Abstract:
A method for operating turbocharger waste gate of a turbocharged engine is disclosed. In one example, the method operates the waste gate synchronous with engine operation via a mechanical coupling between the waste gate and a camshaft or a crankshaft. The approach may reduce turbocharger lag and improve turbocharger efficiency.

Description:
FIELD 
     The present description relates to operation of a turbocharger waste gate for an internal combustion engine. The waste gate may be operated to improve turbocharger efficiency and reduce lag time. 
     BACKGROUND AND SUMMARY 
     A turbocharger may be coupled to an engine to improve engine output. The turbocharger increases engine output via providing compressed air to the engine. More specifically, an amount of fuel provided to the engine is increased as the amount of air provided to the engine increases so as to increase cylinder charge density, thereby increasing engine torque. However, a turbocharger may not be able to respond to changes in engine load as fast as is desired because of turbine inertia and pumping delays through the engine. One way to improve turbocharger response is to reduce a size of a turbine exhaust inlet. By reducing the turbine inlet size, the velocity of exhaust gas entering the turbine increases and improves turbocharger response. On the other hand, the efficiency of the turbine may be reduced at part load conditions where a waste gate of the turbocharger is at least partially open when the size of the turbine inlet is reduced. The partially open waste gate can lower exhaust pressure upstream of the turbine causing the turbine wheel to perform work on exhaust gas flowing through the turbocharger rather than the exhaust gas performing work on the turbine wheel. 
     The inventors herein have recognized the above-mentioned disadvantages for operating an engine having a turbocharger with a smaller turbine inlet and have developed a method for overcoming the disadvantages. The method comprises opening and closing a waste gate of a turbocharger synchronously with rotation of an engine. 
     By operating a waste gate synchronous with engine rotation, it may be possible to open the turbocharger waste gate so that excess exhaust flow can bypass the turbine while a portion of exhaust flow drives a turbine to increase engine and compressor output. Further, the waste gate can be closed when exhaust flow is reduced during a cylinder cycle so that more exhaust energy is transferred from the available exhaust flow to the turbocharger turbine during periods of lower exhaust flow. In this way, it may be possible to adjust exhaust flow through the turbine and waste gate in relation to when exhaust flow can be more efficiently utilized to provide a desired turbocharger output and efficiency. 
     The present description may provide several advantages. In particular, the approach may improve turbocharger efficiency. Further, the approach may enable use of turbochargers having smaller turbine inlets so that engine and turbocharger response may be improved. Additionally, in one example, the approach provides for the waste gate to be driven directly by the engine to simplify waste gate actuation. 
     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. 
     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. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The advantages described herein will be more fully understood by reading an example of an embodiment, referred to herein as the Detailed Description, when taken alone or with reference to the drawings, where: 
         FIG. 1  is a schematic diagram of an engine; 
         FIGS. 2A and 2B  show example waste gate designs; 
         FIG. 3  shows a plot of exhaust flow through a turbine during different operating conditions; and 
         FIG. 4  is an example flowchart of a method for operating a turbocharger. 
     
    
    
     DETAILED DESCRIPTION 
     The present description is related to providing a waste gate that improves engine response and turbocharger efficiency. The description also includes a method for operating a turbocharger waste gate. In one example, the turbocharger and waste gate may be part of a system as shown in  FIG. 1 . The waste gate may be mechanically operated such as shown in the example of  FIG. 2A . In other examples, the waste gate may be pneumatically, hydraulically, or electrically operated.  FIG. 2B  shows one example electromechanically operated waste gate.  FIG. 3  is an example simulated plot that illustrates the benefits of operating the waste gate according to the method of  FIG. 4 . 
     In one example, the waste gate may operate synchronously with the engine. For example, the waste gate may open or close at specific times or crankshaft angles that coincide with specific engine events. In one example, the waste gate opens each time an exhaust valve of a cylinder opens delivering exhaust to the engine exhaust system upstream of the turbine and waste gate. Thus, the waste gate operates in synchronism with engine events. 
