Fuel based cylinder knock control

#The present application relates to a method for controlling cylinders of an internal combustion engine operating with a variety of fuels of varying composition and fuel delivery options.

#Engines may use various forms of fuel delivery to provide a desired amount of fuel for combustion in each cylinder. One type of fuel injection, or delivery, uses a port injector for each cylinder to deliver fuel to respective cylinders. Another type of fuel injection uses a direct injector for each cylinder. Engines have also been described using more than one injector to provide fuel to a single cylinder in an attempt to improve engine performance.

#One such example (US 2007/0119422 A1) describes a flexible multiple-fuel engine using both port and direct injection, where different fuel types are provided to the injectors. For example, direct injection of ethanol may be used with port injected gasoline to address knock limitations, especially under boosted conditions. In this example, a desired setting for the various fuels may be predetermined using engine maps, and then adjusted based on feedback from a knock sensor, along with a spark retard, to mitigate the knock. Specifically, the effective knock suppression of the fuels can be varied responsive to operating conditions to improve engine efficiency while meeting engine output requirements.

#FIG. 1 shows an example embodiment of a combustion chamber operating with a plurality of fuel injector options.

#FIG. 2 shows a map illustrating variation in ratio of fuel injected by the different injectors responsive to a desired torque.

#FIG. 3 shows a high level flow chart for cylinder knock control operations.

#The following description relates to systems and methods for operating an engine in a vehicle with a plurality of fuel injector configurations for delivering fuel to each of the cylinders of the engine. The configuration of fuel delivery, as well as the fuel delivery, may be adjusted differently for different cylinders to address how engine knock constraints, air-fuel ratio constraints, and/or various other issues disparately affect various cylinders of the engine. For example, the fuel injection schedule of each cylinder may be independently varied, so that some cylinders may operate with a first fuel injection configuration, while others operate with a different fuel injection configuration, based on the likelihood of knock in respective cylinders. As such, a cylinder that is more prone to knocking may be scheduled to concurrently receive not only different amounts of various fuel types, but also differing delivery of the fuel by different fuel injection types. In one example, direct injection of an alcohol fuel may be used in knock-prone cylinders, while other cylinders operate without such injection. Thus, the charge cooling benefits of direct injection of alcohol can be obtained, without depleting such fuel in other cylinders.

#FIG. 1 depicts an example embodiment of a combustion chamber or cylinder of internal combustion engine 10. Engine 10 may be controlled at least partially by a control system including controller 12 and by input from a vehicle operator 130 via an input device 132. In this example, input device 132 includes an accelerator pedal and a pedal position sensor 134 for generating a proportional pedal position signal PP. Cylinder (herein also “combustion chamber”) 14 of engine 10 may include combustion chamber walls 136 with piston 138 positioned therein. Piston 138 may be coupled to crankshaft 140 so that reciprocating motion of the piston is translated into rotational motion of the crankshaft. Crankshaft 140 may be coupled to at least one drive wheel of the passenger vehicle via a transmission system. Further, a starter motor may be coupled to crankshaft 140 via a flywheel to enable a starting operation of engine 10.

#Cylinder 14 can receive intake air via a series of intake air passages 142, 144, and 146. Intake air passage 146 can communicate with other cylinders of engine 10 in addition to cylinder 14. In some embodiments, one or more of the intake passages may include a boosting device such as a turbocharger or a supercharger. The supercharger may be a supercharger with a bypass or a clutched supercharger. Additionally, the boosting device may be arranged to provide serial or parallel boosting. For example, FIG. 1 shows engine 10 configured with a turbocharger including a compressor 174 arranged between intake passages 142 and 144, and an exhaust turbine 176 arranged along exhaust passage 148. Compressor 174 may be at least partially powered by exhaust turbine 176 via a shaft 180 where the boosting device is configured as a turbocharger. However, in other examples, such as where engine 10 is provided with a supercharger, exhaust turbine 176 may be optionally omitted, where compressor 174 may be powered by mechanical input from a motor or the engine. A throttle 162 including a throttle plate 164 may be provided along an intake passage of the engine for varying the flow rate and/or pressure of intake air provided to the engine cylinders. For example, throttle 162 may be disposed downstream of compressor 174 as shown in FIG. 1, or alternatively may be provided upstream of compressor 174.