Parallel EVAP Canister Diagnostics for Breach and Blockage Detection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Arranging carbon filled fuel vapor storage canisters in parallel for heavy duty vehicles presents challenges in detecting breaches or blockages in hoses or conduits connecting the canisters, which are crucial for effective evaporative emissions control.
Innovation Solution
A method involving the operation of canister purge and vent valves in parallel during a diagnostic sequence to diagnose vent valves and vent lines, using pressure sensor outputs to indicate evaporative emissions degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If carbon filled fuel vapor storage canisters are arranged in parallel to capture large amounts of fuel vapor, then the system can handle heavy duty vehicle emissions requirements, but it becomes difficult to detect breaches or blockages in connecting hoses or conduits
Solution Approach 1:
The diagnostic process is segmented into multiple distinct phases (Phase 1: both vent valves closed, Phase 2: first vent valve open, Phase 3: second vent valve open) with specific valve configurations in each phase. This segmentation allows systematic isolation and testing of different system components, enabling detection of breaches or blockages that would be impossible to identify with a single diagnostic approach.
Solution Approach 2:
The system performs preliminary diagnostic actions by closing both vent valves before the actual diagnostic test begins. This preliminary configuration establishes a known baseline state (sealed system) against which subsequent diagnostic phases can be compared, allowing detection of pressure changes that indicate breaches or blockages.
2Reliability
If multiple valves are operated in different open/closed combinations during diagnostic sequence, then individual valves and conduits can be evaluated for breaches and blocked conditions, but the diagnostic process complexity increases
Solution Approach 1:
The diagnostic system dynamically changes valve configurations across three distinct phases: Phase 1 (both vent valves closed), Phase 2 (first vent valve open, second closed), and Phase 3 (first vent valve closed, second open). This dynamic reconfiguration allows the same physical hardware to perform multiple diagnostic functions, evaluating different components in each phase without requiring additional sensors or actuators.
Solution Approach 2:
The existing vent valves and pressure sensor are made multi-functional by using them in different combinations across multiple diagnostic phases. The same pressure sensor detects conditions in all three phases, and the same vent valves serve both operational and diagnostic functions, eliminating the need for separate diagnostic hardware.
3Measurement precision
If pressure sensor output is used to generate indication of evaporative emissions degradation, then degraded components can be detected, but the system requires additional sensing and control infrastructure
Solution Approach 1:
The evaporative emissions system performs self-diagnosis using its own existing components. The pressure sensor, already present for operational monitoring, is repurposed to detect breaches and blockages during diagnostic phases. The vent valves, already present for emissions control, are reused to create the diagnostic test conditions, eliminating the need for separate diagnostic hardware.
Solution Approach 2:
The system uses feedback from the pressure sensor readings across multiple diagnostic phases to determine system health. By comparing pressure values and their changes between Phase 1, Phase 2, and Phase 3, the system generates feedback about the condition of vent valves and conduits, enabling detection of degraded components through analytical evaluation of pressure data patterns.
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
Enables the detection of degraded components and blocked passages in the evaporative emissions system, allowing for the evaluation of individual system components for degradation.
Implementation Method 1
generating an indication of evaporative emissions degradation in response to output of a pressure sensor generated during the sequence
Data Source
AI summary
Methods and systems are presented for diagnosing operation of an evaporative emissions system that included two carbon filled fuel vapor storage canisters that are arranged in parallel. In one example, operation of a first canister vent valve, a second canister vent valve, and a canister purge valve are adjusted to diagnose breaches and obstructions within the evaporative emissions system.