     Referring to  FIG. 1 , internal combustion engine  10 , comprising a plurality of cylinders, one cylinder of which is shown in  FIG. 1 , is controlled by electronic engine controller  12 . Engine  10  includes combustion chamber  30  and cylinder walls  32  with piston  36  positioned therein and connected to crankshaft  40 . Combustion chamber  30  is shown communicating with intake manifold  46  and exhaust manifold  48  via respective intake valve  52  and exhaust valve  54 . Each intake and exhaust valve may be operated by an intake cam  51  and an exhaust cam  53 . The opening and closing time of exhaust valve  54  may be adjusted relative to crankshaft position via cam phaser  58 . The opening and closing time of intake valve  52  may be adjusted relative to crankshaft position via cam phaser  59 . The position of intake cam  51  may be determined by intake cam sensor  55 . The position of exhaust cam  53  may be determined by exhaust cam sensor  57 . 
     Fuel injector  66  is shown positioned to inject fuel directly into cylinder  30 , which is known to those skilled in the art as direct injection. Alternatively, fuel may be injected to an intake port, which is known to those skilled in the art as port injection. Fuel injector  66  delivers liquid fuel in proportion to the pulse width of signal FPW from controller  12 . Fuel is delivered to fuel injector  66  by a fuel system (not shown) including a fuel tank, fuel pump, and fuel rail (not shown). Fuel injector  66  is supplied operating current from driver  68  which responds to controller  12 . In one example, a high pressure, dual stage, fuel system is used to generate higher fuel pressures. In addition, intake manifold  46  is shown communicating with optional electronic throttle  62  which adjusts a position of throttle plate  64  to control air flow from intake boost chamber  44 . Compressor  162  draws air from air intake  42  to supply intake boost chamber  44 . Exhaust gases spin turbine  164  which is coupled to compressor  162  which compresses air in boost chamber  44 . Turbocharger waste gate  171  is a valve that allows exhaust gases to bypass turbine  164  via bypass passage  173  when turbocharger waste gate  171  is in an open state. Substantially all exhaust gas passes through turbine  164  when waste gate  171  is in a fully closed position. 
     Distributorless ignition system  88  provides an ignition spark to combustion chamber  30  via spark plug  92  in response to controller  12 . Universal Exhaust Gas Oxygen (UEGO) sensor  126  is shown coupled to exhaust manifold  48  upstream of turbocharger compressor  164  and catalytic converter  70 . Alternatively, a two-state exhaust gas oxygen sensor may be substituted for UEGO sensor  126 . 
     Converter  70  can include multiple catalyst bricks, in one example. In another example, multiple emission control devices, each with multiple bricks, can be used. Converter  70  can be a three-way type catalyst in one example. 
     Controller  12  is shown in  FIG. 1  as a conventional microcomputer including: microprocessor unit  102 , input/output ports  104 , read-only memory  106 , random access memory  108 , keep alive memory  110 , and a conventional data bus. Controller  12  is shown receiving various signals from sensors coupled to engine  10 , in addition to those signals previously discussed, including: engine coolant temperature (ECT) from temperature sensor  112  coupled to cooling sleeve  114 ; a position sensor  134  coupled to an accelerator pedal  130  for sensing force applied by foot  132 ; a measurement of engine manifold absolute pressure (MAP) from pressure sensor  122  coupled to intake manifold  46 ; a measurement of boost pressure from pressure sensor  123 ; a measurement of air mass entering the engine from sensor  120 ; and a measurement of throttle position from a sensor  5 . Barometric pressure may also be sensed (sensor not shown) for processing by controller  12 . In a preferred aspect of the present description, engine position sensor  118  produces a predetermined number of equally spaced pulses every revolution of the crankshaft from which engine speed (RPM) can be determined. 
     In some examples, the engine may be coupled to an electric motor/battery system in a hybrid vehicle. The hybrid vehicle may have a parallel configuration, series configuration, or variation or combinations thereof. Further, in some examples, other engine configurations may be employed, for example a diesel engine. 
