Medicament Delivery Assembly With Tangential Plunger Release
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Solution Overview
Problem
Existing medicament delivery devices face challenges in expelling medicaments with higher viscosity due to mechanical weakening of flexible tongues over time, requiring a higher biasing force for the plunger rod, which can lead to structural damage.
Innovation Solution
An administration assembly with a plunger rod, a first resilient member, an elongated plunger rod holder, and an activation sleeve that maintains an axially locking contact to prevent movement until a tangential release, allowing the plunger rod to move proximally with a high biasing force without rotation, using a beveled structure to facilitate tangential movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a higher biasing force is applied to the plunger rod to expel high-viscosity medicaments, then the expulsion capability is improved, but the flexible tongues may be mechanically weakened or damaged over time
Solution Approach 1:
The plunger rod holder is segmented into a resilient body with flexible tongues that can deflect independently. This segmentation allows the flexible tongues to absorb and distribute the high biasing forces through elastic deformation, preventing concentration of stress that would cause mechanical weakening or damage over time.
Solution Approach 2:
The flexible tongues are designed with specific geometric parameters including thickness, length, and curvature radius that optimize their elastic properties. These parameter changes enable the tongues to provide the necessary flexibility to withstand high biasing forces while maintaining structural integrity during repeated use and storage.
2Reliability
If the flexible tongues are subjected to continuous forward-biasing force during storage, then the plunger rod remains pre-loaded, but the plastic structure of the flexible tongues weakens over time
Solution Approach 1:
The flexible tongues are designed as dynamic elements that can deflect and absorb energy through elastic deformation. This dynamic capability allows them to withstand continuous pre-loading forces during long-term storage without permanent deformation or structural weakening, maintaining device readiness while preserving material integrity.
Solution Approach 2:
The resilient body with flexible tongues acts as a cushioning element that absorbs and dissipates the continuous forward-biasing force during storage. This beforehand cushioning prevents the force from causing cumulative damage to the plastic structure, ensuring the device remains reliable after extended storage periods.
3Ease of operation
If the plunger rod is allowed to rotate during expulsion, then the movement freedom is improved, but the delivery accuracy and consistency are compromised
Solution Approach 1:
The resilient body is designed with an asymmetric cross-sectional shape that provides guiding surfaces for the plunger rod. This asymmetric geometry allows the plunger rod to move freely in the axial direction while the non-circular cross-section prevents rotation, ensuring consistent delivery accuracy without compromising movement freedom.
Solution Approach 2:
The resilient body with flexible tongues acts as an intermediary element between the plunger rod and the housing. It provides guiding and constraining functions through its geometric shape, allowing linear movement while preventing rotation, thus mediating between the need for movement freedom and delivery precision.
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 ensures robust and reliable expulsion of high-viscosity medicaments by maintaining structural integrity and preventing rotation, even after long storage periods, ensuring consistent performance.
Implementation Method 1
a first resilient member configured to bias the plunger rod in the proximal direction
Implementation Method 2
an activation sleeve configured to receive a portion of the plunger rod holder, and configured to move axially from a first position relative to the plunger rod holder to a second position
Data Source
Figure 1~3
Figure 2
Figure 4~5a
AI summary
The present disclosure relates to an administration assembly (10) for a medicament delivery device (1), comprising: a plunger rod (15), a first resilient member (17) configured to bias the plunger rod (15) in the proximal direction, an elongated plunger rod holder (21) configured to receive the plunger rod (15), an activation sleeve (23) configured to receive a portion of the plunger rod holder (21), and configured to move axially from a first position relative to the plunger rod holder (21) to a second position, wherein the activation sleeve (23) is configured to be biased towards the first position, wherein the plunger rod holder (21) has a first hold and release structure (21a) and the plunger rod (15) has a second hold and release structure (15a), wherein in the first position the activation sleeve (23) is configured to maintain the first hold and release structure (21a) in an axially locking contact position with the second hold and release structure (15a) in which the second hold and release structure (15a) is prevented from movement relative to the first hold and release structure (21a), thereby locking the plunger rod (15) axially relative to the plunger rod holder (21), wherein in the second position the activation sleeve (23) is configured to allow the first hold and release structure (21a) to move from the axially locking contact position, whereby biasing of the plunger rod provided by the first resilient member (17) causes the second hold and release structure (15a) to act with a proximally directed force on the first hold and release structure (21a), moving the first hold and release structure (21a) tangentially from the axially locking contact position to thereby release the plunger rod (15) from the plunger rod holder (21).