Engine Crankcase Ventilation Controller Using PCV and Ejector
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Solution Overview
Problem
Internal combustion engines with positive crankcase ventilation (PCV) systems face challenges in effectively ventilating the crankcase when there is insufficient negative pressure of intake air or supercharging pressure, leading to inadequate gas ventilation.
Innovation Solution
A controller for the internal combustion engine that adjusts the air-fuel ratio, fuel injection amount, and intake manifold pressure using an electronic control unit to enhance crankcase ventilation, combining the efforts of the PCV valve and ejector, while maintaining constant engine torque and minimizing fuel consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the PCV valve is used to ventilate the crankcase, then the in-case gas can be vented under normal operating conditions, but the ventilation capability becomes insufficient when negative pressure of intake air hardly occurs
Solution Approach 1:
The patent combines two ventilation mechanisms (PCV valve and ejector) into a unified crankcase ventilation system. The PCV valve handles ventilation under normal negative pressure conditions, while the ejector activates when supercharging pressure is sufficient. This merging allows the system to maintain reliable ventilation across varying operating conditions without sacrificing adaptability.
Solution Approach 2:
The system dynamically switches between PCV valve operation and ejector operation based on real-time pressure conditions. The control unit monitors intake air negative pressure and supercharging pressure levels, activating the appropriate ventilation mechanism accordingly. This dynamic adaptation ensures optimal ventilation performance regardless of operating conditions.
2Reliability
If the ejector is used to ventilate the crankcase, then the in-case gas can be vented under supercharging conditions, but the ventilation capability becomes insufficient when supercharging pressure is insufficient
Solution Approach 1:
The patent integrates the ejector as a supplementary ventilation mechanism that works in conjunction with the PCV valve. The ejector is activated when supercharging pressure is sufficient to provide the necessary pressure differential for effective operation. This combination ensures reliable ventilation under supercharging conditions while maintaining system adaptability through conditional activation.
Solution Approach 2:
The control unit dynamically determines whether to activate the ejector based on monitored supercharging pressure levels. When pressure conditions are favorable, the ejector is activated to enhance ventilation; when pressure is insufficient, the system relies on the PCV valve. This dynamic control ensures the ejector contributes effectively without compromising system adaptability.
3Productivity
If the air-fuel ratio is changed to increase ventilation amount, then the crankcase ventilation capability is improved, but the exhaust characteristics and power characteristics may deteriorate
Solution Approach 1:
The control unit dynamically adjusts the air-fuel ratio within a predetermined range specifically when crankcase ventilation is prioritized. This dynamic adjustment increases ventilation amount by modifying intake air characteristics while constraining the air-fuel ratio change to a range that preserves acceptable exhaust and power characteristics. The system adapts operating parameters to achieve ventilation goals without sacrificing overall performance reliability.
Solution Approach 2:
The system changes the air-fuel ratio parameter to control crankcase ventilation effectiveness. By adjusting this parameter within a predetermined range, the system can modify intake air flow characteristics to enhance ventilation while ensuring that the change remains within bounds that maintain adequate exhaust characteristics and power output. This parameter-based control resolves the contradiction between ventilation productivity and performance reliability.
4Productivity
If the ventilation amount is increased by changing operating conditions, then the crankcase ventilation capability is improved, but fuel consumption increases
Solution Approach 1:
The control unit dynamically determines the optimal balance between ventilation amount and fuel consumption by monitoring operating conditions. When crankcase ventilation is required, the system adjusts operating parameters to achieve the necessary ventilation while minimizing the impact on fuel consumption. This dynamic optimization ensures that ventilation productivity is improved only to the extent necessary, avoiding unnecessary fuel consumption increases.
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 solution effectively increases crankcase ventilation capacity without deteriorating power and exhaust characteristics, ensuring efficient gas removal even under conditions of low intake air pressure and supercharging pressure, and reduces fuel consumption.
Implementation Method 1
The PCV valve is disposed between the crankcase and the intake passage so as to suck the in-case gas into the intake passage by using the negative pressure of the intake air.
Implementation Method 2
The ejector has an inlet that is in communication with the interior of the crankcase, an outlet that is in communication with a part upstream of the compressor and a pressure introduction port that is in communication with a part downstream of the compressor. When a pressure difference occurs between before and after the compressor, an air flow from the pressure introduction port to the outlet occurs in the ejector.
Data Source
AI summary
A PCV valve that ventilates a crankcase is provided. A three-way catalyst and a NOx storage/reduction catalyst are provided in an exhaust passage. An electronic control unit performs a stoichiometric control and a lean control. When a crankcase ventilation request is issued, a relationship between a ventilation amount of ventilation achieved by the PCV valve and a fuel consumption resulting from the ventilation is calculated. Furthermore, an operational condition under which the ventilation amount meets a required ventilation amount and the fuel consumption is minimized is calculated. The operational condition is calculated so that a constant engine torque is maintained and the air-fuel ratio falls within a range that ensures purification.