Express Mail Label No. EV700316110US
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`Record ID 81134110
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`SYSTEM AND METHODFORTIP-IN KNOCK COMPENSATION
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`Background and Summary
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`Engines may use various forms of fuel delivery to provide a desired amount of fuel for
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`combustion in each cylinder. One type of fuel delivery uses a port injector for each cylinder to
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`deliver fuel to respective cylinders. Still another type of fuel delivery uses a direct injector for
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`each cylinder.
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`Engines have also been described using more than one injector to provide fuel to a single
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`cylinder in an attempt to improve engine performance. Specifically, in US 2005/0155578 an
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`engine is described using a port fuel injector and a direct injector in each cylinder of the engine.
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`In this system, transient errors in delivered fuel from the port injector, such as due to sudden
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`airflow increases, can be addressed by subsequently delivering fuel of the same type from a
`direct cylinder injector.
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`However, the inventors herein have recognized a disadvantage with such an approach.
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`Under such transient conditions where sudden load increases may occur, engine knock may be
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`more likely. As such, even if the air-fuel ratio is correctly maintained, engine knock maystill
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`occur, thus reducing performance and driversatisfaction.
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`Another approach that utilizes multiple injection locations for different fuel types to
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`reduce knock is described in the papers titled “Calculations of Knock Suppression in Highly
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`Turbocharged Gasoline/Ethanol Engines Using Direct Ethanol Injection” and “Direct Injection
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`Ethanol Boosted Gasoline Engine: Biofuel Leveraging for Cost Effective Reduction of Oil
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`Dependence and CO2 Emissions” by Heywoodet al. Specifically, the Heywood et al. papers
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`Express Mail Label No. EV700316110US
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`Record ID 81134110
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`describe directly injecting ethanol to improve charge cooling effects under various conditions,
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`such as in response to a knocksensoror steady state operating conditions.
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`However, the inventors herein have recognized that transient engine knock maystill
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`occur during transient conditions,
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`such as aggressive driver
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`tip-ins,
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`since the feedback
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`information from the sensor becomeavailable too late to correct the combustion mixture during
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`the transient and reduce knock. As such, performanceandsatisfaction maystill be degraded.
`Therefore, in one approach, a method of controlling an engine, the method comprising:
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`- providing fuel having a blend to a cylinder of the engine; actively varying said fuel blend in
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`response to at least an operating condition; where during a transient operating condition, said
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`blend is adjusted to increase a heat capacity ofsaid fuel to reduce a tendency for knock.
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`In this way, it is possible to adjust the blend before the onset of knock, and thus improve
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`performance. For example, it may be possible to continue engine boosting during the transient to
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`thereby provide improved vehicle performance.
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`Description of the Drawings
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`Figure 1 is a block diagram ofa vehicle illustrating various components of the powertrain
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`system;
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`Figure 2 showsa partial engine view;
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`Figure 3 shows an engine with a turbocharger;
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`Figures 4-5 show example engine cylinder and port configurations;
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`Figure 6 shows two fuel injectors;
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`Figure 7 shows a fuel pump system;
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`Figures 8-10 shows fuel vapor purge system configurations;
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`Express Mail Label No. EV700316110US
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`Record ID 81134110
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`Figures 11-12 shows high level flow charts for air-fuel ratio feedback control;
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`Figures 13-14 and 16 showhigh level flow charts for fuel type enablement;
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`Figure 15 shows graphsillustrating example ratios of fuel type enablement based on
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`operating conditions;
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`Figures 16-18 show high level flow charts for engine starting and running operation;
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`Figure 19 showsa high level flow chart for engine starting taking into account fuel levels
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`of different fuel types;
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`Figure 20 showsa high level flow chart for compensating for depleting a fuel source;
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`Figure 21 showsa graphillustrating different fuel injector characteristics for two example
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`injectors;
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`Figure 22 shows a graph illustrating an example relationship of fuel
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`injection as a
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`function of knock tendency;
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`Figure 23 showsa high level flow chart of an alternative embodiment for controlling fuel
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`injection of a first and second fuel type taking into account minimum pulse width issues and
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`different fuel type characteristics;
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`Figures 24-25 show high level flow charts for controlling operation using waterinjection;
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`Figures 26-27 show graphs illustrating an amount of injection to reduce knock for
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`varying water content and varying amounts of desired charge cooling;
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`Figure 28 showsa high level flow chart for controlling fuel type injection amounts (and
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`relative amounts) and/or adjusting ignition timing to reduce knock;
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`Figure 29 showsgraphsillustrating example knock control operation;
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`Figure 30 showsa high level flow chart for event-based enginestarting;
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`Express Mail Label No. EV700316110US
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`Record ID 81134110
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`Figures 31-34 shows high level flow charts for fuel vapor purging control, estimation,
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`and adaptive learning;
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`Figure 35 showsa graph of an example injector characteristic;
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`Figures 36-38 show example fuel tank and pump configurations;
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`Figure 39 showsa high level flow chart for transitioning on a second fuel type;
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`Figure 40 shows example operation according to the routine of Figure 39;
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`Figure 41 showsa high level flow chart for selecting injection timing(s);
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`Figure 42 showsa graphillustrating example injection timing operation;
`Figure 43 showsa graph illustrating fuel types and injection timings for various engine
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`speed and load regions; and
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`Figure 44 showsa high level flow chart for controlling boost.
