Eccentric Element Interlocking for Orbital Power Tools
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Solution Overview
Problem
Existing eccentric elements in hand-held power tools have limited mutual interlocking functionality, leading to bulky and heavy fastening elements due to high centrifugal and shear forces, and require multiple parts that increase manufacturing scrap.
Innovation Solution
The eccentric element comprises a press-fit connection between the eccentric part and counterweight part, utilizing mutual interlocking relationships to reduce the need for separate fastening elements and minimize centrifugal forces, thereby reducing part count and weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If separate fastening elements (screws) are used to attach the counterweight part to the eccentric part, then the connection strength is improved, but the device complexity and weight increase
Solution Approach 1:
The patent merges the counterweight part and eccentric part into a single integral component manufactured from one piece of material. This eliminates the need for separate fastening elements like screws, reducing the number of parts while maintaining structural strength through the unified design.
Solution Approach 2:
The single-piece structure serves multiple functions simultaneously: it provides the eccentric mass for orbital motion, the counterweight for vibration reduction, and the structural integrity that would otherwise require separate fastening elements. The unified component performs all these functions without requiring additional connecting parts.
2Object-affected harmful factors
If a heavy counterweight part is used to compensate for working element weight and reduce vibrations, then the vibration reduction is improved, but the centrifugal forces and shear forces on fastening elements increase
Solution Approach 1:
By combining the counterweight and eccentric parts into a single integral structure, the patent eliminates the fastening elements that would be subjected to centrifugal and shear forces. The unified design allows the heavy counterweight to reduce vibrations without creating stress concentration points at connection interfaces.
3Ease of manufacture
If multiple separate parts are used to construct the eccentric element, then the manufacturing flexibility is improved, but the manufacturing scrap increases
Solution Approach 1:
The patent manufactures the entire eccentric element including both the eccentric part and counterweight part as a single integral component from one piece of material. This eliminates the need for separate manufacturing processes and assembly operations, significantly reducing manufacturing scrap while maintaining design flexibility through monolithic construction.
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
This design results in a smaller, lighter, and more efficient eccentric element with reduced manufacturing scrap, while effectively managing centrifugal and other forces during tool operation.
Implementation Method 1
The centrifugal force acting on the counterweight part of the eccentric element is rather large due to its large distance to the first rotational axis and due to its high weight, which should be so large as to compensate for the weight of the working element and reduce vibrations to a minimum during intended use of the power tool.
Data Source
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AI summary
The invention refers to an eccentric element (10) configured for use in a hand-held power tool comprising a tool motor for driving a tool shaft (16), in particular for use in an orbital sanding or polishing machine. The eccentric element (10) comprises: - an eccentric part (12) with a top surface (18) attachable to a distal end (22) of the tool shaft (16) or forming an integral part therewith so as to transmit a torque from the tool shaft (16) to the eccentric element (10) and to rotate the eccentric part (12) about a first rotational axis (28) upon activation of the tool motor, a bottom surface (32) to which a working element (30) of the power tool is releasably attachable in a manner freely rotatable about a second rotational axis (34), and - a counterweight part (14) attached to the eccentric part (12). The eccentric part (12) and the counterweight part (14) are separate components and formed such that they enter into a mutual interlocking relationship upon attachment of the counterweight part (14) to the eccentric part (12), the interlocking relationship acting in at least one direction (76; 82; 86).