An injection system for an internal combustion engine including at least one injector and a high-pressure accumulator, which has a fluid connection to the at least one injector on the one side and has a fluid connection to a fuel reservoir via a high-pressure pump on the other side, wherein a suction throttle is associated with the high-pressure pump as a first pressure-setting element. At least two pressure control valves are provided, via which the high-pressure accumulator can be brought into fluid connection with the fuel reservoir.

Various methods and systems are provided for health assessments of a fuel system. In one example, a fuel system includes a low-pressure pump operable to pump fuel from a fuel source at a first pressure, a high-pressure pump operable to increase the first pressure to a second pressure, a valve positioned between the low-pressure pump and the high-pressure pump and operable to control fuel flow to the high-pressure pump, a common fuel rail fluidly coupling the high-pressure pump to a plurality of fuel injectors coupled to cylinders of an engine, and a controller. The controller is operable to adjust an amount of valve electrical current supplied to the valve to reach a commanded pressure of the common fuel rail during cylinder firing conditions, the supplied valve electrical current adjusted based on a valve pre-firing correction factor for the valve obtained based on valve electrical current prior to cylinder firing commencing.

A method is disclosed to determine the opening degree of injectors in cylinders of a combustion engine, where the combustion engine has at least three cylinders. The injectors are connected to a fuel accumulator in a common rail fuel injection system; the fuel supply to the fuel accumulator is interrupted; and subsequently a test injection of fuel is carried out into at least two and, at most, all but for one cylinder at a time, in different combinations, at such a time that the injection does not cause any combustion in the cylinders. The pressure decreases caused in connection with the different test injections are measured, and the pressure decrease that is attributable to at least one specific injector is calculated based thereupon, which is, in turn, used in the determination of the injector's opening degree.

A method for automatically operating a cam-driven pump is disclosed. The pump is monitored to determine whether a specified detachment condition or potential detachment of an actuator of the pump from a driving cam is occurring. The pump is operated in a minimal pressure holding mode to provide a minimal pressure within a working chamber of the pump so as to bias the actuator towards the cam if it is determined that the detachment condition is occurring.

A torque request module determines a torque request for an engine based on a driver input. A cylinder control module determines a target fraction of a total number of cylinders of the engine to be activated based on the torque request. An air fuel imbalance (AFIM) module selectively commands that the cylinder control module set the target fraction based on a predetermined fraction of the total number of cylinders of the engine to be activated. The cylinder control module further: sets the target fraction based on the predetermined fraction in response to the command; and activates and deactivates opening of intake and exhaust valves of the cylinders of the engine based on the target fraction. The AFIM module further, while the target firing fraction is set based on the predetermined fraction, selectively diagnoses the presence of an AFIM fault based on samples of a signal from an oxygen sensor.

In a high pressure pump in a system for fuel injection in a combustion engine, determining whether a predetermined partial load operating condition prevails in the combustion engine, at which one single of several pump elements (10) in the high pressure pump is capable of alone delivering a fuel pressure requested in an accumulator tank (6), according to a first reference value, and to achieve a reproducible increase of the fuel pressure to a second reference value. If applicable, the high pressure pump's pump elements are controlled so that one single pump element alone delivers the fuel pressure in the accumulator tank according to the first reference value, whereupon this reference value is changed to the second reference value, and the actual development of the pressure in the accumulator tank as a function of time is determined, and compared with stored values of similar developments for the determination of information regarding the pump element's performance ability.

A method includes operating a fuel injector to perform a fuel injection, determining an estimate of the actual injected quantity of the fuel injection, determining a change in a commanded on time to achieve an injected quantity relative to the commanded on time required to initiate injection of the injector in response to the estimate of the actual injected quantity and a commanded injection quantity, and determining an injector opening rate shape slope estimate for the injector in response to the commanded on time required to initiate injection. The method may further include one or more of outputting a diagnostic or prognostic of the fuel injector, adjusting an injection control parameter, or adjusting an injector monitoring operation in response to the injector opening rate shape slope estimate.

According to one aspect of the present disclosure, a method of controlling a common rail fuel system of an engine system is provided. The common rail fuel system includes a fuel pump, a fuel rail, a plurality of fuel injectors, and a pressure-responsive relief valve fluidly coupled to the fuel rail. The method comprises identifying a pressure condition of the fuel rail indicative of the pressure-responsive relief valve being in an open and latched condition, the identification being based on detecting a rise and reduction in rail pressure within a threshold time period. The method further comprises terminating flow from the fuel pump, while the common rail fuel system is operating, to unlatch and close the pressure-responsive relief valve.

A method includes operating a pump to pump fuel to a rail and concurrently operating one or more injectors to inject fuel from the rail into one or more cylinders of an engine. The method further includes filtering measurements of fuel pressure of the rail to determine filtered pressures for at least a first pressure measurement zone preceding a target event and a second pressure measurement zone succeeding a target fuel mass change event, determining a pressure change in response to the filtered pressures, and determining a fuel mass change of the target event in response to the pressure change.

A method for determining a characteristic variable for opening and/or closing a flow-through opening of a solenoid valve, in which solenoid valve a solenoid coil is energized to raise an armature to open the flow-through opening for a fluid. During operation of the solenoid valve, a profile of a current in the solenoid coil being determined, and using a pattern recognition method based on artificial intelligence, the characteristic variable(s) is/are determined based on at least one section of the profile or a profile derived therefrom using a neural network. A method for applying and for training a pattern recognition method based on artificial intelligence are also described.