A combustion system is applied to an engine. The combustion system includes an injection device that injects a fuel into a combustion chamber, a spark plug that ignites fuel in the combustion chamber, and a control device that controls the injection device and the spark plug. The control device includes a first control unit that executes predetermined first control. In the first control, control is performed such that, a total injection amount corresponding to all the fuel injected by the injection device in one combustion cycle of the engine is injected within a first period corresponding to a period from valve close timing which brings an intake valve into a closed state until a first half of a compression stroke of the engine ends.

A variety of methods and arrangements for reducing noise, vibration and harshness (NVH) in a skip fire engine control system are described. In one aspect, a firing sequence is used to operate the engine in a skip fire manner. A smoothing torque is determined that is applied to a powertrain by an energy storage/release device. The smoothing torque is arranged to at least partially cancel out variation in torque generated by the skip fire firing sequence. Various methods, powertrain controllers, arrangements and computer software related to the above operations are also described.

An ignition assembly configuration in piston engine with a main piston and an auxiliary piston, the ignition assembly is mounted on the cylinder wall and connects to the combustion chamber; the ignition assembly comprises an connection cut-out passage, an ignition device, or ignition device combined with a fuel injection nozzle, or an ignition device combined with a fuel injection nozzle and a pressure sensor passage. Wherein the auxiliary piston has a by-pass passage to keep the ignition assembly connected to the combustion chamber when the auxiliary piston moves down below the uppermost position of the main piston and blocks the ignition assembly cut-out passage; wherein the uppermost position of the ignition assembly is at or aligned with the uppermost position of the auxiliary piston in combustion stroke, the lowermost position of the ignition assembly is at or aligned with the uppermost position of the main piston. Fuel-water injection, multiple fuel injections and combustions can be easily practiced in the new configuration.

Methods and systems of controlling operation of a dual fuel engine are provided, comprising determining a target exhaust temperature, sensing an actual exhaust temperature, determining an exhaust temperature deviation by comparing the actual exhaust temperature to the target exhaust temperature, comparing the exhaust temperature deviation to a threshold, adjusting at least one of an intake throttle, a wastegate, a compressor bypass valve, an exhaust throttle, a VGT and engine valve timing when the exhaust temperature deviation exceeds the threshold to control charge-flow to the engine, and continuing the adjusting until the exhaust temperature deviation is less than the threshold.

In a method for operating an internal combustion engine of a motor vehicle having an automatic transmission, a torque generated by the internal combustion engine is reduced as a function of an operating state of a drive train of the motor vehicle. As a function of an excess of combustion air occurring when the torque is reduced and supplied to the internal combustion engine by an exhaust gas turbocharger, fuel combustion efficiency in at least one combustion chamber of the internal combustion engine, which is related to the torque generated by the combustion chamber, is reduced. The combustion efficiency is reduced by at least one late post-injection of fuel into the at least one combustion chamber of the internal combustion engine.

The present invention relates to a method for operating an internal combustion engine provided as a medium-speed gas engine or dual fuel engine in a gas fuel mode. The method comprises the step of directly injecting a gas fuel into a combustion chamber of the engine at a maximum injection pressure that is lower than a compression-end pressure of the engine.

Methods and systems are provided for a vehicle engine having a pre-chamber ignition system. In one example, a method may include adjusting one or more of an air injection amount and a fuel injection amount to a pre-chamber of an engine based on an air injection offset and a fuel injection offset learned while discontinuing fueling to cylinders of the engine and reducing air flow through the engine. In this way, air and fuel may be more accurately provided to the pre-chamber, thereby decreasing an occurrence of pre-chamber misfire.

An electronic control unit of an internal combustion engine is configured to, when cooling fuel is supplied to a combustion chamber, calculate a target amount of supply of the cooling fuel and calculate a first upper limit injection amount that is an upper limit of an amount of fuel allowed to be injected from a second valve as the cooling fuel, when the target amount of supply is less than or equal to the first upper limit injection amount, supply the cooling fuel in the entire target amount of supply from the second valve to the combustion chamber in a first mode in which single-stage injection is performed, and, when the target amount of supply is greater than the first upper limit injection amount, supply the cooling fuel to the combustion chamber in a second mode in which the cooling fuel more easily diffuses than in the first mode.

An engine according to an embodiment includes at least one cylinder, at least one piston disposed in the at least one cylinder, a plurality of fuel injection valves disposed on the at least one cylinder, the plurality of fuel injection valves including a first fuel injection valve having a predetermined total hole area and a second fuel injection valve having a total hole area smaller than the total hole area of the first fuel injection valve, and a control device for controlling the first fuel injection valve and the second fuel injection valve according to a load of the engine.

Systems and methods for operating an engine that includes an exhaust system with a differential pressure sensor are described. In one example, output of the differential pressure sensor is compared to output of a barometric pressure sensor to determine whether or not the barometric pressure sensor is degraded. The output of the differential pressure sensor may be monitored while the engine is rotated without being fueled.