Opposite-Handed Thread Gearing for Low Injection Force
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Solution Overview
Problem
Existing dose delivery devices face challenges in providing a low injection force that is not sensitive to friction, while being suitable for automated assembly and simple production, and often require complex mechanisms that are not suitable for disposable devices.
Innovation Solution
A dose delivery device with a gearing mechanism that includes a first and second gearing member, where the second member has opposite-handed threads, allowing for a low-friction, low-injection-force design suitable for automated assembly, featuring a ratchet or teeth connection between the dial and dose setting member, and a non-rotating lead screw that expels medication with minimal axial movement during injection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a gearing mechanism is introduced to reduce injection force and improve user feedback, then the injection force and user clarity are improved, but the device complexity increases making it unsuitable for disposable devices
Solution Approach 1:
The gearing mechanism is divided into two separate gearing members (first and second gearing members) with opposite-handed threads, allowing independent optimization of each component's function and simplifying manufacturing and assembly processes
Solution Approach 2:
Different portions of the push button are designed with different functions: the first portion engages with the first gearing member while the second portion engages with the second gearing member, allowing localized optimization of force transmission and friction reduction
2Force
If traditional gearing mechanisms are used to provide force multiplication, then injection force is reduced, but friction losses increase reducing efficiency
Solution Approach 1:
Instead of using conventional gearing approaches, the patent uses opposite-handed threads on the two gearing members, where one thread engages a right-handed lead screw and the other engages a left-handed lead screw, creating a differential gearing effect that reduces friction losses while maintaining force multiplication
Solution Approach 2:
The two gearing members act as intermediaries between the push button and the lead screw, translating the user's linear push motion into rotational motion with reduced friction through the opposite-handed thread mechanism
3Force
If a gearing mechanism with multiple sliding surfaces is used to achieve force reduction, then injection force is lowered, but the number of friction interfaces increases
Solution Approach 1:
The first and second gearing members are merged into a single integrated component in some embodiments, reducing the number of separate sliding surfaces while maintaining the force reduction benefit through the opposite-handed thread design
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 solution achieves a low-friction, low-injection-force mechanism that is suitable for automated assembly and simple production, ensuring efficient medication delivery with minimal energy loss and preventing over-dosing by using a gearing ratio that reduces friction and allows for easy assembly.
Implementation Method 1
A gearing mechanism is provided in a dose delivery device with a very low loss of energy due to friction and thereby a very low injection force
Data Source
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AI summary
The invention relates to a gearing mechanism for a dose delivery device wherein the dose can be set by rotating a dose setting member (2, 102), and by which the dose setting member (2, 102) and a push-button (4) elevates from one end of the device proportional to the set dose from a position fixed relative to a housing (1, 101), and by which an injection of the set dose can be done by pressing the push-button back to its not elevated position, moving a piston rod (10, 110) cooperating with the piston in an cartridge (12, 112) and expelling a medicament out of the through a needle. The gearing mechanism is arranged in the device in such a way, that the loss of energy is very low.