     During operation, each cylinder within engine  10  typically undergoes a four stroke cycle: the cycle includes the intake stroke, compression stroke, expansion stroke, and exhaust stroke. During the intake stroke, generally, the exhaust valve  54  closes and intake valve  52  opens. Air is introduced into combustion chamber  30  via intake manifold  46 , and piston  36  moves to the bottom of the cylinder so as to increase the volume within combustion chamber  30 . The position at which piston  36  is near the bottom of the cylinder and at the end of its stroke (e.g. when combustion chamber  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. Piston  36  moves toward the cylinder head so as to compress the air within combustion chamber  30 . The point at which piston  36  is at the end of its stroke and closest to the cylinder head (e.g. when combustion chamber  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 means such as spark plug  92 , resulting in combustion. During the expansion stroke, the expanding gases push piston  36  back to BDC. Crankshaft  40  converts piston movement into a rotational torque of the rotary shaft. Finally, during the exhaust stroke, the exhaust valve  54  opens to release the combusted air-fuel mixture to exhaust manifold  48  and the piston returns to TDC. Note that the above is shown 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. 
       FIG. 2A  shows an example turbocharger waste gate  171  that is mechanically operated. Turbocharger waste gate  171  is comprised of a poppet valve  202 , return spring  204 , and bypass passage  173 . Turbocharger waste gate  171  may be actuated by first cam lobe  206  or second cam lobe  208 . Second cam lobe  208  provides additional lift to poppet valve  202  when second cam lobe  208  opens poppet valve  202  as compared to when first cam lobe  206  opens poppet valve  202 . In one example, a lost-motion device is hydraulically pinned into place to operate second cam lobe  208 . Further, lost motion devices may be unpinned to allow first cam lobe  206  and second cam lobe  208  to rotate without opening poppet valve  202 . In other examples, lift of poppet valve  202  may be adjusted anywhere between zero lift and a predetermined lift. In one example, first cam lobe  206  and second cam lobe  208  have a number of lobes equal to one half of a number of engine cylinders. First cam lobe  206  and second cam lobe  208  are shown mechanically coupled to crankshaft  40  via belt or chain  210 . In other examples, one or more gears may couple crankshaft  40  to first cam lobe  206  and second cam lobe  208 . Alternatively, a camshaft may drive first cam lobe  206  and second cam lobe  208 . Phase actuator  231  adjusts the timing of first cam lobe  206  and second cam lobe  208  relative to a position of crankshaft  40 . Thus, first cam lobe  206  and second cam lobe  208  may be advanced or retarded with respect to a particular location of crankshaft  40 . 
     Turbocharger waste gate  171  operates to selectively allow exhaust to bypass turbine  164  as crankshaft  40  rotates. In particular, first cam lobe  206  and second cam lobe  208  rotate synchronously with crankshaft  40 . Poppet valve  202  opens when first cam lobe  206  or second cam lobe  208  reaches a position off of a base circle of first cam lobe  206  or second cam lobe  208 . Further, the lobe of first cam lobe  206  and second cam lobe  208  may be manufactured to open and close for a predetermined portion of a blow-down portion of a cylinder cycle. For example, for a four cylinder engine, if an exhaust valve opening duration is 260 crankshaft degrees beginning at 60 crankshaft degrees before bottom dead center expansion stroke and closing 20 crankshaft degrees after top dead center compression stroke, the cam lobe may be manufactured to have 90 crankshaft degrees of waste gate opening beginning at 60 crankshaft degrees before bottom dead center expansion stroke. The cam lobe closing time is also 90 crankshaft degrees in this example since two lobes are provided to open the waste gate twice during each crankshaft revolution. Of course, other mechanical valve actuators are also envisioned. 
     Referring now to  FIG. 2B , an alternative turbocharger waste gate  171  that is electromechanically operated is shown. Turbocharger waste gate  171  is comprised of poppet valve  202 , return spring  204 , and bypass passage  173 . Turbocharger waste gate  171  may be actuated by electromechanical actuator  250 . In the present example, electromechanical actuator  250  includes a first coil  254  and a second coil  252 . Poppet valve  202  closes when current is passed through first coil  254  to magnetize first coil  254 . A magnetic field draws steel plate  253  which is coupled to shaft  251  to first coil  254 . Poppet valve  202  fully opens when current is passed through second coil  252  to magnetize second coil  252 . A magnetic field draws steel plate  253  to first coil  254 . Steel plate  253  is coupled to shaft  251 . Poppet valve  202  fully opens when current flows through second coil  252  so that a magnetic field draws steel pate  253  to second coil  252 . Poppet valve  202  occupies a neutral state as shown when no current passes through either of first coil  254  and second coil  252 . 
