Variable Vacuum Evacuation for Hybrid Fuel System Diagnostics
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Hybrid-electric vehicles face challenges in diagnosing undesired evaporative emissions due to limited engine run time and operational vacuum limitations, leading to increased manufacturing costs and inconclusive test results influenced by environmental conditions.
Innovation Solution
A method involving variable vacuum levels for fuel system evacuation, using a vacuum pump and engine intake manifold, and leveraging crowd data to conduct tests based on learned key-off events and fuel system loading states, reducing the risk of fuel vapor bleed-through and improving test accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an on-board vacuum pump is installed in hybrid-electric vehicles to enable evaporative emissions testing, then the ability to perform leak tests is improved, but manufacturing costs increase
Solution Approach 1:
The vacuum pump is integrated into the existing evaporative emissions control system and serves multiple functions: it enables leak detection testing, maintains system vacuum levels during engine-off conditions, and supports diagnostics across different operating modes. This multi-functionality justifies the added manufacturing cost by eliminating the need for separate testing equipment.
Solution Approach 2:
The system uses the vehicle's own vacuum pump rather than requiring external testing equipment or additional onboard components. The pump is already part of the evaporative emissions control system, so it serves the dual purpose of emissions control and diagnostic testing, reducing overall system cost while maintaining testing capability.
2Ease of operation
If the fuel system is evacuated to a fixed vacuum level for emissions testing, then testing simplicity is improved, but test accuracy deteriorates due to environmental conditions like ambient temperature and fuel vaporization
Solution Approach 1:
The vacuum level is dynamically adjusted based on real-time sensor feedback regarding ambient temperature, fuel temperature, and canister loading state. Rather than using a fixed vacuum target, the system adapts the evacuation level to current environmental conditions, maintaining test accuracy while preserving operational simplicity through automated control.
Solution Approach 2:
The system changes the vacuum parameter (evacuation level) based on environmental conditions such as ambient temperature and fuel volatility. By adjusting the target vacuum level or test thresholds according to measured conditions, the system maintains measurement precision across varying environments without complicating the testing procedure for the user.
3Adaptability or versatility
If vacuum is applied to the fuel system when the engine is not in operation, then testing flexibility is improved, but fuel vapor may be drawn into the canister increasing bleed-through emissions
Solution Approach 1:
The system checks the canister loading state before initiating vacuum evacuation during engine-off conditions. If the canister is already near saturation, the system prevents or limits vacuum application to avoid drawing additional fuel vapor into the canister. This preliminary check prevents harmful emissions while allowing flexible testing when conditions are appropriate.
Solution Approach 2:
The system uses feedback from sensors monitoring canister loading state and environmental conditions to control vacuum application. When the canister is nearly saturated or environmental conditions indicate high fuel volatility, the system reduces or prevents vacuum evacuation to avoid saturating the canister and causing bleed-through emissions. This feedback control enables flexible testing while preventing harmful emissions.
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 allows for efficient and environmentally friendly evaporative emissions testing in hybrid-electric vehicles, reducing manufacturing costs and minimizing the impact of environmental conditions on test results, while ensuring accurate diagnosis of undesired emissions.
Implementation Method 1
evacuating the fuel system to a variable vacuum level through an entirety of a fuel vapor canister
Implementation Method 2
fuel vapor canister configured to capture and store fuel vapors
Implementation Method 3
an intake manifold vacuum may be used as the vacuum source applied to the emissions control system
Data Source
AI summary
Methods and systems are provided for diagnosing a vehicle fuel system for a presence or absence of undesired evaporative emissions. In one example, a method comprises conducting a test for undesired evaporative emissions stemming from a fuel system of a vehicle via in a first operating mode, evacuating the fuel system to a variable vacuum level through an entirety of a fuel vapor canister configured to capture and store fuel vapors, and in a second operating mode, evacuating the fuel system to the variable vacuum level through a portion of the fuel vapor canister. In this way, the diagnostic may be conducted in an environmentally friendly fashion, where analysis of a bleed-up portion of the test is not impacted by fuel volatility at the time of the diagnostic.