Elastomeric Load Spring Washer for Controlled Drug Delivery Force

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Solution Overview

Problem

Medical injection devices face challenges with current resilient members, such as a lack of control and load recovery, which affect the accuracy of drug delivery.

Innovation Solution

A load spring washer with a main body having a proximal and distal surface, and one or more protrusions extending proximally, is designed for use in medical injection devices. The load spring washer can have various shapes, including circular with a sinusoidal cross-sectional profile, frustoconical, or ring-shaped with arms and flanges, and is typically made of elastomeric materials like EPDM rubber.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional helical coil springs are used as resilient members in medical injection devices, then the device can provide basic spring functionality, but the load recovery and control are insufficient, affecting drug delivery accuracy

Engineering Contradiction:

Improveload recoveryVSAvoiddrug delivery accuracy

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The spring is segmented into multiple protrusions (typically 3-6) extending from the main body, each acting as an independent load-bearing element. This segmentation allows for controlled deformation and recovery of each protrusion, improving overall load recovery characteristics and providing more predictable force delivery for accurate drug administration.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The protrusions are designed with curved or rounded geometries rather than sharp edges, and the main body often features a circular or annular shape. This curvature distributes stress more evenly during compression and rebound, enhancing load recovery consistency and reducing stress concentration that could lead to premature failure or inconsistent performance.

Inventive Principle:

Principle #14Spheroidality (Curvature)

2Ease of operation

If traditional springs are used, then the structure is simple, but the control over compressive forces is insufficient

Engineering Contradiction:

Improvecontrol over compressive forcesVSAvoidconsistency of drug delivery

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

Different regions of the spring exhibit different mechanical properties through varied protrusion geometries, heights, and distributions. The main body may have different thicknesses or material compositions in different zones, allowing tailored control over compressive forces at various stages of compression, thereby improving operational control and delivery consistency.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The spring's mechanical parameters (protrusion height, diameter, spacing, angle) are precisely controlled during manufacturing to achieve specific force-displacement characteristics. By adjusting these parameters, the spring can be optimized for different drug delivery requirements, providing consistent and controllable compressive forces throughout the injection process.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If the spring has complex geometries (sinusoidal, frustoconical, multi-armed), then the load recovery and control improve, but the manufacturing complexity increases

Engineering Contradiction:

Improveload recoveryVSAvoidmanufacturing complexity

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The spring is constructed as a thin-walled elastomeric or polymeric component that can be formed through injection molding or similar processes. This approach allows complex three-dimensional geometries (sinusoidal profiles, frustoconical shapes, multi-armed configurations) to be manufactured as single-piece components without requiring complex assembly, thereby maintaining ease of manufacture while achieving superior load recovery through optimized geometry.

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

The spring may utilize composite material structures, such as elastomeric compounds with varying durometers in different regions, or combinations of rigid and flexible materials, to achieve the desired mechanical performance. This allows complex geometries to be manufactured with consistent material properties that enhance load recovery while remaining compatible with standard manufacturing processes for molded components.

Inventive Principle:

Principle #40Composite materials

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 load spring washer enhances load recovery and control in medical injection devices, improving the accuracy and reliability of drug delivery by providing modified compressive forces and buckling characteristics.

Implementation Method 1

the load spring washer comprises an elastomeric material

Methodology Applied

Scientific EffectElasticity: Elasticity

Implementation Method 2

enhances load recovery and control in medical injection devices

Methodology Applied

Scientific EffectElastic Recovery: Elastic Recovery

Implementation Method 3

providing modified compressive forces and buckling characteristics

Methodology Applied

Scientific EffectBuckling:

Data Source

PatentUS12274862B2Self-controllable load spring washer

Publication Date: 2025.04.15 BECTON DICKINSON & CO

AI summary

Provided herein is a load spring washer configured for use with a medical injection device, having a main body having a proximal surface and a distal surface and one or more protrusions extending proximally away from the proximal surface of the main body.