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`Detailed Description
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`Referring to Figure 1, in this example, internal combustion engine 10, further described
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`herein with particular reference to Figures 2 and 3, is shown coupled to torque converter 11 via
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`crankshaft 13. Torque converter 11 is also coupled to transmission 15 via turbine shaft 17.
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`Torque converter 11 has a bypass, or lock-up clutch 14 which can be engaged, disengaged, or
`partially engaged. When the clutch is either disengaged or partially engaged, the torque converter
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`is said to be in an unlocked state. The lock-up clutch 14 can be actuated electrically,
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`hydraulically, or electro-hydraulically, for example. The lock-up clutch 14 receives a control
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`signal (not shown) from the controller, described in more detail below. The control signal may
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`be a pulse width modulated signal to engage, partially engage, and disengage, the clutch based
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`on engine, vehicle, and/or transmission operating conditions. Turbine shaft 17 is also known as
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`Record ID 81134110
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`transmission input shaft. Transmission 15 comprises an electronically controlied transmission
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`with a plurality of selectable discrete gear ratios. Transmission 15 also comprises various other
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`gears, such as, for example, a final drive ratio (not shown). Transmission 15 is also coupled to
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`tire 19 via axle 21. Tire 19 interfaces the vehicle (not shown) to the road 23. Note that in one
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`example embodiment, this powertrain is coupled in a passenger vehicle that travels on the road.
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`In an alternative embodiment, a manual transmission operated by a driver with a clutch
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`may be used. Further, various types of automatic transmissions may be used.
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`Figure 2 showsone cylinder of a multi-cylinder engine, as well as the intake and exhaust
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`path connected to that cylinder.
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`In the embodiment shownin Figure 2, engine 10 is capable of
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`using two different fuels, and/or two different injectors in one example. For example, engine 10
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`may use gasoline and an alcohol containing fuel such as ethanol, methanol, a mixture of gasoline
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`and ethanol (e.g., E85 which is approximately 85% ethanol and 15% gasoline), a mixture of
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`gasoline and methanol (e.g., M85 which is approximately 85% methanol and 15% gas), etc.
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`In
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`another example, two fuel systems are used, but each uses the same fuel, such as gasoline.
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`In
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`still another embodiment, a single injector (such as a direct injector) may be used to inject a
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`mixture of gasoline and such an alcohol based fuel, where the ratio of the two fuel quantities in
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`the mixture may be adjusted by controller 12 via a mixing valve, for example.
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`In still another
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`‘ example, two different injectors for each cylinder are used, such as port and direct injectors.
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`In
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`even another embodiment, different sized injectors,
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`in addition to different
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`locations and
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`different fuels, may be used.
