Abstract:
A bearing is provided which includes a first set of rolling elements, a second set of rolling elements spaced away from the first set of rollers, a race at least partially enclosing the first and second sets of rolling elements, and a pre-loading element in the race between two outer sections of the race applying pre-load forces to the first and second set of rolling elements. In this way, a simplified bearing structure is achieved while better maintaining pre-load forces.

Description:
FIELD 
       [0001]    The present disclosure relates a bearing having a pre-loading element in a bearing race. 
       BACKGROUND AND SUMMARY 
       [0002]    Turbochargers are used in engines to convert exhaust gas energy into boost provided to the intake system of the engine. Turbochargers may be used to increase the power output of engines or to downsize an engine while providing an equivalent amount of power as a larger naturally aspirated engine. In this way, the power output of the engine may be increased and/or the size of the engine may be reduced. 
         [0003]    Turbocharger bearings are provided in turbochargers to support a turbocharger shaft and enable rotation of the shaft. Turbocharger bearings may have lower natural frequencies with higher displacements and deflections when the bearings have tolerances above a desired level and/or pre-loading below a desired level. As a result, noise, vibration, and harshness (NVH) is increased in the turbocharger, thereby increasing the likelihood of turbocharger degradation. 
         [0004]    U.S. Pat. No. 6,048,101 discloses a bearing system including a spring positioned between two bearings, each bearing including a separate outer and inner race. The two bearings are spaced away from one another and the spring exerts a pre-load force on the separate bearings. 
         [0005]    The inventor has recognized several drawbacks with the bearing assembly disclosed in U.S. Pat. No. 6,048,101. For example, the spring may increase the size and complexity of the bearing assembly. Moreover, it may be costly to manufacture two bearings. 
         [0006]    The inventor herein has recognized the above issues and developed a bearing including a first set of rolling elements, a second set of rolling elements spaced away from the first set of rollers, a race at least partially enclosing the first and second sets of rolling elements, and a pre-loading element in the race between two outer sections of the race applying pre-load forces to the first and second set of rolling elements. 
         [0007]    In this way, the pre-loading element may be integrated into the bearing race, thereby simplifying the assembly of the bearing. Further, locating the pre-loading element in the race between two outer sections to apply pre-load forces can reduce the complexity of the bearing when compared to bearings which may include additionally elements that provide a pre-loading force. As a result, the reliability of the bearing is increased and the manufacturing and/or repair cost of the bearing is reduced. The pre-loading element may also reduce the likelihood of thermal expansion of the bearing, and the resulting degrading effects of such expansion. 
         [0008]    The above advantages and other advantages, and features of the present description will be readily apparent from the following Detailed Description when taken alone or in connection with the accompanying drawings. 
         [0009]    It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure. Additionally, the above issues have been recognized by the inventor herein, and are not admitted to be known. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]      FIG. 1  shows a schematic depiction of an engine; 
           [0011]      FIG. 2  shows a first example turbocharger bearing that may be included in a turbocharger in the engine shown in  FIG. 1 ; 
           [0012]      FIG. 3  shows an inner race that may be included in the turbocharger bearing shown in  FIG. 2 ; 
           [0013]      FIG. 4  shows a second example turbocharger bearing that may be included in a turbocharger in the engine shown in  FIG. 1 ; 
           [0014]      FIG. 5  shows an example outer race that may be included in the turbocharger bearing shown in  FIG. 4 ; 
           [0015]      FIG. 6  shows an example turbocharger that may be included in the engine shown in  FIG. 1 , the turbocharger including the turbocharger bearing shown in  FIG. 4 ; 
           [0016]      FIG. 7  shows a method for operation of a turbocharger; and 
           [0017]      FIG. 8  shows another example turbocharger bearing that may be included in the turbocharger in the engine shown in  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION 
       [0018]    A bearing including a pre-loading element in a bearing race is discussed herein. The pre-loading element exerts a pre-load force on two sets of rolling elements in the bearing to decrease compliance and clearances in the bearing. In this way, a single race may be used to guide two rows of bearings as well as exert a pre-load force. The pre-loading element may be a helical spring machined, cast, or otherwise manufactured with the race. The incorporation of the pre-loading element reduces the size and complexity of the bearing. Additionally, the assembly process may be simplified when the pre-loading element is incorporated into the race. As a result, the reliability of the bearing is increased and the manufacturing and repair costs of the bearing are decreased. 
