A fuel estimation apparatus includes a combustion characteristic acquisition portion and a mixing ratio estimation portion. The combustion characteristic acquisition portion acquiring a combustion characteristic value indicating a physical amount relating to a combustion of an internal combustion engine acquires the combustion characteristic values of the combustions executed in different combustion conditions. The mixing ratio estimation portion estimates the mixing ratios of various components included in a fuel, based on the combustion characteristic values acquired by the combustion characteristic acquisition portion.

A combustion system controller controls an operation of a combustion system including an internal combustion engine. The combustion system controller includes a mixing ratio acquisition portion and a control portion. The mixing ratio acquisition portion acquires the mixing ratios of various components included in a fuel. The control portion controls the operation of the combustion system based on the mixing ratios acquired by the mixing ratio acquisition portion.

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.

Various methods and systems are provided for venting fuel lines in a dual-fuel engine. In one example, a method may include in response to an engine shut-down request, venting fuel lines to remove hydrogen from the fuel lines.

The invented system adds some petrol fuel to the vehicle engine which runs with natural gas (CNG or LPG). It causes a simultaneous combustion of petrol and natural gas (CNG or LPG). This action decreases depreciation of engine, increases power of the engine and reduces fuel consumption in natural gas vehicles. The above-mentioned system consists of an innovative petrol holder storage, an electronically circuit, a relay, a lever micro switch and a petrol fuel injector. Whenever the accelerator pedal is pressed more than a certain amount, the system will be activated and command to inject petrol collected in the storage into the air manifold.

Methods and systems are provided for adjusting a location of a fuel injection in response to a substitution rate and a desired EGR flow. In one example, a method may include injecting a first fuel to a combustion chamber via a direct injector positioned to inject directly into the combustion chamber, injecting a second, different, fuel to the combustion chamber via an exhaust port injector positioned to inject toward an exhaust valve of the combustion chamber, and combusting the first and second fuels together in the combustion chamber.

Methods and systems are provided for adjusting the amount of secondary fluid being injected into an engine. In one example, a method may include adjusting an amount of secondary fluid injected at an engine cylinder based on a secondary fluid injection amount estimated from outputs of an exhaust oxygen sensor. For example, the secondary fluid injection amount may be estimated based on a first change in pumping current of the exhaust oxygen sensor between a first and second reference voltage when only fuel is injected into the engine cylinder and a second change in pumping current of the exhaust oxygen sensor between the first and second reference voltage when fuel and the secondary fluid are injected into the engine cylinder.

The present invention discloses a method of introducing fuel into a diesel engine for combustion within the engine. A natural gas in liquid form is injected into the engine for combustion therein with diesel fuel so as to maintain a natural gas concentration derived from the liquid in the range of greater than 0.6% to 3.0% of air intake by volume of natural gas. Suitable gases include natural gas, methane or substantially methane gas mixtures and substitute natural gas such as propane air mixtures providing a mixture with similar combustion properties to methane/natural gas.

Various methods and systems are provided for using only hydrogen as fuel in a duel fuel engine. In one example, a method may include direct injecting only hydrogen as fuel to one or more engine cylinders and compression igniting the injected hydrogen.

A system may include a first methanol tank and a second methanol tank connected to the first tank. The system may include a first valve fluidly connected to the first methanol tank and the second methanol tank. The system may include a heat exchanger connected to the second methanol tank and a turbine of a turbocharger. The system may include a second valve fluidly connected to an intake system of an engine.