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`Aswill be described in more detail below, various advantageous results may be obtained
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`by various of the above systems. For example, when using both gasoline and a fuel having
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`alcohol (e.g., ethanol), it may be possible to adjust the relative amounts ofthe fuels to take
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`Express Mail Label No. EV700316110US
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`Record ID 81134110
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`advantage of the increased charge cooling of alcohol fuels (e.g., via direct injection) to reduce
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`the tendency of knock. This phenomenon, combined with increased compression ratio, and/or
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`boosting and/or engine downsizing, can then be used to obtain large fuel economy benefits (by
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`reducing the knock limitations on the engine).
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`Figure 2 shows one example fuel system with two fuel injectors per cylinder, for at least
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`one cylinder. Further, each cylinder may have two fuel injectors. The two injectors may be
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`configured in various locations, such as two port injectors, one port injector and one direct
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`injector (as shownin Figure 2), or others.
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`Also, as described herein, there are various configurations of the cylinders, fuel injectors,
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`and exhaust system, as well as various configuration for the fuel vapor purging system and
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`exhaust gas oxygen sensorlocations.
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`Continuing with Figure 2, it shows a dual injection system, where engine 10 has both
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`direct and port fuel
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`injection, as well as spark ignition.
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`Internal combustion engine 10,
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`comprising a plurality of combustion chambers, is controlled by electronic engine controller 12.
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`Combustion chamber 30 of engine 10 is shown including combustion chamber walls 32 with
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`piston 36 positioned therein and connected to crankshaft 40. A starter motor (not shown) may be
`coupled to crankshaft 40 via a flywheel (not shown), or alternatively direct engine starting may
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`be used.
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`In one particular example, piston 36 may include a recess or bowl (not shown)to help in
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`forming stratified charges of air and fuel, if desired. However, in an alternative embodiment, a
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`flat piston may be used.
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`Combustion chamber, or cylinder, 30 is shown communicating with intake manifold 44
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`and exhaust manifold 48 via respective intake valves 52a and 52b (not shown), and exhaust
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`Record ID 81134110
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`valves 54a and 54b (not shown). Thus, while four valves per cylinder may be used, in another
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`example, a single intake and single exhaust valve per cylinder may also be used.
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`In still another
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`example, two intake valves and one exhaust valve per cylinder may be used.
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`Combustion chamber 30 can have a compression ratio, which is the ratio of volumes
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`whenpiston 36 is at bottom center to top center.
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`In one example, the compression ratio may be
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`approximately 9:1. However, in some examples where different fuels are used, the compression
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`ratio may be increased. For example, it may be between 10:1 and 11:1 or 11:1 and 12:1, or
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`greater.
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`Fuel injector 66A is shown directly coupled to combustion chamber 30 for delivering
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`injected fuel directly therein in proportion to the pulse width of signal dfpw received from
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`controller 12 via electronic driver 68. While Figure 2 shows injector 66A as a side injector, it
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`may also be located overhead of the piston, such as near the position of spark plug 92. Such a
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`position may improve mixing and combustion due to the lower volatility of some alcohol based
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`fuels. Alternatively, the injector may be located overhead and near the intake valve to improve
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`mixing.
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`Fuel may be delivered to fuel injector 66A by a high pressure fuel system (not shown)
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`including a fuel tank, fuel pumps, and a fuelrail. Alternatively, fuel may be delivered by a single
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`stage fuel pump at lower pressure, in which case the timing of the direct fuel injection may be
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`more limited during the compression stroke than if a high pressure fuel system is used. Further,
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`while not shown, the fuel tank (or tanks) may (each) have a pressure transducer providing a
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`signal to controller 12.
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`Fuel injector 66B is shown coupled to intake manifold 44, rather than directly to cylinder
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`30. Fuel injector 66B delivers injected fuel in proportion to the pulse width of signal pfpw
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`Record ID 81134110
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`received from controller 12 via electronic driver 68. Note that a single driver 68 may be used for
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`both fuel injection systems, or multiple drivers may be used. Fuel system 164 is also shown in
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`schematic form delivering vapors to intake manifold 44. Various fuel systems and fuel vapor
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`purge systems may be used, such as those described below herein with regard to Figures 8-10,
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`for example.
