Venturi Vacuum for Boosted Engine Fuel Vapor Purging
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Solution Overview
Problem
Downsizing and boosting engines make it difficult to purge fuel vapors from a fuel vapor canister, especially when intake manifold pressure is high, as it limits the flow from the canister to the intake manifold and reduces engine power.
Innovation Solution
Decreasing the throttle opening area and increasing the boost pressure produced by the compressor to enhance the vacuum flow from the fuel vapor canister to the intake system, using a venturi in the compressor bypass loop to create a pressure depression that draws vapors while maintaining desired engine output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the engine is downsized and boosted to increase engine efficiency and output, then engine efficiency and power output are improved, but fuel vapor purging becomes difficult and engine power is reduced
Solution Approach 1:
The system dynamically adjusts the throttle opening area and boost pressure based on real-time fuel vapor levels in the canister. When fuel vapor concentration exceeds a threshold, the controller decreases throttle opening area and increases boost pressure to enhance purging efficiency. This dynamic adjustment allows the system to optimize both engine performance and vapor purging under varying operating conditions.
Solution Approach 2:
The invention changes key operating parameters (throttle opening area and boost pressure) to resolve the contradiction. By decreasing throttle opening area and increasing boost pressure, the system creates stronger vacuum flow through the venturi to improve fuel vapor purging while maintaining engine output. These parameter changes are implemented through controller feedback based on fuel vapor sensor readings.
2Productivity
If the throttle opening is closed to increase vapor flow from the canister, then fuel vapor purging is improved, but engine power is reduced
Solution Approach 1:
The venturi acts as an intermediary device that uses compressed air to create vacuum and draw fuel vapors from the canister without requiring throttle closure. The venturi positioned in the compressor bypass loop creates a pressure differential that facilitates vapor flow while the throttle remains open, thus maintaining engine power while improving purging efficiency.
Solution Approach 2:
The system replaces the traditional mechanical approach of closing the throttle to increase vapor flow with a different mechanism: using the venturi and compressed air to create vacuum flow. This substitution allows vapor purging to occur without restricting the throttle, thereby maintaining engine power output while achieving effective vapor removal.
3Productivity
If boost pressure is increased to improve vapor flow through the venturi, then fuel vapor purging is enhanced, but engine energy consumption increases
Solution Approach 1:
The system uses feedback from fuel vapor sensors to control the boost pressure and throttle opening adjustments. When fuel vapor concentration exceeds a threshold, the controller increases boost pressure to enhance purging. The feedback mechanism ensures that energy-consuming boost pressure increases are applied only when necessary, optimizing the balance between purging efficiency and energy consumption.
Solution Approach 2:
The system applies partial action by increasing boost pressure only to the extent necessary to achieve effective vapor purging, rather than continuously operating at maximum boost. The controller adjusts boost pressure based on real-time vapor levels, applying excessive action only when needed and reducing it when vapor concentrations are low, thereby minimizing unnecessary energy consumption.
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
Improves fuel vapor purging efficiency for boosted engines, maintains engine output, and limits energy consumption by optimizing venturi efficiency only when excess fuel vapors are present.
Implementation Method 1
a venturi located in a compressor bypass loop can provide vacuum to draw fuel vapors from a fuel vapor canister to an intake system by using compressed air to create vacuum at the venturi
Implementation Method 2
the pressure depression created at the venturi also increases, thereby increasing the potential for flow between a fuel vapor canister and the intake system
Data Source
AI summary
A method for improving purging of fuel vapors from a boosted engine is presented. In one embodiment, the method increases the efficiency of a venturi that supplies vacuum to purge fuel vapors from a vapor storage canister.