Self-Locking Nut and Bolt Assembly for Rotating Wheel Stacks
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Solution Overview
Problem
Current rotor designs in rotary machines, such as turbines and compressors, face issues with nut loosening leading to reduced torque carrying capability, requiring redundant methods to prevent rotation, which can be cumbersome and costly, and there is a need for a self-locking nut and bolt assembly that is accessible for inspection and disassembly without adding weight or damaging components.
Innovation Solution
A self-locking nut and bolt assembly featuring a tie bolt with locking nut and washer, where the locking washer is staked in place to prevent rotation, using a locking nut with internal tabs and a malleable washer that can be easily secured without damaging other components, ensuring constant compression load and easy inspection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If redundant locking methods (friction, jam nut, crimped nut) are used to prevent nut rotation, then reliability of torque carrying capability is improved, but device complexity and weight increase
Solution Approach 1:
The locking function is segmented into two distinct components: a locking nut with internal tabs and a separate locking washer with external tabs. This segmentation allows each component to perform a specific locking function, simplifying the overall design while maintaining reliability through the combination of both elements working together to prevent rotation.
Solution Approach 2:
The locking washer is designed to be staked in place, creating a self-locking mechanism that automatically prevents rotation without requiring additional active components or complex adjustment mechanisms. The staking process permanently secures the washer to the bolt, providing automatic and reliable locking.
2Reliability
If redundant locking methods are used to prevent nut rotation, then reliability is improved, but weight increases
Solution Approach 1:
The locking washer is designed as a sacrificial component that is staked in place and cannot be easily removed. This disposable element provides reliable locking functionality while keeping the overall weight low, as the washer itself is a simple, lightweight component compared to more robust permanent locking solutions.
3Reliability
If traditional locking methods are used, then rotation prevention is achieved, but accessibility for inspection and disassembly is reduced
Solution Approach 1:
By separating the locking function into distinct modular components (locking nut and locking washer), the design enables easy inspection of each element individually. The locking washer can be visually inspected for proper staking, and both components can be independently replaced if needed, improving maintenance accessibility.
Solution Approach 2:
The locking washer is staked in place during assembly, creating a pre-configured locked state that requires no additional field adjustments or complex procedures for inspection. The staking is performed beforehand, ensuring rotation prevention is already established when the assembly is installed.
4Reliability
If aggressive locking methods are used to prevent rotation, then reliability is improved, but damage to components occurs
Solution Approach 1:
The harmful locking action is extracted from the bolt and wheel components and concentrated in the dedicated locking washer. The washer absorbs the staking deformation and locking stresses, protecting the expensive bolt and wheel from damage while still providing reliable rotation prevention through the washer's tabs engaging with the locking nut.
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 provides a reliable, lightweight, and accessible self-locking mechanism that maintains constant compression load, preventing rotation of the tie bolt, allowing for efficient operation and maintenance without unnecessary weight or damage to components.
Implementation Method 1
staking the locking washer in place to prevent rotation of the bolt
Implementation Method 2
A sufficient load is applied to the tie bolts to ensure that the rotor torque is carried through the stack by friction between the wheels
Data Source
Figure 1~2
Figure 3~5
AI summary
The present invention provides a self locking nut and bolt assembly (200) for a stack (120) of rotating wheels. The self locking nut and bolt assembly (200) may include a tie bolt (140) extending through the stack (120) of rotating wheels, a locking nut (210) positioned on a first end (160) of the tie bolt (140), and a locking washer (300) positioned on the one end (160) of the tie bolt (140) within the locking nut (210).