Radial Brake Surface for Eccentric Hand-Held Tool
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Solution Overview
Problem
Existing hand-held power tools, such as grinding and polishing machines, experience unwanted heating and variable braking effects due to constant contact between the braking surface and seal, leading to inefficiencies in braking performance.
Innovation Solution
A radial braking surface arrangement that engages only partially with the braking element due to the eccentricity of the tool holder, allowing for adjustable braking through a non-rotatable braking surface and a spring-loaded design, which can be adjusted in length and curvature to optimize braking contact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the braking surface and seal are in permanent contact to ensure continuous braking, then braking reliability is improved, but unwanted heating increases and braking effect becomes variable
Solution Approach 1:
The patent applies periodic action by designing the braking system to engage only during specific portions of the tool holder's rotation cycle. The radial braking surface contacts the seal only when the eccentric tool holder brings them into alignment, creating intermittent rather than continuous braking. This periodic engagement maintains reliable braking when needed while allowing cooling periods that prevent excessive heating.
Solution Approach 2:
The patent implements partial action by having the braking surface engage with the seal for only a portion of the operational cycle rather than continuously. The radial braking surface is positioned such that contact occurs during specific angular positions of the tool holder rotation, providing sufficient braking effect for safety while reducing overall frictional heating compared to permanent contact.
2Reliability
If the radial braking surface is extended to increase braking contact area, then braking effect is improved, but frictional heating increases
Solution Approach 1:
The patent uses partial action by providing the radial braking surface as a segmented or partial circumferential feature rather than a complete 360-degree surface. This partial braking surface engages the seal during specific rotation phases, providing adequate braking effect through concentrated contact pressure while limiting the total contact area and duration to reduce frictional heating.
3Productivity
If the tool holder has high eccentricity to enable radial braking, then braking efficiency is improved, but the complexity of the braking mechanism increases
Solution Approach 1:
The patent applies self-service by utilizing the existing eccentric motion of the tool holder to automatically control the engagement and disengagement of the braking surfaces. The eccentricity itself serves as the control mechanism, causing the radial braking surface to contact the seal during specific rotation phases without requiring external actuators, sensors, or complex control systems. The mechanism serves itself by converting the tool holder's inherent eccentric motion into effective braking control.
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 solution reduces unwanted heating and enhances braking efficiency by ensuring consistent frictional contact only when needed, improving the tool's performance and extending the service life of components.
Implementation Method 1
the radial braking surface and the braking member can only be in frictional engagement with each other over a partial revolution of the disk tool
Implementation Method 2
the radial braking surface is spring-loaded towards the braking member
Data Source
Figure 1~2
Figure 3~11b
Figure 5~7
AI summary
The tool has a drive motor for driving a tool holder (23), and an eccentric gear comprising a drive shaft. A disk tool (24) e.g. grinding disk, is fastened to the motor by a machine holder. A tool shaft (26) executes rotational movements in a rotation-eccentric mode during rotation of the drive shaft. A brake surface arrangement (173) for braking the disk tool is arranged in the tool holder. The disk tool is rotated around a drive axis (36) relative to the arrangement, where the arrangement has a radial braking surface that extends over a circle segment of a circle around the axis.