     In one example, controller  12  of  FIG. 1  provides current to first coil  254  and second coil  252  depending on engine crankshaft position. For example, controller  12  provides current to second coil  252  when an exhaust valve of a cylinder opens. Controller  12  provides current to first coil  254  approximately half way through a blow-down portion of a cylinder cycle. Further, poppet valve  202  may be opened and closed one time for every two engine cylinders during each crankshaft revolution. Thus, poppet valve is opened synchronously with engine rotation. And, since operation of electromechanical actuator  250  is not driven by the engine, it may be opened whenever desired. 
     Referring now to  FIG. 3 , a simulated plot of mass flow through a turbine versus engine crankshaft angle for a four cylinder, four stroke, engine is shown. The Y axis represents mass flow through the turbine and the mass flow rate increases in the direction of the Y axis arrow. The X axis represents engine crankshaft angle and engine crankshaft angle repeats as an engine rotates through an entire cycle (e.g., 720 crankshaft degrees for a four cylinder, four stroke, engine). Top-dead-center compression stroke for cylinder number one is at 0 crankshaft degrees. Top-dead-center compression stroke for cylinder number three is at 180 crankshaft degrees. Top-dead-center compression stroke for cylinder number four is at 360 crankshaft degrees. Top-dead-center compression stroke for cylinder number two is at 540 crankshaft degrees. 
     Turbine mass flow trace  302  represents mass flow through a turbine with a partially open waste gate for a turbocharger having a smaller turbine inlet. Turbine mass flow trace  304  represents mass flow through a turbine for a turbocharger having a larger turbine inlet. The waste gate for the turbocharger having the larger turbine inlet is held to a level to provide a same amount of boost as the turbocharger with the smaller turbine inlet. Thus, the turbocharger with the smaller turbine inlet is operated at substantially the same operating conditions as the turbocharger having the larger turbine inlet. The mass flow trace  306  represents mass flow through the turbocharger with the smaller turbine inlet when a waste gate of the turbocharger is closed partially through a cylinder blow-down cycle (e.g., time between exhaust valve opening and exhaust valve closing) after being open during a first portion of the cylinder&#39;s blow-down cycle. Turbine mass flow trace  306  follows the same trajectory as turbine mass flow trace  302  except as indicated by the dash-dot line  306 . 
     Mass flow peaks for turbine mass flow trace  302  occur at  310 - 318 . The mass flow peaks take place after each time an exhaust valve of one of the four engine cylinders opens and releases exhaust gas to the exhaust manifold. Similar mass flow peaks occur for mass flow trace  304 . However, the peak mass flow rates of mass flow trace  304  are lower in magnitude. The mass flow peak at  310  corresponds to the mass flow increase provided when the exhaust valve for cylinder number four opens. The mass flow peak at  312  corresponds to the mass flow increase provided when the exhaust valve for cylinder number two opens. The mass flow peak  314  corresponds to the mass flow increase provided when the exhaust valve for cylinder number one opens. The mass flow peak  316  corresponds to the mass flow increase provided when the exhaust valve for cylinder number three opens. The cycle repeats and the increase in mass flow provided by cylinder number four is indicated at  318 . 
     In this example, the waste gate is closed at the timings indicated by vertical marking lines  320 - 328 . The waste gate is opened at the timings indicated by vertical marking lines  330 - 338 . Thus, during an engine cycle of 720 crankshaft degrees, the waste gate is opened and closed four consecutive times. In this way, the waste gate may be opened only one time for a blow down of a single cylinder during an engine cycle. Further, the waste gate may be closed only one time for a blow down of a single cylinder during an engine cycle. Of course, the waste gate opening and closing sequence may be repeated for multiple engine cycles. The waste gate closing time can be advanced or retarded depending on operating conditions as shown. The waste gate closing duration is shown at  350 . The waste gate may be closed for at least 45 crankshaft degrees during an exhaust stroke of a cylinder cycle while an exhaust valve of the cylinder is open. Turbocharger turbine mass flow follows mass flow trace  306  when the waste gate is operated according to the description of marking lines  320 - 338 . 