         [0019]      FIG. 1  shows a schematic diagram of an engine  10  included in a propulsion system of a vehicle  100 . Engine  10  may be controlled at least partially by a control system including controller  12  and by input from a vehicle operator  132  via an input device  130 . In this example, input device  130  includes an accelerator pedal and a pedal position sensor  134  for generating a proportional pedal position signal PP. Cylinder (i.e., combustion chamber)  30  of engine  10  may include combustion chamber walls (not shown) with a piston (not shown) positioned therein. 
         [0020]    An intake system  150  and exhaust system  152  in fluidic communication with the engine  10  are also shown in  FIG. 1 . However, it will be appreciated that in some examples the intake system  150  and/or exhaust system  152  may be integrated into the engine  10  in some examples. 
         [0021]    The exhaust system  152  includes an exhaust passage denoted via arrow  154  (e.g., exhaust manifold) and an emission control device  70 . Arrow  156  denotes an exhaust passage coupled to an outlet of the emission control device  70 . It will be appreciated that the emission control device  70  may be arranged along the exhaust passage  154 . The emission control device  70  is positioned downstream of an exhaust gas sensor  126 . Emission control device  70  may be a three way catalyst (TWC), NOx trap, various other emission control devices, or combinations thereof. In some examples, emission control device  70  may be a first one of a plurality of emission control devices positioned in the exhaust system. In some examples, during operation of engine  10 , emission control device  70  may be periodically reset by operating at least one cylinder of the engine within a particular air/fuel ratio. 
         [0022]    The engine  10  includes at least one cylinder  30 . The cylinder  30  includes intake valve  52  and exhaust valve  54 . However in other examples, the cylinder  30  may include two or more intake valves and/or two or more exhaust valves. The intake valve  52  is configured to cyclically open and close to permit and inhibit intake air from flowing from the intake system  150  to the cylinder  30 . Likewise, the exhaust valve  54  is configured to cyclically open and close to permit and inhibit exhaust gas from flowing from the cylinder  30  to the exhaust system  152 . The valves may be actuated by cams. Variable cam timing may be used in the engine  10 , if desired. However, in other examples electronic valve actuation may be used to actuate at least one of the intake valve  52  and the exhaust valve  54 . 
         [0023]    Fuel injector  66  is shown coupled to the cylinder  30  that provides what is known as direct fuel injection to the cylinder. Fuel injector  66  may inject fuel in proportion to the pulse width of signal FPW received from controller  12  via electronic driver  68 . In some examples, cylinder  30  may alternatively or additionally include a fuel injector coupled to an exhaust manifold upstream of the intake valve  52  in a manner known as port fuel injection. 
         [0024]    Ignition system  88  can provide an ignition spark to cylinder  30  via spark plug  92  in response to spark advance signal SA from controller  12 , under select operating modes. Though spark ignition components are shown, in some examples, cylinder  30  or one or more other combustion chambers of engine  10  may be operated in a compression ignition mode, with or without an ignition spark. 
         [0025]    Exhaust gas sensor  126  is shown coupled to exhaust passage  154  of exhaust system  152  upstream of emission control device  70 . Sensor  126  may be any suitable sensor for providing an indication of exhaust gas air/fuel ratio such as a linear oxygen sensor or UEGO (universal or wide-range exhaust gas oxygen), a two-state oxygen sensor or EGO, a HEGO (heated EGO), a NOx, HC, or CO sensor. In some examples, exhaust gas sensor  126  may be a first one of a plurality of exhaust gas sensors positioned in the exhaust system. For example, additional exhaust gas sensors may be positioned downstream of emission control device  70 . 
         [0026]    Controller  12  is shown in  FIG. 1  as a microcomputer, including microprocessor unit  102 , input/output ports  104 , an electronic storage medium for executable programs and calibration values shown as read only memory  106  (e.g., memory chip) in this particular example, random access memory  108 , keep alive memory  110 , and a data bus. Controller  12  may receive various signals from sensors included in the engine  10  such as an absolute manifold pressure signal, MAP, from sensor  122 . It will be appreciated that in other examples the controller  12  may receive signals from additional sensors such as a throttle position sensor, an engine temperature sensor, an engine speed sensor, etc. 
