Injection Device Rotary Member Cam Mechanism Sticking Prevention
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Solution Overview
Problem
Existing injection devices often fail to initiate dispensing of medication promptly when the actuating knob is fully actuated, potentially requiring a mechanical shock to start dispensing due to mechanical sticking issues during long-term storage.
Innovation Solution
A driving and dosing device with a preloaded dispensing spring system that includes multiple springs and a rotary member, allowing for immediate dispensing without the need for re-cocking, and a clutch mechanism that ensures the rotary member rotates when the actuating knob is fully pressed, overcoming sticking issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the injection device uses a preloaded dispensing spring that remains cocked, then the device can dispense multiple doses without re-cocking, but the mechanism may become stuck and fail to initiate dispensing promptly
Solution Approach 1:
The patent employs a cam mechanism that converts the linear motion of the actuating knob into rotational motion of a rotary member. This rotational motion introduces a dynamic element that overcomes static friction and prevents the mechanism from becoming stuck during storage, ensuring reliable dispensing initiation.
Solution Approach 2:
The patent transforms the static preloaded spring system into a dynamic system by introducing a cam and rotary member. The cam converts linear actuation into rotational motion, creating a dynamic mechanism that actively overcomes sticking issues while maintaining the preloaded spring's ability to deliver multiple doses.
2Device complexity
If the actuating knob directly actuates the piston rod, then the structure is simple, but the mechanism may stick and require mechanical shock to start dispensing
Solution Approach 1:
The patent introduces a cam as an intermediary element between the actuating knob and the piston rod. The cam converts the linear motion of the knob into rotational motion of a rotary member, which then drives the piston rod. This intermediary mechanism prevents direct contact that causes sticking while adding only moderate complexity.
Solution Approach 2:
The patent replaces the simple direct linear actuation mechanism with a cam-based rotational mechanism. This substitution introduces a different type of mechanical motion (rotational instead of linear) that fundamentally solves the sticking problem caused by direct contact between actuating components.
3Use of energy by moving object
If the dispensing spring is strongly preloaded to enable multiple dispensing strokes, then the energy storage is sufficient, but the mechanism may become stuck during storage
Solution Approach 1:
The patent maintains the strongly preloaded spring for sufficient energy storage while introducing a cam mechanism that converts linear motion into rotation. This dynamic element actively prevents the mechanism from sticking during storage by creating rotational motion that overcomes static friction, allowing the preloaded energy to be reliably released.
Solution Approach 2:
The cam mechanism introduces dynamic motion that creates slight vibrations and movements during actuation, preventing the strongly preloaded spring mechanism from becoming stuck during storage. This dynamic element ensures that the stored energy can be reliably converted into dispensing action.
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
Ensures immediate and reliable dispensing of medication without the need for additional mechanical force, maintaining the preloaded energy for multiple dispensing strokes and simplifying dose adjustment.
Implementation Method 1
The first and second dispensing springs are preloaded with sufficient energy in the delivery state of the driving and dosing device that they can dispense the dispensable quantity of product from the product container in multiple individual dispensing strokes
Implementation Method 2
The actuating member is coupled to the rotary member in such a manner that actuating the actuating member causes the rotary member to rotate relative to the housing already when the clutch is still closed
Data Source
AI summary
The invention relates to a driving device for an injection device for administration of a liquid drug. The driving device has inter alia a rotary member, rotation of which relative to the housing causes a pretensioned spring to move a propulsion member in the dispensing direction, and a coupling which is closed and is opened by pressing of an actuating member, the opened coupling enabling the rotation of the rotary member in a first direction of rotation, and the actuating member being coupled to the rotary member such that pressing of the actuating member causes the rotary member to rotate already when the coupling is still closed.