Non-backdrivable Gear System with Planetary Locking
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Solution Overview
Problem
Existing self-locking and non-backdrivable gear systems are complex, costly, and composed of non-robust components, often requiring multiple pins, balls, bearings, and fasteners, making them difficult to manufacture and maintain.
Innovation Solution
A gearbox system utilizing simple spur and ring gears with an integrated planetary geartrain, allowing forward and reverse direction driving without back-driving, featuring a compact assembly with laminated ring gears that are easy to manufacture and cost-effective, using materials like thin steel, brass, or aluminum, and optionally hardened for robustness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If prior art self-locking gear systems use flexible metal bands or cups with pins, balls, and bearings, then non-backdrivable locking is achieved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent combines the sun gear, planet gears, and ring gear into a unified planetary gearset where the carrier serves as both a structural support and the output mechanism. This integration eliminates the need for separate flexible bands, pins, balls, and bearings while maintaining self-locking capability through the inherent geometry of the planetary arrangement.
Solution Approach 2:
The invention extracts and eliminates unnecessary intermediate components (flexible bands, pins, balls, bearings) from the gear system, retaining only the essential gear elements (sun gear, planet gears, ring gear, carrier) needed to achieve both motion transmission and self-locking functionality.
2Reliability
If prior art designs use multiple pins, balls, bearings, and fasteners, then locking function is achieved, but ease of manufacture deteriorates
Solution Approach 1:
The patent merges multiple discrete fastening and locking components into a single integrated planetary gearset assembly. The carrier is designed as one piece that naturally positions and secures the planet gears, eliminating the need for multiple pins, balls, bearings, and fasteners that would complicate manufacturing.
3Productivity
If two different sized gears are fixed together on the same shaft, then gear ratio is achieved, but robustness deteriorates due to separate components
Solution Approach 1:
The patent merges the function of multiple gears on separate shafts into a single planetary gearset where the sun gear, planet gears, and ring gear are mechanically integrated through the carrier. This creates a more robust continuous metal cross-section compared to pinned or bolted gear pairs, while achieving the same gear ratio through the planetary arrangement.
4Reliability
If complex components like flex cups or bands are used, then self-locking is achieved, but cost of production increases
Solution Approach 1:
The patent replaces expensive flexible metal bands or cups with simpler, more economical standard gear components (sun gear, planet gears, ring gear, carrier) that can be manufactured using conventional machining processes. This substitution significantly reduces material and manufacturing costs while maintaining self-locking functionality.
Data Source
AI summary
A self-locking non-backdrivable gear system in one embodiment includes an input spur gear mounted to a drive shaft, the input spur gear positioned in meshing engagement with a ring gear on which is mounted at least one planet locking gear which rotates with the ring gear and rotates on its own mounting. The planet locking gear meshes with a fixed spur gear and an output spur gear connected to a bi-rotational load bearing device. The fixed and output gears have different number of teeth and will lock in place with the planet gear should a rotational force be applied to the load bearing device in the absence of a rotational force at the drive shaft.