Engine Knock Detection via Cylinder Deactivation
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Solution Overview
Problem
Existing engine systems face challenges in detecting engine knock due to combustion noise and vibration, which can mask the signals from knock sensors, making it difficult to accurately detect and manage engine knock, especially when cylinders are deactivated.
Innovation Solution
The method involves operating the engine with different groups of combusting cylinders and adjusting spark timing based on indications from multiple knock sensors during various engine conditions, allowing for improved detection of engine knock by optimizing sensor usage and reducing noise interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple knock sensors are deployed to detect engine knock, then the detection coverage is improved, but the combustion noise and vibration from multiple active cylinders masks the knock sensor signals
Solution Approach 1:
The engine cylinders are segmented into different groups (first group and second group) that can be operated independently. By deactivating one group of cylinders, the system reduces the overall combustion noise and vibration in the engine block, thereby improving the signal-to-noise ratio for knock sensors detecting knock in the active cylinders. This segmentation allows selective operation of cylinder groups to optimize knock detection conditions.
2Power
If all engine cylinders are active and combusting air and fuel, then the engine power output is maximized, but the combustion noise masks knock sensor signals
Solution Approach 1:
The system dynamically adjusts the number of active cylinders based on operating conditions. The controller can switch between having all cylinders active (for maximum power) and having only one group of cylinders active (for improved knock detection). This dynamic reconfiguration allows the engine to adapt between power maximization and detection accuracy requirements depending on the operational context.
3Measurement precision
If cylinders are deactivated to reduce combustion noise, then the signal to noise ratio of knock sensors is improved, but the engine power output is reduced
Solution Approach 1:
The system employs periodic or alternating operation of different cylinder groups. During certain operating conditions, one group of cylinders is deactivated to improve knock detection, and during other conditions, all cylinders are activated to maximize power output. This periodic switching between different operational states allows the system to optimize for different objectives depending on the immediate operational requirements.
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 enhances engine knock sensing accuracy, reduces the risk of engine degradation, and improves detection even when cylinders are deactivated, leading to more efficient engine operation and reduced noise interference.
Implementation Method 1
it causes a pressure oscillation in the cylinder that produces a ping or knocking sound in the engine
Implementation Method 2
the air-fuel mixture is ignited by a spark
Data Source
AI summary
Systems and methods for detecting and controlling knock in an engine are presented. In one example, engine knock sensors are selected based on whether or not certain cylinders are activated and combusting air and fuel or deactivated and not combusting air and fuel. Output of selected knock sensors is the basis for adjusting engine spark timing.