Radially Offset Planet Carrier for Compact Multi-Speed Power Tools
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Solution Overview
Problem
Multi-speed power tools are often bulky due to the arrangement of transmission components, making them difficult to operate in confined spaces, and there is a need for a more compact design that enhances utility and functionality.
Innovation Solution
A multi-speed power tool with a compact planetary transmission mechanism that includes multiple subsections with planet gears and ring gears, where a speed selector engages specific subsections to achieve different output speeds, allowing for radial offsetting of carrier segments and sun gears to reduce axial length and stress on components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If traditional multi-speed transmission components are arranged in a conventional configuration, then the tool can achieve multiple speed settings, but the tool becomes relatively large and difficult to operate in confined spaces
Solution Approach 1:
The patent implements a nested planetary transmission system where multiple planet gear sets are arranged concentrically around a central sun gear. Each planet gear set operates at a different radial distance from the sun gear, allowing multiple speed reductions to be achieved within a compact axial footprint. The inner and outer planet gear sets are nested within the same transmission housing, effectively placing one transmission system inside another to minimize overall volume.
Solution Approach 2:
The patent transitions from conventional linear or sequential transmission arrangements to a radial/dimensional arrangement where planet gears are positioned at different radial distances from the sun gear. This dimensional reorganization allows multiple speed stages to be achieved simultaneously in a compact axial space by utilizing the radial dimension, thereby reducing the tool's overall size while maintaining multi-speed functionality.
2Power
If conventional transmission component arrangements are used, then power transmission is achieved, but the tool becomes difficult to operate in confined spaces
Solution Approach 1:
The nested planetary transmission arrangement allows power transmission components to be concentrated in a compact radial footprint. By positioning multiple planet gear sets at different radial distances from the sun gear, the system achieves multiple speed reductions without increasing axial length, making the tool more maneuverable in confined spaces while maintaining full power transmission capability.
Solution Approach 2:
The patent merges multiple transmission functions into a single integrated planetary transmission system. The sun gear, planet gears, and ring gears work together as a unified mechanism to provide multiple speed settings, eliminating the need for separate transmission assemblies and reducing the overall space required for operation.
3Speed
If multiple planet gears are mounted on carrier pins, then speed reduction is achieved, but stress on components increases
Solution Approach 1:
The patent segments the planet carrier into multiple independent carrier segments, each supporting a subset of planet gears. This segmentation distributes the mechanical loads across multiple independent support structures rather than concentrating stress on single carrier pins, thereby reducing component stress while maintaining the speed reduction function.
Solution Approach 2:
The patent applies different local qualities to different regions of the transmission system by positioning planet gears at varying radial distances from the sun gear. Inner planet gears operate under different stress conditions than outer planet gears, allowing each region to be optimized for its specific load requirements. This localized optimization reduces overall component stress while achieving the desired speed reduction.
Data Source
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AI summary
A multi-speed power tool having a transmission comprising a multi-piece planet carrier with radially offset planets. A multi-speed power tool having a transmission comprising a multi-piece carrier with compound planets. A multi-speed power tool having a shutter on a speed selector switch. A multi-speed power tool having a compliant speed shifter.