     Thus, when a waste gate is synchronously operated with engine rotation, flow through the turbocharger with the smaller inlet follows mass flow trace  302  from top-dead-center compression stroke (e.g., 0 degrees) to vertical marker  322 . The waste gate is open during this crankshaft interval. Then, the mass flow follows trace  306  (dot-dash line) to  332 . The waste gate is closed during this crankshaft interval. The waste gate is opened again at  332  as the exhaust valve for cylinder number one opens. The waste gate is closed again at  324 . In this way, mass flow through the turbine of the turbocharger having the smaller turbine inlet can be increased so as not to decline to the level indicated by trough  360 . Accordingly, the average mass flow rate through the turbocharger having the smaller inlet may be increased, thereby improving the efficiency of the turbine with the smaller inlet. 
     Referring now to  FIG. 4 , a method for operating a turbocharger waste gate is shown. The method of  FIG. 4  may be stored as executable instructions in non-transitory memory of a controller. In one example, the instructions may be stored in controller  12  shown in  FIG. 1 . The instructions may provide the sequence illustrated in  FIG. 3 . 
     At  402 , method  400  determines engine operating conditions. Engine operating conditions may include but are not limited to engine speed, engine load, engine position, boost pressure, atmospheric pressure, and engine temperature. Method  400  proceeds to  404  after engine operating conditions are determined. 
     At  404 , method  400  judges whether or not conditions for opening the waste gate are present. In one example, the waste gate may be opened when pressure in the boost chamber is greater than a threshold pressure. In another example, the waste gate may be opened to limit engine torque. If method  400  judges conditions are present to open the waste gate, the answer is yes and method  400  proceeds to  406 . Otherwise, the answer is no and method  400  proceeds to exit. 
     At  406 , method  400  adjusts lift of the waste gate. The waste gate lift amount may be adjusted via the devices shown in  FIGS. 2A-B  or another suitable device. In one example, the lift of the waste gate from a valve seat may be adjusted via selecting between operating the waste gate via one or more cams. In other examples, the lift of the waste gate may be adjusted via a continuously variable mechanical lift adjustment. In still other examples, the waste gate lift may be adjusted by varying current supplied to an electromechanical actuator. In some examples, the waste gate lift amount may be equated with a waste gate opening amount. The waste gate lift or opening amount, at least in part, determines how much exhaust passes through the waste gate. Thus, the waste gate lift or opening amount controls the amount of energy supplied to the turbine and the compressor. Specific waste gate lift or opening amounts may be empirically determined and stored in tables or functions. For example, the waste gate lift may be adjusted as a function of intake manifold pressure and/or turbine speed. The tables or functions may be indexed via engine speed, load, intake manifold pressure, boost, or other variable. Method  400  proceeds to  408 . 
     At  408 , method  400  adjusts waste gate opening time. The waste gate opening time may be adjusted via the devices shown in  FIGS. 2A-B  or another suitable device. In one example, waste gate opening time may be adjusted to occur at for a predetermined crankshaft interval (e.g., 90 crankshaft degrees) as illustrated and described in  FIG. 3 . For example, the waste gate may be open when exhaust flow to the turbine during an engine cycle is higher than a threshold flow rate. The waste gate may be closed when exhaust flow to the turbine during the engine cycle is lower than the threshold flow rate. Further, in some examples where boost pressure is low, the waste gate may not be opened during a particular engine cycle. Specific waste gate opening durations may be empirically determined and stored in tables or functions. The tables or functions may be indexed via engine speed, load, intake manifold pressure, boost, or other variable. Thus, each time an engine cylinder blows down exhaust gas, the waste gate can be opened and closed. Method  400  proceeds to  410  after the waste gate opening time is adjusted. Of course, the waste gate closing time may be alternatively adjusted in a similar manner. 
