Self-Cleaning Air Filter Assembly for Vehicle Evaporative Emissions
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Solution Overview
Problem
The air filters in evaporative emissions control systems for vehicles become dirty and clogged with particulate matter due to low airflow outside of purging operations, leading to decreased performance and flowrate, as they are only used for approximately 10% of the vehicle's engine run time.
Innovation Solution
A self-cleaning air filter assembly that utilizes a filter housing with two ports, one connected to an atmospheric vent and the other to a source of low-pressure air, allowing air to flow through the filter element and expel particulate matter during a cleaning mode, even when the vehicle is in operation and not purging, using the vehicle's motion to create a pressure differential for passive cleaning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the air filter is only used during purging operations (10% of engine run time), then the canister can be purged effectively, but the filter becomes dirty and clogged with particulate matter due to extended periods of low airflow
Solution Approach 1:
The system implements periodic cleaning cycles during engine operation to remove particulate matter from the filter element. A controller activates a fan to generate airflow through the filter at regular intervals or based on accumulated dirt levels, preventing clogging while maintaining the original purging function.
Solution Approach 2:
The filter assembly performs self-cleaning during normal engine operation without requiring external intervention or removal from the system. The controller monitors filter conditions and automatically initiates cleaning cycles using the vehicle's existing airflow resources, making the filter maintain itself during its service life.
2Device complexity
If the filter housing has only one port connected to the canister, then the structure is simple, but there is little to no airflow through the filter during non-purging operations
Solution Approach 1:
The filter housing is designed with multiple ports that enable different flow paths for different functions: one port connects to the canister for purging operations, while additional ports enable cleaning airflow paths during normal operation. This multi-functionality allows the same housing structure to support both filtration during purging and self-cleaning during operation.
Solution Approach 2:
The filter housing is divided into functional zones with separate ports for different airflow purposes. The housing structure is segmented to allow independent flow paths: one for canister purging and another for filter element cleaning, enabling each function to operate optimally without interfering with the other.
3Reliability
If the filter element traps all particulate matter during purging, then the canister is protected from contamination, but the filter becomes covered with dirt and debris over time
Solution Approach 1:
The system converts the harmful accumulation of particulate matter on the filter into a beneficial cleaning process. During designated cleaning cycles, the controller reverses or redirects airflow to flush trapped particulate matter off the filter element and expel it through dedicated ports, transforming the problem of dirt accumulation into an automated cleaning opportunity.
Solution Approach 2:
The system periodically discards accumulated particulate matter from the filter element surface by reversing airflow direction or creating high-velocity cleaning flows that blow dirt off the filter media. This discarding action is performed automatically during engine operation to recover filter performance without requiring manual maintenance.
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
The self-cleaning air filter assembly effectively removes particulate matter from the filter element, maintaining its performance and preventing clogging, even during extended periods of low airflow, thereby ensuring continuous effective operation of the evaporative emissions control system.
Implementation Method 1
an air filter element is disposed in the internal volume of the filter housing... trapping the particulate matter in the filter before it can pass to the canister
Implementation Method 2
The lower portion of the filter housing further includes a second port adapted for fluid connection with a source of low pressure air. During a cleaning mode in which there is nominal airflow through the filter element from one side of the filter element to the other side, air is pulled from the first port and along the second side of the filter element to the second port
Data Source
AI summary
A self-cleaning air filter assembly is provided and includes a filter housing having an upper portion and a lower portion that together define an internal volume. An air filter element is disposed in the internal volume. The upper portion of the filter housing includes a canister port adapted for fluid connection with an evaporative emissions canister. The lower portion of the filter housing includes a first port adapted for fluid connection with an atmospheric vent, and a second port adapted for fluid connection with a source of low pressure air. During a cleaning mode, air is pulled from the first port and along the filter element to the second port in order to remove particulate matter from the filter element. A vehicle evaporative emissions control system including the air filter assembly and a method of cleaning an air filter assembly are also provided.