Abstract: The timing of a controlled event is advanced or retarded in an IC engine by emulating the engine speed and position signal pattern prior to transmission of that signal pattern to an output such as a fuel injector. In a multi-controller engine in which a second controller is controlled at least in part by signals delivered by first controller, the signal preferably is emulated in the first controller prior to transmission to the second engine controller in order to allow the shifting of a timing of a controlled event without direct data transfer from the second controller to the first controller. The technique is particularly well-suited for controlling diesel fuel injection in a dual fuel or other multi-fuel engine. In this case, the first controller must be a dual fuel controller and the second controller may be a diesel controller.

Abstract: A method of fueling an internal combustion engine including operating the internal combustion engine in a dual-fuel mode in which the engine is fueled by a pre-mixed charge of fresh air, recirculated exhaust gases, gaseous fuel as primary fuel and early injected liquid fuel as a secondary fuel, ignited by a late injected pilot fuel to provide low temperature combustion. The method further includes adjusting EGR and/or fresh airflow to the engine to maintain peak in-cylinder temperature in a desired range, preferably between 1500 K and 2000 K. EGR preferably is controlled to obtain a desired in-cylinder O2 mole fraction, and fresh airflow preferably is controlled to obtain a desired fresh air lambda.

Abstract: A computer-implemented method is used to correct deviations between a predicted gas excess air ratio and a calculated excess air ratio in a dual fuel engine or other gas fueled compression ignition engine. The method includes determining gas excess air ratio for the engine based at least in part on at least one detected current operating parameter and calculating a predicted exhaust gas oxygen concentration engine based on the predicted gas excess air ratio. A time based filtered predicted exhaust gas oxygen concentration value may then be calculated and compared to a time-based filtered measured exhaust gas oxygen concentration value. The resultant oxygen concentration deviation value may be used to generate a corrected predicted gas excess air ratio.

Abstract: A computer-implemented method is used to correct deviations between a predicted gas excess air ratio and a calculated excess air ratio in a dual fuel engine or other gas fueled compression ignition engine. The method includes determining gas excess air ratio for the engine based at least in part on at least one detected current operating parameter and calculating a predicted exhaust gas oxygen concentration engine based on the predicted gas excess air ratio. A time based filtered predicted exhaust gas oxygen concentration value may then be calculated and compared to a time-based filtered measured exhaust gas oxygen concentration value. The resultant oxygen concentration deviation value may be used to generate a corrected predicted gas excess air ratio.

Abstract: The timing of a controlled event is advanced or retarded in an IC engine by emulating the engine speed and position signal pattern prior to transmission of that signal pattern to an output such as a fuel injector. In a multi-controller engine in which a second controller is controlled at least in part by signals delivered by first controller, the signal preferably is emulated in the first controller prior to transmission to the second engine controller in order to allow the shifting of a timing of a controlled event without direct data transfer from the second controller to the first controller. The technique is particularly well-suited for controlling diesel fuel injection in a dual fuel or other multi-fuel engine. In this case, the first controller must be a dual fuel controller and the second controller may be a diesel controller.

Abstract: A method of transitioning between operating modes in a multimode engine including a diesel-only mode and a diesel pilot, gas mode includes first terminating or initiating the supply of a gaseous fuel, depending on whether the system is transitioning to or from the pilot mode, and thereafter decreasing or increasing the diesel fuel supply quantity. Liquid fuel supply quantity is preferably altered in steps rather than discretely in order to avoid exceeding the lean limit of gas lambda. The number of steps and the percentage decrease or increase in each step preferably varies based at least in part on prevailing speed and load conditions.

Abstract: A method of transitioning between operating modes in a multimode engine including a diesel-only mode and a diesel pilot, gas mode includes first terminating or initiating the supply of a gaseous fuel, depending on whether the system is transitioning to or from the pilot mode, and thereafter decreasing or increasing the diesel fuel supply quantity. Liquid fuel supply quantity is preferably altered in steps rather than discretely in order to avoid exceeding the lean limit of gas lambda. The number of steps and the percentage decrease or increase in each step preferably varies based at least in part on prevailing speed and load conditions.

