Rail Pressure-based Diagnostic Functions for Gasoline Direct Injection Systems
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© Vitesco Technologies
Rail Pressure-based Diagnostic Functions for Gasoline Direct Injection Systems
In the field of gasoline direct injection, injectors with solenoid actuation are widely used on account of their cost-effective production. Vitesco Technologies investigates diagnostic concepts based on the rail pressure signal for this injector type, which will improve metering of the fuel mass injected or be used as a development tool.
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ACCURATE FUEL QUANTITIES FOR LOW EMISSIONS
Against the backdrop of ever more stringent fuel consumption and emission standards, new challenges arise with regard to the accuracy of fuel metering in injection systems. Raw engine emissions and pollutant conversion during exhaust gas aftertreatment are dependent on the resulting air-fuel ratio in the combustion engine cylinder. Without appropriate extension, however, con ventional lambda control employing a broadband oxygen sensor between the engine and the three-way catalyst only takes into account the resulting overall ratio of air to injected fuel mass in the engine [1]. In addition to a uniform distribution of the mass airflow to the individual cylinders, accurate metering of the fuel mass by the injection system must therefore also be ensured, FIGURE 1. Usually, this is achieved by determining the opening and closing point in time of the injectors based on the actuation voltage and current, in order to then compensate for any differences in the
AU T H OR S
Anselm Wieland, M. Sc. is Doctoral Student at Advanced Development of the Electronic Controls Business Unit at Vitesco Technologies in Regensburg (Germany). FIGURE 1 Layout of the high-pressure fuel system (© Vitesco Technologies)
Dr. Erwin Achleitner is Principal Expert Gasoline Engine Systems at Advanced Development of the Electronic Controls Business Unit at Vitesco Technologies in Regensburg (Germany).
Dr. Anatoliy Lyubar is Head of Advanced Development of the Electronic Controls Business Unit at Vitesco Technologies in Regensburg (Germany).
Prof. Dr. Eberhard Schlücker is Head of the Institute of Process Machinery and Systems Engineering at the University of ErlangenNuremberg in Erlangen (Germany).
hydraulic opening period by adjusting the injector-specific electrical actuation time [2]. However, these processes do not take into account deviations in the nozzle flow rate due to manufacturing tolerances or nozzle coking, for example, which can occur over the injector service life [3]. In order to achieve improved fuel quantity accuracy, dia gnosis and compensation of flow rate differences should therefore be performed in addition to consideration of the hydraulic opening duration. MTZ worldwide 10|2020
The basis for diagnosis is the physical correlation between the fuel mass injected and the resulting pressure drop in the rail. By means of the signal processing presented below, the pressure drop and the hydraulic natural frequency are determined based on the rail pressure signal, which enables a correlation to the cycle-resolved injected fuel quantity meas
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