Auto-injector Single Spring Sequenced Operation
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Solution Overview
Problem
Manual injection devices require continuous user effort, leading to potential underdosing, high injection forces, and discomfort, while current auto-injectors may lack safety features and sequenced operation mechanisms.
Innovation Solution
An auto-injector design utilizing a single compression spring for needle insertion and medicament delivery, with a needle shroud for safety and a sequenced operation requiring two user actions, including a trigger button mechanism to ensure proper injection and prevent accidental operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single compression spring is used to drive needle insertion and medicament delivery, then device complexity is reduced, but control precision over the injection process deteriorates
Solution Approach 1:
The patent segments the spring's functional action through multiple engagement states. The spring is engaged with different components (needle assembly, plunger, needle shroud) at different stages of the injection process, allowing a single spring to provide precisely controlled force at each stage without requiring multiple springs or complex control mechanisms.
Solution Approach 2:
The patent employs dynamic engagement and disengagement of the spring with various components. The spring transitions from engaging the needle assembly during insertion to engaging the plunger during medicament delivery, and finally to engaging the needle shroud during retraction. This dynamic reconfiguration allows precise control of the injection process using a single spring.
2Reliability
If a sequenced operation mechanism with two user actions is implemented, then safety is improved, but ease of operation deteriorates
Solution Approach 1:
The patent requires the first user action (depressing the trigger button) to prepare the device by positioning the needle and engaging the spring. This preliminary action ensures the device is properly configured before the second action (activating the injection) is performed, preventing accidental injection while maintaining a clear, sequential operation flow that is easy to understand.
Solution Approach 2:
The trigger button mechanism serves as an intermediary between the user and the injection activation. The first depression of the trigger button engages intermediate mechanisms (needle positioning, spring engagement) that must occur before the actual injection can be activated by the second trigger depression. This intermediary step provides safety without significantly complicating the overall operation.
3Productivity
If the needle is advanced through the orifice for insertion, then injection effectiveness is improved, but risk of accidental injury increases
Solution Approach 1:
The patent employs a nested structure where the needle is contained within the housing and advanced through a controlled path through the orifice. The needle assembly is nested within the spring mechanism, which is nested within the housing. This nested configuration ensures the needle can be effectively advanced for injection while remaining protected and controlled, minimizing the risk of accidental injury during storage and handling.
Solution Approach 2:
The patent extracts the needle from its protected state within the housing only when necessary for injection. The needle is advanced through the orifice as a controlled extraction action, moving from the safe stored position to the functional injection position. This controlled extraction minimizes the time the needle is exposed and reduces the risk of accidental injury while maintaining injection effectiveness.
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 auto-injector ensures complete and safe medicament delivery with reduced user effort, enhanced safety through sequenced operation and needle protection, and improved compliance with medication administration.
Implementation Method 1
spring means capable of, upon activation: pushing the needle from a covered position inside the housing into an advanced position through the orifice and past the proximal end for insertion into the injection site
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3A~3B
AI summary
The invention refers to an auto-injector (1) for delivering a liquid medicament, comprising: -an elongate housing (2) arranged to contain a syringe (5) with a hollow injection needle (14) and a stopper (15), wherein the syringe (5) is slidably arranged with respect to the housing(2), -spring means (6) capable of, upon activation: -pushing the needle (14) from a covered position inside the housing(2) into an advanced position for insertion into the injection site, -operating the syringe (5) to inject the dose of medicament (M), and -advancing a needle shroud (3) over the needle (14) for providing needle safety, -activating means arranged to lock and release the spring means (6), wherein the spring means (6) is a single drive spring (6) in the shape of a compression spring grounded distally in the housing (2) and proximally bearing against a thrust collar (7) arranged to transmit load from the spring means (7) via a plunger (11) to the syringe (5) and/or the stopper (13) for needle insertion and injection, wherein the plunger (11) is engageable to the thrust collar (7) for joint axial translation, wherein the plunger (11) is disengageable from the thrust collar (7) on relative rotation so as to allow the thrust collar (7) to be advanced further by the drive spring (6) in order to engage the needle shroud (3) for advancing it over the needle (14).