Auto-Injector Motor Body Shell Stops for Assembly Alignment
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Solution Overview
Problem
Existing drug delivery devices, such as auto-injectors, require complex assembly processes with multiple steps and alignment challenges, which can be cumbersome and error-prone, especially for untrained users.
Innovation Solution
A drug delivery device design featuring an upper and lower housing shell, a syringe with a barrel, stopper, and needle, along with a drive assembly including a plunger body, cassette body, and motor body with shell stops and reinforcing ribs, which simplifies assembly by guiding alignment and reducing the number of assembly steps through a subassembly engagement mechanism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If traditional assembly processes are used for auto-injectors, then the device can be assembled with multiple interlocking parts, but the assembly process becomes complex and error-prone
Solution Approach 1:
The device is divided into two subassemblies: a first subassembly containing the lower housing shell, cassette body, and syringe; and a second subassembly containing the upper housing shell and motor body. This segmentation allows each subassembly to be pre-assembled and tested independently, then combined through a simplified engagement mechanism, reducing overall assembly complexity while maintaining reliability
Solution Approach 2:
The motor body acts as an intermediary component that bridges the two subassemblies. It includes shell stops that engage with the upper housing shell and cassette clips that engage with the cassette body, providing a standardized interface that simplifies the connection between subassemblies and reduces alignment errors
2Manufacturing precision
If multiple assembly steps are used to ensure proper alignment, then alignment precision is improved, but the number of assembly steps increases
Solution Approach 1:
Alignment features such as shell stops and reinforcing ribs are designed into the components during manufacturing, allowing proper alignment to be achieved automatically during the final assembly step without requiring multiple manual alignment operations, thus maintaining precision while improving assembly speed
Solution Approach 2:
The shell stops are positioned asymmetrically on the motor body to engage with corresponding features on the upper housing shell, providing self-aligning characteristics that guide proper orientation during assembly without requiring multiple adjustment steps
3Manufacturing precision
If the motor body is designed with shell stops extending outward, then alignment with the upper housing shell is improved, but the device complexity increases
Solution Approach 1:
The shell stops are integrated directly into the motor body structure rather than being separate components. The motor body combines the functions of structural support, alignment (via shell stops), and mechanical connection (via cassette clips), reducing overall device complexity while maintaining alignment precision
Data Source
AI summary
A drug delivery device includes an upper housing shell, a lower housing shell, and a syringe. The syringe includes a barrel, a stopper, and a needle, at least a portion of the syringe positioned within the lower housing shell. The drug delivery device further includes a drive assembly including a plunger body configured to move the stopper within the barrel upon actuation of the drive assembly, a cassette body configured to receive the syringe, and a motor body configured to engage the cassette body. The motor body includes a pair of sidewalls and at least one shell stop extending outward from the sidewalls and configured to engage an internal structure of the upper housing shell.