Flexible Ratchet Element for Dose Adjustment in Injection Devices
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Solution Overview
Problem
Existing self-administered injection devices lack user-friendliness, particularly for elderly patients, as they require significant force to dial down a set dose of medicament, making it difficult for those with less power to adjust the dose accurately before injection.
Innovation Solution
A dose-controlled multi-shot injection device featuring a ratchet mechanism with a flexible ratchet element and rotational element that allows for easy release of the ratchet lock by applying torque to the dose setting handle, enabling controlled reduction of the set medicament dose using a combination of cam sections and teethed portions to deflect the flexible ratchet element radially, facilitating engagement and disengagement with the circumferential teething.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional ratchet mechanism is used to maintain the drive spring in a biased state, then the dose setting is stable and reliable, but the device requires significant force to dial down the set dose, making it difficult for elderly patients to adjust the dose accurately
Solution Approach 1:
The patent employs a flexible ratchet element instead of a rigid traditional ratchet mechanism. This flexible element can elastically deform when torque is applied to the dose setting handle, allowing the teeth to disengage from the circumferential teething with reduced force requirements. The flexibility enables elderly patients to adjust the dose accurately while maintaining reliable dose setting through the elastic recovery of the flexible element.
Solution Approach 2:
The patent changes the mechanical parameters of the ratchet mechanism by introducing a flexible ratchet element that can undergo elastic deformation. This parameter change allows the ratchet teeth to temporarily disengage and re-engage at different positions, enabling smooth dose reduction without requiring excessive force, thus improving ease of operation while maintaining reliability.
2Ease of operation
If the flexible ratchet element is made highly flexible to ease dose reduction, then the ease of operation improves, but the engagement strength with the circumferential teething may be compromised
Solution Approach 1:
The patent introduces dynamic behavior to the ratchet mechanism through the flexible ratchet element that can elastically deform during operation. The element transitions between engaged and disengaged states based on the applied torque, allowing easy dose reduction when needed while maintaining strong engagement during normal operation. This dynamic characteristic resolves the contradiction between flexibility for ease of operation and strength for engagement reliability.
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 allows for a controlled and user-friendly reduction of the medicament dose, making it easier for patients with limited strength to adjust the dose accurately, enhancing usability and safety in self-administration.
Implementation Method 1
a movable flexible ratchet element provided with at least two teethed portions configured to engage the circumferential teething at least pairwise at any one of a plurality of engaging positions
Implementation Method 2
a rotational element coupled to the dose setting handle configured to translate torque from the dose setting handle into a number of forces radially acting on the flexible ratchet element
Data Source
AI summary
The disclosure provides a dose controlled multi-shot injection device comprising a housing and a dose setting mechanism, wherein the dose setting mechanism includes a drive spring, a rotatable dose setting handle adapted to set a dose of medicament, thereby biasing the drive spring, and a ratchet mechanism for maintaining the drive spring in a biased state against a spring force at a set dose. The ratchet mechanism includes a fixed ratchet element coupled to the housing and having a circumferential teething, a movable flexible ratchet element provided with at least two teethed portions configured to engage the circumferential teething at least pairwise at any one of a plurality of engaging positions, which respectively represent a set dose, and a rotational element coupled to the dose setting handle configured to translate torque from the dose setting handle into a number of forces radially acting on the flexible ratchet element resulting in an elastic deformation of the flexible ratchet element, thereby releasing the engagement between the teethed portion and the circumferential teething.