Bogie Rail Joint and Inflatable Seal Design for Misalignment and Ice
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Solution Overview
Problem
The existing rail assembly and bogie systems for large telescope enclosures face challenges with misalignment, fatigue, and costly manufacturing due to large axial and radial loads, and conventional inflatable seals are prone to damage and leakage, especially from ice formation.
Innovation Solution
A rail assembly with oblique connecting bolts to compress and align rail segments, a bogie with elastomeric bearings for reduced misalignment, and an inflatable seal assembly with a tension spring and membrane to prevent ice adhesion and facilitate easy repair.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If rail segments are joined by welds, then the joint strength is improved, but welding at high elevation sites is challenging and can disrupt other construction activities
Solution Approach 1:
The rail is divided into multiple transportable segments that are joined using bolted connections with oblique connecting bolts, allowing assembly at the construction site without welding operations
Solution Approach 2:
A scarf joint interface with tapered surfaces acts as an intermediary between rail segments, distributing loads and enabling bolting connections that achieve full-strength joints without welding
2Ease of manufacture
If scarf joints are used to join rail segments, then the ease of assembly is improved, but the tapered ends may be prone to cracking and spalling
Solution Approach 1:
The scarf joint interface combines tapered geometric configuration with bolted mechanical fastening, creating a composite connection system that distributes stresses and prevents cracking in the tapered ends
Solution Approach 2:
The oblique connecting bolts are installed at an angle to pre-compress the scarf joint interface before full load application, preventing cracking and spalling at the tapered ends during service
3Ease of manufacture
If misalignment of rail segments occurs, then the ease of installation is improved by allowing tolerances, but geometric imperfections induce vibrations and impacts that are detrimental to durability
Solution Approach 1:
The oblique connecting bolts are tensioned to dynamically adjust and maintain alignment of rail segments during assembly, accommodating installation tolerances while preventing geometric imperfections that cause vibrations
Solution Approach 2:
The bolt tensioning process provides feedback control for alignment, where the oblique angle of the connecting bolts self-corrects misalignment as bolts are tightened, ensuring proper rail segment alignment without requiring precise pre-alignment
4Reliability
If conventional inflatable seals are used, then the sealing capability is improved, but they are prone to damage and leakage from ice formation
Solution Approach 1:
A membrane is introduced as an intermediary layer between the inflatable seal and the surrounding environment, protecting the seal from ice formation and mechanical damage while allowing the seal to maintain its sealing function
Solution Approach 2:
The membrane is a flexible thin film that covers and protects the inflatable seal, preventing ice adhesion and damage while allowing the underlying seal to expand and contract for sealing operations
5Force
If large axial and radial loads are applied to bogie components, then the load-bearing capacity is improved, but the components are prone to failure due to fatigue
Solution Approach 1:
The bogie chassis is made movable relative to the support frame through elastomeric bearings, allowing dynamic adjustment and alignment that distributes cyclic loads and reduces fatigue on axle shafts and bearings
Solution Approach 2:
The elastomeric bearings change the stiffness and damping parameters of the bogie-chassis connection, providing vibration isolation and reducing the magnitude of cyclic loads that cause fatigue failure in bearing and axle components
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 enhances the durability and serviceability of the rail and bogie systems by minimizing misalignment and fatigue, while the inflatable seal assembly reduces damage and maintenance costs by preventing ice adhesion and facilitating quick repairs.
Implementation Method 1
The connecting bolt is tensioned to apply a compressive preload to compress the first and second rail segments together
Implementation Method 2
The bogie comprises at least one elastomeric bearing disposed between and in bearing engagement with the support frame and the chassis to limit movement of the chassis relative to the support frame
Implementation Method 3
The tension spring is oriented to bias the membrane against the bladder
Data Source
AI summary
A rail assembly for use with a bogie wheel includes two rail segments having mating end segments abutting against each other, and joined by a connecting bolt that traverse the mating end segments. A bogie for use with a rail includes a support frame, a chassis movably attached to the support frame, and an elastomeric bearing disposed between and in bearing engagement with the support frame and the chassis, to limit movement of the chassis relative to the support frame. A bogie wheel includes a central hub adapted for direct mounting to a bogie chassis, a tread, and a bearing assembly permitting rotation of the tread relative to the hub. An inflatable seal assembly for sealing between a first member and a second member includes an inflatable bladder, a membrane attached to the first member, and a tension spring attached to the membrane to bias the membrane against the bladder.