Electric Toothbrush Coupling Pin and Cantilevered Arms
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Solution Overview
Problem
Existing electric toothbrush refill coupling mechanisms face issues with secure attachment and easy detachment while maintaining minimal play, and are prone to unintentional disengagement due to radial forces and environmental factors like toothpaste residue.
Innovation Solution
A coupling mechanism featuring a coupling pin extending perpendicular to the handle's coupling stem, with cantilevered arms and coupling surfaces that slidably and resiliently engage the pin for a secure and disengageable connection, utilizing a snap-fit mechanism and press-fit segments to ensure stability and ease of use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a latching connection is used to secure the refill to the handle, then axial forces are absorbed, but the coupling becomes prone to unintentional disengagement due to dirt accumulation and external pressure
Solution Approach 1:
The coupling mechanism is divided into separate functional elements: the coupling stem with pin, the cantilevered arms with coupling surfaces, and the refill body. This segmentation allows each component to perform its specific function independently, with the pin providing positioning and the arms providing resilient retention, thereby preventing unintentional disengagement while maintaining ease of operation.
Solution Approach 2:
The coupling surfaces are designed to change their engagement parameters dynamically. During assembly, the surfaces slide along the pin to accommodate alignment tolerances, then transition to a locked position where they resiliently engage the pin's lateral surface. This parameter change from sliding to locked engagement ensures secure attachment while preventing accidental disengagement.
2Force
If a bayonet coupling style connection is used, then radial forces are absorbed, but the coupling becomes prone to unintentional disengagement when forces are applied in certain directions
Solution Approach 1:
The cantilevered arms are designed to be resilient and flexible, allowing them to dynamically respond to applied forces. When radial forces are applied, the arms can deflect elastically to absorb the load, then return to their original position, preventing disengagement. This dynamic behavior contrasts with rigid bayonet couplings that can disengage under directional forces.
Solution Approach 2:
The coupling pin acts as an intermediary element between the handle and refill. The pin's lateral surface serves as a mediator that the coupling surfaces engage with, providing a stable interface for force transmission. This intermediary mechanism prevents direct engagement issues between the handle and refill bodies, eliminating the directional force vulnerability of bayonet couplings.
3Ease of operation
If the coupling surfaces are designed for easy sliding engagement, then ease of operation is improved, but play between the refill and handle increases
Solution Approach 1:
The coupling surfaces are preliminarily positioned to guide the refill onto the coupling stem during assembly. The sliding action is designed to occur along a predetermined path that naturally aligns the components, eliminating the need for complex alignment procedures. This preliminary guiding action ensures easy engagement while maintaining stable, play-free connection through the subsequent resilient locking of the arms against the pin.
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 provides a secure, easy-to-operate coupling that minimizes play between the refill and handle, maintaining a firm attachment while allowing for effortless engagement and disengagement, even in abrasive environments, thus enhancing the durability and usability of the toothbrush.
Implementation Method 1
cantilevered arms and coupling surfaces that slidably and resiliently engage the pin for a secure and disengageable connection
Implementation Method 2
press-fit segments to ensure stability and ease of use
Data Source
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Figure 6
AI summary
A coupling mechanism for an electric toothbrush includes a handle coupling portion and a refill coupling portion structured and configured to engage one another, thereby providing a secure connection between the handle and the refill. The handle coupling portion has a coupling stem disposed at one end of the handle and a coupling pin protruding from the stem. The coupling stem has outer walls terminating at a free end thereof. The refill coupling portion has a tubular structure having refill walls and an interior space for receiving therein the coupling stem, and a pair of mutually opposite and resiliently deformable cantilevered arms disposed in the interior space, each of the arms terminating with a coupling surface for engaging the coupling pin of the handle coupling portion.