Dual Fuel Injection Pulse Timing Correction for Pressure Pulsation Errors
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Solution Overview
Problem
Dual fuel injection systems in internal combustion engines face fueling errors due to sinusoidal fuel pressure fluctuations from camshaft-driven high pressure fuel pumps, particularly when direct injection is disabled, leading to discrepancies in fuel delivery between port and direct injection fuel rails.
Innovation Solution
The system intermittently samples fuel pressure in the port injection fuel rail and adjusts the timing of the port fuel injection pulse to be synchronous with pressure sampling points, reducing fueling errors by centering the fuel pulse around the sampling point and compensating for fuel puddle dynamics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If fuel is supplied to the port injection fuel rail through the high pressure fuel pump, then hardware complexity is reduced, but fuel pulsations enter the port injection fuel rail causing fueling errors
Solution Approach 1:
The harmful fuel pulsations are extracted and isolated from the port injection fuel rail by providing a separate low-pressure fuel source for the port injection system, while the high-pressure fuel pump exclusively serves the direct injection system. This separation removes the source of pulsations from affecting port injection fueling accuracy.
Solution Approach 2:
The fuel system is segmented into two independent fuel supply paths: one path from the high-pressure fuel pump to the direct injection fuel rail, and another path from a low-pressure fuel source through a pressure regulator to the port injection fuel rail. This segmentation prevents cross-contamination of fuel pulsations between the two injection systems.
2Productivity
If the high pressure fuel pump returns all ingested volume back into the low pressure region when direct injection is disabled, then the pump operates efficiently, but fuel pulsations worsen in the port injection fuel rail
Solution Approach 1:
The harmful effect of fuel return pulsations is extracted by separating the port injection fuel supply from the high-pressure pump's return path. The port injection system receives fuel from a dedicated low-pressure source, isolating it from the pulsations generated when the high-pressure pump returns fuel to the low-pressure region.
3Reliability
If fuel pulse timing is asynchronous with pressure sampling, then closed intake valve injection can be achieved, but fueling errors increase due to pressure fluctuations
Solution Approach 1:
A pressure sensor provides real-time feedback on fuel rail pressure to the controller. The controller uses this feedback information to dynamically adjust the fuel injection pulse width, compensating for pressure fluctuations and ensuring accurate fuel metering even when injection timing is advanced for closed intake valve operation.
Solution Approach 2:
The controller dynamically changes the fuel injection parameters (pulse width and timing) based on real-time pressure conditions. By adjusting the injection duration and timing in response to measured pressure fluctuations, the system maintains accurate fuel metering while achieving the desired closed intake valve injection timing.
Data Source
AI summary
Methods and systems are provided for reducing fueling errors resulting from pressure pulsations in a port injection fuel rail. The pressure pulsations result from pressure pulsations generated in a high pressure fuel pump delivering fuel to both the port injection fuel rail and a direct injection fuel rail. A center of a port injection fuel pulse is repositioned on a nearest fuel rail pressure sampling point in the advanced direction to improve the accuracy of the delivered fuel pulse.