466 results about "Auto ignition" patented technology

The present invention relates to methods for robust controlled auto-ignition and spark ignited combustion controls in gasoline direct-injection engines, including transients, using either exhaust re-breathing or a combination of exhaust re-compression and re-breathing valve strategy. These methods are capable of enabling engine operation with either lean of stoichiometric or stoichiometric air/fuel ratio for oxides of nitrogen (NOx) control, with varying exhaust gas recirculation (EGR) rates and throttle valve positions for knock control, and with a combination of homogeneous charge compression ignition (HCCI) and spark ignition (SI) combustion modes to optimize fuel economy over a wide range of engine operating conditions.

A system and method for enhanced combustion control in an internal combustion engine is disclosed. A fuel supply system has a fuel injector positioned to directly inject fuel into a combustion chamber, and it is capable of performing a split injection wherein a first fuel injection in each engine cycle precedes a second fuel injection that occurs during compression stroke in the same engine cycle. A spark plug produces a spark to ignite a first air/fuel mixture portion created due to the second fuel injection, initiating a first stage combustion. The first stage combustion raises temperature and pressure high enough to cause auto-ignition of a second air/fuel mixture portion surrounding the first air-fuel mixture portion, initiating a second stage combustion. An engine controller is programmed to perform control over initiation timing of the second stage combustion in response to at least one of the engine speed and load. This control is accomplished by varying at least one of a fuel injection timing of the first fuel injection, a fuel injection timing of the second fuel injection, spark timing, a proportion of fuel quantity of the second fuel injection to the total fuel injected in each engine cycle, and an EGR rate in response to at least one of engine speed and load.

A method is provided for control of transition between combustion modes of a direct-injection engine operable in a homogeneous charge compression ignition (HCCI) mode at lower loads and a spark ignition flame propagation (SI) mode at higher loads. The engine includes a variable valve actuation system including two-step high and low lift valve actuation and separate cam phasing for both intake and exhaust valves. The method includes operating the engine at steady state, with fuel-air-exhaust gas mixtures at predetermined conditions, for each speed and load, and controlling the engine during mode changes between the HCCI mode and the SI mode by switching the exhaust and intake valves between low lift for HCCI operation and high lift for SI operation. High load may be an SI throttled mode with an intermediate unthrottled mode (SI/NTLC} in which transition between HCCI and SI/NTLC modes requires switching only the exhaust valve lift and transition between SI/NTLC and SI throttled modes requires switching only the intake valve lift, with predetermined phase adjustments in the valve timing phasing.

A method of operating an internal combustion engine including at least a combustion chamber having a piston disposed therein, wherein the combustion chamber is configured to receive air, a first fuel and a second fuel to form a substantially homogeneous mixture, and wherein the piston is configured to compress said mixture so that auto-ignition of said mixture is achieved is disclosed. The method comprises varying the amount of at least one of the first fuel and the second fuel that is received by the combustion chamber to adjust the timing of auto-ignition, where the first fuel includes diesel fuel and the second fuel includes such low cetane fuels as: methanol and ethanol.

The present invention concerns a method and a system for operating an internal combustion engine capable of performing auto-ignition combustion as well as spark-ignition combustion. In auto-ignition combustion mode, inlet and outlet control devices are adjusted to retain a portion of exhaust gas for subjecting the retained exhaust gas to compression. In one preferred embodiment, a parameter indicative of engine-surrounding environment is monitored. Closing timing of the outlet control device is adjusted in response to the monitored parameter, thereby to vary an exhaust gas retaining duration when there is a change in the monitored parameter.

A method of operating an electronically controlled dual fuel compression ignition engine includes injecting a pilot ignition quantity of liquid fuel into an engine cylinder from a dual fuel injector in an engine cycle during an auto ignition condition. An amount of gaseous fuel is also injected into the engine cylinder from the dual fuel injector in the same engine cycle. The amount of gaseous fuel is divided between a pre-mix quantity of gaseous fuel, which may be injected about 90° before top dead center, and a post ignition quantity of gaseous fuel that may be injected after top dead center, with both quantities being greater than zero. An engine controller may change a ratio of the pre-mix quantity of gaseous fuel to the post ignition quantity of gaseous fuel responsive to changing from a first engine speed and load to a second engine speed and load. The pilot ignition quantity of liquid fuel is compression ignited, which in turn causes the gaseous fuel to be ignited. A pre-mix quantity of liquid fuel may also be included in order to speed the combustion process at higher engine speeds.

