Forced-Induction Engine Controller for Crankcase Water Ventilation
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Solution Overview
Problem
Conventional forced-induction engines fail to ventilate the crankcase during naturally-aspirated operation, leading to water mixing with engine oil and causing emulsion due to the absence of compressor pressurization, which is prevalent in naturally-aspirated regions.
Innovation Solution
A controller for a forced-induction engine that includes processing circuitry to determine water accumulation in the engine oil and initiate boost operation by increasing compressor efficiency and reducing throttle valve opening during naturally-aspirated regions to ventilate the crankcase.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the engine operates in naturally-aspirated region without compressor pressurization, then the engine can run without forced induction, but the crankcase cannot be ventilated and water accumulates in the engine oil causing emulsion
Solution Approach 1:
The system dynamically switches between naturally-aspirated and forced-induction modes based on operating conditions. The controller monitors crankcase pressure and water accumulation, then activates boost operation when needed to ventilate the crankcase and discharge water, even during primarily naturally-aspirated operation. This dynamic adaptation resolves the contradiction by allowing the system to maintain versatility while ensuring oil quality through conditional forced induction.
Solution Approach 2:
The controller changes key operating parameters (throttle valve opening, compressor boost pressure) to transition from naturally-aspirated to forced-induction mode when water accumulation is detected. By adjusting these parameters, the system creates positive pressure differential across the unidirectional valve to enable crankcase ventilation and water discharge, thereby maintaining engine oil quality while preserving operating flexibility.
2Stability of the object's composition
If a unidirectional valve is installed in the first ventilation passage to prevent backflow, then gas flow from crankcase to intake passage is restricted, but the system cannot ventilate the crankcase during naturally-aspirated operation
Solution Approach 1:
The unidirectional valve provides stable one-way flow protection during normal operation, while the system dynamically activates forced-induction mode when crankcase ventilation is needed. The controller monitors conditions and temporarily increases compressor boost pressure to create sufficient pressure differential to open the unidirectional valve and enable water discharge, then returns to normal operation. This dynamic approach maintains both intake air quality and periodic ventilation capability.
Solution Approach 2:
The system employs periodic boost operation rather than continuous forced induction. The controller periodically activates the compressor to create pressure pulses that open the unidirectional valve, allowing intermittent crankcase ventilation and water discharge. This periodic action maintains the unidirectional valve's backflow prevention function while providing sufficient ventilation capability during naturally-aspirated operation.
3Reliability
If boost operation is activated during naturally-aspirated region to ventilate the crankcase, then water discharge from the crankcase is enabled, but fuel consumption increases
Solution Approach 1:
Instead of continuous forced induction, the system applies partial action by activating boost mode only when water accumulation reaches threshold levels. The controller monitors water accumulation amount and triggers brief, targeted boost operations sufficient to discharge accumulated water, then returns to naturally-aspirated mode. This partial application of forced induction maintains engine oil quality while minimizing fuel consumption penalties.
Solution Approach 2:
The system uses the engine's own compressor and existing ventilation passages to perform the ventilation function, rather than requiring a separate dedicated system. The compressor, already present for forced-induction operation, is temporarily utilized to create pressure differential for water discharge. This self-service approach enables water removal using existing components, avoiding additional energy-intensive systems while maintaining oil quality.
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
Effectively limits the generation of emulsion by ventilating the crankcase during naturally-aspirated operation, ensuring efficient discharge of water from the crankcase even when water accumulation exceeds a threshold.
Implementation Method 1
When the operation of the forced-induction engine in the naturally-aspirated region with the engine oil cooled, the water generated by the combustion of fuel and leaked into the crankcase continues to remain in the crankcase
Implementation Method 2
a unidirectional valve configured to restrict a flow of gas from the crankcase toward the intake passage through the first ventilation passage
Implementation Method 3
a turbine disposed in an exhaust passage, a compressor disposed in an intake passage
Implementation Method 4
water mixes with the engine oil, causing emulsion
Data Source
AI summary
A forced-induction engine includes a first ventilation passage that connects a crankcase to a portion of an intake passage downstream of a compressor and upstream of a throttle valve, a second ventilation passage that connects the crankcase to a portion of the intake passage upstream of the compressor, and a unidirectional valve configured to restrict a flow of gas from the crankcase toward the intake passage through the first ventilation passage. A controller for the forced-induction engine includes processing circuitry configured to determine whether a water accumulation amount in engine oil is relatively large, and when determining that the water accumulation amount is relatively large during operation of the forced-induction engine in a naturally-aspirated region, perform boost operation of the forced-induction engine by increasing a boost efficiency of the compressor and increasing an opening degree of a throttle valve.