Manual Injection Device with Automatic Sleeve and Pricking Lock
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Solution Overview
Problem
Manual injection devices face challenges in ensuring safe and reliable use, particularly in preventing premature fluid injection and ensuring needle safety, while also being simple and inexpensive to manufacture and use.
Innovation Solution
A manual injection device design featuring a lower body with a movable reservoir, an upper body with a piston rod, and a sleeve that automatically transitions from a rest to a projecting position after injection, with a pricking lock requiring less force than the injection lock, ensuring the needle penetrates fully before injection and providing post-injection safety through a spring-activated sleeve.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the device includes a needle safety device that automatically covers the needle after injection, then safety and reliability are improved, but device complexity increases
Solution Approach 1:
The sleeve is designed to automatically move into the projecting position after injection without requiring user intervention. The spring mechanism self-activates based on the injection process itself, making the safety function autonomous and avoiding the need for complex control systems.
Solution Approach 2:
The sleeve transitions from a static blocked position to a dynamic projecting position that covers the needle. This dynamic movement provides safety only when needed (after injection) while maintaining device simplicity during the injection process.
2Ease of operation
If the force necessary for moving the reservoir axially is made less than the force for triggering the injection lock, then ease of operation is improved, but the risk of premature injection increases
Solution Approach 1:
The device is designed so that the reservoir movement (pricking action) occurs first as a preliminary step. Only after the reservoir has moved axially and the needle has penetrated does the injection lock trigger, ensuring proper sequencing without requiring excessive force.
Solution Approach 2:
The force parameters are carefully calibrated: the pricking lock requires less force to allow easy needle penetration, while the injection lock requires more force to prevent premature activation. This parameter differentiation ensures both ease of operation and reliable injection timing control.
3Reliability
If the sleeve is blocked in rest position before actuation, then premature injection is prevented, but device complexity increases
Solution Approach 1:
The blocking function is extracted as a separate, simple mechanical feature of the sleeve rather than being integrated into a complex control system. The sleeve itself provides the blocking action through its rest position, simplifying the overall device architecture.
Solution Approach 2:
The device functionality is segmented into distinct phases: the blocked rest position prevents premature injection, the unblocked position allows injection, and the automatically projecting position provides post-injection safety. This segmentation allows each function to be implemented with simple, dedicated mechanisms.
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 device ensures safe and reliable use by preventing premature injection, allowing easy penetration of the needle and automatic safety activation, while being cost-effective and simple to manufacture and use.
Implementation Method 1
said sleeve being urged automatically into its projecting position after injection
Implementation Method 2
said upper body co-operating, at the end of injection, via a cam, with said end of said sleeve, so as to deform said end in a radially-inward direction
Data Source
AI summary
A manual injection device having a lower body and a fluid reservoir that moves axially in the lower body. The reservoir includes a piston and needle; an upper body mounted to move axially relative to the lower body, the upper body including a piston rod co-operating with the piston; and a sleeve mounted to move relative to the lower body between a rest position and a projecting position. The sleeve is blocked in its rest position before the injection device is actuated, and urged automatically into its projecting position after injection. The piston rod co-operates with the reservoir to form an injection lock, the force for moving the reservoir axially being less than the force for triggering the injection lock, such that pricking is performed before injection. Before actuation, the piston rod is connected to a ring that is fastened on a radial collar of the reservoir.