PCV Leakage Detection Valve Control for Combustion Stability
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Solution Overview
Problem
Conventional leakage detection devices in PCV systems can affect engine drivability by causing unstable combustion when detecting leakage in the blow-by gas passage, leading to potential drivability issues.
Innovation Solution
A leakage detection device is configured with a first pressure measurement unit, a leakage detection valve, a PCV valve to adjust blow-by gas flow, a second pressure measurement unit, and valve controllers to gradually reduce the PCV valve opening and suppress flow rates, allowing for leakage detection without disrupting engine stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the opening degree of a valve connected to the blow-by gas passage is abruptly changed when leakage is detected, then leakage detection is achieved, but combustion becomes unstable and drivability is affected
Solution Approach 1:
The system performs preliminary actions by gradually changing the PCV valve opening degree before completely closing the leakage detection valve. This gradual adjustment prepares the engine for the upcoming leakage detection test, allowing the combustion system to adapt slowly to changing blow-by gas flow conditions, thereby preventing sudden combustion instability when the test is executed
Solution Approach 2:
The system dynamically adjusts the PCV valve opening degree based on real-time engine operating conditions and pressure measurements. Rather than using a fixed valve position, the control unit continuously modifies the PCV valve opening to maintain optimal blow-by gas flow rates during leakage detection, ensuring combustion stability while accurately detecting leakage
2Reliability
If pressure is measured in the crankcase to detect blow-by gas passage leakage, then leakage detection is enabled, but sudden pressure changes occur in the crank chamber affecting drivability
Solution Approach 1:
The system changes the flow rate parameter of blow-by gas by dynamically adjusting the PCV valve opening degree. By controlling the blow-by gas flow rate to a predetermined amount during leakage detection, the system prevents sudden pressure changes in the crank chamber that would otherwise occur when the leakage detection valve is closed, thereby maintaining drivability while enabling accurate leakage 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
The device effectively detects leakage in the PCV passage with minimal impact on drivability by maintaining stable combustion and accurate pressure control, preventing sudden pressure changes in the crank chamber.
Implementation Method 1
a first pressure measurement unit configured to measure a pressure in the positive crankcase ventilation passage
Implementation Method 2
a second pressure measurement unit configured to measure a pressure in the intake passage of the engine downstream of the throttle valve
Implementation Method 3
a leakage detection valve configured to open and close the fresh air line
Implementation Method 4
a positive crankcase ventilation valve configured to adjust a flow rate of blow-by gas conveyed to the scavenging line from the crank chamber
Data Source
AI summary
A leakage detection device for detecting leakage in a positive crankcase ventilation (PCV) passage having at least a scavenging line and a fresh air line includes: a first pressure measurement unit that measures a pressure in the PCV passage; a leakage detection valve that opens and closes the fresh air line; a PCV valve that adjusts a flow rate of blow-by gas; a second pressure measurement unit that measures a pressure in the intake passage; a first valve controller that controls the leakage detection valve when a leakage diagnostic condition is satisfied; a second valve control unit that reduces an opening degree of the PCV valve, and suppresses a flow rate in the PCV passage based on the pressure in the intake manifold after the leakage detection valve is closed; and a leakage determination unit that determines whether leakage occurs based on the pressure in the PCV passage.