         [0027]    During operation, the cylinder  30  in the engine  10  typically undergoes a four stroke cycle: the cycle includes the intake stroke, compression stroke, expansion stroke, and exhaust stroke. In a multi-cylinder engine the four stroke cycle may be carried out in additional combustion chambers. During the intake stroke, generally, exhaust valve  54  closes and intake valve  52  opens. Air is introduced into cylinder  30  via an intake manifold, for example, and the piston moves to the bottom of the combustion chamber so as to increase the volume within cylinder  30 . The position at which the piston is near the bottom of the combustion chamber and at the end of its stroke (e.g. when cylinder  30  is at its largest volume) is typically referred to by those of skill in the art as bottom dead center (BDC). During the compression stroke, intake valve  52  and exhaust valve  54  are closed. The piston moves toward the cylinder head so as to compress the air within cylinder  30 . The point at which the piston is at the end of its stroke and closest to the cylinder head (e.g. when cylinder  30  is at its smallest volume) is typically referred to by those of skill in the art as top dead center (TDC). In a process hereinafter referred to as injection, fuel is introduced into the combustion chamber. In a process hereinafter referred to as ignition, the injected fuel is ignited by known ignition devices such as a spark plug  92 , resulting in combustion. Additionally or alternatively compression may be used to ignite the air/fuel mixture. During the expansion stroke, the expanding gases push the piston back to BDC. A crankshaft may convert piston movement into a rotational torque of the rotary shaft. Finally, during the exhaust stroke, exhaust valve  54  opens to release the combusted air-fuel mixture to an exhaust manifold and the piston returns to TDC. Note that the above is described merely as an example, and that intake and exhaust valve opening and/or closing timings may vary, such as to provide positive or negative valve overlap, late intake valve closing, or various other examples. Additionally or alternatively compression ignition may be implemented in the cylinder  30 . 
         [0028]    The intake system  150  further includes a compressor  160 . The compressor  160  may be included in a turbocharger  162  also having a turbine  164  positioned in the exhaust system  152 . As shown, the turbine  164  is positioned upstream of the emission control device  70 . However, in other examples the turbine  164  may be positioned downstream of the emission control device. An exhaust conduit denoted by arrow  165  provides fluidic communication between the turbine  164  and the emission control device  70 . Arrow  167  denotes the flow of exhaust gas from the emission control device  70  to the surrounding environment. However in other examples additional components such as emission control devices, conduits, turbines, etc., may be positioned downstream of the emission control device  70 . 
         [0029]    The turbocharger  162  also includes a drive shaft  166  mechanically coupling the  160  to the turbine  164 . The drive shaft  166  is supported by a turbocharger bearing  170 . The turbocharger bearing  170  also enables the drive shaft  166  to rotate. The turbocharger bearing  170  may be referred to as a bearing and may be used in alternate applications, discussed in greater detail herein. The turbocharger bearing  170  may include a pre-loading element  206  (e.g., a spring), shown in  FIG. 2 , in the bearing. Specifically, the pre-loading element may be in an inner race or an outer race of the bearing. Thus, the pre-loading element may be integrated or otherwise incorporated into the bearing race, in some examples. 
         [0030]    The intake system  150  may further include a filter  172 . The filter receives ambient air from the surrounding environment, denoted via arrow  174 . The intake system  150  further includes a throttle  176  positioned downstream of the compressor  160 . However, other suitable throttle locations have been contemplated. An intake conduit denoted via arrow  178  provides fluidic communication between the filter  172  and the compressor  160 . An intake conduit denoted via arrow  180  provides fluidic communication between the compressor  160  and the intake valve  52 . In some examples, the intake conduit  180  may be in fluidic communication with an intake manifold which provides intake air to the cylinder  30  via the intake valve  52 . 
         [0031]      FIG. 2  shows a cross-sectional view of an example turbocharger bearing  170 . The turbocharger bearing includes an inner race  200  and an outer race  202 . The inner race  200  includes an external surface  204  in face sharing contact with the drive shaft  166 . A rotational axis  205  of the drive shaft  166  is shown. 
         [0032]    The turbocharger bearing  170  further includes a pre-loading element  206 . The pre-loading element  206  may at least partially enclose the drive shaft  166 . The pre-loading element  206  is included in a bearing race. Specifically, in the depicted example the pre-loading element  206  is included in the outer race  202 . However, in other examples, such as the example shown in  FIG. 4 , the pre-loading element  206  is included in the inner race  200 . Integrating the pre-loading element  206  into the bearing race simplifies assembly of the bearing as well as reduces the complexity of the bearing when compared to bearings which may include additionally elements which provide a pre-loading force. As a result, the reliability of the bearing is increased and the manufacturing and/or repair costs of the bearing is reduced. The pre-loading element may also reduce the likelihood of thermal expansion of the turbocharger. Additionally, when the pre-loading element  206  is incorporated in the bearing race the bearing may be retained without external load, if desired. Thus, the turbine and compressor rotor threads may simply hold their own joint, if desired. 
