Injection Device End Cap Locking Mechanism
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Solution Overview
Problem
Medicament delivery devices with tensioned drive springs face issues with secure attachment of end caps, leading to potential disengagement during use, which can result in non-delivery of medicament and user injury.
Innovation Solution
A medicament delivery device with a rotator and blocking element that prevents radial movement of attachment elements when activated, ensuring the end cap remains attached and secure during use, utilizing flexible arms and protrusions for attachment and a plunger rod locking mechanism to manage the drive spring's force effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If flexible arms with snap-in attachments are used for attaching the end cap, then assembly speed is improved, but reliability deteriorates due to risk of disengagement during use
Solution Approach 1:
The attachment element is designed with flexible arms that can dynamically adapt their state: remaining flexible during assembly for easy attachment, and becoming rigid when locked by the rotator to prevent disengagement during use. This dynamic transition resolves the contradiction between ease of assembly and attachment security.
Solution Approach 2:
The attachment system undergoes periodic state changes through the rotator mechanism: initially in an unlocked state allowing flexible attachment, then transitioning to a locked state that provides rigid secure attachment during operation. This periodic transition between states resolves the contradiction.
2Reliability
If secure attachment means are used to prevent disengagement, then reliability is improved, but device complexity increases
Solution Approach 1:
The rotator mechanism serves multiple functions: it acts as part of the drive mechanism for medicament delivery, serves as a locking mechanism for the attachment element, and provides a blocking element to prevent disengagement. This multi-functionality achieves reliable attachment without adding separate complex components.
Solution Approach 2:
The locking function is merged into the existing rotator mechanism rather than being a separate component. The blocking element is integrated into the rotator structure, combining the drive function with the security function to maintain simplicity while achieving reliability.
3Reliability
If the end cap is securely attached to withstand drive spring forces, then reliability is improved, but ease of manufacture deteriorates due to complicated attachment requirements
Solution Approach 1:
The attachment element's flexibility parameter is dynamically changed through the locking mechanism. During manufacturing and assembly, the flexible state allows easy attachment. During operation, the locked state provides the necessary rigidity to withstand drive spring forces, resolving the contradiction between ease of manufacture and 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 solution ensures secure attachment of the end cap during activation, preventing disengagement and ensuring reliable medicament delivery while allowing for easy assembly and safe operation of the device.
Implementation Method 1
a power unit comprising a plunger rod arranged to act on the medicament container for expelling a dose of medicament, wherein the power unit further comprising a compression drive spring operably connected to the plunger rod for driving the plunger rod for expelling a dose of medicament
Implementation Method 2
flexible arms with snap-in attachments are often used, providing a fast assembly operation
Data Source
Figure 1
Figure 2a~2b
Figure 3a~3b
AI summary
The present invention relates to a automatic injection device comprising an elongated housing (10) extending in a longitudinal direction, which housing (10) is arranged to accommodate a medicament container (16), an end cap (52) arranged with a first attachment element (98, 100) designed to engage with a second attachment element (102) on said housing for attaching said end cap (52) to said housing (10), a rotator (62) rotatably arranged inside said housing (10), an activator (32) axially slidable with respect to the housing from an extended position to a retracted position and operably connected to said rotator (62) such as to rotate said rotator (62) from an initial non-activated rotational position and an activated rotational position when the activator (32) is moved from the extended to the retracted position, said rotator (62) further comprises a blocking element (76) arranged to cooperate with said first attachment element (98, 100) for preventing disengagement of said first attachment element (98, 100) from said second attachment element (102) when the rotator (62) is in the activated rotational position.