Manifold Pressure Monitoring for Variable Displacement Engine Diagnostics
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Solution Overview
Problem
Existing methods for diagnosing degradation in variable displacement engine (VDE) operation, such as those based on crankshaft vibrations, fail to identify situations where one cylinder valve is properly deactivated but another valve continues to operate, leading to issues like pressure oscillations and noise due to rapid gas expansion.
Innovation Solution
Monitoring manifold pressure at or around the characteristic frequency of the intake manifold during selected conditions, such as the intake stroke, to identify degradation in cylinder valve deactivation or activation by detecting resonance patterns and pressure oscillations, which can indicate improper valve operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If crankshaft vibration-based diagnostic methods are used to monitor VDE operation, then general engine performance monitoring is achieved, but the ability to identify specific valve deactivation failures is lost
Solution Approach 1:
The patent replaces mechanical vibration sensing (crankshaft vibrations) with acoustic pressure wave detection (manifold pressure oscillations). This substitution enables more precise detection of valve deactivation failures because acoustic pressure waves directly reflect the gas dynamics caused by improper valve closure, whereas mechanical vibrations provide only indirect and less specific information about valve operation.
Solution Approach 2:
The patent changes the diagnostic parameter from mechanical vibration frequency to acoustic pressure oscillation frequency. By monitoring pressure oscillations at characteristic frequencies in the intake manifold, the system can specifically identify valve deactivation failures. This parameter change transforms the diagnostic approach from general mechanical monitoring to specific acoustic-based detection of gas dynamics anomalies.
2Measurement precision
If high-frequency sampling and band-pass filtering are used to detect valve degradation, then measurement precision is improved, but computational complexity and data processing requirements increase
Solution Approach 1:
The patent applies preliminary action by pre-identifying and monitoring only the characteristic frequencies relevant to valve deactivation failures. Instead of performing broad high-frequency sampling followed by complex filtering operations, the system focuses measurements on the specific frequency ranges where valve-related pressure oscillations occur. This preliminary frequency identification simplifies the diagnostic process while maintaining high detection precision.
3Loss of information
If general vibration-based monitoring is used, then overall engine health assessment is achieved, but specific location of degraded valves cannot be identified
Solution Approach 1:
The patent applies segmentation by analyzing pressure oscillations from different cylinders independently. By monitoring the intake manifold pressure and identifying which specific cylinder's valve failure causes the oscillations, the system can pinpoint the location of degraded valves. This segmented approach to diagnostic analysis preserves detailed information about which specific valve is malfunctioning, unlike general vibration monitoring that only provides overall engine health assessment.
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 accurate identification of VDE transition issues with reduced reliance on high-frequency sampling and band-pass filtering, enabling precise location of degraded valves and differentiation between intake and exhaust valve degradations, thus improving diagnostic accuracy and reliability.
Implementation Method 1
the compressed gas in the cylinder may be rapidly released and expanded in to the intake manifold
Implementation Method 2
This rapid expansion may excite the resonance frequency of the air in the intake manifold, thereby creating pressure oscillations, vibrations, and noise
Data Source
AI summary
Methods and systems are provided for monitoring cylinder valve deactivation of a cylinder valve of an engine. One example method comprises, indicating degradation of cylinder valve deactivation in response to manifold pressure at or around a characteristic frequency.