V-Shaped Nodal Spring Assembly for Electronic Toothbrush Drive Train
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Solution Overview
Problem
Existing nodal spring arrangements in electronic toothbrush drive trains face challenges in achieving a desired dynamic response while minimizing stress and wear at the node point, and ensuring a linear response along the spring length to prevent interaction between in-phase and out-of-phase rotational modes.
Innovation Solution
A V-shaped spring assembly is secured at both ends with an insert member and shim positioned between the spring and a node spring member connected to the housing, using an attachment member to secure the assembly tightly, with slots in the spring to distribute stress and reduce wear, and materials like brass and bronze for low friction and high yield strength to maintain a stable connection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a V-shaped torsion spring is fixedly mounted at both ends and at a node point, then the desired reciprocating brushhead action is achieved, but high stresses and potential wear occur at the contact area between the V-spring and mounting plate
Solution Approach 1:
A separate node spring member is introduced as an intermediary component between the V-shaped spring and the mounting plate. This node spring member distributes the contact stresses over a larger area and reduces wear at the critical node point, while still maintaining the necessary mechanical connection for the drive train operation.
Solution Approach 2:
The mounting structure is segmented into multiple components: the V-shaped spring, a separate node spring member, and the mounting plate. This segmentation allows each component to be optimized for its specific function, with the node spring member specifically designed to handle the stress distribution at the critical node point.
2Object-affected harmful factors
If the V-spring is rigidly connected to the housing, then vibrations are reduced in the handle, but the dynamic response and linearity of the spring is compromised
Solution Approach 1:
The connection between the V-shaped spring and the housing is made locally optimized: the node spring member provides a flexible yet stable connection at the node point, allowing the spring to maintain its dynamic response characteristics while still reducing vibrations transmitted to the handle housing through controlled energy dissipation.
3Device complexity
If the node spring connection is simplified, then device complexity is reduced, but stress distribution and wear resistance are compromised
Solution Approach 1:
The node spring member integrates multiple functions into a single component: it provides stress distribution, reduces wear at the node point, and maintains the mechanical connection between the V-shaped spring and the mounting plate. This merging of functions achieves reliable stress distribution without proportionally increasing device complexity.
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 reduces stress and wear at the node point, maintains a linear response, and ensures a stable connection, enhancing the reliability and longevity of the drive train assembly by distributing stress evenly and using suitable materials for low friction and high yield strength.
Implementation Method 1
a V-shaped spring member which is secured at both ends so that it can be excited in a torsion mode about a node point along the axial dimension of the V-shaped spring member
Implementation Method 2
an attachment member for securing the node spring member, the shim, the V-shaped spring member and the insert tightly together
Implementation Method 3
materials like brass and bronze for low friction and high yield strength
Data Source
AI summary
A nodal-mounted spring arrangement for an electronic toothbrush includes a V-shaped spring member secured at both ends so that it can operate in out-of-phase torsion mode along the axial dimension thereof. In one embodiment, the V-shaped spring member includes two extended end regions, which extend below a longitudinal edge of the middle portion of the V-spring. The free ends of the extended portions are joined by a flat cross-piece. This “closed end” region is present at both ends of the V-spring.