Systems and methods for reverse flow detection for a dual fuel engine are disclosed. The engine may include an intake manifold, a liquid fuel supply line and a gaseous fuel supply line, the gaseous fuel supply line including a gaseous fuel supply and a gaseous fuel rail. The method may include: receiving sensed values of gaseous fuel supply pressure, intake manifold pressure, and gaseous fuel rail pressure; determining a threshold value based on the sensed value of gaseous fuel supply pressure; determining a reverse flow in the gaseous fuel supply line based on the sensed values of gaseous fuel supply pressure and gas rail pressure and the determined threshold value; and outputting an indication of reverse flow in response to the determination of reverse flow.

Systems, methods and apparatus for controlling operation of dual fuel engines are disclosed that regulate the fuelling amounts provided by a first fuel and a second fuel during operation of the engine. The first fuel can be a liquid fuel and the second fuel can be a gaseous fuel. The fuelling amounts are controlled to improve operational outcomes of the duel fuel engine.

Methods and systems for cleaning a capless refueling system in a vehicle are disclosed. In one example approach, a method comprises, in response to a leak detected following a refueling event, cleaning the capless refueling system using engine vacuum.

Systems, methods and apparatus for controlling operation of an engine structured to combust gaseous fuel such as a dual fuel engine, including an estimation of key parameters dependent on natural gas quality, are disclosed. The natural gas quality parameters are estimated from natural gas properties obtained from various sensed parameters associated with the engine.

The present invention relates to fuel systems for diesel engines. In particular, the invention relates to a dual fuel supply system (10) for a diesel engine having an indirect-injection system (12). The invention extends to a diesel engine incorporating the dual fuel supply system (10) and to a vehicle that incorporates a diesel engine having the dual fuel supply system (10). The dual-fuel supply system (10) includes a mixed fuel supply system (17) that includes a first stage (14) having a diesel tank (42) and LPG tank (44), and as second stage (16) to supply the fuel mixture to the injection system (12). The dual-fuel supply system (10) also includes diesel supply system (80) for delivering diesel to the injection system (12). Moreover, the dual fuel system (10) is configured to permit selective change over between the diesel supply system (80) and the mixed fuel system (17) to supply the injection system (12) selectively with either diesel or liquid fuel mixture respectively.

A gas supply system, having a gas regulating station for supplying an engine with gaseous fuel and a double-walled gas line extending from the gas regulating station to the engine, which comprises an inner and an outer pipe, in a gas fuel operating mode the inner pipe is flowed through by the gaseous fuel towards an engine-side end of the double-walled gas line, an inert gas purging line, and a first shut-off valve assigned to the inert gas purging line. In a purging mode inert gas can be fed to the outer pipe at the gas regulating station-side, which inert gas flows through the outer pipe in the direction of the engine-side end of the double-walled gas line, where it passes into the inner pipe and flows via the inner pipe towards the gas regulating station-side end of the double-walled gas line.

A fuel booster system having a fuel inlet port, a fuel outlet port, and a fuel accumulator fluidically coupled to both ports. The fuel inlet port allows fuel to be delivered to the fuel accumulator and the fuel outlet port is in fluid communication with a combustion engine to deliver fuel from the fuel booster system to the combustion engine. A source of pressurized gas is also fluidically coupled to the fuel accumulator to deliver pressurized gas through a gas port in one end of the fuel accumulator. A piston is located within the fuel accumulator and the source of pressurized gas can be discharged into the fuel accumulator to force accumulated fuel from the fuel accumulator and to the engine when the fuel booster system determines that the engine needs more fuel.

A dual-fuel supply system (100) for direct injection for engines of heavy vehicles, comprising: a supply line of a combustible liquid (160); a supply line of a combustible gas (170); a plurality of injectors (150) in fluid communication with the supply line of the combustible liquid (160) and with the supply line of the combustible gas (170); a pressure regulator device (1) for regulating the combustible gas; an electronic control unit (ECU) configured to control the supply of combustible liquid and of the combustible gas to the injectors (150), the electronic control unit (ECU) being configured to control the pressure regulator device (1) to track a reference pressure (p.sub.target) according to a feedback logic.

In a fuel pressure control device for an internal combustion engine of the invention, a first map (FIG. 4A) for defining a first target fuel pressure for normal time and a second map (FIG. 5A) for defining a second target fuel pressure for suppressing noise and vibration smaller than the first target fuel pressure are stored. When an acquired fuel temperature is higher than a predetermined temperature, the first target fuel pressure defined in the first map is set as a target fuel pressure (steps 1 to 3), and when the fuel temperature is equal to or lower than the predetermined temperature, the second target fuel pressure defined in the second map is set as the target fuel pressure (steps 1, 5, and 6). The fuel pressure is controlled based on the set target fuel pressure (step 7).

Exemplary embodiments include a method for analysis of fuel supplied to a combustion engine during operation of the engine. The method can include obtaining respective indications of a temperature of the fuel supplied to the engine and a density of the fuel supplied to the engine; deriving a temperature-adjusted fuel density based on the indicated density of fuel in dependence of relationship between the indicated temperature of the fuel and a predefined reference temperature; and deriving, based at least on the temperature-adjusted fuel density, a heating value that is descriptive of the amount of heat released during combustion of a predefined amount of the fuel.