Drug Delivery Assembly Key Prevents Telescoping Extension
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Solution Overview
Problem
Drug delivery systems, such as patch injectors, face issues with telescoping assemblies extending unintentionally during transport due to vibrations, leading to difficulties in assembly and potential user perception of malfunction, which can impact market acceptance and patient safety.
Innovation Solution
A locking assembly key is used to secure the telescoping assembly by inserting a locking bit into a key slot on the pushing nut screw and cartridge gear, preventing rotation and extension, and optionally including clips for attachment, ensuring the assembly remains stable during transport and facilitating easy assembly into the delivery device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the telescoping assembly is left unsecured during transport, then the device structure remains simple and easy to manufacture, but vibrations cause unintended extension of the assembly
Solution Approach 1:
The telescoping assembly is pre-secured in a retracted position using a friction fit between the cartridge gear and pushing nut screw before transport. This preliminary securing action prevents vibrations from causing unintended extension, while allowing easy disengagement when needed for assembly.
Solution Approach 2:
A friction interface acts as an intermediary mechanism between the cartridge gear and pushing nut screw. This friction fit provides sufficient holding force during transport to prevent extension, while allowing controlled disengagement during assembly operations without requiring complex locking mechanisms.
2Reliability
If the telescoping assembly is secured tightly to prevent extension, then transport stability is improved, but assembly difficulty increases
Solution Approach 1:
The securing mechanism transitions from a static friction fit during transport to a dynamic state during assembly. The friction interface allows controlled slipping and disengagement when assembly forces are applied, enabling easy assembly while maintaining stability during transport.
Solution Approach 2:
The friction coefficient and contact pressure parameters are optimized to provide sufficient holding force during transport while allowing easy disengagement during assembly. The friction fit parameters are selected to balance retention strength with assembly ease.
3Reliability
If no securing mechanism is used, then manufacturing cost is reduced, but unintended extension during transport occurs
Solution Approach 1:
The friction fit mechanism uses simple, inexpensive components (cartridge gear and pushing nut screw with friction interface) that are integrated into the disposable cartridge assembly. This provides reliable securing during transport without requiring expensive or complex reusable locking mechanisms.
Solution Approach 2:
The securing function is merged into the existing structural components of the telescoping assembly (cartridge gear and pushing nut screw). The friction interface is integrated into the normal assembly structure rather than being a separate securing device, simplifying manufacturing.
Data Source
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AI summary
A method of securing an assembly (101) of a drug delivery system, comprising: configuring at least a first component (202, 204, 206, 208) and a second component (210) of the assembly (101) in a closed configuration ready for placement into the drug delivery system; installing an assembly key (150) including a locking element on the assembly (101) to secure the assembly in said configuration; and, transporting the assembly (101) with the assembly key (150) installed. (Fig. 2)