Cam Actuated Vent Shut-Off Assembly for Fuel Tank Vapor Management
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Solution Overview
Problem
Fuel vapor emission control systems in gasoline-powered vehicles have become increasingly complex due to regulatory requirements, necessitating periodic purging of stored hydrocarbon vapors, which existing systems struggle to manage efficiently.
Innovation Solution
An evaporative emissions control system with an electronically controlled module that includes vent tubes, valves, a vent shut-off assembly, and a control module to recapture and recycle fuel vapor, featuring a cam assembly driven by a motor to manage vapor flow and pressure relief, allowing for universal design compatibility with various fuels and regulatory standards.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple separate vent valves and control systems are used to manage fuel vapor emission under different regulatory standards, then compliance with diverse regulations is achieved, but system complexity increases
Solution Approach 1:
The patent implements a universal vent shut-off assembly that can operate in multiple modes to satisfy different regulatory requirements (EPA, CARB, EU). A single assembly with configurable valve arrangements replaces the need for multiple separate systems, allowing the same hardware platform to comply with various emission standards through software-controlled valve operation sequences
Solution Approach 2:
The vent shut-off assembly is divided into separate controllable valve components (first vent valve, canister vent valve) that can be independently actuated by a cam mechanism. This segmentation allows selective opening/closing of different vent paths based on the specific regulatory mode required, enabling flexible compliance without requiring complete system redesign for different standards
2Device complexity
If a cam actuated mechanism is used to control multiple vent valves, then system complexity is reduced through mechanical integration, but the precision of valve timing and positioning becomes more difficult to control
Solution Approach 1:
The control module receives feedback from sensors monitoring valve positions and cam rotation, enabling closed-loop control of the mechanically actuated valves. This feedback mechanism compensates for manufacturing tolerances in the cam mechanism by dynamically adjusting actuation timing and duration to achieve precise valve control despite mechanical variability
Solution Approach 2:
The system uses a programmable cam mechanism where the effective cam profile can be dynamically altered by changing rotation speed, acceleration profiles, or cam selection. This allows the same physical cam mechanism to achieve different timing and positioning precision levels by modifying operational parameters rather than requiring precision manufacturing across all possible operating conditions
3Device complexity
If the system is designed to handle both overpressure and vacuum conditions with a single vent assembly, then component count is reduced, but the reliability of pressure relief under extreme conditions decreases
Solution Approach 1:
The vent shut-off assembly uses dynamically controllable electrically actuated valves instead of static mechanical pressure relief devices. The control module can actively adjust valve opening degrees and timing based on real-time pressure sensor feedback, allowing the system to reliably handle both overpressure and vacuum conditions with a single integrated assembly rather than requiring separate mechanical relief devices for each condition
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 system effectively recaptures and recycles fuel vapor, reducing system complexity, eliminating the need for unique components, and ensuring compliance with diverse regulatory requirements, while maintaining efficient vapor management across different operating conditions.
Implementation Method 1
a cam assembly having a cam shaft that includes a first cam that selectively opens and closes the second valve and a canister cam that selectively opens and closes the canister valve
Implementation Method 2
The actuator assembly includes a motor
Implementation Method 3
The vent shut-off assembly selectively opens and closes the first vent valve and the canister vent valve to provide overpressure and vacuum relief for the fuel tank
Data Source
AI summary
An evaporative emissions control system configured to recapture and recycle emitted fuel vapor on a vehicle fuel tank is provided. The control system includes a first and second vent tube disposed in the fuel tank, a first and second vent valve, a vent shut-off assembly, a purge canister and a control module. The vent shut-off assembly selectively opens and closes the first and second valves to provide overpressure and vacuum relief for the fuel tank. The control module regulates operation of the vent shut-off assembly based on operating conditions to vent the first and second vent valves to the purge canister. The vehicle fuel tank comprises a saddle tank having first and second lobes and a raised portion arranged generally at a top portion of the fuel tank. The first vent valve is arranged generally in the first lobe and the second vent valve is arranged in the raised portion.