Starter Locking Assembly Using Standard Nut and Retainer
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Solution Overview
Problem
Prior locking assemblies for air turbine starters are expensive and require long assembly times due to the need for customized nuts, shims, and additional components, which complicates the installation process.
Innovation Solution
A locking assembly utilizing an off-the-shelf lock nut threadedly engaged with the rotor shaft and a retainer with a projection portion, secured by a bolt, eliminates the need for custom nuts and shims, providing secure clamping of the sun gear and bearing assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If customized nuts and additional components are used in the locking assembly, then the reliability of the connection is improved, but the device complexity and manufacturing cost increase
Solution Approach 1:
The retainer component performs multiple functions: it provides a mounting surface for the lock nut, engages with the rotor shaft through threaded projection portions, and secures the locking assembly without requiring additional shims or custom components. This multi-functionality reduces overall assembly complexity while maintaining connection reliability.
Solution Approach 2:
The locking assembly merges the retainer, lock nut, and fastener into a single integrated unit that attaches to the rotor shaft. This consolidation eliminates the need for separate customized nuts and additional components, reducing device complexity while maintaining secure connection through the combined action of these integrated elements.
2Reliability
If customized nuts and additional components are used in the locking assembly, then the connection security is improved, but the assembly time increases
Solution Approach 1:
The retainer is pre-configured with projection portions that threadedly engage with the rotor shaft, and the lock nut is pre-positioned on the retainer. This preliminary arrangement of components allows for rapid assembly without requiring sequential installation of multiple separate customized parts, reducing assembly time while maintaining connection security.
Solution Approach 2:
The retainer serves as both the mounting structure for the lock nut and the engagement component with the rotor shaft, eliminating the need for separate customized nuts and shims. This multi-functionality reduces the number of assembly steps and components required, thereby reducing assembly time while ensuring secure connection.
3Ease of manufacture
If standard off-the-shelf components are used in the locking assembly, then the manufacturing cost is reduced, but the connection reliability may be compromised
Solution Approach 1:
The locking assembly combines standard off-the-shelf components (retainer, lock nut, fastener) into an integrated design that achieves reliable connection through their collective action. The threaded engagement of the retainer with the rotor shaft, combined with the lock nut securing the retainer, provides secure connection using only standard components without requiring customized parts.
Solution Approach 2:
The retainer performs multiple critical functions using a standard component: it provides the mounting surface for the lock nut, engages with the rotor shaft through threaded projection portions, and maintains the locking assembly's structural integrity. This multi-functionality of a standard component ensures reliable connection while avoiding the need for expensive customized parts.
Data Source
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AI summary
A starter for a gas turbine engine includes a rotor shaft (142) rotatable about an axis and includes an inner bore (160) extending from an axial end of the rotor shaft (142) with respect to the axis. A sun gear (140) is on the rotor shaft (142). A lock nut (164) is received against an axial end face of the sun gear (140) and threadedly engaged with an outer diameter of the rotor shaft (142). A retainer (168) is positioned to bias the nut (164) against the axial end face and includes a projection portion threadedly engaged with the rotor shaft (142) in the inner bore (160). A bolt (172) through the projection portion is threadedly engaged with the rotor shaft (142).