Cap Assembly Gripper Cam Mechanism for Needle Shield Removal
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Solution Overview
Problem
Existing cap assemblies for removing rigid needle shields in pharmaceutical injection devices complicate the manufacturing process due to the need for precise angular orientation and can result in unsatisfactory gripping if not aligned correctly.
Innovation Solution
A cap assembly comprising a gripper component with a support frame and a resilient liner that can be mounted to a rigid needle shield without requiring a specific angular orientation, allowing for gripping within a range of axial tolerances and enabling the hole in the housing baseplate to be smaller, featuring a gripper component with a cup-like shape and a base cap that cam inward to secure the liner around the needle shield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a two-piece cap assembly with serrated ribs and detents is used to grip the rigid needle shield, then the gripping contact is improved, but the manufacturing process becomes more complex due to the need for precise angular orientation
Solution Approach 1:
The invention changes the engagement parameter from angular/directional (serrated ribs with detents) to radial/omnidirectional (cam-activated compression). The liner is compressed radially inward by the cam mechanism, creating consistent gripping contact regardless of the cap assembly's angular orientation relative to the needle shield.
Solution Approach 2:
The invention introduces a dynamic cam mechanism that transforms rotational motion into radial compression of the liner. As the cam rotates or is pressed, it dynamically compresses the liner inward to engage the needle shield, providing a simple mounting motion that works from any angular position.
2Force
If serrated ribs are used to grip the rigid needle shield, then the gripping force is improved, but the manufacturing precision requirement increases due to angular alignment needs
Solution Approach 1:
The invention changes the gripping mechanism from angular-dependent serrated ribs to radially-symmetric cam-activated compression. The liner compresses uniformly inward from all sides, creating strong gripping force without requiring any specific angular relationship between the cap assembly and needle shield.
Solution Approach 2:
The invention uses asymmetric cam geometry to achieve symmetric radial compression. The cam's asymmetric profile converts unidirectional or rotational motion into omnidirectional radial force, allowing the liner to grip the needle shield evenly from all angles without requiring precise angular alignment during assembly.
3Ease of operation
If the cap assembly is designed with a larger diameter than the protective shield, then the ease of removal is improved, but the device complexity increases
Solution Approach 1:
The invention merges the gripping function and the user interface into a single integrated cap assembly structure. The larger-diameter base cap provides both the user grip surface and the structural framework for the cam mechanism, eliminating the need for separate gripping components and simplifying the overall assembly.
Solution Approach 2:
The cap assembly serves multiple functions: it provides a user grip surface (larger diameter), houses the cam mechanism, compresses the liner to grip the needle shield, and guides the removal motion. This multi-functionality reduces the need for additional components while maintaining ease of operation.
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
Facilitates easier and secure mounting of the cap assembly to the needle shield, allowing for reliable removal of the protective shield without the need for precise angular alignment, simplifying the manufacturing process and ensuring consistent gripping performance.
Implementation Method 1
The base cap is so mounted until its radial protruding tabs within the base of the cavity snap fit into an annular recess on the exterior of the cup tubular portion, thereby locking the base cap and the plastic cup together
Implementation Method 2
a resilient liner that can be mounted to a rigid needle shield
Implementation Method 3
Each finger has an inner surface with serrated ribs, and an outer surface with a ramp formed thereon. After the plastic cup is placed onto the rigid needle shield such that the serrated ribs of the resilient fingers are in angular alignment with detents on the rigid needle shield with which they cooperate
Data Source
Figure 1
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AI summary
A cap assembly mountable to a rigid shield around a needle of a syringe. The cap assembly includes a gripper component and a base cap. The gripper component includes a support frame and a liner that is deformable when sandwiched between the support frame and the rigid shield. When the base cap is installed to the gripper component during manufacture, and with the rigid shield disposed in a bore of the gripper component in any rotational orientation relative thereto, the liner is held by the support frame so as to be deformed against and grip the rigid shield for shield removal purposes so as to allow for removal of the rigid shield from around the needle.