Injection Device Dose Setting Mechanism Fail-Safe Design
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Solution Overview
Problem
Existing medicament delivery devices, such as pen-type injectors, often lack the ability to set fractional doses and fail to prevent unintended dose settings, limiting their customization and accuracy in delivering specific medicament amounts.
Innovation Solution
A dose setting mechanism featuring a floating spline, snap element, and dose selector, which allows for the setting of fractional doses by altering the spacing and arrangement of dose stops on a single component, preventing unintended dose settings through a fail-safe mechanism that uses biasing members to ensure accurate and precise dose delivery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a dose setting mechanism allows variable dose settings with incremental steps, then the device can deliver multiple dose levels, but the user can accidentally set unintended doses (under-dose or over-dose) and cannot set fractional doses
Solution Approach 1:
The patent applies preliminary anti-action by implementing a fail-safe mechanism that prevents unintended dose settings before they can occur. The dose setting mechanism includes a indicator window that only displays predetermined fixed dose values, and the mechanism is designed to prevent setting any other dose. This pre-emptive design eliminates the possibility of accidental under-dosing or over-dosing while still allowing variable dose selection among the predetermined options.
Solution Approach 2:
The patent uses an intermediary approach by introducing a predetermined set of fixed dose values that act as intermediaries between the user's dose selection and the actual medicament delivery. Instead of allowing direct continuous variable dosing, the system mediates through discrete predetermined dose levels (e.g., 10 IU, 20 IU, 30 IU, 40 IU, 50 IU, 60 IU, 70 IU, 80 IU), ensuring that only safe and intended doses can be set while still providing dose variability.
2Ease of operation
If the dose dial sleeve is printed with a range of possible dose settings, then the user can select different doses, but there is nothing to prevent accidental setting of wrong doses
Solution Approach 1:
The patent prevents harmful accidental wrong dose settings through preliminary anti-action by designing the dose setting mechanism to only permit selection of predetermined fixed dose values. The indicator window and dose setting components are configured so that the user can only dial to these pre-approved dose levels, and the mechanism provides feedback (such as visual indication in the window) to confirm the selected dose is one of the intended fixed values. This pre-emptive design blocks the possibility of accidentally selecting wrong doses before the harmful effect can occur.
3Measurement precision
If the injector is designed with a maximum dose setting of 80 IU with 1 IU increments, then each incremental dose can be set, but fractional doses (e.g., 2.3 IU) cannot be set
Solution Approach 1:
The patent applies parameter changes by transforming the dose setting from continuous incremental values to discrete predetermined fixed dose values. Instead of maintaining 1 IU increments that prevent fractional dosing, the system redefines the available dose parameters to include specific fixed values (such as 10, 20, 30, 40, 50, 60, 70, 80 IU) that can represent fractional doses of the maximum dose. This parameter transformation allows the device to achieve fractional dose capability (e.g., 2.3 IU as a fraction of 80 IU maximum) while maintaining manufacturing simplicity through a single component design.
4Measurement precision
If multiple components are redesigned to enable fractional dose settings, then precise fractional doses can be set, but manufacturing cost and complexity increase
Solution Approach 1:
The patent achieves universality by designing a single multi-functional dose setting mechanism component that can provide both integer and fractional dose settings. The dose selector and indicator window system is configured to display and enable selection of predetermined fixed dose values that represent fractions of the maximum dose (e.g., 2.3 IU as a fraction of 80 IU). This universal design allows the same component structure to serve multiple dosing needs without requiring separate mechanisms for integer and fractional dosing, thereby maintaining manufacturing simplicity while achieving precise fractional dose capability.
Data Source
AI summary
A dose setting mechanism is provided that includes a dose knob, a dose selector, a radial projecting rib and a snap element. The radial projecting rib is positioned circumferentially on an inside surface of the dose selector. The snap element includes a protrusion. The protruding rib has a reduced section that allows the protruding rib to move axially relative to the protrusion to initiate dose delivery.