         [0033]    The pre-loading element  206  is schematically represented in  FIG. 3 . However, it will be appreciated that a number of suitable pre-loading elements have been contemplated, such as a helical spring. 
         [0034]    The turbocharger bearing  170  further includes a first set of rolling elements  208  and a second set of rolling elements  210 . Thus, the turbocharger bearing  170  may be referred to as a double row bearing, in some examples. The rolling elements in both the first and second sets of rolling elements are bearing balls. However, other suitable types of rolling elements have been contemplated such as cylindrical rollers, conical rollers, etc. It will be appreciated that the rolling elements may include bearing balls. The first set of rolling elements  208  are adjacent to the compressor  160 , shown in  FIG. 1 , and the second set of rolling elements  210  are adjacent to the turbine  164 , shown in  FIG. 1 . However, in other examples the first set of rolling elements  208  are adjacent to the turbine and the second set of rolling elements  210  are adjacent to the compressor. As shown, the outer race  202  axially extends from the first set of rolling elements  208  to the second set of rolling elements  210 . The inner race  200  axially extends beyond the first set of rolling elements  208  and the second set of rolling elements  210 . 
         [0035]    The inner race  200  at least partially encloses the first set of rolling elements  208  and the second set of rolling elements  210 . Likewise, the outer race  202  at least partially encloses the first set of rolling elements  208  and the second set of rolling elements  210 . The inner race  200  forms a continuous piece of material. Likewise the outer race  202  forms a continuous piece of material. 
         [0036]    Arrows  212  denote the pre-loading force generated by pre-loading element  206 . The pre-loading force is in an inward direction (e.g., inward axial direction). Thus, a force may be exerted on the first set of rolling elements  208  in a direction away from the compressor  160 , shown in  FIG. 1 , and a force may be exerted on the second set of rolling elements  210  in a direction away from the turbine  164  shown in  FIG. 1 . Thus, the direction of the pre-loading force may be parallel to the rotational axis  205 . 
         [0037]    It will be appreciated that when the turbocharger bearing  170  is assembled the pre-loading element is stretched (e.g., axially expanded, put in axial tension). The stretching of the pre-loading element results in exertion of a preloading force on the inner race  200  and the components surrounding the inner race  200 . It will be appreciated that when a pre-loading force is exerted in the bearing race reduces deflection of the drive shaft  166 , thereby reducing noise, vibration, and harshness in the turbocharger as well as increasing turbocharger reliability. 
         [0038]    The inner race  200  and/or the outer race  202  may comprise steel (e.g., UNS G52986, UNS G86200, M50, M50 NiL, etc.) and/or ceramics such as silicon nitride. In lower temperature, speed, and/or stress applications, for example, the inner and outer race may comprise composites or polymers. In one example, the inner race  200  and the outer race  202  may comprise similar materials. However, in other examples, the inner race  200  and the outer race  202  may comprise different materials. The section of the race including the pre-loading element  206  may have a lower hardness and higher ductility, in some examples. 
         [0039]      FIG. 3  shows an example inner race  200  included in the example turbocharger bearing  170  shown in  FIG. 2 . The inner race  200  comprises a continuous piece of material. However, other inner race geometries and configurations have been contemplated. 
         [0040]    As illustrated, the pre-loading element  206  is a helical spring integrated into the inner race  200 . It will be appreciated that the pre-loading element  206  may include at least a helical spring, in other examples. The helical spring  206 , shown in  FIG. 3 , includes a first coil start  300  and a second coil start  302 . Using multiple coil starts in the helical spring may balance (e.g., circumferentially balance) loads. However, a helical spring with alternate number of coil starts has been contemplated. For example, the helical spring may have only a single coil start or greater than two coil starts, in other examples. Specifically, the first coil start  300  and the second coil start  302  form a double helix type shape, in the depicted example. However, other coil start geometries have been contemplated. 
         [0041]    An outer surface  303  of each of the coil starts are axially aligned. Additionally, the radius of the outer surfaces  303  does not exceed a radius of other surfaces in the inner race  200 , in the depicted example. However, in other examples, the radius of the outer surfaces  303  may be greater than other surfaces on the inner race  200 . 
