Stepped Spindle Interference Fit for Planet Carrier Retention
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Solution Overview
Problem
Existing multi-speed transmissions face challenges in securely retaining spindles within rotatable transmission components, often relying on retainers or deforming ends which can be cumbersome and prone to failure under load and temperature variations.
Innovation Solution
A planetary gearset design featuring a spindle with interference fit connections between the spindle and mounting members, ensuring secure axial location without the need for additional retainers or deformation, using a stepped diameter configuration for enhanced fit and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If retainers or deformed ends are used to retain the spindle, then the spindle is secured in the rotatable transmission component, but the device complexity increases and reliability decreases under load and temperature variations
Solution Approach 1:
The patent removes the retainer component entirely from the retention mechanism. Instead of using a separate retainer to secure the spindle, the spindle itself is designed with stepped diameters that create interference fits directly within the mounting members, eliminating the need for additional retention parts and simplifying the overall structure while maintaining reliability under varying loads and temperatures
Solution Approach 2:
The spindle features localized diameter variations (stepped configuration) at specific positions where interference fits are needed. The first end has a larger diameter for a first interference fit, while the second end has a smaller diameter for a second interference fit. This local quality change allows the spindle to be securely retained without requiring complex retention mechanisms throughout its entire structure
2Ease of repair
If retainers are used to retain the spindle, then the spindle is secured, but ease of repair deteriorates due to potential damage to retainers under load
Solution Approach 1:
By removing the retainer component entirely, the patent eliminates the source of potential retainer damage and failure. The spindle can be directly installed and removed from the mounting members through the interference fit connections without risking damage to separate retention components, thereby improving ease of repair and maintenance
Solution Approach 2:
The spindle's stepped diameter configuration enables it to self-retain through interference fits without requiring separate retainers. The spindle structure itself provides the retention function, making the system more robust and easier to maintain since there are no additional retention components that can fail or require replacement
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 robust and reliable retention mechanism for spindles, preventing relative motion under operational loads and temperatures, while allowing for easy removal and reuse of the spindle without damage, thus enhancing the durability and efficiency of the transmission system.
Implementation Method 1
The first end of the spindle has a first diameter and is coupled to the first mounting member through an interference fit connection with a corresponding aperture of the first mounting member. The second end of the spindle has a second diameter and is coupled to the second mounting member through an interference fit connection with a corresponding aperture of the second mounting member.
Data Source
AI summary
A rotatable transmission component rotatable about an axis of rotation includes a first mounting member spaced apart from a second mounting member and a spindle extending from the first mounting member to the second mounting member. An axial location of the spindle between the first and second mounting members is maintained by interference connections between the spindle and the first and second mounting members. An outer diameter of a first end of the spindle is larger than an outer diameter of a second end of the spindle. The rotatable transmission component may be a planet carrier, and a planet gear may be supported on the spindle.