Dose Setting Mechanism Over-Torque Protection

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Solution Overview

Problem

Existing injection devices with dose setting mechanisms risk damage when users exceed the maximum dose limit, leading to potential component damage and safety issues.

Innovation Solution

An injection device with a ratchet arrangement and over-torque feature integrated into a single component, which limits the charging force transferred to the spring when the rotation exceeds a defined limit, preventing damage by reducing the force transferred and allowing for audible and tactile feedback.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a hard endstop is used to prevent further dialling up of the dose, then the maximum dose limit is enforced, but damage to components may occur if the user continues to attempt to increase the dose

Engineering Contradiction:

Improvemaximum dose limit enforcementVSAvoidcomponent damage risk

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent introduces a soft endstop mechanism that engages before the hard endstop to cushion and absorb excessive torque. This soft endstop is configured to deform elastically under excessive force, preventing the transmission of damaging forces to other components while still enforcing the maximum dose limit through the hard endstop's positional constraint.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

2Reliability

If multiple separate components are used for the ratchet arrangement and over-torque feature, then functional requirements are met, but device complexity and manufacturing cost increase

Engineering Contradiction:

Improveover-torque protection functionVSAvoidnumber of components

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines the ratchet arrangement and over-torque feature into a single integrated component. This unified design allows the component to simultaneously provide ratchet functionality (preventing backward movement) and over-torque protection (limiting excessive forward force), thereby reducing the total component count and simplifying the device structure while maintaining both functions.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The single component is designed to perform multiple functions: it acts as both a ratchet mechanism to prevent spring unwinding and as an over-torque feature to limit excessive charging force. This multi-functional design eliminates the need for separate dedicated components for each function, reducing complexity and potential failure points.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Use of energy by moving object

If the charging force is not limited when the maximum dose limit is reached, then the spring can be fully charged, but excessive torque may cause damage to device components

Engineering Contradiction:

Improvespring energy storageVSAvoidcomponent damage from excessive torque

Core Design Contradiction:

Use of energy by moving objectVSObject-affected harmful factors

Solution Approach 1:

The soft endstop is positioned to engage before excessive torque can damage components. When the maximum dose limit is reached, the soft endstop deforms elastically to absorb the excess energy, preventing this energy from being transmitted to and damaging other components while still allowing the spring to be charged to its safe maximum capacity.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

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 enhances the safety and reliability of the injection device by preventing damage from excessive torque, simplifying construction, and potentially reducing costs while maintaining accurate dose settings.

Implementation Method 1

a spring capable of storing energy necessary for ejecting the dose from the injection device, wherein the spring is coupled to the dose selector such that a charging force can be transferred from the dose selector to the spring to increase the energy stored by the spring

Methodology Applied

Scientific EffectElasticity: Elasticity

Implementation Method 2

a ratchet arrangement rotationally coupling a ratchet component and an internal surface of the housing; the ratchet arrangement limits the spring from unwinding from the currently selected dose

Methodology Applied

Scientific EffectRatchet mechanism: Ratchet

Implementation Method 3

an over-torque feature arranged between the dose selector and the spring, the over-torque feature being actuable, when the rotation of the dose selector causes the charging force to exceed a defined limit, to reduce the charging force transferred from the dose selector to the spring

Methodology Applied

Scientific EffectTorque limitation: Torque

Data Source

PatentUS11338089B2Dose setting mechanism

Publication Date: 2022.05.24 NORTON HEALTHCARE LTD

AI summary

An injection device comprising a housing (12) and a dose selector (16) to set a dose of medicament to be ejected from the injection device. A spring (20) coupled to the dose selector stores energy necessary for ejecting the dose from the injection device. A ratchet (25) arrangement is provided to rotationally couple a ratchet component and an internal surface of the housing in a coupled state and to allow relative rotation between the ratchet component and the internal surface of the housing in an uncoupled state. An over-torque feature (27) located between the dose selector and the spring is actuatable, when the rotation of the dose selector causes the charging force to exceed a defined limit, to reduce the charging force transferred from the dose selector to the spring. Both the ratchet component and the over-torque feature are provided on a single component (28).