Exhaust Stroke Fuel Injection for Aftertreatment Heating
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Solution Overview
Problem
Existing methods for enriching exhaust-gas flow with fuel to enhance exhaust-gas temperature in internal combustion engines either diminish engine oil lubrication or increase vehicle complexity and cost by requiring additional fuel injection systems.
Innovation Solution
A method and device that partially deactivate certain cylinders to perform exhaust stroke injections, allowing fuel to be injected during the exhaust stroke instead of the compression stroke, thereby enriching the exhaust-gas flow without the need for additional fuel injection systems, and adjusting fuel delivery based on engine operating conditions to optimize exhaust temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If fuel is injected directly into the engine cylinder during post-injection to enrich exhaust-gas flow, then exhaust-gas temperature is increased, but engine oil lubrication is diminished due to fuel thinning
Solution Approach 1:
The patent divides the engine cylinders into two groups: a first cylinder group that performs exhaust stroke injection to enrich exhaust gas, and a second cylinder group that performs compression stroke injection to maintain power generation. This segmentation allows the first group to handle exhaust enrichment while the second group maintains engine performance, preventing fuel from thinning the engine oil in power-generating cylinders.
2Temperature
If an additional fuel injection system is added to the exhaust tract to enrich exhaust-gas flow, then exhaust-gas temperature is increased, but vehicle complexity and cost increase
Solution Approach 1:
The patent makes the existing fuel injection system perform multiple functions: it injects fuel during compression stroke for power generation in the second cylinder group, and during exhaust stroke for exhaust enrichment in the first cylinder group. This eliminates the need for a separate exhaust tract injection system, reducing vehicle complexity and cost while achieving exhaust temperature increase.
3Power
If fuel is injected during compression stroke to power the vehicle drivetrain, then engine power is maintained, but exhaust-gas temperature is insufficient for optimal aftertreatment device operation
Solution Approach 1:
The patent implements periodic switching between two operating modes: during normal power generation, the second cylinder group performs compression stroke injection; when exhaust aftertreatment heating is required, the first cylinder group performs exhaust stroke injection. This periodic action allows the engine to alternate between power optimization and exhaust temperature optimization, ensuring both functions are satisfied at different times.
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 effectively increases exhaust-gas temperature at oxidation catalytic converters while reducing engine complexity and cost by utilizing existing fuel injection systems, ensuring adequate fuel delivery with precise control, thus enhancing the operation of exhaust-gas aftertreatment devices.
Implementation Method 1
the fuel injected may be sprayed onto a heating element that further assists with the fuel evaporation process before introduction into the exhaust-gas flow
Implementation Method 2
the exhaust temperature is increased by means of an exothermic reaction of unburned fuel contained within the exhaust-gas flow on an oxidation catalytic converter element
Implementation Method 3
an oxidation catalytic converter element
Data Source
AI summary
A system and methods for operating four in-line cylinders with common rail injection is described that comprises operating a first cylinder group without a compression and power stroke injection, but with an exhaust stroke injection while operating a second cylinder group with at least a compression stroke injection. In this way, the unburned fuel injected during the exhaust stroke enriches the exhaust-gas flow and further allows heating of the exhaust aftertreatment system. In one example provided, the first cylinder group is further configured to operate in an exhaust heating mode while also operating in a power generating mode.