In a method, dynamic pressure oscillations in the intake tract or outlet tract of a respective internal combustion engine are measured during normal operation, and from these measured oscillations, a corresponding pressure oscillation signal is generated. A crankshaft phase angle signal is determined at the same time. From the pressure oscillation signal, an actual value of at least one characteristic of at least one selected signal frequency of the measured pressure oscillations in relation to the crankshaft phase angle signal is determined, and the current trimming of the intake tract is determined on the basis of the determined actual value, taking into consideration reference values of the corresponding characteristic of the respectively identical signal frequency for different trimmings of the intake tract.

A lubricity estimation device is applied to a fuel supply system that supplies a fuel to an internal combustion engine, and includes a mixing ratio estimation unit and a lubrication index calculation unit. The mixing ratio estimation unit estimates the mixing ratio of each of plural types of molecular structures included in the fuel. The lubrication index calculation unit calculates a lubrication index, representing the lubricity of an outer peripheral portion S1 of the piston of a fuel pump and an outer peripheral portion of the valve body of a fuel injection valve by the fuel, based on the mixing ratio estimated by the mixing ratio estimation unit.

Methods and systems are provided for estimating ethanol content in fuel and an age of the fuel in a vehicle engine. In one example, a method may include estimating fuel ethanol content and/or fuel age based on fuel temperature, a speed of sound in fuel, and an attenuation co-efficient of an ultrasonic signal in fuel. One or more engine operating parameters may be adjusted based on the estimated fuel ethanol content and fuel age.

Methods and systems are provided for estimating ethanol content in fuel, water content in fuel, and an age of the fuel in a vehicle engine. In one example, a method may include estimating fuel ethanol content, water content, or fuel age based on fuel rail temperature, and two or more of a resonant frequency (f) of pressure pulsations, a change in fuel rail pressure (p), and a damping coefficient () of pressure pulsations in the fuel rail as estimated after a fuel injection or a pump stroke. One or more engine operating parameters may be adjusted based on the estimated fuel ethanol content, water content, and fuel age.

Methods and systems are provided for estimating ethanol content in fuel, water content in fuel, and an age of the fuel in a vehicle engine. In one example, a method may include estimating fuel ethanol content, water content, or fuel age based on a resonant frequency (f) of pressure pulsations, a change in fuel rail pressure (p), and a damping coefficient () of pressure pulsations in the fuel rail as estimated after a fuel injection or a pump stroke. One or more engine operating parameters may be adjusted based on the estimated fuel ethanol content, water content, and fuel age.

A controller includes a valve control unit and a target calculation unit. The valve control unit is configured to control a fuel injection valve such that divergence decreases between an ignition delay of fuel injected into a cylinder through main injection and an ignition delay target value. The target calculation unit is configured to calculate the ignition delay target value such that the ignition delay target value decreases as estimated ignitability of the fuel in the cylinder increases during an engine operation in a region where diffusion combustion and premix combustion are both performed, the ignitability of the fuel in the cylinder being estimated based on a parameter that varies the ignitability.

An estimation device is applicable to a combustion system in which relative movement of a piston to a cylinder is lubricated with a lubricating oil. An estimation device includes a mixing acquisition unit and a piercing force estimation unit. The mixing acquisition unit acquires a mixing ratio of various components contained in a fuel injected into the combustion chamber. The piercing force estimation unit estimates a piercing force of the fuel injected into the combustion chamber according to the mixing ratio acquired with the mixing acquisition unit to manage reach of the fuel, which is injected into the combustion chamber of the internal combustion engine, at least one of the cylinder and the piston.

A method for ascertaining a viscosity of a fuel with the aid of an electric fuel pump which is integrated into a fuel circuit including an overflow valve which includes a permanently open discharge channel, a fuel supply and delivery being adjusted with the aid of the electric fuel pump in the fuel circuit at a specific pressure and the viscosity of the fuel being ascertained by taking into account a delivery rate of the electric fuel pump.

A vehicle propulsion system includes a first pump having an inlet for receiving fuel from a fuel reservoir and an outlet for providing pressurized fuel to a fuel feed line at a first pressure, a fuel feed line pressure sensor, a second pump having an inlet for receiving fuel from the fuel feed line and an outlet for providing pressurized fuel to an engine fuel rail at a second pressure, the second pressure being higher than the first pressure, a fuel temperature sensor, and a controller controlling the first pump to reduce the pressure of the fuel in the fuel feed line and determining whether the pressure of the fuel in the fuel feed line has reached a vaporization pressure of a component in the fuel.

The invention determines at least one combustion property of a two-phase fuel gas. The invention comprises providing the fuel gas from substantially only a first phase of the fuel gas to a combustion engine and operating the combustion engine such that a first -value is achieved in the combustion process. The invention further provides the fuel gas from substantially only a second of the two phases of the fuel gas to the combustion engine, wherein the second phase is different from the first phase and wherein the same volumetric air/fuel ratio is kept as when the combustion engine was operated with the first -value. The invention determines a second -value when the combustion engine is operated with the fuel gas from substantially only the second of the two phases of the fuel gas and determines at least one first combustion property of the fuel gas based on the second -value.