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`Intake manifold 44 is shown communicating with throttle body 58 via throttle plate 62. In
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`this particular example, throttle plate 62 is coupled to electric motor 94 so that the position of
`elliptical throttle plate 62 is controlled by controller 12 via electric motor 94, This configuration
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`may bereferred to as electronic throttle control (ETC), which can also be utilized during idle
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`speed control. In an alternative embodiment (not shown), a bypass air passageway is arranged in
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`parallel with throttle plate 62 to control inducted airflow during idle speed control via an idle
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`control by-pass valve positioned within the air passageway.
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`Exhaust gas sensor 76 is shown coupled to exhaust manifold 48 upstream of catalytic
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`converter 70 (where sensor 76 can correspond to various different sensors). For example, sensor
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`76 may be any of many knownsensors for providing an indication of exhaust gas air/fuel ratio
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`such as a linear oxygen sensor, a UEGO,a two-state oxygen sensor, an EGO, a HEGO,or an HC
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`or CO sensor. In this particular example, sensor 76 is a two-state oxygen sensor that provides
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`signal EGO to controller 12 which converts signal EGO into two-state signal EGOS. A high
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`voltage state of signal EGOS indicates exhaust gasesare rich of stoichiometry and a low voltage
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`state of signal EGOS indicates exhaust gases are lean of stoichiometry. Signal EGOS may be
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`used to advantage during feedback air/fuel control to maintain average air/fuel at stoichiometry
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`during a stoichiometric homogeneous mode of operation. Furtherdetails of air-fuel ratio control
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`are included herein.
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`Record ID 81134110
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`Distributorless ignition system 88 provides ignition spark to combustion chamber 30 via
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`spark plug 92 in response to spark advance signal SA from controller 12.
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`Controller 12 may cause combustion chamber 30 to operate in a variety of combustion
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`modes, including a homogeneousair/fuel mode andastratified air/fuel mode by controlling
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`injection timing,
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`injection amounts, spray patterns, etc. Further, combined stratified and
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`homogenous mixtures may be formed in the chamber.
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`In one example, stratified layers may be
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`formed by operating injector 66A dunng a compression stroke.
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`In another example, a
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`homogenous mixture may be formed by operating one or both of injectors 66A and 66B during
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`an intake stroke (which may be open valve injection).
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`In yet another example, a homogenous
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`mixture may be formed by operating one or both of injectors 66A and 66B before an intake
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`stroke (which may be closed valve injection).
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`In still other examples, multiple injections from
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`one or both of injectors 66A and 66B may be used during one or morestrokes (e.g., intake,
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`compression, exhaust, etc.). Even further examples may be where different injection timings and
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`mixture formationsare used underdifferent conditions, as described below.
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`Controller 12 can control the amount of fuel delivered by fuel myectors 66A and 66B so
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`that the homogeneous,stratified, or combined homogenous/stratified air/fuel mixture in chamber
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`30 can be selected to be at stoichiometry, a value rich of stoichiometry, or a value lean of
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`stoichiometry.
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`Emission control device 72 is shown positioned downstream of catalytic converter 70.
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`Emission control device 72 may be a three-way catalyst or a NOx trap, or combinationsthereof.
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`Controller 12 is shown as a microcomputer,
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`including microprocessor unit 102,
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`input/output ports 104, an electronic storage medium for executable programs and calibration
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`values shown as read only memory chip 106 in this particular example, random access memory
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`Record ID 81134110
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`108, keep alive memory 110, and a conventional data bus. Controller 12 is shown receiving
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`various signals from sensors coupled to engine 10,
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`in addition to those signals previously
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`discussed, including measurement of inducted mass air flow (MAF) from massair flow sensor
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`100 coupled to throttle body 58; engine coolant temperature (ECT) from temperature sensor 112
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`coupled to cooling sleeve 114; a profile ignition pickup signal (PIP) from Hall effect sensor 118
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`coupled to crankshaft 40; and throttle position TP from throttle position sensor 120; absolute
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`Manifold Pressure Signal MAP from sensor 122; an indication of knock from knock sensor 182;
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`and an indication of absolute or relative ambient humidity from sensor 180. Engine speed signal
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`RPM is generated by controller 12 from signal PIP in a conventional manner and manifold
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`pressure signal MAP from a manifold pressure sensor provides an indication of vacuum, or
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`pressure,
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`in the intake manifold. During stoichiometric operation,
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`this sensor can give an
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`indication of engine load. Further, this sensor, along with engine speed, can provide an estimate
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`of charge (including air) inducted into the cylinder. In a one example, sensor 118, which is also
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`used as an engine speed sensor, produces a predetermined number of equally spaced pulses every
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`revolution of the crankshaft.