     At  410 , method  400  adjusts the waste gate opening phase. The waste gate start of opening timing phase (e.g., the crankshaft angle at which the waste gate first opens) may be adjusted via the devices shown in  FIGS. 2A-B  or another suitable device. In one example, the waste gate start of opening timing phase is adjusted with exhaust valve opening and/or closing timing. Further, the waste gate start of opening timing phase may be adjusted in response to engine speed, load, intake manifold pressure, boost, or other variable. For example, the waste gate opening time may be retarded at higher engine speeds to allow more exhaust gas to flow from the engine cylinder. The waste gate closing phase may also be adjusted in a similar manner. Method  400  proceeds to  412  after waste gate timing phase is adjusted. 
     At  412 , method  400  operates the waste gate synchronous with engine rotation. The waste gate is operated according to the lift amount determined at  406 , the opening timing determined at  408 , and the opening and closing phase determined at  410 . In one example, the waste gate is opened and closed multiple times as described in  FIG. 3 . In particular, the waste gate is opened and closed at several predetermined crankshaft angles. In one example, the waste gate is opened via a cam as shown in  FIG. 2A  or via an electromechanical actuator as shown in  FIG. 2B . Method  400  proceeds to exit after the waste gate is operated. 
     Thus, the method of  FIG. 4  provides for a method for operating a turbocharger, comprising: opening and closing a waste gate of a turbocharger synchronously with rotation of an engine. The method includes where the waste gate is closed during a blow down portion of a cylinder cycle. The method includes where the waste gate is closed one time for each cylinder of the engine during a cycle of the engine. In this way, spin up time (e.g., time for a turbine to change speed from a lower speed to a higher speed) turbine may be reduced while turbocharger efficiency is increased. 
     In one example, the method includes where the waste gate is comprised of a poppet valve. The method includes where the poppet valve is operated via rotation of the engine. In some examples, the method includes where the poppet valve is electromechanically operated. The method also includes where the poppet valve is operated via a cam. The method includes where the waste gate is operated synchronously with rotation of a crankshaft or a camshaft. The method includes where the waste gate is mechanically coupled to the crankshaft or camshaft. 
     The method of  FIG. 4  also provides for a method for operating a turbocharger, comprising: opening and closing a waste gate of a turbocharger synchronously with rotation of an engine; and adjusting an opening amount of the waste gate in response to a pressure of an air intake of the engine. The method further comprises adjusting a closing time or an opening time of the waste gate relative to a crankshaft position in response to engine operating conditions. The method includes where the engine operating conditions are comprised of at least one of engine speed, engine load, and boost pressure. 
     In some examples, the method includes where the opening amount is a crankshaft angle duration when the waste gate is open. The method also includes where the opening amount is a lift amount of a valve from a valve seat. In still another example, the method includes where the waste gate is operated via rotation of the engine. 
     In another example, the method of  FIG. 4  provides for operating a turbocharger, comprising: opening and closing a waste gate of a turbocharger during each engine cycle of a plurality of engine cycles, the plurality of engine cycles being consecutive. The method also includes where the waste gate is opened during a blow down portion of a cylinder cycle. The method includes where the waste gate begins closing during a blow down portion of the cylinder cycle. The method also includes where the waste gate is closed for at least 45 crankshaft degrees during an exhaust stroke of a cylinder while an exhaust valve of the cylinder is open. The method further comprises adjusting an opening time and a closing time of the waste gate in response to engine operating conditions. 
     As will be appreciated by one of ordinary skill in the art, routines described in  FIG. 4  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 steps 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 objects, features, and advantages described herein, but is provided for ease of illustration and description. Although not explicitly illustrated, one of ordinary skill in the art will recognize that one or more of the illustrated steps or functions may be repeatedly performed depending on the particular strategy being used. 
     This concludes the description. The reading of it by those skilled in the art would bring to mind many alterations and modifications without departing from the spirit and the scope of the description. For example, I3, I4, I5, V6, V8, V10, and V12 engines operating in natural gas, gasoline, diesel, or alternative fuel configurations could use the present description to advantage.