Torsion Spring Attenuation for Electric Power Tool Reaction Forces
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Solution Overview
Problem
Existing electric torque delivering power tools face challenges in efficiently managing reaction forces during tightening operations, requiring complex and space-demanding arrangements that are difficult to produce and mount, while also needing flexibility in force distribution to prevent overshooting target torque.
Innovation Solution
An electric power tool with a modular design featuring a torsion spring that counteracts rotation of the load-sensitive part of the reduction gear, with connective interfaces for easy installation and replacement, reducing the number of parts and simplifying the assembly process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a spring is arranged to receive reaction forces above a certain magnitude, then torque control precision is improved, but device complexity increases due to requirements for bearings and attachment pieces
Solution Approach 1:
The patent combines the spring mounting function with the existing gear structure by integrating the spring directly into the gear assembly. The spring is positioned to engage with the gear rim and housing without requiring separate mounting brackets or additional bearing supports, thereby reducing part count while maintaining torque attenuation functionality.
Solution Approach 2:
The gear structure serves multiple functions: it provides mechanical advantage for torque multiplication, supports the spring mounting, and acts as a load-sensitive element that rotates to engage the spring. This multi-functionality eliminates the need for dedicated attachment pieces and simplifies the overall device architecture.
2Force
If a spring arrangement with bearings and attachment pieces is used, then reaction force attenuation is achieved, but space requirements increase
Solution Approach 1:
The spring is nested within the existing gear housing structure, utilizing the internal space of the gear assembly. The spring is positioned concentrically with the gear rim, allowing it to occupy the same spatial envelope as the gear mechanism without requiring additional external mounting space.
3Measurement precision
If a complex spring arrangement with multiple parts is used, then torque control is improved, but ease of manufacture deteriorates
Solution Approach 1:
The spring mounting features are integrated directly into the gear and housing components during their primary manufacturing processes. The gear includes built-in engagement features for the spring, and the housing incorporates corresponding mounting structures, eliminating the need for separate attachment pieces that would require additional manufacturing steps and assembly operations.
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 modular design with a torsion spring allows for flexible force distribution, easy mounting, and replacement, reducing the complexity and space requirements of the power tool, while ensuring precise torque control and efficient operation.
Implementation Method 1
A torsion spring is arranged to counteract any such rotation of the load sensitive part
Implementation Method 2
The element for prohibiting axial movement between the connected parts may be comprised of a threaded connection
Data Source
AI summary
An electric power tool includes an electric motor, an output shaft, a housing that houses the electric motor and at least part of the output shaft, and a reduction gear drivingly arranged between the electric motor and the output shaft. The reduction gear includes a load sensitive part that is rotatable in response to reaction forces created during operation of the power tool. A torsion spring, arranged to counteract any such rotation, includes a first end and a second end, the first end including a first connective interface that is rotationally lockable to a connective interface of the load sensitive part, and the second end including a second connective interface that is rotationally lockable with respect to at least one of the housing and the motor. At least one of the first and the second connective interfaces includes an element for prohibiting axial movement between the connected parts.