An auto-ignition timing control and calibration method for use in an internal combustion engine having more than one ignition modes including the mode of compression ignition of a premixed fuel/air mixture (CAI/HCCI), wherein when the engine is operating in the CAI/HCCI mode, in order to determine a prescribed setting or combination of settings of engine operating parameters necessary to achieve a target auto-ignition timing according to a predetermined auto-ignition timing map, the associated compression temperature trajectory of the cylinder charge with time, calculated in dependence on the initial and boundary conditions of the said charge subjected to the said prescribed setting or combination of settings of the said engine operating parameters, and further in dependence on the interim heat exchange processes affecting the said charge, is used for testing and verifying that the said trajectory reaches a target temperature at a target reference timing relative to TDC of the engine, and wherein the said target temperature and timing are predetermined by calibration.

Part load operating point for a controlled auto-ignition four-stroke internal combustion engine is reduced without compromising combustion stability through negative valve overlap control operative to retain and compress combusted gases within the combustion chamber into which fuel is introduced. Combustion chamber pressures and temperatures are increased as engine load decreases. Various split-injection fuel controls are implemented during low and intermediate part load operation whereas a single-injection fuel control is implemented during high part load operation. Split-injections are characterized by lean fuel/air ratios and single-injections are characterized by either lean or stoichiometric fuel/air ratios. Controlled autoignition is thereby enabled through an extended range of engine loads while maintaining acceptable combustion stability and emissions.

A method to operate a multi-cylinder direct-injection engine in one of a controlled auto-ignition and a spark-ignition combustion mode is described. Engine operation and an operator torque request are monitored. Fuel delivery to a portion of the cylinders is selectively deactivated and torque output from non-deactivated cylinders is selectively increased to achieve the operator torque request when the monitored engine operation is above a predetermined threshold. An engine operating point at which an engine load demand exceeds an operating capability of the engine in a stoichiometric HCCI mode is identified. The engine is selectively operated in an unthrottled spark-ignition mode with at least one cylinder unfueled and torque output from the remaining cylinders is selectively increased.

In an internal combustion engine a fuel-air mixture having compression temperatures and pressures sufficiently low as not to support auto ignition, ignition is achieved by injecting igniting active radicals into the air-fuel mixture. In one embodiment the active radicals are provided by withdrawing a portion of the mixture, treating it to produce active radicals in the portion and returning the portion to the mixture. Treatment of the portion typically includes simultaneously injecting, mixing, and compression of a predetermined amount of pilot fuel within the portion.

A direct injection controlled auto-ignition engine is operated at steady state, within a homogeneous charge compression-ignition (HCCI) load range and with fuel-air-diluent mixtures at predetermined conditions, for each speed and load, of engine control inputs, including at least injection timing (FI), spark timing (SI), throttle position, exhaust gas recirculation (EGR) valve setting and exhaust recompression obtained by negative valve overlap (NVO). During engine speed transients, the control inputs are synchronized to changes in the current engine speed, and also with any concurrent changes in the engine fueling rate. Inputs that are inactive during all or part of a speed change have a zero change rate while inactive. The method maintains robust auto-ignition combustion during speed transients with constant or variable fueling rates and with or without load changes.

In a method for operating an internal combustion engine in which fuel is injected directly into a combustion chamber in a pre-injection and a main fuel injection step, and, if appropriate, also in a post-injection step by means of an injection nozzle with a plurality of injection bores, the injection of fuel takes place in a timed fashion and, to limit pressure and temperature during combustion of the fuel in the combustion chamber, a quantity of water is introduced into the combustion chamber during or after the pre-injection step.

A method of operating an internal combustion engine having a combustion chamber with a piston and a spark plug, comprising during a first mode, bringing the temperature of the combustion chamber to auto-ignition temperature by adjusting engine operating conditions and producing auto-ignition in said combustion chamber without requiring spark from said spark plug; and during a second mode, bringing the temperature of the combustion chamber close to auto-ignition temperature by adjusting engine operating conditions, forming a small cloud of stratified air-fuel mixture near said spark plug, igniting said fuel cloud by a spark form said spark plug, and then causing cylinder pressure to rise, thereby producing auto-ignition at other sites in said combustion chamber wherein said first mode is implemented in a first operating range and said second mode is implemented only in a second operating range where engine speed and load are lower than said first operating range.

The technique of the present invention produces a first fuel-air mixture containing a first fuel and the air at a specific ratio, which does not allow for auto ignition of the first fuel-air mixture by simple compression, in a combustion chamber. The technique then injects a second fuel, which has a higher octane value than that of the first fuel, into a partial area of the combustion chamber, so as to produce a second fuel-air mixture. The technique ignites the second fuel-air mixture for combustion, so as to compress and auto-ignite the first fuel-air mixture. The second fuel has the higher octane value, so that a combustion start timing of the second fuel-air mixture is reliably regulated by ignition. Namely the technique positively controls the timing of auto ignition of the first fuel-air mixture. Setting an adequate value to the ignition timing thus effectively prevents the occurrence of knocking in an internal combustion engine that adopts a premix compression ignition combustion system.