Dose Delivery Device Without Gearing
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Solution Overview
Problem
Existing dose delivery devices lack a numbered scale drum and require complex gearing mechanisms, making it difficult for users with small hands to set and inject doses without changing grip, especially when using the index finger, and often result in high injection force due to friction losses.
Innovation Solution
A dose delivery device with a piston rod that does not rotate during dose setting but rotates during injection, featuring a driver threadedly engaged with the piston rod and a numbered scale drum rotationally locked to the driver, allowing for a simple and compact design with a short push-button movement, and incorporating a ratchet mechanism for tactile feedback and efficient dose display.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a traditional gearing mechanism is used to provide a numbered scale drum, then the dose setting precision is improved, but the device complexity increases and friction losses increase
Solution Approach 1:
The patent removes the traditional gearing mechanism entirely, extracting only the essential function of dose setting. The push button directly translates rotational movement into linear movement of the piston rod without intermediate gears, eliminating the complex gearing structure while maintaining dose setting capability through a simplified direct-drive mechanism.
Solution Approach 2:
The patent introduces a thread engagement between the push button and the piston rod as an intermediary mechanism. This thread converts rotational movement of the push button into linear movement of the piston rod, providing the necessary gearing function (10 revolutions for 1 unit dose) without requiring complex gear trains, thus reducing device complexity while maintaining precision.
2Measurement precision
If a traditional gearing mechanism with multiple threads is used, then the numbered scale drum can be provided, but the injection force increases due to friction losses
Solution Approach 1:
The patent eliminates multiple thread engagements and complex gearing that cause friction losses. By using a single direct thread engagement between the push button and piston rod, the mechanism reduces friction points, thereby reducing the injection force required while still providing adequate dose display readability through the simplified mechanism.
3Measurement precision
If the push button movement is made long to accommodate gearing, then the dose setting precision is improved, but the ease of operation deteriorates for users with small hands
Solution Approach 1:
The patent makes the push button dynamic by allowing it to perform both rotational movement (for dose setting) and linear movement (for injection) through a single component. This dynamic design eliminates the need for long linear movement distances while maintaining precision, as the rotational-to-linear conversion happens within the compact push button structure itself, making it easier for users with small hands to operate.
4Measurement precision
If a numbered scale drum with traditional gearing is used, then the dose display readability is improved, but the device complexity and production costs increase
Solution Approach 1:
The patent extracts the dose display function from the complex traditional gearing system and integrates it directly into the push button and piston rod assembly. The numbered scale is simplified to work with the direct-drive mechanism, reducing the number of parts that need to be manufactured and assembled, thereby lowering production costs while maintaining dose display readability.
Solution Approach 2:
The patent merges the dose setting mechanism, dose display mechanism, and injection mechanism into a more integrated structure. The push button directly engages the piston rod through thread engagement, combining multiple functions into fewer components, which simplifies manufacturing and reduces production costs while maintaining the numbered scale drum functionality for dose display.
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 allows for precise dose setting and injection with minimal grip change, reduced complexity and production costs, and enhanced readability through a gearing ratio of 1:1, ensuring users with small hands can easily administer doses using their index finger without excessive force.
Implementation Method 1
a driver (6) which is rotated an angle in one direction when setting the dose, and together with the piston rod the same angle in the opposite direction when injecting the set dose
Data Source
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AI summary
A dose delivery device is disclosed wherein a dose can be set by rotating a dose setting member, whereby a push button (4) is elevated from one end of the device a distance proportional to the set dose from a position fixed relative to the housing, and wherein the set dose can then be injected by pressing the push button back to its non- elevated position, through which motion a piston rod will move approximately the same distance. The invention provides a method of forcing a numbered scale drum to rotate both during dose setting and injection to allow the user to read the remaining dose at any time during setting and injecting a dose.