Power Toothbrush Brushhead Interface Spring Coupling
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Solution Overview
Problem
Existing power toothbrush designs face challenges in reliably transferring torque and maintaining axial retention of the brushhead on the driveshaft while allowing for frequent removal and reattachment without degrading the interface functions over time.
Innovation Solution
A brushhead/handle interface using a single spring and coupling combination, where the spring exerts force against the coupling member to ensure reliable torque transfer and axial retention during operation, and allows easy removal by providing sufficient frictional and physical contact between the driveshaft and the brushhead assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single spring and coupling combination is used to achieve both torque transfer and axial retention, then device complexity is reduced, but reliability of maintaining both functions simultaneously becomes challenging
Solution Approach 1:
The patent combines two previously separate functions (torque transfer and axial retention) into a single integrated spring-coupling mechanism. The spring member simultaneously provides both the torque transfer function through its elastic deformation and the axial retention function through its spring force, eliminating the need for separate components for each function and reducing overall interface complexity.
Solution Approach 2:
The spring member's physical parameters (material properties, wire diameter, coil diameter, active coils) are specifically designed and optimized to provide the required force characteristics. By adjusting these parameters, the spring can maintain sufficient spring force for axial retention while also providing adequate torque transfer capability, resolving the contradiction between simplified structure and reliable dual-function performance.
2Reliability
If high axial retention force is applied to hold the brushhead securely, then axial retention is improved, but ease of removal by the user deteriorates
Solution Approach 1:
The spring member provides a dynamic retention force that adapts to operational conditions. During normal operation, the spring maintains sufficient compressive force for secure retention. During removal, when the user applies axial pulling force, the spring can compress further or deflect, allowing the brushhead to be removed without requiring excessive force. This dynamic response resolves the contradiction between secure retention and easy removal.
Solution Approach 2:
The spring force is designed to be sufficient for retention during operation but not excessively strong to prevent removal. The spring parameters are optimized so that the retention force exceeds the minimal requirement for secure operation, yet remains below the threshold that would make removal difficult for the user, achieving a balanced partial action that satisfies both requirements.
3Ease of operation
If the interface is designed for easy removal and reattachment, then ease of operation is improved, but reliability of maintaining torque transfer and axial retention after numerous removals deteriorates
Solution Approach 1:
The spring member automatically maintains optimal contact force between the driveshaft and coupling member after each reattachment. When the brushhead is reattached, the spring compresses and exerts a self-adjusting force that ensures proper engagement and torque transfer without requiring manual adjustment or intervention. This self-service mechanism ensures consistent performance after numerous removal and reattachment cycles.
Solution Approach 2:
The spring member acts as a cushioning element that compensates for variations in assembly tolerances and wear over time. By providing a compliant, force-exerting connection, the spring ensures reliable torque transfer and axial retention even after repeated use, beforehand preventing degradation of interface performance that would otherwise occur with rigid 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 solution effectively maintains torque transfer and axial retention even after numerous removals, ensuring consistent performance and convenience in cleaning and maintenance.
Implementation Method 1
a spring member positioned so as to exert a force against the coupling member large enough that the physical contact between said interface portion or portions of the coupling member and said one or more contact regions of the driveshaft is sufficient to produce a reliable torque transfer
Implementation Method 2
the physical contact between said interface portion or portions of the coupling member and said one or more contact regions of the driveshaft is sufficient to produce a reliable torque transfer
Data Source
AI summary
The brushhead/handle interface includes a brushhead assembly (20) which has a brush member (26) for cleaning teeth. A driveshaft (14) extends from a handle portion (12) of the toothbrush (10), which is driven in an oscillating manner through a selected rotational angle. The driveshaft includes one or more contact regions (49). The coupling member includes an interface portion or portions (46) which are forced against the contact regions of the driveshaft by a single spring member when the driveshaft is inserted into the coupling member. The single spring (34) exerts a sufficient force on the interface portions of the coupling member against the contact regions of the driveshaft to produce both a reliable torque transfer between the driveshaft and the brushhead assembly and to maintain axial retention of the brushhead assembly on the driveshaft during operation of the toothbrush.