Fixed-Dose Injection Mechanism With Pre-Strained Torsion Spring

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Solution Overview

Problem

Existing drug delivery devices for fixed doses are complex, costly, and require user interaction to arm or strain the drive mechanism between doses, posing risks of under- or over-dosing, especially for users who lack dexterity or require simplicity.

Innovation Solution

A drug delivery device utilizing a pre-strained torsional drive spring to deliver a predefined plurality of fixed doses without arming or straining the mechanism between doses, featuring a guide structure and a drive mechanism with a pre-strained torsional drive spring that conserves energy to deliver multiple fixed doses using a drive tube guided along specific guide portions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a normal multi-dose device is used with a ratchet tube locked to the housing until the full dose has been set, then the user can adjust the dose size, but the device complexity increases and the risk of user error remains

Engineering Contradiction:
Improvedose adjustment capabilityVSAvoiddevice complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The drive mechanism is pre-strained during manufacturing to store the necessary energy for delivering multiple fixed doses. This preliminary action eliminates the need for user interaction to arm or strain the mechanism between doses, thereby reducing device complexity while maintaining the fixed dose delivery function.

Inventive Principle:
Principle #10Preliminary action

2Ease of operation

If the drive mechanism requires user interaction to arm or strain between doses, then the device can be operated, but the reliability decreases due to risks of under- or over-dosing

Engineering Contradiction:
Improveease of operationVSAvoidreliability
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The pre-strained torsional drive spring automatically provides the driving force for multiple fixed doses without requiring user intervention to arm or strain the mechanism between doses. This self-service approach ensures consistent and reliable dose delivery, eliminating the risks of under- or over-dosing associated with user interaction.

Inventive Principle:
Principle #25Self-service

3Device complexity

If a pre-strained torsional drive spring is used to deliver multiple fixed doses without arming between doses, then the device complexity is reduced, but the energy management becomes more challenging

Engineering Contradiction:
Improvedevice complexityVSAvoidenergy management
Core Design Contradiction:
Device complexityVSUse of energy by moving object

Solution Approach 1:

The torsional drive spring is pre-strained during manufacturing to store the necessary energy for delivering multiple fixed doses. This preliminary action consolidates energy management into a single setup process, eliminating the need for repeated user interaction to arm or strain the mechanism between doses, thereby reducing device complexity.

Inventive Principle:
Principle #10Preliminary 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 device ensures safe, user-friendly, and robust delivery of a predefined plurality of fixed doses with consistent force, reducing complexity and costs by eliminating the need for user interaction between doses.

Implementation Method 1

a drive mechanism comprising a pre-strained torsional drive spring (108, 208) conserving an initial amount of energy, and adapted for rotating the drive tube

Methodology Applied
Scientific EffectElastic energy storage and release: Spring

Implementation Method 2

the drive mechanism comprises a pre-strained torsional drive spring (108, 208) conserving an initial amount of energy, and adapted for rotating the drive tube

Methodology Applied
Scientific EffectTorsional spring mechanism: Torsion Spring

Data Source

PatentEP4076595B1Fixed dose injection device
Publication Date: 2026.04.15 NOVO NORDISK AS
  • EP4076595B1 patent drawingFigure 1A
  • EP4076595B1 patent drawingFigure 1B~1C
  • EP4076595B1 patent drawingFigure 1D~1F

AI summary

A drug delivery device for sequentially delivering a predefined plurality of fixed doses, wherein the drug delivery device comprises a housing assembly, a drive mechanism comprising a drive tube and adapted to sequentially deliver the predefined plurality of doses, and an activation mechanism for activating the drive mechanism. The drive mechanism further comprises a pre-strained torsional drive spring (108, 208) conserving an initial amount of energy, and adapted for rotating the drive tube, wherein each activation of the drive mechanism, and completion of a drive tube dose sequence reduces the amount of conserved energy in the drive spring, and wherein the initial amount of conserved energy, which is the conserved energy before the first activation, is sufficient to deliver the predefined plurality of fixed doses.