Crankcase Breach Detection via Intake Manifold Vacuum
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Solution Overview
Problem
Existing methods for monitoring crankcase ventilation system integrity in engines often fail to accurately detect small breaches due to insufficient signal-to-noise ratio and increase system complexity and cost with the use of multiple sensors and valves.
Innovation Solution
A method that involves increasing intake manifold vacuum during engine cranking by adjusting the throttle or PCV valve, allowing for enhanced detection of crankcase breaches using existing sensors in the crankcase vent tube, reducing the need for additional sensors and valves.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple pressure sensors and valves are used to monitor crankcase ventilation system integrity, then the ability to detect breaches is improved, but system complexity and cost increase
Solution Approach 1:
The patent makes the existing pressure sensor in the crankcase vent tube serve multiple functions: both monitoring crankcase pressure during normal operation and detecting breaches in the ventilation system. By utilizing the sensor's existing position and capability, the system avoids adding dedicated breach detection sensors, thereby reducing complexity while maintaining detection accuracy.
Solution Approach 2:
The crankcase ventilation system performs self-diagnosis by using its own operational parameters (pressure changes in the vent tube) to detect breaches. The system monitors its own integrity through the existing pressure sensor without requiring external diagnostic equipment or additional sensors, making the system self-sufficient and reducing overall complexity.
2Measurement precision
If multiple pressure sensors are positioned at different locations in the crankcase ventilation system, then breach detection capability is improved, but redundancy increases without proportional accuracy improvement
Solution Approach 1:
The patent positions the pressure sensor in the crankcase vent tube to serve dual purposes: monitoring crankcase pressure during normal operation and detecting breaches in the ventilation system. This multi-functional use of the existing sensor eliminates the need for additional sensors at different locations, reducing redundancy while maintaining detection accuracy.
3Ease of operation
If diagnostic tests are performed during engine cranking with low manifold airflow, then crackcase breach detection is enabled, but signal-to-noise ratio becomes insufficient for small breaches
Solution Approach 1:
The patent dynamically adjusts engine operating conditions based on the diagnostic requirements. The controller modifies manifold airflow, throttle position, and PCV valve position during cranking to create optimal pressure differential conditions for breach detection. This dynamic control ensures sufficient signal strength for detecting even small breaches while maintaining ease of operation.
Solution Approach 2:
The patent changes key parameters including manifold airflow rate, throttle opening degree, and PCV valve position to create optimal diagnostic conditions. By dynamically adjusting these parameters during engine cranking, the system generates sufficient pressure differentials to overcome noise and achieve high signal-to-noise ratios for breach detection.
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 improves the accuracy of crankcase breach detection, reduces hardware and software complexity, and maintains the crankcase ventilation system active during diagnostics, enabling effective identification of breaches and degradation in various system components.
Implementation Method 1
a pressure sensor positioned within the crankcase vent tube for providing an estimate of flow or pressure of air flowing through the vent tube
Implementation Method 2
the controller may increase opening of an intake throttle to enhance the intake manifold vacuum
Implementation Method 3
the controller may open (or increase opening of) a PCV valve coupled between the crankcase and the engine intake manifold to enhance the manifold vacuum
Data Source
AI summary
Methods and systems are provided for using a crankcase vent tube pressure or flow sensor for diagnosing a location and nature of crankcase system integrity breach. The same sensor can also be used for diagnosing air filter plugging and PCV valve degradation. Use of an existing sensor to diagnose multiple engine components provides cost reduction and sensor compaction benefits.