Autoinjector Detent Mechanism With Resilient Beam And Rhomboid Ramp
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Solution Overview
Problem
Conventional auto-injectors face issues with sudden force changes during injection, leading to unpredictable component positions and potential safety hazards, particularly for high viscosity medicaments, and often result in wet injections.
Innovation Solution
A detent mechanism using a resilient beam and rhomboid ramp member controls the translation of components, ensuring defined positions and separate springs for needle insertion and retraction, preventing sudden force changes and reducing manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional auto-injectors are used without a detent mechanism, then the injection process is simpler, but sudden force changes occur during injection leading to unpredictable component positions and potential safety hazards
Solution Approach 1:
The detent mechanism is segmented into distinct functional components: resilient beams (first and second), rhomboid ramp members (first and second), and interaction surfaces. This segmentation allows each component to perform its specific function independently while contributing to the overall position control system, resolving the contradiction by making the complexity manageable and functional.
Solution Approach 2:
The detent mechanism uses resilient beams that can dynamically deflect and return to their original positions, allowing the mechanism to adapt to force changes during injection. The rhomboid ramp members provide dynamic geometric transformation that controls the translation phases, enabling the system to handle varying forces while maintaining reliable position control.
2Reliability
If a detent mechanism with multiple resilient beams and ramp members is implemented, then reliable position control is achieved, but the device complexity increases
Solution Approach 1:
The detent mechanism merges multiple functions into a compact structure where resilient beams and rhomboid ramp members work together in an integrated assembly. The first and second resilient beams are combined with their corresponding ramp members to control both translation phases within a unified mechanism, reducing overall complexity while maintaining reliable injection cycle control.
Solution Approach 2:
The resilient beams serve multiple functions: they provide detent engagement, control translation phases, and absorb force variations. The rhomboid ramp members similarly perform multiple roles in guiding motion and maintaining positional control. This multi-functionality reduces the need for separate components, achieving reliable control without excessive complexity.
3Reliability
If separate springs for needle insertion and retraction are used, then sudden force changes are prevented, but the manufacturing cost increases
Solution Approach 1:
The force control system is segmented into separate spring mechanisms for needle insertion and retraction phases. This segmentation allows each spring to be optimized for its specific function and manufactured independently using standard spring manufacturing processes, preventing sudden force changes while keeping manufacturing costs manageable through modular production.
Solution Approach 2:
The spring parameters (force constants, preload, geometry) are specifically designed and adjusted to provide smooth force control during needle insertion and retraction. By optimizing spring parameters rather than using complex mechanical systems, the patent achieves reliable force control while maintaining ease of manufacture through standard spring design and manufacturing techniques.
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 detent mechanism ensures reliable, safe, and efficient injection cycles, preventing wet injections and allowing for versatile drug delivery with reduced part count and customizable designs for various medicaments.
Implementation Method 1
The resilient beam is essentially straight when relaxed and has a first beam head, which is arranged to interact in a ramped engagement with respectively one of two ramps, each ramp on one longitudinal, i.e. proximal or distal side of the rhomboid ramp member in such a manner that when the first beam head is engaged with one of the ramps in a first state, application of a translative force between the components in one longitudinal direction for pushing the first beam head against the ramp deflects the resilient beam in one transversal direction
Implementation Method 2
The resilient beam is allowed to relax and flex back when the first beam head has reached the other one of the ramps in a second state so that is now engaged with the other ramp thus defining a second relative position of the components
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3A~3B
AI summary
The invention relates to a detent mechanism (18) for controlling translation between two components (2, 7) in a longitudinal direction (P, D), the detent mechanism (18) comprising a resilient beam (2.1) on one of the components (2, 7) and a rhomboid ramp member (7.1) on the other component (7), the resilient beam (2.1) being essentially straight when relaxed and having a first beam head (2.2) and arranged to interact in a ramped engagement with respectively one of two ramps (7.2, 7.3), each ramp on one longitudinal side of the rhomboid ramp member (7.1) in such a manner that application of a translative force between the components (2, 7) in one longitudinal direction (P, D) with the first beam head (2.2) engaged to one of the ramps (7.2, 7.3) in a first state (A, C) deflects the resilient beam (2.1) in one transversal direction (0, I) when a predetermined value of the translative force, at least depending on the resilience of the resilient beam (2.1), is overcome so as to allow the first beam head (2.2) to travel along one transversal side of the rhomboid ramp member (7.1) on continued relative translation of the components (2, 7), wherein the resilient beam (2.1) is allowed to relax when the first beam head (2.2) has reached the other one of the ramps (7.3, 7.2) in a second state (C, A), wherein application of a translative force between the components (2, 7) in the other longitudinal direction (D, P) with the first beam head (2.2) engaged to the other one of the ramps (7.3, 7.2) deflects the resilient beam (2.1) in the other transversal direction (I, O) when a predetermined value of the translative force, at least depending on the resilience of the resilient beam (2.1), is overcome so as to allow the first beam head (2.2) to travel along the other transversal side of the rhomboid ramp member (7.1) on continued relative translation of the components (2, 7).