Variable Compression Ratio Particulate Filter Regeneration
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Solution Overview
Problem
Existing methods for particulate filter regeneration in engines, such as spark retard and heater use, lead to increased engine noise, vibration, and harshness, and reduced combustion stability due to reliance on spark retard for heating, which can trigger misfires and affect emissions and fuel efficiency.
Innovation Solution
Adjusting the engine compression ratio using a variable compression ratio mechanism and optimizing spark timing based on residual gas fraction to increase exhaust temperature for particulate filter regeneration, reducing reliance on spark retard and improving engine smoothness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If spark timing is retarded to increase exhaust temperature for particulate filter regeneration, then the particulate filter temperature increases, but engine noise, vibration, and harshness increase and combustion stability decreases
Solution Approach 1:
The patent changes the compression ratio parameter to increase exhaust temperature for particulate filter regeneration instead of relying on spark timing retard. By lowering the compression ratio, the engine produces higher exhaust temperatures that can regenerate the particulate filter without the negative effects of spark timing retard on combustion stability and engine smoothness.
2Temperature
If spark timing is retarded to increase exhaust temperature for particulate filter regeneration, then the particulate filter temperature increases, but engine noise, vibration, and harshness increase
Solution Approach 1:
The patent changes the compression ratio parameter to increase exhaust temperature for particulate filter regeneration instead of relying on spark timing retard. By lowering the compression ratio, the engine produces higher exhaust temperatures that can regenerate the particulate filter without the negative effects of spark timing retard on combustion stability and engine smoothness.
3Temperature
If compression ratio is lowered to increase exhaust temperature for particulate filter regeneration, then exhaust temperature increases and reliance on spark retard is reduced, but engine efficiency decreases
Solution Approach 1:
The patent dynamically changes the compression ratio parameter based on particulate filter regeneration needs. By temporarily lowering the compression ratio during regeneration events, the system achieves higher exhaust temperatures to burn off accumulated particulates, accepting a temporary trade-off in engine efficiency for the benefit of emissions control and filter maintenance.
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 allows for efficient particulate filter regeneration with reduced noise, vibration, and harshness, while maintaining combustion stability and improving engine performance, emissions quality, and fuel economy by leveraging the effects of compression ratio adjustments on exhaust temperature and residual gas fraction.
Implementation Method 1
selectively lowering an engine compression ratio (CR), mechanically, via a variable compression ratio (VCR) mechanism
Implementation Method 2
burn or oxidize the trapped particulate matter
Data Source
AI summary
Methods and systems are provided for adjusting engine compression ratio (CR) and spark timing to attain particulate filter (PF) regeneration temperature. In one example, a method may include, in response to PF load reaching a threshold and PF temperature being lower than the PF regeneration temperature, lowering the CR and then selectively adjusting spark timing based on an estimated residual gas fraction (RGF) at the lower CR.