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.

Embodiments of the present invention include a method and computer readable memory for supplying conditioned natural gas to dual fuel engines. Some embodiments of the present invention include an apparatus and process for controlling and optimizing the heating value or BTU per cubic foot of gas (BTU/cf) of the natural gas substituted for diesel fuel in the operation of transport vehicles and field equipment such as generators.

Embodiments of the present invention include a method and apparatus for supplying conditioned natural gas to dual fuel engines.

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 operating a motor vehicle provided with a hybrid drive apparatus. The hybrid drive device is equipped with an internal combustion engine that can be operated with a fuel, as well as with an electric engine, and a lubricant is supplied at least intermittently to the internal combustion engine. At the same time, a lubricant dilution value is determined with a dilution of the lubricant so that the internal combustion engine is started when a first threshold value is exceeded by the lubricant dilution value, and when the motor vehicle is located on a regeneration route of an anticipated driving route of the motor vehicle and the regeneration route is sufficient to reduce the lubricant dilution value by a specified value.

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.

Methods and systems are provided for integrating a bi-fuel engine with a CVT transmission. Responsive to a driver demand, a controller may determine whether to maintain usage of a current fuel or transition to an alternate fuel based on the cost efficiency of the transition and further based on any engine limitations that may be incurred at the engine speed-load following the transition. To improve the net fuel economy benefit while addressing the engine limitation, a fuel transition may be combined with a CVT adjusted engine speed-load regime, while maintaining engine power output.

A fuel supply system for a reciprocating-piston engine includes a storage tank; a wall of the storage tank defining a first aperture and a second aperture therethrough; a first fuel injector fluidly coupled with the first aperture of the storage tank via a pressure control module and a first fuel injector supply conduit; a pump fluidly coupled with the second aperture of the storage tank; and a second fuel injector fluidly coupled with an outlet port of the pump via a second fuel injector supply conduit. The pressure control module is configured to maintain a pressure in the first fuel injector supply conduit within a pressure range that includes a pressure value that is less than a pressure inside the storage tank. The pump is configured to maintain a pressure inside the second fuel injector supply conduit that is greater than the pressure inside the first fuel injector supply conduit.

Methods and systems are provided for a multi-fuel engine. In one example, a method includes adjusting a substitution ratio based on an intake manifold temperature. The method further including adjusting the intake manifold temperature to increase the substitution ratio.

The invention relates to a method for operating an internal combustion engine (1), which comprises at least one combustion chamber (3) and an injector (5) which is assigned to the combustion chamber (3) and intended for introducing a first gaseous fuel into the combustion chamber (3), wherein a second liquid fuel is used for operation of the injector (5), wherein in a start-up operation of the internal combustion engine (1) the injector (5) is actuated in at least one operational cycle, avoiding complete combustion of the fuel introduced into the combustion chamber (3) via the injector (5).