Automatic Injection Device Delay Mechanism with Dual Biasing
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Solution Overview
Problem
Automatic injection devices face challenges in ensuring complete medication delivery and reliable needle retraction without interfering with the driving spring and in maintaining a slim profile with reduced parts complexity.
Innovation Solution
A delay mechanism featuring a shuttle, follower, locking member, damping compound, and dual functioning biasing member that allows timely needle retraction without releasing the driving spring, while maintaining a slim profile and reducing the number of parts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a delay mechanism is used to ensure complete medication delivery and reliable needle retraction, then the reliability of injection is improved, but the device complexity increases
Solution Approach 1:
The patent combines multiple functions into a single integrated delay mechanism assembly. The follower rotates on the shuttle, the biasing member provides both torsional and axial forces, and the damping compound provides viscous resistance. This merging of functions into a compact assembly achieves reliable needle retraction while minimizing device complexity.
Solution Approach 2:
The follower acts as an intermediary element between the syringe plunger and the shuttle. It translates the linear motion of the plunger into rotational motion, which then drives the shuttle to retract the needle. This intermediary mechanism ensures reliable needle retraction while keeping the overall device design compact and manageable.
2Duration of action of moving object
If a delay mechanism with multiple parts is used to control needle retraction timing, then the duration of action is improved, but the device complexity increases
Solution Approach 1:
The biasing member is designed to provide both torsional force (for rotating the follower) and axial force (for pushing the shuttle). The damping compound provides viscous resistance to control the rotation speed. This multi-functionality within a minimal number of parts achieves precise control over needle retraction timing while minimizing part count.
Solution Approach 2:
The patent replaces complex mechanical camming systems with a simpler system based on torsional spring rotation and viscous damping. The follower's rotation, driven by the biasing member and controlled by the damping compound, substitutes for traditional multi-component mechanical delay mechanisms, reducing part count while maintaining timing control.
3Reliability
If a locking mechanism is added to prevent premature device triggering, then the reliability is improved, but the device complexity increases
Solution Approach 1:
The locking mechanism is integrated with the existing follower and shuttle assembly. The follower's rotation, which is already necessary for the delay mechanism to function, also serves to engage or disengage the locking mechanism. This merging of locking function with the delay mechanism prevents premature triggering while avoiding the need for separate locking components.
4Ease of operation
If the device is designed with a slim profile, then the ease of operation is improved, but the volume available for delay mechanism components is reduced
Solution Approach 1:
The delay mechanism components are nested within each other to minimize the overall volume. The follower rotates on the shuttle, the biasing member is positioned within the follower assembly, and the damping compound is contained within a minimal space. This nested arrangement maintains a slim device profile while providing sufficient space for all necessary delay mechanism components.
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
Enables reliable and timely needle retraction without operational forces applied to the syringe during injection, achieving a slim profile and simplified device operation with fewer parts.
Implementation Method 1
a damping compound between the follower and a supporting surface to dampen rotation of the follower relative to the shuttle
Implementation Method 2
a dual functioning biasing member acting between the shuttle and the follower, the biasing member providing both a torsional force urging the follower to rotate relative to the shuttle
Implementation Method 3
a dual functioning biasing member acting between the shuttle and the follower, the biasing member providing both a torsional force urging the follower to rotate relative to the shuttle and an axial force urging the shuttle away from the follower
Data Source
AI summary
An automatic injection apparatus including a delay mechanism for properly delivering medication prior to the needled syringe of the apparatus being retracted. In one form, the delay mechanism includes a shuttle for the syringe, a follower, a locking member, a damping compound between the follower and a supporting surface to dampen rotation of the follower relative to the shuttle, and a dual functioning biasing member acting between the shuttle and the follower. When the locking member moves to a release position during an injection, the dual functioning biasing member first provides a torsional force to force the follower to rotate relative to the shuttle from a latching position to an unlatching position, and then the dual functioning biasing member provides an axial force to force the shuttle axially relative to the follower to move the shuttle for retracting the syringe needle into the housing of the apparatus after injection.