Capless Refueling Neck Cleaning Cycle for Leak Test Accuracy
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Solution Overview
Problem
Capless refueling systems can trap residual fuel between doors, leading to false-fail diagnoses during evaporative emissions leak tests due to vaporization and pressure buildup, which complicates accurate leak detection.
Innovation Solution
Implementing a method that involves venting the capless refueling assembly to the fuel tank after a refueling event, using a vacuum pump to clear residual fuel before conducting an evaporative emissions leak test, thereby preventing pressure buildup and ensuring accurate test results without additional hardware.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If residual fuel is trapped between the upstream door and downstream door after refueling, then the refueling assembly remains sealed, but pressure buildup during temperature increase causes false-fail diagnoses during leak tests
Solution Approach 1:
The system performs a preliminary venting operation after refueling to remove residual fuel from the refueling assembly before the leak test is conducted. This preliminary action prevents the subsequent problem of pressure buildup and false-fail diagnoses during temperature increases.
Solution Approach 2:
The system extracts and removes the harmful residual fuel from the refueling assembly by opening the downstream door and allowing the fuel to drain back into the fuel tank. This extraction eliminates the source of the pressure buildup problem.
2Measurement precision
If the downstream door is forced open during leak test due to positive pressure from trapped fuel vaporization, then vacuum is drawn on the fuel system, but the door opening causes false-fail diagnosis
Solution Approach 1:
The system applies preliminary anti-action by removing the trapped fuel before the leak test, thereby preventing the vaporization and pressure buildup that would otherwise cause the downstream door to open and invalidate the test results.
3Object-generated harmful factors
If additional hardware is added to clear residual fuel from the refueling assembly, then fuel removal capability is improved, but system complexity and cost increase
Solution Approach 1:
The system uses the existing downstream door mechanism, which serves dual purposes: it seals the refueling assembly during refueling operations and enables fuel removal by opening to allow drainage back to the fuel tank. This eliminates the need for additional dedicated fuel removal hardware.
Solution Approach 2:
The system uses its own existing components (downstream door, fuel tank connection) to perform the fuel removal function, rather than requiring external or additional specialized hardware. The refueling assembly essentially services itself by utilizing its existing structure for fuel drainage.
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 enhances the robustness and accuracy of evaporative leak check module-based tests, reducing false-fail results and potentially lowering in-field warranty services and associated costs for vehicle manufacturers.
Implementation Method 1
activating a vacuum pump within an evaporative leak check module coupled between the fuel vapor canister and atmosphere
Implementation Method 2
An increase in ambient temperature may cause the trapped fuel to vaporize, creating a positive pressure between the upstream and downstream doors
Data Source
AI summary
A method for a vehicle, comprising: following a refueling event, venting a capless refueling assembly to a fuel tank; and then executing an evaporative emissions leak test. In this way, residual fuel trapped in the capless refueling assembly may be removed. This, in turn will prevent a pressure build-up in the capless refueling assembly which could lead to the downstream door opening during a leak test, thereby confounding results.