Rail Vehicle Component Connection Managing Thermal Expansion
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Solution Overview
Problem
In rail vehicles, connections between components made of different materials with varying thermal expansion coefficients lead to interface forces and screw connection slippage during temperature changes, resulting in a loose connection.
Innovation Solution
A connection system comprising a first component, a shim with a different thermal expansion coefficient, and a second component, where the shim is immovably connected to the first component and the second component is movable, using a fitting connection with precise fit and a screw connection with play to absorb thermal expansion without causing stress on the screw.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a screw connection is used to connect components with different thermal expansion coefficients, then the components are securely attached, but the screw connection slips and loosens during temperature changes
Solution Approach 1:
The connection system is divided into two independent attachment mechanisms: a fitted connection (e.g., dowel pin or tight fit) that handles thermal expansion movements, and a screw connection that provides secure attachment without bearing thermal stress. This segmentation allows each connection type to perform its specialized function, preventing the screw from slipping or loosening while maintaining strong overall connection.
Solution Approach 2:
The patent introduces an intermediate component (such as a shim or adapter plate) between the two components with different thermal expansion coefficients. This intermediary absorbs and accommodates the differential thermal expansion through its own expansion characteristics or compliance, thereby protecting the screw connection from direct thermal stress and preventing loosening.
2Stability of the object's composition
If a fitted connection with precise fit is used to attach components, then the connection is rigid and stable, but thermal expansion causes stress on the screw connection
Solution Approach 1:
The attachment function is segmented between a fitted connection that provides rigid stability and a screw connection that is deliberately designed with play/clearance to avoid stress. The fitted connection (e.g., between the shim and one component) maintains positional stability, while the screw connection accommodates thermal movements without generating stress.
Solution Approach 2:
The patent changes the fit parameter of the screw connection from precise fit to intentional play or clearance. This parameter change allows the screw connection to accommodate thermal expansion and contraction movements without generating stress, while the overall connection stability is maintained by the fitted connection between other 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 system effectively transmits shearing forces via friction and prevents screw loosening by allowing the second component to move during temperature expansion, maintaining a secure connection without bending stress on the screw.
Implementation Method 1
the second material having a different coefficient of thermal expansion than the first material has, preferably a higher coefficient of thermal expansion
Implementation Method 2
On the one hand, twice the shearing force can be transmitted via friction between the shim and the second component
Data Source
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AI summary
The invention relates to a rail vehicle comprising a first component (10) made of a first material, a shim plate (30), a second component (20) which is arranged between the first component (10) and the shim plate (30), wherein the second material has a different coefficient of thermal expansion from the first material. Also arranged is a fitted bolt connection (40) in order to ensure a first fastening of the first component (10), second component (20) and shim plate (30) to one another. Furthermore, a screw connection (50) is arranged in order to ensure a second fastening of the first component (10), second component (20) and shim plate (30) to one another. The fitted bolt connection (40) is fitted with a precise fit relative to the first component (10) and to the shim plate (30) and is fitted with play relative to the second component (20). The screw connection (50) is fitted with play relative to the first component (10), to the second component (20) and to the shim plate (30).