A dual fuel system for a combustion engine includes an air and fuel mixer configured to mix air and fuel provided to the combustion engine, a first fuel path for a first fuel, and a second fuel path for a second fuel. The first and second fuels have different physical and chemical properties. The dual fuel system also includes a common fuel path coupled to the air and fuel mixer and both the first and second fuel paths, wherein the common fuel path includes an electronically controlled valve configured to regulate the air to fuel ratio of an air/fuel mixture provided to the combustion engine in response to control signals from a controller, and both the first and second fuel paths are coupled to the common fuel path at a location upstream of the electronically controlled valve.

One exemplary embodiment is a system comprising a dual-fuel engine structured to selectably combust a first fuel type and a second fuel type, and an electronic control system in operative communication with the dual-fuel engine. The electronic control system is structured to control a transition of the dual-fuel engine from a dual-fuel mode to a single-fuel mode. After initiating the transition from the dual-fuel mode to the single-fuel mode, the control system stops provision of the second fuel type, requires combustion using control parameters configured for the dual-fuel mode until a transition ventilation condition is satisfied, permits non-emergency commanded engine shutdown only if the transition ventilation condition is satisfied.

When switching the fuel to be used for engine operation from gasoline to CNG, in a state where CNG is supplied experimentally to one cylinder serving as a judgment object and gasoline is supplied to other cylinders, whether or not CNG can be supplied to the cylinder serving as a judgment object is judged based on an amount of change Pc in fuel pressure inside a CNG delivery pipe (Step S13 to Step S16). When it is judged that a gas fuel can be supplied to all cylinders (Step S19: YES), the fuel to be used for engine operation is switched from the liquid fuel to the gas fuel (Step S20).

A device is provided, which makes it possible to perform a failure diagnostics for a filter more accurately even in the case of an internal combustion engine which is constructed to be capable of using both of gaseous fuel and liquid fuel. The device of the invention comprises judging means which judges any failure of the filter by comparing the added-up amount of the particulate matter contained in the exhaust gas as detected by a PM amount detecting sensor during a predetermined period and the added-up amount of the particulate matter contained in the exhaust gas as estimated by PM amount estimating means during the predetermined period, wherein the PM amount estimating means estimates the added-up amount of the particulate matter contained in the exhaust gas on the basis of the predetermined parameter and only a fuel injection amount of the liquid fuel out of a fuel injection amount of the gaseous fuel and the fuel injection amount of the liquid fuel.

An engine control system is a system configured to selectively switch between first fuel and second fuel and perform an operation control of a single engine, including: a sensor configured to detect an oxygen concentration of an exhaust gas that is exhausted from the engine; and a control device configured to perform an air-fuel ratio feedback control such that an air-fuel ratio becomes a target air-fuel ratio based on an output signal of the sensor, wherein the control device calculates a correction coefficient of an air-fuel ratio feedback control during an operation with the second fuel, and further stores a fuel composition correction coefficient that is a value in a predetermined range and corrects a difference between the calculated correction coefficient and a targeted correction coefficient arising from a change in composition of the second fuel.

A dual fuel injector may be used to inject both gas and liquid fuel into a cylinder of a compression ignition engine. An injector body defines a first set of nozzle outlets, a second set of nozzle outlets, a first fuel inlet and a second fuel inlet. A dual solenoid actuator includes a first armature, a first coil, a second armature and a second coil that share a common centerline. The dual solenoid actuator has a non-injection configuration at which the first armature is at an un-energized position and the second armature is at an un-energized position. The dual solenoid actuator has a first fuel injection configuration at which the first fuel inlet is fluidly connected to the first set of nozzle outlets, the first armature is at an energized position and the second armature is at the un-energized position.

A method of operating a vehicle powertrain includes determining a selected powertrain operational mode. A demand fraction is determined. An internal combustion engine (ICE) is to output a maximum power when a gaseous fuel is conveyed to an injector of the ICE at a source pressure greater than a cutoff pressure. The source pressure in a container in fluid connection with the injector is determined. The gaseous fuel is received at the source pressure by the injector to inject the gaseous fuel into the ICE for combustion in response to the source pressure, demand fraction, or selected powertrain operation mode meeting a first set of criteria. The injector is prevented from injecting the gaseous fuel into the ICE and the powertrain is driven from an alternative power source in response to the source pressure, demand fraction, or selected powertrain operation mode meeting a second set of criteria.

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 control apparatus is applied to an internal combustion engine in which fuel used for operation is changed between liquid fuel containing alcohol and gas fuel. The control apparatus includes an electronic control unit configured to prohibit use of the gas fuel when a ratio of dilution of lubricating oil by the liquid fuel in a lubricating oil storage portion of the internal combustion engine is equal to or larger than a predetermined value or when an amount of the liquid fuel mixed in the lubricating oil in the lubricating oil storage portion is equal to or larger than a predetermined amount.

A method of controlling a dual fuel engine configured to receive a first fuel and a second fuel includes operating the engine using the first fuel, measuring a current load of the engine, sending a first signal to a first fuel system to deliver an amount of the first fuel to the engine, and determining at least one first operating parameter associated with the engine. The method also includes determining an engine load estimate based on the first signal and the at least one first operating parameter, comparing the engine load estimate to the measured load, and based on the comparison, determining, an adjusted engine load estimate to compensate for a drift in the first fuel system.