Pre-stressed Battery Spring for Hearing Aid Contact Reliability
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Solution Overview
Problem
Conventional hearing aid battery compartments and spring-loaded contacts face challenges in achieving a high load against the battery surface while maintaining a simple design and accommodating varying battery thicknesses, due to the need for a long spring movement and limited material thickness, which complicates the design and affects reliability and durability.
Innovation Solution
A pre-stressed spring with a body part and torque part, made from the same sheet material, is used to provide internal torque and increased load at the battery contact point, allowing for a more reliable and durable contact with less space and weight, and accommodating battery thickness variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional spring is used to provide high load on the battery contact point, then the electrical contact reliability is improved, but the spring movement distance becomes long and the design becomes complicated
Solution Approach 1:
The spring is pre-stressed during manufacturing to have initial internal forces and internal torque before installation. This preliminary action allows the spring to provide the required contact load with minimal movement during battery insertion, eliminating the need for long spring travel and complex spring designs while ensuring reliable electrical contact from the first insertion.
Solution Approach 2:
The spring's physical parameters are changed by introducing pre-stress through controlled deformation during manufacturing. This creates a spring with non-zero initial force and torque characteristics, allowing it to maintain high contact pressure with minimal deflection, thus resolving the contradiction between contact reliability and design simplicity.
2Weight of moving object
If the spring material is made thinner to reduce weight, then the hearing aid weight is reduced, but the load on the battery contact point becomes insufficient
Solution Approach 1:
The spring is manufactured with pre-applied internal forces and torque through controlled deformation. This preliminary stress state compensates for the reduced cross-sectional area of thinner spring material, allowing the spring to generate sufficient contact load despite using less material and having reduced weight.
Solution Approach 2:
By changing the stress state parameters of the spring material through pre-stressing, the spring achieves higher effective force output from reduced material thickness. The internal torque and forces created during manufacturing allow thin spring material to generate adequate contact pressure on the battery surface.
3Volume of moving object
If the spring movement distance is limited to accommodate small hearing aid size, then the hearing aid compactness is improved, but the contact load on the battery surface becomes insufficient
Solution Approach 1:
The spring is pre-stressed during manufacturing to have initial internal forces and torque that provide the required contact load immediately upon battery insertion. This eliminates the need for large spring movement distances, allowing the battery compartment to be compact while still achieving sufficient contact pressure on the battery surface.
Solution Approach 2:
The spring's force-generation parameters are fundamentally changed by introducing pre-stress. This allows the spring to produce high contact loads with minimal deflection, enabling compact battery compartment design while maintaining adequate electrical contact force despite the reduced movement space.
4Ease of manufacture
If a simple spring design with few parts is used, then the manufacturing complexity is reduced, but the ability to accommodate battery thickness variations is compromised
Solution Approach 1:
The spring is manufactured with pre-applied internal torque and forces that create a compliant contact mechanism. This preliminary action allows the simple single-piece spring design to automatically adapt to varying battery thicknesses by distributing the contact load through its pre-stressed structure, maintaining reliable electrical contact across the full range of battery dimension tolerances.
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 pre-stressed spring design enhances the mechanical load on the battery surface by approximately 58%, providing a more stable and reliable electrical contact with reduced complexity and size, while accommodating dimensional tolerances and frequent battery changes.
Implementation Method 1
By a pre-stressed spring is meant a spring with internal forces and internal torque, which will affect the response of the spring when exposed to an external load. This could be done by bending the torque part with a permanent deformation, and then moving it back with elastic force alone and holding it in the original position.
Implementation Method 2
wherein said torque part is adapted to provide a torque to the point of contact
Data Source
AI summary
A hearing aid comprises a battery compartment prepared for receiving a battery (10) and two contacts (4) arranged to draw an electrical current from an inserted battery in order to power electrical parts of the hearing aid. At least one of the contacts (4) is loaded by a pre-stressed spring (1), which comprises a body part (2) and a torque part (3), said body part (2) being arranged in a fixed attachment in a first end from where it extends to the point of battery contact in a second end, where the torque part (3) is adapted to provide a torque to the point of contact (4).