Radially Deflectable Arm Housing Interface for Drug Delivery
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Solution Overview
Problem
Disposable drug delivery devices are prone to unintended disassembly, which can lead to misuse and health risks, especially when users attempt to replace empty cartridges, due to their complex design and high number of components, making them bulky and difficult to handle.
Innovation Solution
The introduction of a radially deflectable arm and recess interface, along with a locking member, axially retains the inner housing within the outer housing, increasing the force required for disassembly and preventing unintended disassembly, while also serving as a tamper-evident closure to prevent cartridge replacement without damaging the device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a complex design with high number of components is used in disposable drug delivery devices, then the device can achieve complete disposability and prevent refilling, but the device becomes bulky and prone to unintended disassembly
Solution Approach 1:
The patent combines the inner housing and outer housing into a more integrated structure with interlocking features. The radially deflectable arms are integrated into the housing assembly, reducing the number of separate fastening components while maintaining secure assembly. This merging approach prevents unintended disassembly without requiring numerous separate parts.
Solution Approach 2:
The patent introduces radially deflectable arms that can dynamically change their radial position during assembly and disassembly processes. These arms deflect radially inward during normal operation to maintain secure engagement, but can be deliberately actuated to allow controlled disassembly. This dynamic behavior provides reliability against unintended disassembly while maintaining manageable device complexity.
2Ease of operation
If the device is designed to be easily disassembled for cartridge replacement, then ease of operation improves, but misuse and health risks increase due to improper refilling
Solution Approach 1:
The patent segments the cartridge replacement function from the housing disassembly function. The cartridge can be replaced through a dedicated access mechanism without requiring complete disassembly of the housing. The radially deflectable arms remain engaged during cartridge replacement, maintaining structural integrity while allowing controlled access. This segmentation enables safe cartridge replacement while preventing harmful refilling attempts.
Solution Approach 2:
The radially deflectable arms act as an intermediary mechanism between the housing and cartridge assembly. They provide controlled access points that allow legitimate cartridge replacement while preventing unauthorized disassembly. The arms mediate between the need for ease of operation and the need to prevent misuse by requiring specific actions for disengagement.
3Ease of manufacture
If the inner housing is loosely retained in the outer housing, then ease of assembly improves, but the device becomes prone to unintended disassembly
Solution Approach 1:
The radially deflectable arms provide dynamic retention that is easy to engage but difficult to disengage unintentionally. During assembly, the arms naturally deflect to accommodate the inner housing. During use, they maintain secure engagement. For deliberate disassembly, a specific actuation force causes the arms to deflect radially inward, allowing controlled separation. This dynamic behavior simplifies manufacturing while ensuring reliability.
Solution Approach 2:
The patent utilizes changes in radial position of the deflectable arms as a key parameter for assembly and disassembly. The arms transition between radially outward (engaged) and radially inward (disengaged) positions. This parameter change provides a simple yet reliable mechanism that is easy to manufacture but resistant to unintended disassembly, as the arms naturally maintain the engaged state under normal conditions.
Data Source
AI summary
The disclosure relates to a disposable drug delivery device for selecting and dispensing a number of user variable doses of a medicament. The device comprises an outer housing, an inner housing, a cartridge holder for retaining a cartridge containing the medicament, a piston rod displaceable relative to the cartridge holder, a driver coupled to the piston rod, a display member for indicating a set dose and being coupled to the housing and to the driver, and a button coupled to the display member and to the driver. Engagement of the inner housing in the outer housing may be improved by the inner housing is axially retained in the outer housing by an interface comprising at least one radially deflectable arm with a lateral protrusion, at least one recess adapted for engagement with the protrusion and at least one locking member adapted for hindering disengagement of the at least one protrusion from the at least one recess.