Abstract: In various described embodiments skip fire control is used to deliver a desired engine output. A controller determines a skip fire firing fraction and (as appropriate) associated engine settings that are suitable for delivering a requested output. In one aspect, the firing fraction is selected from a set of available firing fractions, with the set of available firing fractions varying as a function of engine speed such that more firing fractions are available at higher engine speeds than at lower engine speeds. The controller then direct firings in a skip fire manner that delivers the selected fraction of firings.

Abstract: A variety of methods and arrangements for controlling the operation of an internal combustion engine in a skip fire variable displacement mode are described. In one aspect, the working chamber firing that are selected to deliver the desired engine output are determined at least in part based on torque feedback. The torque feedback may be an indication of the torque output of the engine or the torque experienced at some other location in the drive train. In some embodiments, the torque feedback signal is filtered to remove high frequency components of the torque feedback signal in order to help stabilize the system. In another aspect, other operational parameters are used as feedback in the determination of the firing sequence. In yet another aspect, a filter is arranged to filter a feedback signal to provide a filtered feedback signal that is used in the determination of the working chamber firings.

Abstract: A variety of methods and arrangements for controlling the operation of an internal combustion engine in a skip fire variable displacement mode are described. In general, a firing control unit determines working chamber firings during operation of the engine that are suitable for delivering a desired engine output. In one aspect, the firing control unit is arranged to isolate the generation of firing sequences having frequency components in a frequency range of concern and to alter the firing sequence in a manner that reduces the occurrence of frequency components in the frequency range of concern. In another aspect, a filter is arranged to filter a feedback signal to provide a filtered feedback signal that is used in the determination of the working chamber firings. In preferred embodiments, the frequency characteristics of the filter are variable.

Abstract: A variety of methods and arrangements for improving the fuel efficiency of internal combustion engines based on skip fire operation of the engine are described.

Abstract: A variety of methods and arrangements for improving the fuel efficiency of internal combustion engines are described. In some aspects, methods and arrangements are described for operating an engine in a throttled skip fire mode. In other aspects, methods and arrangements are described for controlling the operational state of a variable displacement engine.

Abstract: A variety of methods and arrangements for controlling the operation of an internal combustion engine in a skip fire variable displacement mode are described. Generally, an engine is controlled to operate in a skip fire variable displacement mode. In one aspect, the spark timing associated with each fired working cycle is based at least in part on the firing history of the fired working chamber.

Abstract: The present invention relates to a diesel engine control system and methods for substantially operating a diesel engine at stoichiometric fuel to air ratios. The system may include a fuel processor which receives instructions for a desired engine output and current operating conditions. The fuel processor may also generate fueling instructions for the cylinders, including: substantially regulating fuel delivery into to a first group of cylinders at or near stoichiometric fuel levels, and substantially disabling fuel injection into to a second grouping of cylinders. The number of cylinders being fueled, and therefore undergoing a combustion event corresponds to the desired engine output. This may be calculated by dividing the desired output by the power provided by one cylinder operating at substantially stoichiometric fuel levels. The number of cylinders receiving fuel may be varied over a succession of engine revolutions such that the actual average engine power output conforms to the desired output.

Abstract: A variety of methods and arrangements for improving the fuel efficiency of internal combustion engines are described. In some aspects, methods and arrangements are described for operating an engine in a throttled skip fire mode. In other aspects, methods and arrangements are described for controlling the operational state of a variable displacement engine.

Abstract: A variety of methods and arrangements for controlling the operation of an internal combustion engine in a skip fire variable displacement mode are described. Generally, an engine is controlled to operate in a skip fire variable displacement mode. In one aspect, the spark timing associated with each fired working cycle is based at least in part on the firing history of the fired working chamber.

Abstract: A variety of methods and arrangements for controlling the operation of an internal combustion engine in a skip fire variable displacement mode are described. Generally, an engine is controlled to operate in a skip fire variable displacement mode. In the variable displacement mode, selected combustion events are skipped so that other working cycles can operate at better thermodynamic efficiency. More specifically, selected “skipped” working cycles are not fired while other “active” working cycles are fired. Typically, fuel is not delivered to the working chambers during skipped working cycles. In one aspect of the invention, a firing pattern is determined that is not fixed but the active working cycles are selected to favor the firing of working chambers that have recently been fired at least in part to reduce wall wetting losses.

Abstract: A variety of skip fire engine controllers and control techniques are described. In some preferred embodiments, a skip fire engine controller is provided that includes a firing fraction calculator, an engine settings controller, a firing fraction adjuster and a firing controller. The firing fraction calculator determines a reference firing fraction indicative of a firing fraction suitable for delivering a desired engine output at a reference working chamber firing output. The engine settings controller is arranged to set selected engine settings. The firing fraction adjuster determines an adjusted firing fraction that scales the reference firing fraction appropriately such that the engine will deliver the desired engine output at the current engine settings even when the actual working chamber firing outputs do not equal the reference working chamber firing output. The firing controller direct workings chamber firings in a skip fire manner that delivers the adjusted firing fraction.

Abstract: A variety of methods and arrangements for operating an internal combustion engine and one or more motor/generators in a hybrid vehicle are described. In various embodiments, the engine is operated in a skip fire mode. Depending on the state of charge of an energy storage device and/or other factors, the engine is operated to generate more or less than a desired level of torque. The one or more motor/generators are used to add or subtract torque so that the motor/generator(s) and the engine collectively deliver the desired level of torque. In some embodiments, the engine may be run with a substantially open throttle to reduce pumping losses and improve fuel efficiency.

