Closed Breather Disconnection Detection via Mass Flow Divergence
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Solution Overview
Problem
Existing methods for detecting disconnection of the gas return pipe in a closed breather system are prone to errors due to environmental changes, such as temperature and pressure variations, leading to incorrect determination of pipe connection status.
Innovation Solution
A method that calculates the mass flow rate of in-cylinder working gas based on boost pressure, intake temperature, and engine rotational frequency, and compares this with air flow sensor readings, using divergence analysis and sensor normality checks to accurately determine pipe disconnection, while accounting for sensor deterioration and environmental factors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Difficulty of detecting and measuring
If air flow sensor detection is used to determine gas return pipe disconnection, then detection capability is provided, but measurement precision deteriorates under environmental changes
Solution Approach 1:
The patent changes the detection parameters from direct air flow measurement to mass flow rate calculation based on boost pressure, intake temperature, and engine rotational frequency. This parameter transformation allows the system to determine gas return pipe disconnection while compensating for environmental changes such as temperature and pressure variations, thereby maintaining measurement precision across different operating conditions.
2Device complexity
If simple air flow rate comparison is used, then device complexity is reduced, but reliability deteriorates due to false determination
Solution Approach 1:
The patent implements a feedback mechanism where the calculated mass flow rate is continuously compared with the air flow sensor detection value, and the divergence between these two values is analyzed over time. This feedback loop enables the system to distinguish between temporary fluctuations and actual disconnection events, significantly improving reliability while maintaining relatively simple device complexity through software-based logic.
Solution Approach 2:
The patent performs preliminary calculation of the mass flow rate of in-cylinder working gas based on boost pressure, intake temperature, and engine rotational frequency before comparing it with the air flow sensor value. This preliminary action allows the system to establish an expected baseline and detect deviations that indicate disconnection, thereby improving reliability through proactive monitoring rather than reactive response.
3Measurement precision
If mass flow rate calculation based on multiple parameters is used, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent utilizes a control device that already performs multiple functions including monitoring boost pressure, intake temperature, and engine rotational frequency for normal engine management. By leveraging these existing multi-functional sensors and processing capabilities, the system can calculate mass flow rate and detect gas return pipe disconnection without adding significant device complexity, as the same control unit handles both traditional engine control and the new disconnection detection function.
Data Source
Figure 1
AI summary
Disclosed is a method for detecting disconnection of a closed breather 18 separating and recovering oil mist from blow-by gas 17 extracted from an engine 1 to return the blow-by gas through a gas return pipe 19 to an intake pipe 5. Under condition of no exhaust gas 9 recirculation being conducted, a mass flow rate of in-cylinder working gas is calculated based on a boost pressure, an intake temperature of an intake manifold 7 and a rotational frequency of the engine, and whether the calculated mass flow rate is divergent from a value detected by an air flow sensor 24 is determined. When determined to be divergent, the divergence in a last determination is compared with a current divergence; if difference between the divergences is beyond a predetermined range, the gas return pipe 19 is determined to be in disconnection from the intake pipe 5.