Parallel Canister ORVR System for Heavy Duty Vapor Recovery
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Solution Overview
Problem
Heavy duty vehicles with large fuel tanks face challenges in efficiently capturing and purging fuel vapors due to inherent restrictions in fuel vapor canisters, leading to increased evaporative emissions and reduced system robustness during refueling, especially when conventional EVAP systems are not equipped for onboard refueling vapor recovery (ORVR).
Innovation Solution
The implementation of a method that adjusts the flow of fuel vapors between multiple canisters arranged in parallel by using a balance valve and canister vent valves to equalize the load on each canister, ensuring efficient purging and reducing back pressure, thereby adapting to changes in canister restrictions over time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a large canister is used to capture refueling vapors from large fuel tanks, then the vapor recovery capacity is improved, but the canister restriction increases causing system back pressure that reduces refueling robustness
Solution Approach 1:
The patent divides a single large canister into multiple smaller canisters arranged in parallel. This segmentation maintains the total vapor recovery capacity while reducing the restriction in each individual canister, thereby lowering system back pressure during refueling operations.
2Reliability
If multiple canisters are used to reduce canister restriction, then the refueling robustness is improved, but the system complexity increases due to flow distribution challenges
Solution Approach 1:
The patent employs a balance valve that automatically equalizes the flow distribution among multiple canisters based on their individual restrictions. This self-regulating mechanism eliminates the need for complex external control systems while ensuring optimal flow distribution and maintaining refueling robustness.
3Area of stationary object
If canisters are arranged in series, then the footprint is reduced, but the total restriction increases causing excessive back pressure
Solution Approach 1:
The patent arranges multiple canisters in parallel rather than in series, which increases the footprint slightly but dramatically reduces the total restriction. This parallel configuration allows vapor flow to be distributed across multiple pathways, lowering back pressure while maintaining compact design within reasonable limits.
4Device complexity
If conventional EVAP systems are used without ORVR equipment, then the device complexity is reduced, but the evaporative emissions increase due to inability to capture refueling vapors
Solution Approach 1:
The patent implements a modular multi-canister ORVR system that can be integrated into existing heavy duty vehicles. The segmented design allows for gradual implementation and maintains relative simplicity while enabling effective refueling vapor recovery and reducing evaporative emissions.
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 effectively recovers and utilizes fuel vapors as fuel, reducing evaporative emissions and enhancing the robustness of the refueling process by ensuring equal loading and purging of canisters, thus minimizing atmospheric emissions and system constraints.
Implementation Method 1
vaporized hydrocarbons (HCs) from a fuel tank may be stored in a fuel vapor canister packed with an adsorbent which adsorbs and stores the vapors
Implementation Method 2
the evaporative emission control system allows the vapors to be purged into the engine intake manifold for use as fuel
Data Source
AI summary
Methods and systems are provided for an evaporative emissions control system for onboard refueling vapor recovery of a heavy duty vehicle. In one example, a method may include adjusting flow among at least two canisters during canister purging, where the at least two canisters are arranged in a parallel loading and unloading flow direction, to increase flow through a higher loaded canister. Flow may be adjusted using a first valve coupled to the first canister, a second valve coupled to the second canister, and so on for n number of canisters and n number of valves, and a balancing valve used to selectively couple the at least two canisters to a fuel tank.