Direct Injection Engine Overrun Cutoff Transition Control
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Solution Overview
Problem
Internal combustion engines with direct fuel injection face challenges in reducing particle emissions during the transition from overrun cut-off to normal operation, as conventional methods can cause jerking and increased emissions due to sudden fuel supply resumption.
Innovation Solution
The method involves shifting the injection start time during the transition phase after overrun cut-off, using an adaptation value to delay the injection start time beyond the normal operation time, and optionally using multiple injections to reduce fuel jet penetration, with the adaptation value dependent on the duration of overrun cut-off and engine parameters like air mass flow and load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If fuel supply is stopped during overrun operation to save fuel and reduce emissions, then fuel consumption and pollutant emissions are reduced, but a step change in torque occurs causing jerking and impaired driving comfort
Solution Approach 1:
The patent applies preliminary action by gradually reducing fuel supply to individual cylinders before completely stopping it during overrun operation. Instead of abruptly cutting off fuel to all cylinders simultaneously, the control device deactivates fuel injection sequentially for each cylinder over multiple combustion cycles, allowing the engine torque to transition smoothly while still achieving fuel savings and emission reduction.
2Productivity
If fuel supply is abruptly stopped during overrun operation, then fuel consumption is reduced, but torque fluctuation increases causing perceptible jerking
Solution Approach 1:
The patent applies segmentation by dividing the fuel supply deactivation process into individual cylinder stages. Each cylinder's fuel injection is deactivated separately over successive combustion cycles rather than all cylinders simultaneously. This segmented approach distributes the torque impact across time and individual cylinders, maintaining overall torque stability while achieving the fuel efficiency benefits of overrun cut-off.
3Speed
If fuel injection is resumed immediately after overrun cut-off, then normal operation is restored quickly, but particle emissions increase due to improper fuel evaporation
Solution Approach 1:
The patent applies preliminary action by preparing the engine for fuel injection resumption before actually restarting fuel supply. During the transition from overrun cut-off back to normal operation, the control device adjusts ignition timing and fuel injection parameters in advance to ensure proper fuel evaporation and combustion conditions are established before full fuel supply is restored, thereby minimizing particle emissions while maintaining quick response.
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 significantly reduces particle emissions during the transition phase by ensuring fuel evaporates properly and reduces the wetting of piston surfaces, enhancing driving comfort and compliance with emission standards like Euro 6.
Implementation Method 1
fuel is injected into a cylinder of the Otto-cycle engine in the form of multiple injections, wherein at least a partial amount of the fuel to be injected is deposited during the compression phase
Implementation Method 2
ensuring fuel evaporates properly
Data Source
AI summary
A method for controlling an internal combustion engine operated with direct fuel injection may include, during a transition phase after the end of an overrun cut-off with resumption of fuel injection and normal operation of the internal combustion engine, shifting an injection start time (SOI) by an adaptation value (ΔSOI) in relation to an injection start time (SOI) which lies later than an injection start time (SOI_Norm) determined during normal operation of the internal combustion engine.