Ion Sensing for EVAP Control and Lambda Adjustment
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Solution Overview
Problem
Conventional evaporative emissions (EVAP) systems rely on expensive hydrocarbon (HC) sensors to measure fuel vapor composition, necessitating a need for cost-effective alternatives that can maintain stoichiometric engine operation during engine cold starts.
Innovation Solution
An EVAP system incorporating an in-cylinder ion sensing system to measure the fuel/air ratio (FAR) for open-loop lambda control, eliminating the need for HC sensors by adjusting the EVAP system and fuel injectors to maintain stoichiometric operation, and transitioning to closed-loop lambda control post-cold start using oxygen sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an HC sensor is used to measure fuel vapor composition in the EVAP system, then measurement precision of fuel vapor is improved, but device complexity and cost increase
Solution Approach 1:
The ion sensing system originally designed for lambda control during cold starts is made multi-functional by using it also for EVAP system control. The same sensor serves dual purposes: measuring in-cylinder air-fuel ratio for combustion control and detecting fuel vapor composition for EVAP management, thereby eliminating the need for a separate HC sensor and reducing overall system complexity
Solution Approach 2:
Instead of using a dedicated HC sensor for fuel vapor measurement, the patent utilizes the ion sensing system as a substitute or 'copy' that can perform similar measurement functions. The ion sensor replicates the capability to detect hydrocarbon content through alternative measurement methodology, providing the necessary data for EVAP control without requiring the original HC sensor hardware
2Device complexity
If the ion sensing system is used for open-loop lambda control during cold starts, then the need for HC sensor is eliminated, but measurement precision for fuel vapor may be compromised
Solution Approach 1:
The ion sensing system operates at enhanced capacity during cold starts to provide both lambda control and EVAP measurement functions. By utilizing the sensor's full measurement capability during this period when O2 sensors are not yet functional, the system achieves sufficient measurement precision for EVAP control without requiring additional dedicated sensors
Solution Approach 2:
The ion sensing system performs preliminary measurement of fuel vapor composition and lambda control during the cold start period before the O2 sensors become operational. This early action ensures that fuel vapor management can proceed with adequate measurement data available from the ion sensor, establishing proper combustion conditions before closed-loop control is established
3Productivity
If open-loop lambda control is performed during engine cold start, then engine component warming is accelerated, but emission control precision may be reduced
Solution Approach 1:
The ion sensing system provides continuous feedback on in-cylinder air-fuel ratio during cold start operation, enabling the control system to adjust fuel injection and EVAP system operation in real-time. This feedback mechanism maintains sufficient lambda control precision during open-loop operation by continuously monitoring combustion conditions and making corrective adjustments, bridging the gap between open-loop speed and closed-loop precision
Solution Approach 2:
The ion sensing system enables the engine control to be self-regulating during cold starts by providing real-time measurement data that allows the system to automatically adjust fuel delivery and air-fuel mixing without external intervention. This self-service capability maintains adequate control precision while accelerating warm-up by eliminating delays associated with external measurement systems
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 solution reduces engine emissions (HC, NOx, CO) and accelerates engine component warming by enabling accurate fuel vapor combustion during cold starts, eliminating the need for HC sensors and improving operational efficiency.
Implementation Method 1
an ion sensing system configured to measure a fuel/air ratio (FAR) within cylinders of the engine
Implementation Method 2
The vapor canister traps fuel vapor that evaporates from liquid fuel (e.g., gasoline) stored in a fuel tank
Data Source
AI summary
An evaporative emissions (EVAP) system for an engine of a vehicle includes an ion sensing system configured to measure a fuel/air ratio (FAR) within cylinders of the engine and a controller configured to, during an engine cold start period, perform open-loop lambda control of the engine including obtaining, from the ion sensing system, the measured FAR within the cylinders of the engine, comparing the measured FAR within the cylinders of the engine to a target FAR within cylinders of the engine, and based on the comparing, adjusting operation of at least one of the EVAP system and fuel injectors of the engine to maintain a stoichiometric operation of the engine, wherein the use of the ion sensing system for open-loop lambda control of the engine eliminates the need for a hydrocarbon (HC) sensor in the EVAP system.