Abstract: Apparatus for controlling emissions from an internal combustion engine including an enclosed housing one end of which is provided with an inlet and the other end an outlet. A coaxial tubular member extends from the inlet into the housing. A catalytic cell surrounds the tubular member and separates two chambers, a first surrounding the tubular member near the inlet and the other on the opposite side of the catalytic cell. Exhaust gases from the internal combustion engine flow through the tubular member, expanding into the other chamber, then through the catalytic cell for conversion of nitrogen oxides, carbon monoxide and unburned hydrocarbons to less noxious components, expanding into the first chamber for eventual discharge through the outlet.

Abstract: At least one engine operating parameter other than total fuel energy content is taken into account when transitioning between operating modes in a dual fuel or other multimode engine (20) in order to maintain a smooth transition between modes. The parameter preferably comprises at least one of primary fuel excess air ratio (lambda) and ignition timing and preferably is controlled in addition to total fuel energy content control. Lambda control is especially beneficial because it permits the control system to compensate for the engine's inability to substantially alter the instantaneous air mass in the combustion chamber during the transition period. For instance, during a transition from pilot ignited gaseous fuel mode to diesel mode, the controlled parameter preferably comprises diesel lambda, and the controlling step comprises setting diesel lambda at a relatively high value at the beginning of the transition period and thereafter reducing diesel lambda during the transition period.

Abstract: A liquid primary fuel is ignited by HCCI with the assistance of the early injection of a liquid pilot fuel. Pilot fuel injection and/or ignition are preferably controlled so as to permit the injected pilot fuel to become thoroughly distributed through and mixed with the primary fuel/air charge in the combustion chamber and vaporized prior to ignition. Pilot fuel having a lower autoignition temperature will be ignited by compression ignition, followed by the ignition of the homogeneous mixture of the primary fuel and air. HCCI combustion of the primary fuel is facilitated by 1) selection of the properties of the primary and pilot fuels and 2) obtaining a homogenous mixture of primary fuel and air by injecting primary fuel into the engine's intake air stream in the form of finely atomized droplets having a mean diameter in the micron range.

Abstract: An EGR equipped internal combustion engine is controlled to maximize the beneficial effects and minimize the detrimental effects of EGR on engine operation. Specifically, at least one parameter indicative of the O2 concentration in the intake mixture and/or at least one parameter indicative of the H2O concentration in the intake mixture is monitored, and the monitored parameter is relied on to control one or more aspects of engine operation by open loop adjustment of other control strategies and/or by a separate closed loop control strategy. These controls are applicable to virtually any engine, and are particularly beneficial to lean burn engines such as diesel (compression ignition) engines, spark ignited natural gas engines, and dual fuel or other compression ignited natural gas engines. The engine may be equipped with either actively controllable EGR or passive and uncontrolled EGR.

Abstract: EGR mass fraction or a value indicative thereof can be calculated based on temperature measurements rather than mass flow and/or pressure measurements, hence negating the need for expensive and relatively unreliable measurement devices in an active EGR system for an internal combustion engine. The EGR system may be a low pressure EGR system configured to direct cooled, filtered EGR to the engine's air intake system using an effective, simple venturi and/or a continuously regenerated catalytic particulate trap. The resultant system can reduce NOx emissions in a diesel engine on the order of 50% and approximately 90% for CO, HC, and PM. NOx and other emissions can be reduced still further when the EGR system is combined with other pretreatment and/or after treatment devices. Many components of the low pressure EGR system are also usable in a passive EGR system.

Abstract: A control system for a dual fuel engine that can operate in either dual fuel mode or in diesel only mode includes two controllers. One controller controls operation of the gaseous fuel supply system, and the other controls the liquid fuel supply system. Each controller receives signals from sensors monitoring particular engine operation characteristics and is able to transmit the data it collects to the other controller by way of a broadband communications link such as a controller area network (CAN). When the engine is operating in dual fuel mode, one controller directly controls the gaseous fuel supply and also controls the liquid fuel supply by its control of the other controller. When the engine is operating in diesel only mode, the other controller controls all aspects of engine operation. A method of controlling operation of a dual fuel engine is also disclosed.