A method of operating a fuel injector includes determining an actual energizing time correction value for a fuel injector at a first fuel rail pressure, calculating an extrapolated energizing time correction value by performing a mathematical calculation on the actual energizing time correction value, and controlling the operation of the fuel injector based on the actual energizing time correction value and the extrapolated energizing time correction value.

Provided is a method for diagnosing unintended fuelling from one or more fuel injectors of a multi cylinder internal combustion engine during engine operation. Pressurized fuel is intended to be distributed by means of said fuel injectors from said accumulator tank to the cylinders for combustion. An oxidation catalyst is arranged downstream said cylinders. The method comprises: determining the pressure in the fuel accumulator tank and whether said pressure is decreasing; and determining whether the actual amount of fuel provided by the pump unit exceeds the demanded amount of fuel. The method further comprises the steps of: determining whether the temperature associated with the oxidation catalyst is above a certain level and/or determining whether the air/fuel ratio is below a certain level and/or determining whether an amount of particulate matter is above a certain level; and confirming an unintended fuelling based on the determined conditions.

An apparatus and a method for testing a fuel injector nozzle with a tip having at least one fuel outlet are provided. The apparatus comprises a test chamber, a holder for holding the fuel injector nozzle such that the outlet is within the test chamber, a fuel supply arrangement for supplying fuel to the fuel injector nozzle, a sensor having a sensor surface for sensing an atomized fuel spray supplied by the fuel injector nozzle through the fuel outlet and movement module for moving the sensor. The movement module is configured to position the sensor surface of the sensor at a plurality of positions corresponding to a surface of a sphere having a radius R and a center point C adjustable to match a center point c.sub.t of the tip of the fuel injector nozzle or a center point c.sub.f of an orifice of the fuel outlet.

An apparatus and a method for testing a fuel injector nozzle with a tip having at least one fuel outlet are provided. The apparatus comprises a test chamber, a holder for holding the fuel injector nozzle such that the outlet is within the test chamber, a fuel supply arrangement for supplying fuel to the fuel injector nozzle, a sensor having a sensor surface for sensing an atomized fuel spray supplied by the fuel injector nozzle through the fuel outlet and movement module for moving the sensor. The movement module is configured to position the sensor surface of the sensor at a plurality of positions corresponding to a surface of a sphere having a radius R and a center point C adjustable to match a center point c.sub.t of the tip of the fuel injector nozzle or a center point c.sub.f of an orifice of the fuel outlet.

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.

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.

A device (1) for measuring the injection rate dm(t)/dt of an injection valve (2) for a fluid (4a), wherein m(t) is the injection quantity of the fluid (4a) as a function of the time (t), having a measurement volume (3) which is closed off on all sides and which is filled with a test fluid (4), having an opening (5a) in one wall (5) of the measurement volume (3) for the purposes of receiving the injection valve (2) such that the injection valve (2), in the installed position, projects with at least one injection opening (2a) into the measurement volume (3), and having a pressure sensor (6) which is arranged in the measurement volume (3), wherein correction means (8, 8a, 9a, 9b, 9c) are provided for determining the propagation time of a pressure wave (12), which originates from the injection opening (2a) and which propagates through the test fluid (4), to the pressure sensor (6) and for correcting the measured injection rate dm(t)/dt, taking said propagation time into consideration, to give a rectified injection rate dm(t)/dt. A method for producing the device (1), wherein the characteristic map (8a) is determined by way of a fluid-dynamic simulation of the time-dependent and position-dependent local speed of sound c(t,x) in a partial volume of the measurement volume (3) which encompasses at least the path (11) from the injection opening (2a) to the pressure sensor (6), which simulation is based on at least one time-dependent boundary condition for the pressure (p) in the measurement volume (3) and/or for the injection quantity (dm). A method for measuring the injection rate dm(t)/dt of an injection valve (2) for a fluid (4a).

A method for operating a fuel injection system for a vehicle is provided. In particular, the fuel injection system includes an injection nozzle having a nozzle body, a nozzle orifice and a nozzle needle movable in the nozzle body. The method including: measuring an actual injection timing of the injection nozzle during injection based on an electrical signal generated by the nozzle needle through an electric contact with the nozzle body so that the electrical signal identifies an open state and a closed state of the injection nozzle; calculating a deviation of the actual injection timing from a scheduled injection timing of the fuel injection system; and controlling the injection nozzle by adjusting injection parameters of the injection nozzle based on the evaluated deviation.

In certain embodiments, a method and an apparatus which can be implemented with a simplified and inexpensive configuration without causing a misfire in a combustion state. In a fuel-Cetane-number estimation method according to embodiments, a map which specifies a relationship between the Cetane number and a control parameter at which NOx concentration of exhaust gas reaches a predetermined value is prepared in advance. Then, the control parameter is controlled variably to detect transition of the NOx concentration of the exhaust gas of the internal combustion engine, and thereby the control parameter of the internal combustion engine at which the NOx concentration has reached the predetermined value is obtained, and the Cetane number which corresponds to the obtained control parameter is estimated on the basis of the map.

In certain embodiments, a method and an apparatus which can be implemented with a simplified and inexpensive configuration without causing a misfire in a combustion state. In a fuel-Cetane-number estimation method according to embodiments, a map which specifies a relationship between the Cetane number and a control parameter at which NOx concentration of exhaust gas reaches a predetermined value is prepared in advance. Then, the control parameter is controlled variably to detect transition of the NOx concentration of the exhaust gas of the internal combustion engine, and thereby the control parameter of the internal combustion engine at which the NOx concentration has reached the predetermined value is obtained, and the Cetane number which corresponds to the obtained control parameter is estimated on the basis of the map.