Torsion Spring Injection Device Rotatable Dose Display

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Solution Overview

Problem

Existing automatic injection devices have limited angular resolution due to dose indicator barrels or wheels that can only rotate less than one revolution, restricting the accuracy of dose setting and requiring inefficient linear spring systems.

Innovation Solution

A torsion spring-based injection device with a rotatable dose setting mechanism that allows rotation over one revolution, utilizing a torsion spring to provide a linear working range for improved dose setting accuracy and incorporating a helical path or counting device with enhanced resolution.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If a linear spring is used to move the piston rod, then axial displacement is provided for dose indicator movement, but the system exhibits high mechanical losses and non-linear force characteristics

Engineering Contradiction:

Improvemechanical lossesVSAvoidspring system complexity

Core Design Contradiction:

Loss of energyVSDevice complexity

Solution Approach 1:

The patent replaces the linear spring system with a torsion spring system. This substitution changes the mechanical approach from axial compression to rotational torsion, eliminating the non-linear force characteristics and high mechanical losses associated with linear springs while maintaining the dose indicator movement functionality.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the operational parameters from linear axial movement to rotational movement. The dose indicator barrel and setting member operate through rotational angles rather than linear displacements, which aligns with the torsion spring's natural mode of operation and improves efficiency.

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If the dose indicator barrel is limited to less than one revolution, then the device structure is simplified, but the angular resolution and dose setting accuracy are limited

Engineering Contradiction:

Improvedose setting accuracyVSAvoidrotation mechanism complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent extends the dose indicator barrel rotation from a limited single-revolution constraint to multiple revolutions. This dimensional extension in the rotational domain allows for finer angular resolution and more precise dose setting, with the barrel capable of rotating through angles exceeding 360 degrees to accommodate higher precision requirements.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The patent segments the rotation scale into multiple revolutions, with each revolution providing a complete set of dose units. This segmentation allows the dose indicator to cover a broader range with finer resolution, dividing the total rotation into manageable angular increments that enhance measurement precision.

Inventive Principle:

Principle #1Segmentation

3Loss of energy

If a torsion spring system is implemented, then mechanical losses are reduced and linear response is achieved, but the system requires rotational movement instead of axial displacement

Engineering Contradiction:

Improvemechanical lossesVSAvoidoperation mechanism

Core Design Contradiction:

Loss of energyVSEase of operation

Solution Approach 1:

The patent transforms the operational parameters from linear axial displacement to rotational angular displacement. The dose setting and indication mechanisms operate through rotation rather than linear movement, which is naturally suited to the torsion spring's mode of operation and eliminates the need for axial spring compression and extension.

Inventive Principle:

Principle #35Parameter changes

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 torsion spring-based system increases the angular resolution, allowing for more precise dose setting with up to 100 units per revolution, reducing mechanical losses, and providing a user-friendly interface for setting and ejecting doses with higher accuracy.

Implementation Method 1

a torsion spring operatively connected to a dose setting member

Methodology Applied

Scientific EffectTorsion spring: Torsion Spring

Data Source

PatentUS9687611B2Injection device with torsion spring and rotatable display

Publication Date: 2017.06.27 NOVO NORDISK AS

AI summary

The present invention relates to an injection device comprising a torsion spring operatively connected to a dose setting member being adapted to set a dose to be ejected from the injection device. A rotatably mounted display member adapted to display the dose to be ejected in accordance with a setting of the dose setting member is also provided. The rotatably mounted display member is adapted to be rotated over an angle corresponding to at least one revolution of the display member. The display member may be implemented as a dose indicator barrel having numerals arranged along a helical path on an outer surface thereof, or alternatively, as a counting device having two or more display wheels having numerals arranged on an outer surface thereof.