Compressor Recirculation Valve Sludge Detection and Compensation
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Solution Overview
Problem
Existing engine systems face issues with compressor surge, noise, vibration, and harshness due to sludge accumulation on the throttle valve body, which affects airflow and is not adequately addressed by adjusting other actuators or sensing CCRV position.
Innovation Solution
A method to estimate and adjust the position of the compressor recirculation valve based on the difference between total intake flow and engine flow, using a mass air flow sensor to accurately control recirculation flow and estimate sludge accumulation, thereby addressing compressor surge and improving boost pressure control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If CCRV position is sensed and controlled accurately, then valve positioning precision is improved, but sludge accumulation still adversely affects flow control and overall flow control degrades
Solution Approach 1:
The system uses feedback from the mass air flow sensor to continuously monitor actual intake flow and compares it with expected flow based on CCRV position. This feedback loop enables detection of sludge accumulation effects and triggers compensation adjustments to the CCRV position, maintaining reliable flow control despite valve body contamination.
Solution Approach 2:
The system changes the control parameter from fixed CCRV position commands to dynamic position adjustments based on measured flow deviations. By modifying the CCRV position parameter in response to detected sludge accumulation effects, the system compensates for reduced airflow and maintains intended flow control performance.
2Reliability
If other actuators such as wastegate and intake throttle are adjusted in response to CCRV degradation, then boost control is attempted to be maintained, but sludge accumulation on valve body is not sufficiently addressed and flow control degrades
Solution Approach 1:
The system extracts and specifically addresses the CCRV sludge accumulation problem separately from general boost control. By using the mass air flow sensor to specifically monitor flow through the compressor recirculation passage and detecting deviations attributable to CCRV contamination, the system applies targeted compensation rather than generic boost control adjustments.
Solution Approach 2:
The system segments the airflow measurement function by positioning the mass air flow sensor specifically to measure total intake flow downstream of the compressor recirculation passage outlet. This segmented measurement approach allows independent monitoring and compensation of CCRV performance degradation separate from other intake system components.
3Reliability
If CCRV is operated to control boost pressure, then compressor surge is addressed, but sludge accumulation gradually reduces effective airflow rate and valve performance degrades over time
Solution Approach 1:
The system performs preliminary detection of sludge accumulation effects using the mass air flow sensor before significant performance degradation occurs. By continuously monitoring actual versus expected airflow and detecting deviations early, the system triggers compensatory CCRV position adjustments to prevent substantial airflow rate reduction and maintain valve effectiveness.
Data Source
AI summary
Methods and systems are provided for improving boost pressure control by adjusting a variable compressor recirculation valve. In one example, a method may include adjusting a position of a continuously variable compressor recirculation valve based on amount of sludge accumulation on the valve. The amount of sludge accumulation may be estimated based on a difference between total intake flow downstream of a compressor recirculation passage outlet but upstream of the passage, and total engine flow entering engine cylinders.