Multi-path Purge Ejector System for Evaporative Emissions Control
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Solution Overview
Problem
The existing fuel vapor recovery systems for vehicles with boosted internal combustion engines face issues with ejector blockages due to contaminants, which hinder vacuum generation and delay canister purging, leading to decreased emissions quality.
Innovation Solution
Incorporating a two-way valve in the fuel vapor recovery system to route contaminants from the ejector to the engine intake manifold during naturally aspirated operation, utilizing engine vacuum to clear the blockage, and repeating the process until the ejector is clean, ensuring effective purging during both naturally aspirated and boosted engine conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If an ejector is used to generate vacuum during boosted engine operation for canister purging, then purging effectiveness is improved, but the ejector nozzle may become blocked by contaminants hindering vacuum generation
Solution Approach 1:
The system performs preliminary diagnostic checks to detect ejector blockage before it completely fails, and initiates cleaning cycles during naturally aspirated operation to prevent complete clogging. The controller monitors vacuum levels and triggers cleaning routines proactively to maintain ejector functionality.
Solution Approach 2:
The ejector is cleaned using the engine's own vacuum during naturally aspirated operation, without requiring external cleaning equipment. The system uses its existing vacuum source to reverse-flow contaminants out of the ejector nozzle, making the cleaning process self-contained and automatic.
2Reliability
If the ejector nozzle is blocked by contaminants, then vacuum generation is hindered, but prolonged operation with blocked ejector delays canister purging causing decreased emissions quality
Solution Approach 1:
The controller continuously monitors vacuum levels in the EVAP system and compares them against threshold values to detect ejector blockage. This feedback mechanism triggers diagnostic routines and cleaning cycles when blockage is detected, and adjusts purging strategies based on real-time ejector performance to prevent emissions violations.
Solution Approach 2:
The system dynamically switches between different purging paths and modes depending on engine operating conditions (boosted vs. naturally aspirated) and ejector health status. When the ejector is blocked during boosted operation, the system transitions to using the intake manifold vacuum path during naturally aspirated operation to maintain purging effectiveness.
3Reliability
If a two-way valve is added to route contaminants from the ejector to the engine intake manifold for cleaning, then device complexity increases, but the ejector can be cleaned using intake manifold vacuum during naturally aspirated operation
Solution Approach 1:
The two-way valve serves multiple functions: it enables the cleaning path by routing ejector contaminants to the intake manifold, and also provides an additional purging path when the ejector is blocked. The same valve and piping infrastructure is used for both cleaning and alternative purging operations, reducing the need for separate dedicated components.
4Measurement precision
If diagnostic routines are implemented to detect ejector blockage, then measurement precision of system state improves, but the complexity of detecting and measuring increases
Solution Approach 1:
The diagnostic system uses feedback from existing vacuum sensors and pressure data to infer ejector blockage conditions. By monitoring vacuum levels during boosted operation and comparing against expected thresholds, the system achieves accurate blockage detection without requiring additional dedicated sensors or complex diagnostic hardware.
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 continuous canister purging and improved emissions quality by diagnosing and mitigating ejector clogs, ensuring effective vacuum generation and emissions control across all engine operating conditions.
Implementation Method 1
An ejector may be housed in the second purge line to generate a vacuum in the second purge line during boosted engine operation, the vacuum causing the second check valve to open and allowing purging of the canister to the engine inlet
Implementation Method 2
The contaminants lodged in the ejector may be sucked to the intake manifold by engine vacuum freeing the clogging
Data Source
AI summary
Methods and systems are provided for diagnostics and subsequent cleaning of an ejector in a fuel vapor purge system of a vehicle with a boosted internal combustion engine. In one example, a method may include, in response to indication of blockage in a fuel vapor purge system, a purge system valve may be actuated to a position enabling routing of contaminants blocking the ejector to an engine intake manifold, thereby cleaning the ejector.