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`In this particular example, temperature Tcatl of catalytic converter 70 is provided by
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`temperature sensor 124 and temperature Tcat2 of emission contro! device 72 is provided by
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`temperature sensor 126.
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`In an alternate embodiment, temperature Tcatl and temperature Tcat2
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`maybe inferred from engine operation.
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`Continuing with Figure 2, a variable camshaft timing system is shown. Specifically,
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`camshaft 130 of engine 10 is shown communicating with rocker arms 132 and 134 for actuating
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`intake valves 52a, 52b and exhaust valves 54a, 54b. Camshaft 130 is directly coupled to housing
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`136. Housing 136 forms a toothed wheel having a plurality of teeth 138. Housing 136 is
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`Record ID 81134110
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`hydraulically coupled to crankshaft 40 via a timing chain or belt (not shown). Therefore, housing
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`136 and camshaft 130 rotate at a speed substantially equivalent to the crankshaft. However, by
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`manipulation of the hydraulic coupling as will be described later herein, the relative position of
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`camshaft 130 to crankshaft 40 can be varied by hydraulic pressures in advance chamber 142 and
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`retard chamber 144. By allowing high pressure hydraulic fluid to enter advance chamber 142, the
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`relative relationship between camshaft 130 and crankshaft 40 is advanced. Thus, intake valves
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`52a, 52b and exhaust valves 54a, 54b open and close at a time earlier than normalrelative to
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`crankshaft 40. Similarly, by allowing high pressure hydraulic fluid to enter retard chamber 144,
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`the relative relationship between camshaft 130 and crankshaft 40 is retarded. Thus, intake valves
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`52a, 52b, and exhaust valves 54a, 54b open and close at a time later than normal relative to
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`crankshaft 40.
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`While this example shows a system in which the intake and exhaust valve timing are
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`controlled concurrently, variable intake cam timing, variable exhaust cam timing, dual
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`independent variable cam timing, or fixed cam timing may be used. Further, variable valvelift
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`may also be used. Further, camshaft profile switching may be used to provide different cam
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`profiles under different operating conditions. Further still, the valvetrain may beroller finger
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`follower, direct acting mechanical bucket, electromechanical, electrohydraulic, or other
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`alternatives to rocker arms.
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`Continuing with the variable cam timing system, teeth 138, being coupled to housing 136
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`and camshaft 130, allow for measurement of relative cam position via cam timing sensor 150
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`providing signal VCT to controller 12. Teeth 1, 2, 3, and 4 are preferably used for measurement
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`of cam timing and are equally spaced (for example, in a V-8 dual bank engine, spaced 90 degrees
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`apart from one another) while tooth 5 is preferably used for cylinder identification, as described
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`-ll-
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`later herein. In addition, controller 12 sends control signals (LACT, RACT) to conventional
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`solenoid valves (not shown) to control the flow of hydraulic fluid either into advance chamber
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`142, retard chamber 144, or neither.
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`Relative cam timing can be measured in a variety of ways. In general terms, the time, or
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`rotation angle, between the rising edge of the PIP signal and receiving a signal from one of the
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`plurality of teeth 138 on housing 136 gives a measure of the relative cam timing. For the
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`particular example of a V-8 engine, with two cylinder banks and a five-toothed wheel, a measure
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`of cam timing for a particular bank is received four times per revolution, with the extra signal
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`used for cylinder identification.
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`Sensor 160 may also provide an indication of oxygen concentration in the exhaust gas via
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`signal 162, which provides controller 12 a voltage indicative of the O2 concentration. For
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`example, sensor 160 can be a HEGO, UEGO, EGO,or other type of exhaust gas sensor. Also
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`note that, as described above with regard to sensor 76, sensor 160 can correspond to various
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`different sensors.
