Coupling Section Tolerance Compensation for Personal-Care Implements
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Solution Overview
Problem
The challenge in mass manufacturing of multi-component personal-care implements, such as electric toothbrushes, is achieving and maintaining tight tolerances in parts manufactured at different locations with varying conditions, which can lead to misalignment and reduced uniformity.
Innovation Solution
A coupling section with a tolerance-compensation element is introduced, allowing for adjustments in the drive shaft's position within the bushing to compensate for minor variations in part dimensions, thereby relaxing strict tolerances while ensuring reliable assembly and functionality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If strict tolerances are applied to ensure uniformity of parts manufactured at multiple locations, then manufacturing precision is improved, but device complexity and production cost increase
Solution Approach 1:
The patent applies parameter changes by introducing a tolerance compensation element that modifies the dimensional parameters of the coupling section. This element has a controlled dimensional variation (0.1-0.5mm) that compensates for cumulative tolerances in the drive shaft assembly, allowing manufacturers to use less precise manufacturing processes while maintaining final assembly uniformity.
Solution Approach 2:
The tolerance compensation element acts as an intermediary component between the drive shaft and the housing. It mediates the tolerance accumulation by providing an adjustable dimensional interface that absorbs variations from multiple manufacturing locations, simplifying the overall assembly process without requiring extremely tight tolerances on all components.
2Reliability
If tight tolerances are maintained for drive shaft positioning, then reliability of assembly is improved, but manufacturing cost increases
Solution Approach 1:
The tolerance compensation element introduces dynamic adjustability to the assembly process. It can be positioned at different locations along the drive shaft to compensate for variations, allowing the assembly to adapt to manufacturing variations rather than requiring fixed tight tolerances. This dynamic approach maintains reliability while reducing manufacturing costs.
Solution Approach 2:
By changing the dimensional parameters of the coupling section through the tolerance compensation element, the patent allows manufacturers to use more economical manufacturing processes. The element's controlled variation (0.1-0.5mm) provides enough adjustment range to ensure reliable assembly without requiring expensive high-precision manufacturing on all components.
3Productivity
If multiple manufacturing locations are used to increase productivity, then production volume is improved, but manufacturing precision deteriorates due to varying conditions
Solution Approach 1:
The tolerance compensation element serves multiple functions: it compensates for tolerances, adjusts positioning, and standardizes the final assembly dimensions. This universal component can be used across all manufacturing locations regardless of their specific capabilities, allowing each facility to produce parts within wider tolerances while the compensation element ensures uniform final products.
Solution Approach 2:
The patent uses parameter changes in the coupling section's dimensional specifications to accommodate variations from different manufacturing locations. By building in a controlled dimensional variation (0.1-0.5mm) in the tolerance compensation element, the design absorbs the precision variations that naturally occur when multiple facilities produce components, maintaining overall uniformity without sacrificing productivity.
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 enables manufacturers to simplify and streamline the assembly process, reduce production costs, and maintain the required reliability and functionality of the personal-care implements by allowing for flexible adjustments within acceptable tolerance ranges.
Implementation Method 1
at least one first magnetic coupling element mounted adjacent at the free end of the drive shaft for connection, by magnetic interaction, with at least one second magnetic coupling element of a replacement tool head
Data Source
AI summary
A coupling section for coupling a handle of a personal-care implement and a replaceable attachment tool includes a cap, a bushing mounted inside the cap, a drive shaft having a free end terminating in the bushing, a first magnetic coupling element mounted in the cap, and an elastic magnet seal disposed between the first magnetic coupling element and the bushing. The magnet seal is structured and configured to flex in at least a direction along the longitudinal axis of the bushing, thereby providing at least longitudinal tolerance compensation for the drive shaft relative to the first magnetic coupling element.