Fuel Injection Rate Shaping via Zero Hydraulic Dwell Time
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Solution Overview
Problem
Current fuel injection rate shaping strategies in common rail fuel injection systems, which aim to minimize fuel consumption and pollutant emissions by ensuring the main fuel injection starts without discontinuity with the pilot injection, face limitations due to computational errors in modeling fuel spray and combustion phenomena, particularly at high fuel injection pressures, where the small size ratio of fuel microdrops to combustion chamber size necessitates unrealistic computational cells and introduces significant errors.
Innovation Solution
Implementing a fuel injection rate shaping strategy where the main fuel injection starts exactly when the pilot injection terminates, with an electronic control unit generating specific electrical commands to ensure a zero hydraulic dwell time between the two injections, thereby achieving a two-hump instantaneous fuel flow rate profile that maximizes benefits in reducing fuel consumption and emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If computational models are used to optimize fuel injection timing and duration, then fuel consumption and emissions can be reduced, but computational errors occur particularly at high fuel injection pressures due to the small size ratio of fuel microdrops to combustion chamber size
Solution Approach 1:
The patent changes the approach from computational modeling to empirical measurement by introducing a measurement device that directly measures the instantaneous fuel flow rate during injection. This avoids computational errors at high pressures by using actual measured data instead of modeled data, while still enabling optimization of fuel consumption and emissions through accurate measurement feedback.
2Object-generated harmful factors
If multiple fuel injections are performed in sequence with overlapping timing to achieve continuous combustion, then emissions can be reduced, but precise control of injection timing and duration is required to avoid discontinuities
Solution Approach 1:
The measurement device provides real-time feedback on the actual fuel flow rate during sequential injections. This feedback enables the control system to adjust injection timing and duration to ensure continuous fuel delivery between pilot and main injections, reducing emissions while managing control complexity through data-driven optimization.
Solution Approach 2:
The system dynamically adjusts the timing and duration of sequential fuel injections based on measured flow rate characteristics. By making the injection parameters adaptive rather than fixed, the system can optimize emission reduction while managing the complexity of coordinating multiple injections with precise timing.
3Loss of energy
If fuel injection pressure is increased to improve atomization and combustion efficiency, then fuel consumption decreases, but computational errors increase due to the smaller size of fuel microdrops relative to the combustion chamber
Solution Approach 1:
The patent replaces computational modeling with direct physical measurement using a measurement device that captures actual fuel flow rate data. This substitution eliminates the computational errors that arise at high injection pressures while maintaining the benefit of improved atomization and combustion efficiency, allowing accurate measurement and optimization even at high pressures.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach results in a 2% mean reduction in fuel consumption and up to 30% reduction in pollutant emissions, meeting Euro 5 and Euro 6 standards, while maintaining robustness and repeatability of the main injection, and is advantageous in engine operating conditions with reduced ignition delays and diffusive combustion.
Implementation Method 1
the electronic control unit is programmed to supply the electroinjector with at least a first electrical command, with a pre-set time duration, to cause a pilot fuel injection to be performed, and a subsequent electrical command
Implementation Method 2
common rail fuel injection system in which the electronic control unit is programmed to cause the fuel injection system to carry out, in one and the same engine cylinder and in one and the same engine cycle, multiple temporally consecutive fuel injections
Implementation Method 3
two fuel injections prior to the main fuel injection, one sufficiently far from the main fuel injection as to give rise to a combustion distinct from that of the main fuel injection
Data Source
AI summary
A fuel injection system for an internal combustion engine, comprising at least one fuel electroinjector (1), and an electronic control unit (11) configured to supply the fuel electroinjector (1), in a fuel injection phase in an engine cylinder, with at least a first electrical command (Si) to cause a first fuel injection (P) to be carried out, and a second electrical command (S2) to cause a second fuel injection (M) temporally subsequent to the first fuel injection (P) to be carried out, the first and second electrical commands (Si, S2) being separated in time by an electrical dwell time (DT) such that the second fuel injection (M) starts without any discontinuity in time with respect to the first fuel injection (P). The electronic control unit (11) is further configured to cause the first and second fuel injections (P, M) to be carried out in engine operating conditions characterized by reduced fuel ignition delays, wherein fuel combustion is prevalently diffusive and heat released during fuel combustion is sensitive to fuel injection law.