Starter Locking Assembly Using Standard Nut and Bolted Retainer
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Solution Overview
Problem
Existing locking assemblies for air turbine starters are costly and require long assembly times due to the use of customized nuts and additional components like shims and pins, which complicate the installation process.
Innovation Solution
A locking assembly utilizing an off-the-shelf lock nut and a bolted retainer that engages both the inner and outer portions of the rotor shaft, eliminating the need for custom nuts and additional components by threading the lock nut against the sun gear and using a bolt through a projection portion for secure locking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If customized nuts and additional components (shims, pins) are used in the locking assembly, then the locking mechanism provides secure retention, but the assembly cost increases and assembly time is extended
Solution Approach 1:
The patent combines multiple functions into a single lock nut component. The lock nut integrates the retention function previously requiring separate shims, pins, and custom nuts into one standardized component that threads directly onto the rotor shaft and secures the sun gear and bearing assembly simultaneously, reducing component count while maintaining secure locking
Solution Approach 2:
The lock nut is designed as a universal standardized component that performs multiple functions: it provides threaded engagement with the rotor shaft, secures the sun gear against axial movement, and retains the bearing assembly. This multi-functional design eliminates the need for specialized custom nuts and additional retention components
2Reliability
If customized nuts and additional components are used in the locking assembly, then the locking mechanism provides secure retention, but the assembly time increases
Solution Approach 1:
By merging the functions of multiple components (custom nut, shims, pins) into a single lock nut assembly with integrated retainer, the patent reduces the number of assembly steps. The lock nut threads directly onto the rotor shaft in one motion, securing both the sun gear and bearing assembly simultaneously, eliminating the time required to install and adjust multiple separate components
Solution Approach 2:
The retainer is pre-positioned on the rotor shaft with its projection portion already threadedly engaged, allowing the lock nut to be installed and immediately secured with a single bolt. This preliminary positioning of the retainer eliminates the need for on-site adjustment and assembly of multiple components during the final assembly process
3Reliability
If customized nuts are used in the locking assembly, then the locking mechanism provides secure retention, but the component cost increases
Solution Approach 1:
The patent employs a standardized lock nut instead of a customized one, allowing the component to be manufactured using standard threading and production processes. This universal component can be produced more economically while still performing the secure retention function through its integrated design that combines multiple functions in one piece
Solution Approach 2:
By using a standardized lock nut and simple retainer design with a single bolt, the patent replaces expensive custom-machined components with simpler, more economical parts that can be manufactured at lower cost while maintaining adequate retention reliability for the application
4Reliability
If additional components like shims and pins are used in the locking assembly, then the locking mechanism provides secure retention, but the installation process becomes more complex
Solution Approach 1:
The patent merges the functions of shims (axial positioning), pins (retention), and custom nuts (securing) into a single integrated lock nut assembly with a retainer. This eliminates the need to handle, position, and secure multiple separate components during installation, simplifying the installation process to threading one nut and installing one bolt while maintaining secure retention
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
This solution reduces component costs and assembly time by using standard parts, providing a secure and balanced locking mechanism without the need for custom components or complex geometries, thus simplifying the installation process.
Implementation Method 1
A lock nut is received against an axial end face of the sun gear and threadedly engaged with an outer diameter of the rotor shaft
Implementation Method 2
A retainer is positioned to bias the nut against the axial end face and includes a projection portion threadedly engaged with the rotor shaft in the inner bore
Implementation Method 3
A bolt through the projection portion is threadedly engaged with the rotor shaft
Data Source
AI summary
A starter for a gas turbine engine includes a rotor shaft rotatable about an axis and includes an inner bore extending from an axial end of the rotor shaft with respect to the axis. A sun gear is on the rotor shaft. A lock nut is received against an axial end face of the sun gear and threadedly engaged with an outer diameter of the rotor shaft. A retainer is positioned to bias the nut against the axial end face and includes a projection portion threadedly engaged with the rotor shaft in the inner bore. A bolt through the projection portion is threadedly engaged with the rotor shaft.