Injection Device Dose Setting Mechanism with Floating Spline

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Solution Overview

Problem

Existing medicament delivery devices, particularly pen-type injectors, lack the ability to set fractional doses and often require users to physically step through incremental dose settings, risking accidental under or over dosing, especially for users with impairments.

Innovation Solution

The proposed dose setting mechanism includes a floating spline, a dose knob, a dose selector, and a snap element, allowing for the setting of one or more fractional predetermined fixed dose settings. This mechanism prevents unintended dose settings by using a biasing member that exerts a counter rotation force on the snap element during dose setting.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a dose setting mechanism allows users to step through incremental dose settings, then users can select from a range of dose values, but users risk accidental under or over dosing

Engineering Contradiction:

Improvedose selection rangeVSAvoiddose setting accuracy

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The mechanism applies a counter rotation force (biasing member) that opposes the user's rotation during dose setting. This preliminary anti-action prevents accidental dose selections by requiring deliberate force to overcome the bias and reach the desired dose setting, thereby improving reliability while maintaining adaptability.

Inventive Principle:

Principle #9Preliminary anti-action

Solution Approach 2:

The dose setting mechanism provides tactile feedback through the interaction between the dose knob, floating spline, and biasing member. Users feel resistance and confirmation points during rotation, allowing them to verify the selected dose before administration, reducing accidental under or over dosing.

Inventive Principle:

Principle #23Feedback

2Ease of manufacture

If a dose setting mechanism uses fixed incremental dose settings, then manufacturing is simplified, but fractional doses cannot be set

Engineering Contradiction:

Improvedose setting mechanism simplicityVSAvoidfractional dose capability

Core Design Contradiction:

Ease of manufactureVSAdaptability or versatility

Solution Approach 1:

The floating spline allows the dose selector to rotate independently during dose setting, enabling fractional dose selections. During dose delivery, the floating spline engages to provide fixed incremental steps. This dynamic behavior allows the same mechanism to support both fractional dosing flexibility and simplified manufacturing through standardized components.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The mechanism changes its operational parameters between dose setting and dose delivery phases. During setting, it allows continuous fractional rotation; during delivery, it locks into fixed incremental positions. This parameter change enables fractional dose capability while maintaining manufacturing simplicity through a single versatile mechanism.

Inventive Principle:

Principle #35Parameter changes

3Ease of operation

If a dose setting mechanism allows rapid dose selection, then user convenience is improved, but precision in dose selection may be compromised

Engineering Contradiction:

Improvedose setting speedVSAvoiddose setting accuracy

Core Design Contradiction:

Ease of operationVSMeasurement precision

Solution Approach 1:

The biasing member provides counter rotation force that must be deliberately overcome, preventing accidental or hasty dose selections. Users must apply sufficient force to overcome the bias, which naturally slows the process and improves precision while still allowing rapid intentional dose changes when needed.

Inventive Principle:

Principle #9Preliminary anti-action

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 enables cost-effective manufacturing of injection devices that can be customized for specific dosing regimens, allowing for precise delivery of fractional doses, thereby enhancing user safety and efficacy in medicament administration.

Implementation Method 1

a biasing member that exerts a counter rotation force on the snap element during dose setting

Methodology Applied

Scientific EffectElasticity: Elasticity

Data Source

PatentUS12285595B2Injection device with flexible dose selection

Publication Date: 2025.04.29 MEDMIX SWITZERLAND AG

AI summary

An injection device incorporating a dose setting mechanism is presented where the dose setting mechanism contains a dose selector having one or more dose stops corresponding to a finite set of predetermined fixed doses, where the set of finite predetermined fixed doses includes a lowest fixed dose and one or more higher fixed doses, and where at least one of the one or more higher fixed doses is equal to the lowest fixed dose plus a fractional amount of the lowest fixed dose. The dose setting mechanism can further include a floating spline that is rotationally engaged with a snap element such that the snap element can rotate relative to the floating spline during both dose setting and dose delivery.