         [0042]    In the depicted example, each of the coils circumscribe a central axis  320  of the inner race  200  at least once. Thus, the coils extend at least 360 degrees around the central axis  32 . The pitch  312  of the coils may be constant and/or substantially equivalent. However, in other examples the pitch of the coils may differ from coil to coil and may vary along the length of the coil. It will be appreciated that the pitch and/or number of coils may be selected to achieve a desired amount elasticity, hardness, spring rate, etc., in the helical spring. 
         [0043]    The inner race  200  further includes a hollow central cavity  304 . The hollow central cavity may axially extend from a first end  306  of the inner race  200  to a second end  308  of the inner race. However, in other examples the hollow central cavity  304  may only partially extend through the inner race  200 . 
         [0044]    The inner race  200  includes curved sections  310  that partially enclose the first and second set of rolling elements ( 208  and  210 ). Additionally, it will be appreciated that the curved sections  310  may be in contact with the rolling elements. Curved sections of the outer race  200 , shown in  FIG. 2 , may also be in contact with the rolling elements. Additionally, a layer of lubricant (e.g., oil) may be provided between the rolling elements and the curved sections. 
         [0045]    Again arrows  212  denote the inward axial force generated by the inner race  200  when the inner race is assembled in the turbocharger bearing  170 , shown in  FIG. 2 , and stretched. Specifically, the curved sections  310  may exert a force on the sets of rolling elements ( 208  and  210 ) shown in  FIG. 2 . 
         [0046]      FIG. 4  shows a cross-sectional view of another example turbocharger bearing  170 . The turbocharger bearing shown in  FIG. 4  includes the pre-loading element  206  in the outer race  202  of the turbocharger bearing  170 . Arrows  400  denote the outward force generated by the pre-loading element  206 . It will appreciated that the pre-load force may be exerted on the first set of rolling elements  208  and the second set of rolling elements  210 . It will be appreciated that the pre-loading element  206  may be axially compressed during assembly to provide this pre-load force. The drive shaft  166  and inner race  200  are also shown in  FIG. 4 . 
         [0047]      FIG. 5  shows an example pre-loading element  206  that may be included in the turbocharger bearing  170  shown in  FIG. 4 . Specifically, the pre-loading element  206  is included in the outer race  202 . The pre-loading element  206  shown in  FIG. 5  is a helical spring including a single coil start  500 . The first set of rolling elements  208  and the second set of rolling elements  210  are also shown in  FIG. 5 . 
         [0048]    In some examples, the pre-loading element (e.g., helical spring) may be machined into the race before finishing or electrical discharge machining (EDM) may be used to manufacture the helical spring into an otherwise finished race. Still further in one example, induction tempering may be applied to the pre-loading element to increase the ductility. Suitable machines may be used to perform the EDM and/or the induction tempering. 
         [0049]    In another example, the turbocharger bearing  170  may include multiple pre-loading elements, a pre-loading element included in both the inner race and outer race. In this way axial compression as well as expansion may provide a pre-load force. 
         [0050]      FIG. 6  shows an example turbocharger  162  and the example turbocharger bearing  170 , previously shown in  FIG. 4 . The turbocharger bearing  170  includes the pre-loading element  206 . In some examples, the turbocharger  162  may not include any additional pre-loading components, if desired. The turbocharger  162  includes a housing  600 . The compressor  160  and the turbine  164  are also shown in  FIG. 6 . The compressor  160  includes a compressor rotor  602 . Additionally, the turbine  164  includes a turbine rotor  604 . A lubrication passage  606  extends through the housing  600 . The lubrication passage  606  may be in fluidic communication with a lubrication system included in the engine  10 , shown in  FIG. 1 . The lubrication passage  606  opens into the pre-loading element  206  which in the example in  FIG. 6  is a helical spring. Specifically, a lubrication outlet  607  opens into the pre-loading element  206 . In this way, lubricant may flow through the helical spring to the first set of rolling elements  208  and the second set of rolling elements  210  and between the inner race  200  and the outer race  202 . 
         [0051]    In some examples, the compressor rotor  602  and/or turbine rotor  604  may not be coupled to the drive shaft  166  via threads. In such an example an attachment apparatus, such as a press-fit ring, a retaining ring (e.g., snap ring), or a weld, may couple the compressor rotor  602  and/or turbine rotor  604  to the drive shaft  166 . However, in other examples threads may be used to couple the compressor and turbine rotors to the drive shaft. 
