main housing. Once the anti-thrust mounting bolts  174  secure the anti-thrust bearings  156  from the compressor side that provides superior access due to the much smaller diameter of the anti-thrust bearings  156 , the anti-thrust bearings  156  hold the bolt  174  captive and secure from rotating components once attached. The bearings  152 ,  154 ,  156  typically require replacement after years of service through normal wear or degraded performance due to foreign object damage to either the turbine wheel  32  or the compressor impeller  36 . The complete bearing assembly  128  protects the turbine housing  72  from damage if a rotor failure damages the bearings  152 ,  154 ,  156 , thereby facilitating remanufacture of the turbocharger  12 . 
     While the preceding text sets forth a detailed description of numerous different embodiments, it should be understood that the legal scope of protection is defined by the words of the claims set forth at the end of this patent. The detailed description is to be construed as exemplary only and does not describe every possible embodiment since describing every possible embodiment would be impractical, if not impossible. Numerous alternative embodiments could be implemented, using either current technology or technology developed after the filing date of this patent, which would still fall within the scope of the claims defining the scope of protection. 
     It should also be understood that, unless a term was expressly defined herein, there is no intent to limit the meaning of that term, either expressly or by implication, beyond its plain or ordinary meaning, and such term should not be interpreted to be limited in scope based on any statement made in any section of this patent (other than the language of the claims). To the extent that any term recited in the claims at the end of this patent is referred to herein in a manner consistent with a single meaning, that is done for sake of clarity only so as to not confuse the reader, and it is not intended that such claim term be limited, by implication or otherwise, to that single meaning.