Fuel Tank Isolation Valve Latching for Powerless Assembly Refuelling
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Solution Overview
Problem
Fuel tank isolation valves in vehicles require a mechanism for one-time powerless opening during vehicle assembly to facilitate refuelling, as they are normally closed and battery connections are not available at that time, making it difficult to partially open the valve for intermediate pressure management.
Innovation Solution
The improved fuel tank isolation valve incorporates a latch assembly with a torsional spring and hinge that locks the moving core in an intermediate position, allowing one-time powerless opening for refuelling, and remains partially open until first electrical actuation, after which it becomes non-functional.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the valve is designed to be normally closed for safety, then pressure containment is improved, but refuelling capability during vehicle assembly without power connections deteriorates
Solution Approach 1:
The latch assembly is pre-configured in a latched state during manufacturing, enabling the valve to be opened without power during vehicle assembly. The latch mechanism is designed to be manually or automatically released, allowing the valve to transition from its normally closed state to an open state for refuelling operations before electrical systems are operational.
Solution Approach 2:
The latch assembly acts as an intermediary mechanism between the normally closed valve state and the required open state for refuelling. This mechanical intermediary enables temporary bypass of the electrical control system, allowing fuel vapour flow during assembly without requiring power connections or solenoid actuation.
2Reliability
If the valve remains closed in powerless condition for safety, then pressure protection is improved, but one-time powerless opening for refuelling deteriorates
Solution Approach 1:
The valve system transitions from a static normally closed state to a dynamic system with multiple possible states (closed, latched open, electrically controlled open). The latch assembly introduces mechanical dynamics that allow temporary override of the default closed position, enabling adaptability for refuelling while maintaining pressure protection through the solenoid's ability to reclose the valve when powered.
Solution Approach 2:
The system changes the operational parameter of valve position from exclusively electrically controlled to include a mechanical latched state. This parameter change allows the valve to maintain pressure protection (closed state) under normal conditions while enabling one-time powerless opening (latched state) during assembly, thus achieving both safety and adaptability requirements.
3Measurement precision
If the valve is electrically actuated for control, then precision pressure management is improved, but complexity of the valve system deteriorates
Solution Approach 1:
The latch assembly is integrated with the solenoid valve body, merging the mechanical latching function with the electrical control system. This combined design allows the valve to function as a unified system where the latch provides preliminary opening capability and the solenoid provides precise electrical control, reducing overall system complexity compared to having separate mechanisms.
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
Enables refuelling during vehicle assembly without power connections by maintaining the valve in a partially open state for one-time delivery, ensuring pressure management within safe limits and facilitating efficient fuel vapour flow.
Implementation Method 1
the solenoid housing includes a solenoid, a moving core
Implementation Method 2
a compression spring fixed inside the valve housing for performing OPR function, a compression spring fixed over flow limiter to perform over-pressure relief function
Implementation Method 3
The latch assembly comprises of a torsional spring and a hinge that locks the moving core in axial direction to provide an intermediate latching position for single operation
Data Source
AI summary
The present invention provides an improved fuel tank isolation valve (10). In particular, the invention is directed to provide an improved fuel tank isolation valve (10) which is normally open for one time delivery condition of the valve to enable refuelling function at the time of vehicle assembly. Said valve (10) comprises of a valve housing (1) and a solenoid housing (2), wherein the solenoid housing (2) includes one latch assembly that locks the moving core (12) in radial or axial direction to provide an intermediate latching position for single operation.