         [0052]    A retention element  608  is also included in the turbocharger  162  shown in  FIG. 6 . The retention element  608  is in face sharing contact with an outer surface  610  of the outer race  202 , in the depicted example. The retention element  608  is configured to reduce the axial movement of the turbocharger bearing  170 . In the depicted example, the retention element  608  includes at least a retention pin. However other suitable retention elements have been contemplated. 
         [0053]      FIG. 7  shows a method  700  for operation of a turbocharger. The method  700  may be implemented by the turbocharger discussed above with regard to  FIGS. 1-6  or another suitable turbocharger. 
         [0054]    At  702  the method includes applying a pre-load force to a first and second set of rolling elements in a turbocharger bearing via a pre-loading element integrated into a bearing race in the turbocharger bearing. 
         [0055]    At  704  the method includes rotating a turbocharger drive shaft coupled to the turbocharger bearing during application of the pre-load force. In one example, the pre-loading element includes at least a helical spring. In such an example the method includes at  706  flowing lubrication oil through the helical spring to an interface between the bearing race and the first and second set of rolling elements. It will be appreciated that step  706  may be implemented in a bearing with the pre-loading element integrated into the outer race. Further in another example, when the helical spring is integrated into an inner race, lubricant may be flowed through an outer race. 
         [0056]    Further in one example, the bearing race is an outer race and the pre-load force is applied in an outward direction. In another example, the bearing race is an inner race and the pre-load force is applied in an inward direction. 
         [0057]    Although the turbocharger bearing is discussed above with regard to turbocharger applications in an engine it will be appreciated that the bearing may be used in other applications which may include but are not limited to transmissions, drivelines, geartrains, aircraft turbines geartrains, turbomachinery, and/or machinery drives and spindles. 
         [0058]      FIG. 8  shows another example bearing  170  included in a geartrain application, the drawing to scale (although other relative dimensions may also be used). The first set of rolling elements  208  and the second set of rolling elements  210  are shown in  FIG. 8  as cylindrical rollers. The pre-loading element  206  is also shown in  FIG. 8 . Specifically, the pre-loading element  206  is a preloaded “crush spacer” spring. However, other types of pre-loading elements have been contemplated. The pre-loading element  206  is integrated into the inner race  200 . The outer race  202  is also shown in  FIG. 8 . A transmission gear  800  is coupled to the inner race  200 . A retaining nut  802  is also shown coupled to the inner race  200  in  FIG. 8 . The retaining nut  802  is configured to load the pre-loading element  206 . In other examples, a snap ring may be used in place of the retaining nut. When a snap ring is used in the geartrain the use of large nuts, threads, and/or staking may be negated, if desired. It will be appreciated that snap rings and grooves may be more robust than gear threads (e.g., hardened or masked gear threads). 
         [0059]    Note that the example control and estimation routines included herein can be used with various engine and/or vehicle system configurations. The specific routines described herein may represent one or more of any number of processing strategies such as event-driven, interrupt-driven, multi-tasking, multi-threading, and the like. As such, various acts, operations, or functions illustrated may be performed in the sequence illustrated, in parallel, or in some cases omitted. Likewise, the order of processing is not necessarily required to achieve the features and advantages of the example embodiments described herein, but is provided for ease of illustration and description. One or more of the illustrated acts or functions may be repeatedly performed depending on the particular strategy being used. Further, the described acts may graphically represent code to be programmed into the computer readable storage medium in the engine control system. 
         [0060]    It will be appreciated that the configurations and methods disclosed herein are exemplary in nature, and that these specific embodiments are not to be considered in a limiting sense, because numerous variations are possible. For example, the above technology can be applied to V-6, I-4, I-6, V-12, opposed 4, and other engine types. The subject matter of the present disclosure includes all novel and non-obvious combinations and sub-combinations of the various systems and configurations, and other features, functions, and/or properties disclosed herein. 
         [0061]    The following claims particularly point out certain combinations and sub-combinations regarded as novel and non-obvious. These claims may refer to “an” element or “a first” element or the equivalent thereof. Such claims should be understood to include incorporation of one or more such elements, neither requiring nor excluding two or more such elements. Other combinations and sub-combinations of the disclosed features, functions, elements, and/or properties may be claimed through amendment of the present claims or through presentation of new claims in this or a related application. Such claims, whether broader, narrower, equal, or different in scope to the original claims, also are regarded as included within the subject matter of the present disclosure.