Planetary Gear Power Tool With Direction-Based Ratio Switching
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing power tools with changeable speed reducers experience excessively large differences in output speeds due to the planetary gear transmission mechanism's speed reducing ratio changes, leading to inefficient operation.
Innovation Solution
A power tool design incorporating multiple stages of planetary gear mechanisms with a one-way clutch and lock mechanism, allowing the internal gears to function as fixed or rotatable elements based on motor shaft direction, reducing the number of effective stages and thus the speed reducing ratio, enabling flexible switching between high-speed low-torque and low-speed high-torque modes without motor speed control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the speed reducing ratio is changed by switching internal gears between fixed and freely-rotatable states in a planetary gear transmission mechanism, then the speed reducing ratio can be adjusted, but the difference between output speeds before and after the change becomes excessively large
Solution Approach 1:
The patent applies dynamics by making the speed reducing ratio changeable through a speed-reducing-ratio change mechanism that switches between different gear engagement states. The internal gears transition between fixed and freely-rotatable states, dynamically adjusting the transmission characteristics to match different operational requirements without excessive speed variation.
Solution Approach 2:
The patent changes the speed reducing ratio parameter by altering the mechanical configuration of the planetary gear mechanism. By switching the engagement state of internal gears between fixed and freely-rotatable, the transmission ratio is adjusted while maintaining relatively small output speed differences through careful design of the gear stages.
2Speed
If multiple stages of planetary gear mechanisms are used to reduce speed, then the speed reducing ratio increases, but the gear strength requirements increase
Solution Approach 1:
The patent uses dynamic switching of gear engagement states to achieve speed reduction without requiring all gear stages to operate at maximum load simultaneously. By selectively engaging internal gears in different states, the mechanism achieves cumulative speed reduction while distributing mechanical stress more evenly across the gear train.
Solution Approach 2:
The internal gears serve multiple functions: they can operate as fixed elements for speed reduction, as freely-rotatable elements for different transmission paths, or be selectively engaged/disengaged. This multi-functionality allows the same gear components to achieve speed reduction across multiple stages without proportionally increasing strength requirements for each stage.
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 allows for selective performance of actions with relatively small differences in output speed by adjusting the speed reducing ratio, enhancing operational efficiency and reducing gear strength requirements, while maintaining compactness and ease of assembly.
Implementation Method 1
The one-way clutch is disposed in a torque transmission path and configured to transmit rotation only when the motor shaft rotates in specific one of the two directions
Implementation Method 2
The lock mechanism is operably coupled to the one-way clutch and to the internal gears of the at least two stages of the planetary gear mechanisms. The lock mechanism is configured to non-rotatably lock the internal gears of the at least two stages when the one-way clutch does not transmit rotation. The lock mechanism is also configured to rotate the internal gears of the at least two stages when the one-way clutch transmits rotation
Implementation Method 3
The speed reducer includes planetary gear mechanisms arranged in multiple stages
Data Source
AI summary
A power tool includes a motor, a speed reducer and a speed-reducing-ratio change mechanism. The speed reducer includes planetary gear mechanisms arranged in multiple stages. The speed-reducing-ratio change mechanism is configured to change a speed reducing ratio of the speed reducer in response to a change of a rotating direction of a motor shaft. At least two stages of the planetary gear mechanisms are configured such that an internal gear in each stage selectively functions as a fixed element. The speed-reducing-ratio change mechanism includes a one-way clutch and a lock mechanism configured to non-rotatably lock the internal gears of the at least two stages when the one-way clutch does not transmit rotation, and to rotate the internal gears of the at least two stages when the one-way clutch transmits rotation. The at least two stages include a speed-increasing planetary gear mechanism and a speed-reducing planetary gear mechanism.