Rotator Guide Ledges Reduce Activation Force
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Solution Overview
Problem
Existing auto-injector medicament delivery devices face challenges in user comfort, ease of use, safety features, and operational performance, particularly in device activation and preventing accidental reuse.
Innovation Solution
The medicament delivery device features a robust design with a tubular housing, an actuator with a flexible finger locking mechanism, and a rotator with guide ledges that reduce activation force and ensure smooth operation, along with a needle cover with a radial flange for improved contact and a transport lock assembly for secure powerpack handling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a traditional locking mechanism is used to secure the plunger rod, then the device structure becomes simpler, but the activation process becomes less smooth and responsive
Solution Approach 1:
The patent employs a dynamic flexible finger that can deflect and rotate during the activation process. The finger transitions from a locked position to an unlocked position through controlled deflection and rotation, enabling smooth and responsive activation. This dynamic behavior allows the locking mechanism to adapt during operation, providing both simplicity and smooth activation.
Solution Approach 2:
The flexible finger changes its physical state during activation by deflecting and rotating. The finger moves from a rigid locked position to a deflected unlocked position, changing its orientation and position parameters. This parameter change enables the transition from locked to unlocked state, achieving smooth activation without complex mechanisms.
2Ease of operation
If the device is designed for easy activation, then user comfort improves, but the risk of accidental activation or reuse increases
Solution Approach 1:
The rotator is pre-configured with guide ledges that direct the activation process through a specific rotational path. This preliminary structural arrangement ensures that activation only occurs when the correct rotational movement is performed, preventing accidental activation while maintaining ease of use when intended.
Solution Approach 2:
The guide ledges on the rotator create an asymmetric activation path that must be followed in a specific direction. This asymmetric design prevents reverse or incorrect activation attempts, ensuring that once activated, the device cannot be accidentally reactivated or misused, while still allowing smooth intended activation.
3Force
If inclined guide ledges are added to reduce activation force, then ease of activation improves, but device complexity increases
Solution Approach 1:
The guide ledges on the rotator are designed with inclined and curved surfaces that guide the activation process. These curved surfaces reduce the activation force by providing a gradual rotational path, allowing the user to activate the device with less effort. The curvature integrates smoothly into the rotator structure, minimizing added complexity.
4Reliability
If a robust locking mechanism is implemented to prevent accidental contact, then safety improves, but the lockout feature becomes less smooth
Solution Approach 1:
The flexible finger provides a dynamic lockout mechanism that smoothly transitions between locked and unlocked states. During normal operation, the finger maintains a secure locked position, but during the activation process, it smoothly deflects and rotates to unlock. This dynamic behavior ensures both effective lockout and smooth operation during intended activation.
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
The design enhances user experience by providing a more responsive and smooth activation process, improves manufacturing quality, and includes an effective lockout feature to prevent accidental contact or reuse, thereby increasing the device's robustness and operational reliability.
Implementation Method 1
A compressed drive spring is positioned within the plunger rod and biases the closed proximal end in a proximal direction
Implementation Method 2
The tubular proximal portion of the actuator has a flexible finger that releasably locks the plunger rod when it is in the first biased position
Data Source
AI summary
The present disclosure relates to a medicament delivery device comprising a housing having a proximal end and contains a pre-filled syringe positioned within the housing, where the syringe has a needle, a dose of medicament and a sliding stopper. A tubular activation member, e.g., a needle cover that is slidably positioned within a housing of the delivery device to move from a first position to a second position, and then to a final locked position. The needle cover has two distally projecting arms and a proximal end portion terminating in a radial flange. A plunger rod can only move proximally relative to the needle cover when the needle cover is in the second position. The radial flange is positioned outside of the proximal end of the housing when the needle cover is in the first position, the second position, and the locked position. The radial flange has an outer diameter D3 greater than the outer diameter of the proximal end portion D2, but less than the outer diameter D1 of the proximal end of the housing.