Wave Spring Mechanism for Compact Medical Device Force Generation
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Solution Overview
Problem
Medical devices, particularly those of restricted dimensions like portable injection pens, face challenges in providing sufficient spring force while minimizing volume occupancy, as conventional spring elements are inefficient in generating strong spring forces within compact spaces.
Innovation Solution
The use of a wave spring or wave washer, comprising multiple waved spring layers made of elastic material, particularly metal, which enhances spring force while maintaining a small volume footprint and ensures homogeneous force distribution across elevated contact areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If conventional spring elements are used, then the mechanism can provide spring force, but the volume occupied by the spring is too large for compact medical devices
Solution Approach 1:
The patent changes the geometric parameters of the spring element by using a wave spring design with specific wave patterns, wavelength, and amplitude ratios that optimize the spring constant while minimizing volume. The wave spring's unique geometry allows achieving high spring force in a compact configuration compared to conventional helical springs
Solution Approach 2:
The wave spring utilizes a two-dimensional waved geometry rather than the three-dimensional helical structure of conventional springs. This dimensional change allows the spring to achieve comparable or superior force characteristics while occupying significantly less volume, making it suitable for compact medical devices
2Volume of moving object
If the spring volume is reduced to fit compact devices, then the device size is minimized, but the spring force becomes insufficient
Solution Approach 1:
The patent optimizes the wave spring parameters including wave amplitude, wavelength, and the ratio between them to achieve maximum spring constant per unit volume. By carefully selecting these geometric parameters, the spring delivers sufficient force while maintaining a compact size appropriate for portable medical devices
Solution Approach 2:
The wave spring is made from elastic materials with optimized mechanical properties, particularly metals or metal alloys selected for their high elastic modulus and strength-to-density ratio. This material selection ensures that the compact spring generates adequate spring force despite its reduced volume
3Force
If a strong spring force is generated with small compression, then the spring constant is large, but the spring dimensions must be kept small which conflicts with conventional spring design
Solution Approach 1:
The wave spring's geometry is specifically designed with optimized wave parameters that achieve a high spring constant in a short length. The waved structure with appropriate amplitude and wavelength ratios allows the spring to generate strong restoring forces with minimal compression distance, overcoming the limitation of conventional springs which require longer lengths to achieve similar force characteristics
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
This configuration allows for a strong and efficient spring force generation with minimal volume occupation, enabling effective operation within the limited dimensions of medical devices like injection pens, facilitating improved mechanical performance and ease of use.
Implementation Method 1
a spring arranged in contact with at least one of the elements and tending to disengage the first element and the second element. The spring is selected to be a wave spring or wave washer, preferably a multiple wave washer having a plurality of waved spring layers of an elastic material
Data Source
Figure 1
Figure 2A~2B
Figure 3
AI summary
The medical device comprises a wave spring (15) or wave washer (15) in a mechanism (20) to engage or disengage a first element (13) and a second element (14). The invention also discloses the use of a multiple wave spring or wave washer comprising at least two waved spring layers in a medical device.