Autoinjector Injection Lock Radial Recess Blocking
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Solution Overview
Problem
Existing autoinjectors face challenges in preventing untimely triggering, ensuring complete fluid delivery, correct needle depth, and safe needle retraction, particularly for elderly or handicapped users, and in preventing fluid backflow due to user error or difficulty in determining when to remove the device after injection.
Innovation Solution
An autoinjector design featuring a piston rod with a radial recess and a blocking element, an injection spring, and a blocking member that requires a controlled force to unlock, along with a retarding device to delay needle retraction, ensuring secure and complete injection with tactile and auditory feedback for user safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a blocking member is used to prevent premature actuation, then reliability is improved, but device complexity increases
Solution Approach 1:
The blocking element is nested within the piston rod's radial recess, and the blocking member is integrated into the control sleeve structure. This nested arrangement allows the locking components to be compact and interconnected, reducing overall device complexity while maintaining reliable prevention of premature actuation through the blocking element-mechanism interaction.
Solution Approach 2:
The blocking element is stressed radially towards the exterior by the piston rod itself, and the control sleeve automatically positions the blocking member to engage or disengage the blocking element. This self-service mechanism eliminates the need for additional external locking components, simplifying the device structure while ensuring reliable prevention of premature injection.
2Reliability
If a blocking element stressed radially towards the exterior is used, then reliability is improved, but manufacturing precision requirements increase
Solution Approach 1:
The blocking element is substantially spherical in shape, which allows it to be easily stressed radially towards the exterior by the piston rod while maintaining reliable engagement with the blocking member. The spherical geometry provides natural point contact and rotational freedom, reducing sensitivity to manufacturing tolerances in the radial recess while ensuring consistent locking behavior.
3Ease of manufacture
If the autoinjector is designed for single use, then ease of manufacture is improved, but cost of manufacture increases
Solution Approach 1:
The locking mechanism components (blocking element, blocking member, control sleeve) are integrated into the existing single-use autoinjector structure, combining the safety function with the disposable device. This merging allows the complex locking system to be manufactured as part of the single-use device assembly, reducing overall manufacturing steps and costs while ensuring reliable prevention of premature actuation.
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 autoinjector ensures reliable and secure operation, preventing premature actuation, ensuring complete fluid delivery, correct needle placement, and safe needle retraction, while providing user feedback to prevent fluid backflow, enhancing usability and safety for all users.
Implementation Method 1
an injection spring (8) which stresses said piston rod (5) towards its injection position
Data Source
AI summary
An autoinjector includes a body (1; 1010), a reservoir containing fluid product, a piston, a needle, a piston rod (5 5; 1005) that is displaceable between a loaded position and an injection position, and an injection spring (8; 1008) to stress 10 the piston rod towards the injection position. The autoinjector also includes an injection lock having a control sleeve (4; 1004) containing the piston rod and the injection spring. The piston rod includes a radial recess (50; 1050) receiving a substantially spherical blocking element (7; 1007) mobile between a blocking position and an unblocking position, stressed radially towards the exterior by the piston rod, and held in the blocking position by a blocking member (23; 1004) that is displaceable relative to the piston rod to release the blocking element.