Compact Planetary Transmission for 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 a carrier assembly with radially offset planet gear sets and a speed selector that engages ring gears to achieve multiple output speeds, allowing for axial compaction and reduced bending stresses in 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 bulky and difficult to operate in confined spaces
Solution Approach 1:
The patent employs nested planetary gear sets where planet gears are arranged in multiple radial offset stages within a compact carrier assembly. Each planet gear set is nested within the same radial space but at different angular positions, allowing multiple speed reductions to be achieved in a concentrated volume rather than requiring sequential axial stacking of separate transmission stages.
Solution Approach 2:
The invention transitions from conventional axial stacking of transmission components to radial offset arrangement of planet gear sets. By utilizing the radial dimension and angular positioning around the transmission axis, the patent packs multiple speed reduction stages into a compact axial footprint, effectively moving the design from one-dimensional axial arrangement to two-dimensional radial distribution.
2Volume of moving object
If transmission components are compacted axially, then the tool becomes more suitable for confined spaces, but bending stresses in components may increase
Solution Approach 1:
The patent applies local quality by providing individual supports or pins for each planet gear set at its specific radial offset position, rather than using a single centralized support structure. This localized support arrangement optimizes the structural integrity at each stress concentration point, allowing the compact design to maintain adequate stress distribution across all planet gears despite reduced axial spacing.
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 compact design enables the tool to operate efficiently in confined spaces while maintaining multiple speed settings, enhancing user utility and reducing component stress, thus improving overall tool functionality.
Implementation Method 1
a first subsection having a first set of planet gears and a first ring gear meshed with the first set of planet gears, and a second subsection having a second set of planet gears and a second ring gear meshed with the second set of planet gears
Data Source
AI summary
A multi-speed, power-driven tool may include a transmission mechanism that transmits power from a motor to an output device. A speed selection mechanism may be coupled to the transmission mechanism, to control a speed reduction through the transmission mechanism, and an output speed of the tool. The transmission mechanism may employ a compound, stepped, planetary gear assembly, to provide for an axially compact arrangement of transmission mechanism components, to reduce an axial length of the tool. The speed selection mechanism may employ a multi-staged grounding device, corresponding to the reduced axial length of the transmission mechanism.