Evaporative Emissions Testing via Ambient Light Trigger
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Solution Overview
Problem
Existing vehicle evaporative emission control systems face issues with false failures in diagnosing undesired evaporative emissions due to customer driving habits and ambient temperature variations, leading to potential unnecessary engine service and battery drain from continuous monitoring.
Innovation Solution
A method that adjusts the timing of evaporative emissions tests based on ambient light changes, using a solar cell to wake the controller during sunrise or sunset when heat gains or losses are greatest, allowing for more accurate pressure and vacuum builds to indicate the presence of undesired emissions while reducing battery drain by maintaining the controller in a sleep mode otherwise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the controller continuously monitors evaporative emissions, then the reliability of emissions detection is improved, but the battery power consumption increases
Solution Approach 1:
The controller performs evaporative emissions monitoring at periodic intervals rather than continuously, specifically waking from sleep mode at scheduled times to conduct pressure build-up tests and then returning to sleep mode. This periodic operation reduces battery power consumption while maintaining adequate emissions detection capability.
Solution Approach 2:
The system uses ambient light sensors to automatically determine optimal test timing based on diurnal temperature cycles, eliminating the need for continuous controller intervention. The system self-regulates when to perform monitoring based on environmental conditions that naturally favor accurate emissions detection.
2Reliability
If the EONV test is conducted under all conditions, then the emissions monitoring coverage is improved, but the false failure rate increases
Solution Approach 1:
The system changes the operational parameters of the EONV test based on ambient conditions, specifically using ambient light levels as a trigger to determine when to conduct tests. By aligning tests with diurnal temperature cycles (when ambient light changes indicate temperature changes), the system ensures optimal pressure build-up conditions for accurate leak detection.
Solution Approach 2:
The system performs preliminary assessment of ambient conditions (light levels) before initiating the EONV test. This preliminary action ensures that tests are only conducted when environmental conditions are favorable, preventing false failures from occurring in unsuitable conditions.
3Speed
If the controller remains awake for continuous monitoring, then the response time for emissions detection is improved, but the battery drain increases
Solution Approach 1:
The controller alternates between sleep mode and active monitoring mode at periodic intervals, waking up at scheduled times to perform emissions tests and then returning to sleep. This periodic operation maintains the ability to detect emissions issues while significantly reducing battery power consumption compared to continuous monitoring.
Solution Approach 2:
The ambient light sensor acts as an intermediary that triggers controller wake-up events. Instead of the controller continuously checking conditions, the sensor mediates by detecting ambient light changes and automatically signaling the controller to wake and perform monitoring, optimizing the balance between response time and power 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
This approach improves the reliability of evaporative emissions monitoring by conducting tests during optimal diurnal temperature cycles, reducing false failures and conserving battery power by only waking the controller during necessary diagnostic procedures.
Implementation Method 1
A method that adjusts the timing of evaporative emissions tests based on ambient light changes, using a solar cell to wake the controller during sunrise or sunset
Implementation Method 2
The pressure in such a fuel system and evaporative emissions control system will increase if the tank is heated further (e.g., from hot exhaust or a hot parking surface) as liquid fuel vaporizes
Implementation Method 3
a vacuum is generated in the fuel system and evaporative emissions system as fuel vapors condense to liquid fuel
Data Source
AI summary
Methods and systems are provided for conducting a test for undesired evaporative emissions in a vehicle fuel system and evaporative emissions control system based on diurnal temperature fluctuations. In one example, a method includes maintaining a vehicle controller in a sleep mode, where a sunrise or sunset event as sensed by a solar cell configured on an external surface of the vehicle triggers the controller to an awake mode whereupon the test for undesired evaporative emissions is conducted. In this way, in use monitoring performance completion rates may be improved, undesired evaporative emissions may be reduced, and the test for undesired evaporative emissions may be conducted during both heat gains and heat losses during a diurnal cycle without negatively impacting the main battery supply.