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`Asdescribed above, Figure 2 merely shows one cylinder of a multi-cylinder engine, and
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`that each cylinder has its own set of intake/exhaust valves, fuel injectors, spark plugs,etc.
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`Also, in the example embodiments described herein, the engine may be coupled to a
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`starter motor (not shown) for starting the engine. The starter motor may be powered when the
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`driver turns a key in the ignition switch on the steering column, for example. The starter is
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`disengaged after engine starting, for example, by engine 10 reaching a predetermined speedafter
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`a predetermined time. Further,
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`in the disclosed embodiments, an exhaust gas recirculation
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`(EGR) system may be used to route a desired portion of exhaust gas from exhaust manifold 48 to
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`intake manifold 44 via an EGR valve (not shown). Alternatively, a portion of combustion gases
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`may beretained in the combustion chambers by controlling exhaust valve timing.
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`As noted above, engine 10 mayoperate in various modes, including lean operation, rich
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`operation, and "near stoichiometric" operation. "Near stoichiometric” operation can refer to
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`oscillatory operation around the stoichiometric air fuel ratio. Typically, this oscillatory operation
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`is governed by feedback from exhaust gas oxygen sensors. In this near stoichiometric operating
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`mode, the engine may be operated within approximately oneair-fuel ratio of the stoichiometric
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`air-fuel ratio. This oscillatory operation is typically on the order of 1 Hz, but can vary faster and
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`slower than 1 Hz. Further, the amplitude of the oscillations are typically within 1 a/f ratio of
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`stoichiometry, but can be greater than | a/f ratio under various operating conditions. Note that
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`this oscillation does not have to be symmetrical in amplitude or time. Further note that an air-
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`fuel bias can be included, where the bias is adjusted slightly lean, or rich, of stoichiometry (e.g.,
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`within 1 a/fratio of stoichiometry). Also note that this bias and the lean andrich oscillations can
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`be governed by an estimate of the amount of oxygen stored in upstream and/or downstream three
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`waycatalysts.
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`As described below, feedback air-fuel ratio control
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`is used for providing the near
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`stoichiometric operation. Further, feedback from exhaust gas oxygen sensors can be used for
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`controlling air-fuel ratio during lean and during rich operation. In particular, a switching type,
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`heated exhaust gas oxygen sensor (HEGO) can be used for stoichiometric air-fuel ratio control
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`by controlling fuel injected (or additional air via throttle or VCT) based on feedback from the
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`HEGOsensor and the desired air-fuel ratio. Further, a UEGO sensor (which provides a
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`substantially linear output versus exhaust air-fuel ratio) can be used for controlling air-fuel ratio
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`during lean, rich, and stoichiometric operation. In this case, fuel injection (or additional air via
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`-13-
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`throttle or VCT) can be adjusted based on a desired air-fuel ratio and the air-fuel ratio from the
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`sensor. Further still, individual cylinder air-fuel ratio control could be used, if desired. As
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`described in more detail below, adjustments may be made with injector 66A, 66B, or
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`combinations therefore depending on variousfactors.
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`Also note that various methods can be used to maintain the desired torque such as, for
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`example, adjusting ignition timing, throttle position, variable cam timing position, exhaust gas
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`recirculation amount, and numberof cylinders carrying out combustion. Further, these variables
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`can be individually adjusted for each cylinder to maintain cylinder balance among all
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`the
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`cylinders.
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`Referring now to Figure 3, an example engine 10 is shown with four in-line cylinders.
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`In
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`one embodiment, engine 10 may have a turbocharger 319, which has a turbine 319a coupled in
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`the exhaust manifold 48 and a compressor 319b coupled in the intake manifold 44. While Figure
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`3 does not show an intercooler, one may optionally be used. Turbine 319ais typically coupled to
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`compressor 319b via a drive shaft 315. Various types of turbochargers and arrangements may be
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`used. For example, a variable geometry turbocharger (VGT) may be used where the geometry of
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`the turbine and/or compressor may be varied during engine operation by controller 12.
