Planet Gear Impact Tool Layout for Compact Rotational Impacts
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Solution Overview
Problem
Existing impact tools struggle to efficiently deliver consecutive rotational impacts to loosen or remove stuck fasteners, particularly when using hand tools are ineffective.
Innovation Solution
The impact tool incorporates a drive assembly with a camshaft and gear system that converts continuous rotational input into consecutive rotational impacts, featuring a camshaft with a front and rear portion, a ring gear fixed to the housing, and planet gears meshed with the ring gear, along with a bushing to support the anvil, optimizing the axial length and support ratio for improved impact delivery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a gear assembly with planet gears and ring gear is used to convert continuous rotation to intermittent impacts, then the impact delivery effectiveness is improved, but the device complexity increases
Solution Approach 1:
The gear assembly is segmented into distinct functional components: a ring gear with internal teeth, multiple planet gears with external teeth that mesh with the ring gear, and a camshaft with eccentric lobes. Each component performs a specific function in the conversion of continuous rotation to intermittent impacts, allowing for optimized design of each segment while maintaining overall system effectiveness.
Solution Approach 2:
The system employs dynamic elements including the rotation of planet gears around the camshaft, the engagement and disengagement of gear teeth during rotation, and the intermittent contact between the camshaft lobes and the anvil. This dynamic operation enables the conversion of continuous motor rotation into the desired intermittent impact pattern.
2Reliability
If the bushing axial length is increased to improve anvil support and alignment, then the support ratio improves, but the total tool length increases
Solution Approach 1:
The bushing is designed with an optimized axial length that provides sufficient support and alignment for the anvil before the impact action occurs. This preliminary support structure ensures proper alignment and stability during the impact operation without requiring excessive length that would increase overall tool size.
Solution Approach 2:
The design optimizes the bushing axial length parameter to achieve the critical support ratio needed for reliable anvil alignment. By carefully selecting this dimensional parameter, the system achieves adequate support while minimizing the increase in overall tool length.
3Length of moving object
If the camshaft rear portion is positioned closer to the motor, then the tool length is reduced, but the radial load distribution on the housing changes
Solution Approach 1:
The camshaft is designed with asymmetric positioning where the rear portion is located closer to the motor than the front portion. This asymmetric arrangement reduces the overall tool length while the gear assembly distributes the resulting radial loads through the planet gears and ring gear to the housing, managing the stress distribution caused by this non-uniform configuration.
Solution Approach 2:
The gear assembly acts as an intermediary mechanism between the camshaft and the housing. The planet gears and ring gear transmit and distribute the radial loads generated by the asymmetric camshaft positioning, preventing excessive stress concentration at any single point on the housing while maintaining the compact layout.
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 enhances the impact tool's ability to effectively loosen or remove stuck fasteners by providing consecutive rotational impacts, improving efficiency and reducing tool length while maintaining robust support and alignment.
Implementation Method 1
a gear assembly coupled between the motor shaft and the drive assembly, the gear assembly including a ring gear that is rotationally and radially fixed relative to the housing and a plurality of planet gears meshed with the ring gear
Implementation Method 2
a camshaft having a front portion and a rear portion... a hammer configured to reciprocate along the camshaft and to impart consecutive rotational impacts to the anvil
Data Source
AI summary
An impact tool includes a housing, a motor supported within the housing and having a motor shaft, a drive assembly configured to convert a continuous rotational input from the motor shaft to consecutive rotational impacts upon a workpiece, the drive assembly including a camshaft having a front portion and a rear portion defining a carrier, the rear portion being closer to the motor than the front portion, a thrust bearing engageable with the rear portion of the camshaft, and a gear assembly coupled between the motor shaft and the drive assembly. The gear assembly includes a ring gear and a plurality of planet gears meshed with the ring gear. Each of the plurality of planet gears is coupled to the carrier of the camshaft, and the ring gear rotationally and radially supports the rear portion of the camshaft via the plurality of planet gears.