Autoinjector Blocking Ring Mechanism for Accidental Activation Prevention
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Solution Overview
Problem
Existing autoinjectors face challenges in providing a reliable and safe locking mechanism that prevents accidental activation, while also being easy to use and inexpensive to manufacture and assemble, particularly for elderly or handicapped users.
Innovation Solution
An autoinjector design featuring a piston rod with a radial recess for a spherical blocking element, an injection spring, and a blocking ring that moves to release the blocking element, allowing for easy actuation without excessive force, along with a visual, audible, and tactile indicator for confirmation of injection completion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If reliable locking means are provided to prevent accidental activation, then safety and reliability are improved, but device complexity increases and ease of operation deteriorates
Solution Approach 1:
The locking mechanism is divided into distinct functional elements: a blocking element (ball) that can be in blocking or non-blocking positions, a blocking ring that constrains the ball, and a control sleeve that moves to release the block. This segmentation allows each component to perform its specific function independently, achieving reliable locking while maintaining ease of operation through simple axial movement of the control sleeve.
Solution Approach 2:
Instead of requiring complex multi-step unlocking procedures, the design inverts the approach by using a simple axial movement of the control sleeve to automatically trigger the release sequence. The control sleeve's movement directly causes the blocking ring to disengage from the support member, which then allows the blocking element to be pushed back by the piston rod, creating an intuitive and easy-to-operate system.
2Ease of manufacture
If simple and inexpensive manufacturing is achieved, then manufacturing cost is reduced, but manufacturing precision and assembly complexity may worsen
Solution Approach 1:
The blocking element is designed as a simple substantially spherical ball that can be easily manufactured and replaced. This simple geometry allows for low-cost manufacturing while maintaining functional reliability. The ball's simplicity also facilitates easy assembly and disassembly, reducing assembly precision requirements while keeping manufacturing costs low.
Solution Approach 2:
The blocking element is designed as a substantially spherical ball, which is one of the easiest shapes to manufacture with high precision using standard machining or molding processes. The spherical shape also provides smooth movement through the radial recess and reduces stress concentration, maintaining reliability while enabling cost-effective manufacturing.
3Reliability
If robust locking mechanism is provided to withstand drops, then reliability is improved, but device complexity and ease of operation may worsen
Solution Approach 1:
The blocking element is preliminarily positioned in the blocking position by the blocking ring before any drop or accidental event occurs. The blocking ring is pre-configured to engage with the support member, creating a robust locked state that can withstand drops. The preliminary arrangement of components ensures that the locking mechanism is ready to prevent accidental activation without requiring complex active control systems.
Solution Approach 2:
The blocking function is extracted as a separate, movable blocking ring that can be independently engaged or disengaged from the support member. This separation allows the locking mechanism to be robust and reliable during normal conditions while enabling simple release when needed. The blocking ring's ability to be easily removed from the support member's engagement provides drop resistance without excessive complexity.
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 ensures reliable prevention of accidental activation, easy and safe use, and cost-effective manufacturing, while providing a stable and robust locking mechanism that withstands drops and simplifies the actuation process.
Implementation Method 1
an injection spring being provided for urging said piston rod towards its injection position
Implementation Method 2
said piston rod including a radial recess that receives at least one substantially-spherical blocking element, such as a ball, that is movable between a blocking position and an unblocking position, said at least one blocking element being urged radially outwards by said piston rod
Data Source
AI summary
An autoinjector having a piston rod for a piston of a reservoir, the piston rod movable between a primed position and an injection position; an injection spring urging the piston rod towards its injection position; and an injection lock including a control sleeve containing the piston rod and the injection spring. The piston rod includes a radial recess receiving a substantially-spherical blocking element movable between a blocking and unblocking position and urged radially outwards by the piston rod and held in its blocking position by a blocking ring; and a support member fastened in the control sleeve and having a ring with an axial end in contact with the injection spring, the other axial end supports the blocking element. The blocking ring is engaged on the support member and disengaged by the control sleeve.