Segmented Canister Adsorbent Sections Reduce Fuel Vapor Breakthrough
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Fuel vapor treatment systems in vehicles face challenges in reducing breakthrough emissions of fuel vapor from the adsorbent canister, particularly when the vehicle is stopped, due to diffusion of fuel into the adsorbent section closest to the atmospheric port from upstream sections.
Innovation Solution
A canister design with three adsorbent sections arranged in series, where the first adsorbent section has an adsorption capacity equal to or greater than the second, and the second greater than the third, along with a narrowing element and coil springs to manage fluid flow and resistance, reducing diffusion and breakthrough emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a single adsorbent section is used in the canister, then the device complexity is reduced, but breakthrough emissions increase due to diffusion of fuel vapor into the atmospheric port side section
Solution Approach 1:
The canister is divided into three distinct adsorbent sections (first, second, and third sections) arranged in series from the tank port side to the atmospheric port side. Each section contains adsorbent with specific adsorption capacity characteristics, creating a staged treatment system that prevents breakthrough emissions while managing diffusion effects across multiple zones
Solution Approach 2:
Each adsorbent section is assigned different adsorption capacity characteristics tailored to its position in the flow path. The first section (tank port side) has lower adsorption capacity to allow controlled diffusion, the second section has intermediate capacity for transition, and the third section (atmospheric port side) has highest capacity to capture any remaining vapor and prevent breakthrough emissions
2Object-generated harmful factors
If the adsorbent section closest to the atmospheric port has low adsorption capacity, then diffusion into this section is reduced, but breakthrough emissions increase as vapor passes through to the atmosphere
Solution Approach 1:
The third adsorbent section (atmospheric port side) is specifically designed with the highest adsorption capacity to act as a final barrier against breakthrough emissions. This localized high-capacity zone ensures that any vapor diffusing through the first two sections is captured before reaching the atmosphere, resolving the contradiction between diffusion management and emission prevention
3Reliability
If fuel vapor diffuses into the adsorbent section closest to the atmospheric port, then the adsorbent capacity is wasted, but this diffusion cannot be completely prevented without increasing resistance to fluid flow
Solution Approach 1:
By segmenting the adsorbent into three sections with progressively increasing adsorption capacity from tank port to atmospheric port, the system creates controlled diffusion zones that minimize wasteful diffusion while maintaining adequate fluid flow. The staged configuration allows vapor to be progressively treated rather than encountering a single high-resistance barrier
Solution Approach 2:
The adsorption capacity parameter is varied across the three sections to optimize the balance between diffusion control and flow resistance. The first section uses lower capacity adsorbent to reduce flow resistance, the second section provides intermediate treatment, and the third section uses high-capacity adsorbent to ensure emission control without creating excessive backpressure
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 design effectively minimizes breakthrough emissions by ensuring that fuel vapor is adequately adsorbed across the sections, with the first adsorbent section's higher capacity preventing excess vapor from diffusing into the atmosphere, and the second's higher capacity ensuring sufficient diffusion into the third section, thereby reducing overall emissions.
Implementation Method 1
The fuel evaporated from the fuel tank is adsorbed by the adsorbent in the canister. When the vehicle is traveling, that is, when the internal combustion engine is operating, the fuel vapor adsorbed in the adsorbent is desorbed into the purge line
Implementation Method 2
reducing breakthrough emissions of fuel vapor from the adsorbent canister, particularly when the vehicle is stopped, due to diffusion of fuel into the adsorbent section closest to the atmospheric port from upstream sections
Data Source
AI summary
A canister includes a casing defining an adsorbent chamber. The casing includes a tank port in fluid communication with a fuel tank and an atmospheric port in fluid communication with the atmosphere. The canister includes at least three adsorbent sections arranged in series in the adsorbent chamber. The at least three adsorbent sections include a first adsorbent section proximate to the atmospheric port, a second adsorbent section disposed on a tank port side of the first adsorbent section, and a third adsorbent section disposed on a tank port side of the second adsorbent section. The first adsorbent section contains a first adsorbent, the second adsorbent section contains a second adsorbent, and the third adsorbent section contains a third adsorbent. An adsorption capacity of the first adsorbent is equal to or greater than an adsorption capacity of the second adsorbent. The adsorption capacity of the second adsorbent is greater than an adsorption capacity of the third adsorbent.