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`Alternately, or in addition, a variable nozzle turbocharger (VNT) may be used when a variable
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`area nozzle is placed upstream and/or downstream of the turbine in the exhaust line (and/or
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`upstream or downstream of the compressorin the intake line) for varying the effective expansion
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`or compression of gasses through the turbocharger. Still other approaches may be used for
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`varying expansion in the exhaust, such as a waste gate valve. Figure 3 shows an example bypass
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`valve 320 around turbine 319a and an example bypass valve 322 around compressor 319b, where
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`Express Mail Label No. EV700316110US
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`Record ID 81134110
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`each valve may be controller via controller 12. As noted above, the valves may be located
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`within the turbine or compressor, or may be a variable nozzle.
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`Also, a twin turbocharger arrangement, and/or a sequential turbocharger arrangement,
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`may be used if desired.
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`In the case of multiple adjustable turbocharger and/or stages, it may be
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`desirable to vary a relative amount of expansion though the turbocharger, depending on
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`operating conditions
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`(e.g. manifold pressure, airflow, engine speed, etc.).
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`Further, a
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`supercharger maybe used,if desired.
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`Referring now to Figure 4, an alternative embodiment of engine 10 is shown with two
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`port fuel injectors per cylinder for cylinders with three or more valves (e.g., two or more intake
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`valves, such as a 3-valve engine or a 4-valve engine). Even though this example utilizes port
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`injection, it may still be possible to exploit increased charge cooling effects of various fuels
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`(such as ethanol, gasoline, mixtures thereof, etc). For example, in some cases, port injection can
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`attain some charge cooling benefits at wide-open throttle conditions by using open valve
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`injection (OVI). However, since an additional injector is supplied, the wide-open throttle OVI
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`benefit may not be reduced by the need to design single port-injector systems to satisfy other
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`constraints, such as: control at
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`low fuel flows, cold start fuel behavior, and transient fuel
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`behavior (usually with closed-valve injection). Thus, by using two fuel injectors it is possible to
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`better exploit open valve injection, while still retaining desired functionality during various
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`operating conditions.
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`As one example, since two injectors are used, they may each be designed with smaller
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`valve flows/openings so that under low load conditions it may be possible to provide more
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`accurate quantity control (e.g., by using only oneofthe injectors).
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`FORD Ex. 1146, page 15
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`Express Mail Label No. EV700316110US
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`Record ID 81134110
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`As another example, when using different fuels for two the injectors (e.g., one injecting
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`gasoline and oneinjecting a fuel having an alcohol component, such as ethanol or E85) many of
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`the above system constraints can be satisfied. For example, by using separate port injectors for
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`fuels with alcohol (e.g., ethanol) and gasoline, and using the alcohol injector at higher loads
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`when the engine is warmed up, some of the constraints at low fuel flow and cold start are
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`avoided for the alcohol injector. Further, if the alcohol injector is operated with OVI timing, or
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`at least partial OVI timing, then transient fuel problems may also be reduced for the ethanol
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`injector.
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`Additionally, using OVI timing (at least under some conditions) allows the alcohol
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`injector spray pattern and targeting to be optimized for OVI. The spray could be much narrower
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`angle than for the gasoline port injector, to increase the probability that most of the fuel enters
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`the cylinder as a liquid, instead of evaporating from intake port and intake valve metal surfaces.
`This would increase the evaporative cooling benefit in a manner similar to direct injection. Also,
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`the injector targeting may be selected to reduce bore wash issues, in which liquid fuel washesoil
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`off cylinder walls, potentially causing excessive wear.
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`In this way, in some cases, it may be possible to achieve advantageous results without
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`requiring direct injection. For example, by using two port fuel injectors per cylinder it may be
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`possible to reduce system cost, reduce required fuel rail pressure (high fuel rail pressure can
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`reduce fuel economy due to parasitic losses of the fuel pump), and reduce packaging issues
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`(direct injection may require compromised valve sizes and/or angles, intake or exhaust port
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`shapes,etc.).
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`Specifically, Figure 4 shows a cylinder 430 with twointake ports 446a and 446b ofintake
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`manifold 444 coupled respectively to intake valves 452a and 452b. A first injector 466A is
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`FORD Ex. 1146, page 16
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`FORD Ex. 1146, page 16
` IPR2020-00013
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`Express Mail Label No. EV700316110US
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`Record ID 81134110