Abstract: The present invention relates to system and methods for improving efficiency of an internal combustion engine. This system may include a fuel processor. The system receives instructions for a desired engine output and operating conditions. The system may then determine an operational state corresponding to the desired output. The operational state includes designating the cylinders into one of three categories: working, deactivated and passive. The number of working cylinders is calculated by dividing the desired output by the power provided by one cylinder operating at substantially optimal efficiency. Then the system substantially disables fuel flow to and air flow to the deactivated cylinders, substantially disables fuel flow to and firing of the passive cylinders, and substantially regulates fuel flow to, air flow to and firing of the working cylinders. Firing of the working cylinders is synchronized with engine speed to reduce unwanted engine vibrations.

Abstract: A variety of methods and arrangements for improving the fuel efficiency of internal combustion engines are described. Generally, an engine is controlled to operate in a skip fire variable displacement mode. Feedback control is used to dynamically determine the working cycles to be skipped to provide a desired engine output. In some embodiments a substantially optimized amount of air and fuel is delivered to the working chambers during active working cycles so that the fired working chambers can operate at efficiencies close to their optimal efficiency. In some embodiments, the appropriate firing pattern is determined at least in part using predictive adaptive control. By way of example, sigma delta controllers work well for this purpose. In some implementations, the feedback includes feedback indicative of at least one of actual and requested working cycle firings. In some embodiments, the appropriate firings are determined on a firing opportunity by firing opportunity basis.

Abstract: A variety of methods and arrangements for controlling the operation of an internal combustion engine in a skip fire variable displacement mode are described. In general, a firing control unit determines working chamber firings during operation of the engine that are suitable for delivering a desired engine output. In one aspect, the firing control unit is arranged to isolate the generation of firing sequences having frequency components in a frequency range of concern and to alter the firing sequence in a manner that reduces the occurrence of frequency components in the frequency range of concern. In another aspect, a filter is arranged to filter a feedback signal to provide a filtered feedback signal that is used in the determination of the working chamber firings. In preferred embodiments, the frequency characteristics of the filter are variable. In various embodiments, the frequency characteristics of the filter vary as a function engine speed and/or a transmission gear ratio.

Abstract: A variety of methods and arrangements for controlling the operation of an internal combustion engine in a skip fire variable displacement mode are described. In one aspect, the working chamber firing that are selected to deliver the desired engine output are determined at least in part based on torque feedback. The torque feedback may be an indication of the torque output of the engine or the torque experienced at some other location in the drive train. In some embodiments, the torque feedback signal is filtered to remove high frequency components of the torque feedback signal in order to help stabilize the system. In another aspect, other operational parameters are used as feedback in the determination of the firing sequence. In yet another aspect, a filter is arranged to filter a feedback signal to provide a filtered feedback signal that is used in the determination of the working chamber firings.

Abstract: A variety of methods and arrangements for improving the fuel efficiency of internal combustion engines are described. Generally, selected combustion events are skipped during operation of the internal combustion engine so that other working cycles can operate at a better thermodynamic efficiency. In one aspect of the invention, an engine is controlled to operate in a variable displacement mode. In the variable displacement mode, fuel is not delivered to the working chambers (e.g. cylinders) during selected “skipped” working cycles. During active (“non-skipped”) working cycles, a maximum (e.g., unthrottled) amount of air and an optimized amount of fuel is delivered to the relevant working chambers so that the fired working chambers can operate at efficiencies closer to their optimal efficiency. A controller is used to dynamically determine the chamber firings required to provide the engine torque based on the engine's current operational state and conditions.

Abstract: A variety of methods and arrangements for improving the fuel efficiency of internal combustion engines are described. Generally, an engine is controlled to operate in a skip fire variable displacement mode. Predictive Adaptive control is used to dynamically determine the working cycles to be skipped to provide a desired engine output.

Abstract: The present invention relates to a compression ignition engine control system and methods for improving fuel efficiency. The system includes a fuel processor which receives instructions for a desired engine output and current operating conditions. The fuel processor generates fueling instructions for a plurality of cylinders. The fueling instructions include a low power skip fire mode of operation and a high power mode of operation. The instructions substantially regulate fuel delivery into to a first group of cylinders at or near optimal efficiency fuel levels during each of their respective working cycles. Likewise, the instructions may either substantially disable fuel injection into to a second grouping of cylinders or regulate fuel injection into to the second grouping of cylinders at an elevated high power fuel to air ratio. The fuel processor may include a synchronizer for synchronizing firing of the cylinders with the engine speed.

Abstract: Systems and methods for skip fire spark ignition engine operation with a lean NOx trap after-treatment are provided. This system includes engine control circuitry capable of fueling and firing subsets of the engine's cylinders. Other cylinders are not provided fuel and are not fired (i.e. “skip fired”). The system includes an exhaust manifold for channeling the exhaust from at least some cylinders through a multistage catalytic converter. This may include a standard two-way or three-way catalytic converter. From the catalytic converter the exhaust may be channeled through a lean NOx trap. The lean NOx trap is able to chemically absorb the NOx emissions for regeneration according to a regeneration protocol. Lean NOx traps may include a substrate, an absorption material (also referred to as a ‘sorbent’) and a catalyst. The regeneration protocol may include monitoring NOx emissions downstream from the lean NOx trap, and comparing them against either a threshold or a lean NOx trap saturation model.