Rotary Impact Tool Multi-Stage Speed Reduction Mechanism
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Solution Overview
Problem
Conventional rotary impact tools lack the ability to perform screw tightening at high speeds and drilling large-diameter holes efficiently, as they often have speed reduction ratios that are not sufficient for these tasks, leading to slower performance compared to single-function drill drivers and a tendency to lock up during heavy operations.
Innovation Solution
A rotary impact tool with a multi-stage speed reduction mechanism that includes at least two planetary speed changer units and a speed reducer unit, allowing for three speed modes: one for impact and two for drill driver modes, with adjustable reduction ratios to match conventional drill driver tools, minimizing motor size and tool size increase.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a single-stage speed reduction mechanism is used in conventional rotary impact tools, then the structure is simple, but the screw tightening speed is slower and the tool cannot drill large-diameter holes efficiently
Solution Approach 1:
The speed reduction mechanism is divided into multiple independent planetary speed changer units (first, second, and third units) that can be selectively engaged. Each unit provides a different reduction ratio, allowing the system to achieve multiple speed modes without requiring a completely complex redesign. The segmentation of the reduction mechanism into discrete, selectable stages enables high-speed operation while maintaining structural manageability.
Solution Approach 2:
The planetary speed changer units are designed to be dynamically selectable through engagement and disengagement mechanisms. The clutch mechanism allows dynamic switching between different reduction ratios based on operational requirements. This dynamic capability enables the tool to adapt between high-speed screw tightening mode and high-torque drilling mode, resolving the contradiction between speed and versatility.
2Force
If the reduction ratio is increased for heavy tightening operations, then the torque is sufficient, but the tool comes into a locked state and is difficult to use
Solution Approach 1:
The system provides dynamic adaptability through multiple selectable reduction ratios. Users can switch between different planetary speed changer units depending on the operational requirements. For heavy tightening operations, a higher reduction ratio can be selected to provide sufficient torque, while for general-purpose operations, a lower reduction ratio maintains ease of use and prevents locked states. This dynamic selection capability resolves the contradiction between force and usability.
Solution Approach 2:
The reduction ratio parameter can be changed by engaging different planetary speed changer units. The system offers at least three different reduction ratios, allowing the user to optimize the parameter based on the specific task. This parameter variability enables the tool to provide high torque when needed while maintaining ease of operation during normal use, resolving the contradiction between force and usability.
3Productivity
If a multi-stage speed reduction mechanism with multiple planetary units is implemented, then high-speed screw tightening and large-diameter hole drilling are achieved, but the size of the speed changer mechanism increases
Solution Approach 1:
The planetary speed changer units are arranged in a nested or compact configuration where multiple planetary mechanisms share common structural elements. The first, second, and third planetary speed changer units are integrated into a unified housing structure, with shared input and output shafts. This nesting approach allows multiple reduction stages to be accommodated in a compact volume, achieving high-speed performance without excessive size increase.
Solution Approach 2:
Each planetary speed changer unit is designed to serve multiple functions: providing different reduction ratios for both screw tightening and drilling operations. The same planetary mechanism structure is used across different units, allowing for standardized, space-efficient design. This multi-functionality reduces the overall volume required compared to having separate dedicated mechanisms for each function.
4Device complexity
If the reduction ratio in drill driver mode is the same as impact mode, then the structure is simple, but the tool locks during heavy operations
Solution Approach 1:
The speed reduction mechanism is segmented into multiple independently selectable planetary units. This segmentation allows the drill driver mode to use a different effective reduction ratio than the impact mode by engaging different combinations of planetary units. The first planetary speed changer unit can be engaged for drill driver operations to provide a reduction ratio optimized for drilling, while the second and third units provide additional reduction for heavy tightening operations, preventing locked states.
Solution Approach 2:
The reduction ratio parameter is made variable between impact mode and drill driver mode through selective engagement of different planetary speed changer units. In drill driver mode, a lower reduction ratio is used to maintain ease of operation and prevent locking, while in impact mode, a higher reduction ratio provides the necessary torque. This parameter change capability resolves the contradiction between simplicity and reliability.
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 tool achieves high-speed screw tightening and efficient drilling of large-diameter holes, with reduced motor torque requirements and smaller size, enhancing ease of use and performance comparable to single-function drill drivers.
Implementation Method 1
a multi-stage speed reduction mechanism for transferring the rotational power produced by the drive power source to the output shaft through the drive shaft at variable speeds in at least three speed modes
Implementation Method 2
at least two planetary speed changer units shiftable between a reduction state and a non-reduction state
Implementation Method 3
an impact mechanism operatively couplable with the drive shaft, the impact mechanism including a hammer and an anvil
Data Source
AI summary
A rotary impact tool includes a drive power source (13) for producing rotational power, a drive shaft (132) driven by the rotational power supplied from the drive power source, an output shaft (9) operatively connected to the drive shaft for receiving the rotational power, an impact mechanism (6) operatively couplable with the drive shaft. The rotary impact tool further includes a changeover unit (44,45) for changing over an impact mode in which the impact mechanism is operated and a drill driver mode in which the rotational power produced by the drive power source is transferred to the output shaft without operating the impact mechanism and a multi-stage speed reduction mechanism (2,3,5) for transferring the rotational power produced by the drive power source to the output shaft through the drive shaft at variable speeds in at least three speed modes including a low speed mode, a middle speed mode and a high speed mode.