Pressure Vessel Neck Mount With Flex Plate for Tank Stress Relief
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Solution Overview
Problem
Existing strap mounting systems for pressurized fuel tanks in vehicles constrain radial expansion and impose torsional flex modes, leading to internal stresses, friction, and misalignments, while consuming valuable space and reducing hydrogen storage capacity.
Innovation Solution
A neck mounting arrangement using a flex plate assembly with a first neck mount fixed to the chassis and a second neck mount movably connected via a flex plate, allowing out-of-plane translation and tilting, and constraining in-plane translations and rotations, forming a statically determinate structure to absorb dimensional variations and misalignments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If strap mounting is used to secure the pressure vessel, then the tank is protected from radial forces and crash impacts, but the tank's radial expansion is constrained and internal stresses are generated
Solution Approach 1:
The suspension arrangement allows the pressure vessel to dynamically expand and contract radially in response to pressure changes while maintaining secure mounting. The system transitions from a static constrained mounting to a dynamic adaptive mounting that accommodates normal operational variations.
Solution Approach 2:
The mounting system applies different characteristics to different parts of the pressure vessel: the cylindrical body is allowed to expand freely while the axial ends are securely constrained. This localized differentiation resolves the contradiction by permitting radial expansion where needed while maintaining crash protection where required.
2Reliability
If strap mounting is used to secure the pressure vessel, then crash safety is improved, but valuable radial space is consumed reducing hydrogen storage capacity
Solution Approach 1:
The mounting elements are extracted from the cylindrical body of the pressure vessel and relocated to the axial ends only. This removal of redundant mounting components from the cylindrical surface frees up radial space while maintaining secure attachment through the axial neck mounts.
3Quantity of substance
If neck mounting is used to suspend the pressure vessel at axial ends only, then radial space is optimized and hydrogen storage capacity is improved, but dimensional variations and misalignments cause stresses on the neck mounts
Solution Approach 1:
The suspension arrangement incorporates dynamic compliance to accommodate dimensional variations in the pressure vessel and misalignments with the chassis. The system adapts to changes in tank dimensions due to pressure variations and manufacturing tolerances without generating excessive stresses.
Solution Approach 2:
The mounting system is designed to accommodate parameter changes in the pressure vessel, including dimensional variations from manufacturing tolerances and expansion/contraction due to pressure changes. The suspension arrangement adjusts to these parameter variations while maintaining secure attachment.
4Quantity of substance
If heavy large volume fuel tanks are used to achieve extended driving range, then driving range is improved, but reaction forces on the neck mounts increase significantly
Solution Approach 1:
The suspension arrangement is designed to dynamically support heavy large volume fuel tanks, accommodating the increased weight and corresponding reaction forces. The system maintains proper alignment and reduces stress concentrations even when supporting extended hydrogen storage capacities for 80km+ driving ranges.
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 solution minimizes internal stresses, prevents damage to the fuel tanks, optimizes fuel storage capacity, and ensures crash safety by allowing axial expansion and contraction without inducing large internal stresses, while maintaining the tanks securely attached during collisions.
Implementation Method 1
The at least one flex plate has a flexibility, e.g. is bendable, in an out-of-plane direction for allowing an out-of-plane translation and tilting, preferably in one or more perpendicular directions, of the vessel mount with respect to the chassis mount
Implementation Method 2
Hence, apart from static variations in tank dimension, e.g. related to tank production and in-vehicle assembly tolerances and expansion as function of internal tank pressure (0 to 900 bar), also dynamic misalignments resulting from chassis and cabin back frame deformations, need to be absorbed by the tank fixation system
Data Source
Figure 1
Figure 2
Figure 3A~3E
AI summary
A truck comprising a suspension arrangement for suspending an elongate pressure vessel to the chassis. The suspension arrangement comprises a first and second neck mount. The second neck mount is formed by a flex plate assembly including a vessel mount that is movably coupled to a chassis mount by at least one flex plate, which has a flexibility in an out-of-plane direction and a rigidity in an in-plane direction. The first neck mount is arranged for constraining translations and allowing rotations of the first axial end of the elongate pressure vessel with respect to the chassis.