Various methods and systems are provided for an engine with an exhaust gas treatment system. In one example, under a first condition, a first fuel is delivered for combustion in the engine. Under a second condition, a second fuel is delivered for combustion in the engine, the second fuel different than the first fuel. Under a third condition, the first fuel is delivered as a reductant for the exhaust gas treatment system.

An internal combustion engine to which the apparatus is applied is a multi-cylinder internal combustion engine that includes a passage injection valve and a cylinder injection valve and that can use gasoline and alcohol as fuel. The apparatus performs abnormality determination for a determination object device, based on a detection signal of an oxygen sensor provided in an exhaust passage of the internal combustion engine. The concentration sensor detects alcohol concentration ALp of the fuel in a first fuel passage through which the fuel is fed to the passage injection valve, and alcohol concentration ALd of the fuel in a second fuel passage through which the fuel is fed to the cylinder injection valve. When a difference AL between the alcohol concentrations ALp, ALd is a determination value or greater (S13: YES), the execution of the abnormality determination is prohibited (S12).

A control device calculates an estimate of negative intake pressure based on the relationship between the rotation speed of a crankshaft and a throttle opening degree (Step S24). Then, the control device sets the estimate PE of the negative intake pressure, which is calculated in Step S24, to a greater value as combustion efficiency of CNG used in engine operation becomes higher (Step S25). When the corrected estimate PE of the negative intake pressure becomes smaller than or equal to a reference value PTh (Step S26: YES), the control device starts a negative pressure recovery procedure (Step S27).

A dual-fuel injection system having a combustion gas-supply device and a liquid fuel-supply device, including a combustion gas-injector unit with a liquid fuel-control part and a gas nozzle part, to which combustion gas can be supplied. The stroke of a gas nozzle needle of the combustion gas-injector unit can be controlled by liquid fuel supplied to the liquid fuel-control part. The combustion gas-injector unit defines a leakage collecting space, via which a leakage path is lead, the leakage path extending from the liquid fuel-control part into the gas nozzle part. The dual-fuel injection system has a pressure-regulating device, by which a defined pressure level can be set in the leakage collecting space. An implementation method using such a dual-fuel injection system is also proposed.

In a control system for an internal combustion engine that can use a plurality of kinds of fuel including compressed natural gas, the invention prohibits a changeover from CNG to another fuel from being made in a period from a time when CNG is used for the first time after the start of the internal combustion engine to a time when it is determined that properties of CNG do not need to be learned, or a period from the time when CNG is used for the first time after the start of the internal combustion engine to a time when a processing of learning the properties of CNG ends.

Various methods and systems are provided for maintaining combustion stability in a multi-fuel engine. In one example, a system comprises a first fuel system to deliver liquid fuel to at least one cylinder of an engine, a second fuel system to deliver gaseous fuel to the at least one cylinder, and a controller. The controller is configured to supply the gaseous fuel to the at least one cylinder, inject the liquid fuel to the at least one cylinder thereby to ignite the liquid fuel and the gaseous fuel in the at least one cylinder via compression-ignition, and adjust an amount of the gaseous fuel relative to an amount of the liquid fuel based on a measured parameter associated with auto-ignition of end gases subsequent to the compression-ignition of the liquid fuel.

A technique for fuel system protection for an internal combustion engine includes introducing a directly injected fuel into a combustion chamber through a direct fuel injector, introducing a fumigated fuel upstream of an intake valve, selectively operating the internal combustion engine with at least one of the directly injected fuel and the fumigated fuel, determining a temperature of the direct fuel injector as a first function of engine operating parameters, and performing a temperature mitigation technique when the temperature rises above a first predetermined value such that the temperature is maintained below a second predetermined value.

A method for a turbocharged engine, comprising: during high load conditions, in response to an elevated engine temperature, after port injecting a first quantity of a first gaseous fuel, direct injecting a second quantity of a second, liquid fuel at a first timing that is a function of a desired air-fuel ratio. In this way, engine power may be maximized while simultaneously decreasing the maximum combustion temperature and mitigating engine knock.

An engine device, which employs various types of fuels, plural fuel pipes can compactly be disposed without being thermally affected by exhaust gas. In the engine device, a gas fuel pipe that supplies gas fuel to a gas injector, a fuel oil pipe that supplies liquid fuel to a main fuel injection valve are disposed to be divided on both sides of a row of head covers arranged in a line. In addition, in the engine device, an intake manifold that supplies air taken in by a main combustion chamber toward an intake valve extends in parallel to the row of head covers in a cylinder block, and the fuel gas pipe and the intake manifold are arranged on the same side of the row of head covers.

An ignition timing control device for an internal combustion engine including: a setting unit configured to set a target ignition timing of the internal combustion engine based on a reference ignition timing and an advance correction amount; a start determination unit configured to determine, based on change in an alcohol concentration, whether or not the fuel injected from a fuel injection valve starts to switch from a first fuel to a second fuel higher in the alcohol concentration than the first fuel; a completion determination unit configured to determine whether or not switching to the second fuel is completed; a restriction unit configured to restrict the advance correction amount during a switching period to the advance correction amount corresponding to the alcohol concentration of the first fuel or lower; and a cancel unit configured to cancel restriction of the advance correction amount after the completion of the switching is determined.