Removable Toothbrush Head Friction Coupling Without Springs
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Solution Overview
Problem
Existing electric toothbrushes face challenges in maintaining a secure connection between the brush head and the handle due to high-speed vibrations, often requiring metal springs or loose fits, which increase costs and affect vibratory effectiveness.
Innovation Solution
A toothbrush head design featuring a coupling member with a chamber and irregular surfaces that provide a friction fit with the drive shaft, eliminating the need for metal springs, ensuring a stable connection through a combination of friction and geometric alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If metal springs are used inside the brush head to facilitate tight coupling to the drive shaft, then the connection stability is improved, but the manufacturing cost increases
Solution Approach 1:
The patent removes the metal spring component from the brush head assembly entirely. Instead of using a spring-based coupling mechanism, the invention employs a direct friction fit between the drive shaft and the brush head housing, eliminating the need for separate spring components and reducing manufacturing complexity while maintaining connection stability.
Solution Approach 2:
The patent replaces expensive metal spring components with a simpler, likely plastic or polymer-based friction fit mechanism. This substitution uses cheaper materials and simpler geometry to achieve the same functional outcome of securing the brush head to the drive shaft without requiring precision-engineered metal springs.
2Reliability
If metal springs are used to ensure tight coupling, then the vibratory effect is improved, but the device complexity increases
Solution Approach 1:
The patent extracts the spring component from the system, replacing it with a direct friction-based coupling between the drive shaft and brush head. This simplification reduces the number of parts and assembly steps while maintaining the necessary vibratory transmission through the brush head.
Solution Approach 2:
The friction fit mechanism is self-adjusting and self-regulating. The interference fit between the drive shaft and housing automatically provides the necessary coupling force and vibration transmission without requiring additional springs or complex mechanical elements to maintain tension or contact pressure.
3Ease of manufacture
If a loose fit is used to avoid metal springs, then the manufacturing cost is reduced, but the connection stability deteriorates
Solution Approach 1:
The patent applies a localized interference fit specifically at the coupling interface between the drive shaft and brush head housing. Rather than a completely loose fit throughout, the design creates a targeted tight fit zone where the drive shaft contacts the housing, providing secure connection exactly where needed while keeping the rest of the assembly easy to manufacture.
Solution Approach 2:
The patent modifies the dimensional parameters of the coupling interface to create an interference fit. By carefully controlling the diameter and tolerance of the drive shaft and housing opening, the design achieves a friction-based secure connection that is both stable and manufacturable without requiring metal springs.
4Reliability
If a tight coupling is used to maintain vibratory effectiveness, then the vibratory effect is improved, but the ease of assembly and disassembly deteriorates
Solution Approach 1:
The patent optimizes the interference fit parameters to achieve a balance between secure connection and easy assembly. The dimensional tolerances and fit parameters are carefully selected to provide sufficient friction for vibration transmission while allowing the brush head to be assembled and disassembled by hand or with minimal force, avoiding permanent or difficult-to-reverse connections.
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 design achieves a secure, cost-effective, and stable attachment of the brush head to the handle, maintaining vibratory effectiveness without the need for metal springs, facilitating easy assembly and disassembly.
Implementation Method 1
The interior sidewall of the stem comprises an irregular surface that is positioned to contact the drive shaft when inserted into the toothbrush head. The drive shaft also comprises an irregular surface that is positioned to contact the interior sidewall of the stem when the drive shaft is inserted into the toothbrush head.
Data Source
AI summary
A toothbrush head includes a bristle tray, a base having an opening for receiving an electric toothbrush a drive shaft, a stem that connects the bristle tray to the base, and a coupling member, The coupling member does not require a spring to contact the drive shaft or stem. In some embodiments, the coupling member includes an interior sidewall that surrounds a chamber for receiving the drive shaft and a receptacle positioned to align with an opening of the stem, and a pin is positioned within the opening and the receptacle. In other embodiments, the coupling member includes a relatively narrower section positioned to align with the stem and a relatively wider section positioned to align with the base, and when the drive shaft is inserted into the coupling member, the drive shaft will extend from the relatively narrower section and into an interior cavity within the stem.