Pen-Type Injector Housing Window Retention via Clamp Lug
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Solution Overview
Problem
Existing drug delivery devices face challenges in securing a transparent lens or window robustly to the outer housing, with methods like two-shot molding being costly and adhesives requiring careful control, while clip arrangements can complicate printing and increase device size.
Innovation Solution
A housing design featuring a catch or locking device, such as a clamp with a lug, engages a recess in the insert, providing a robust connection by using a notch or recess within the insert that is attached to the outer shell, ensuring the insert is securely locked in place.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If two-shot molding is used to form the window and housing together, then the connection between window and housing is robust, but the manufacturing cost increases and material options are limited
Solution Approach 1:
The device is divided into separate components (housing and window) that are manufactured independently and then assembled together using a clip arrangement. This segmentation allows each part to be manufactured using optimal processes and materials independently, reducing overall manufacturing complexity and cost while maintaining connection reliability through the designed clip interface.
Solution Approach 2:
The window component is nested within the housing aperture and secured by the clip arrangement. The clip itself is nested within the housing structure, creating a hierarchical assembly where smaller components are integrated into larger ones. This nesting approach allows for compact design while maintaining secure connections without requiring complex manufacturing processes.
2Reliability
If the window and housing are clipped together with sufficient engagement depth, then the connection is robust, but the device size increases and printing options are complicated
Solution Approach 1:
Instead of requiring deep engagement across the entire window-housing interface, the clip arrangement concentrates the securing function at specific localized points. The clip features are strategically positioned to provide sufficient mechanical engagement and retention at critical locations, ensuring connection robustness without requiring the window to extend deeply into the housing structure.
Solution Approach 2:
The clip arrangement utilizes the thickness dimension of the housing wall to provide engagement features, rather than requiring deep radial engagement. The clip can engage with features on the inner surface of the housing, effectively using the housing wall thickness as the engagement depth, thereby maintaining compact overall device dimensions while achieving secure connection.
3Reliability
If adhesives or double-sided tape are used to bond the window to the housing, then the connection is strong, but production control becomes complex and costs increase
Solution Approach 1:
The chemical bonding method (adhesives or tape) is replaced with a purely mechanical clip arrangement. The clip uses elastic deformation and mechanical interlocking features to secure the window to the housing, eliminating the need for adhesives. This substitution simplifies production control as it relies on straightforward mechanical assembly rather than requiring controlled chemical bonding processes.
Solution Approach 2:
The clip arrangement is designed to be self-securing through its elastic properties and geometric features. When the window is inserted into the housing aperture, the clip automatically engages and secures it through its elastic deformation and mechanical interlocking features, without requiring additional bonding materials or complex assembly procedures. The clip serves its own function of providing both the securing mechanism and the bonding interface.
Data Source
AI summary
The present invention is directed to a housing for a drug delivery device. The housing comprises an outer shell with an aperture, an insert received within the aperture and a clamp attached to the outer shell. The insert has at least one recess which is engaged by a lug of the clamp to retain the insert within the aperture of the outer shell. The invention is further directed to a pen-type injector having such a housing.