Dose Counter Flexible Tabs Prevent Over-Counting
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Solution Overview
Problem
Existing dose counters for fluid or powder dispensing devices, particularly in MDI-type dispensers, face challenges of under-counting and over-counting due to the short actuation stroke and manufacturing tolerances, requiring complex mechanisms to ensure accurate counting.
Innovation Solution
A dose counter design featuring an actuation element with flexible tabs and a stop element that rotates counting wheels, ensuring accurate counting by engaging with toothing to prevent over-counting and maintaining precise dose tracking, independent of the actuation stroke length.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the maximum stroke of the counter actuation is reduced to be less than the minimum actuation stroke of the valve or pump (to avoid under-counting), then under-counting is prevented, but the available distance for reliable actuation becomes very short and manufacturing tolerances further reduce the effective distance
Solution Approach 1:
The patent employs flexible tabs that can dynamically adapt their engagement position with the toothing elements. The flexible nature allows the tabs to engage with multiple teeth along the actuation stroke, ensuring reliable counting regardless of the short stroke length or manufacturing tolerances. This dynamic engagement resolves the contradiction by making the counting mechanism robust to variations in actuation distance.
Solution Approach 2:
The patent changes the parameter of engagement flexibility by using flexible tabs instead of rigid connectors. This allows the system to accommodate varying actuation stroke lengths while maintaining reliable counting. The flexible tabs can engage with different numbers of teeth depending on the actual stroke length, thus adapting to the constrained geometric conditions.
2Reliability
If a complex mechanism is used to provide operational and reliable counting with short actuation stroke, then counting reliability is improved, but device complexity increases
Solution Approach 1:
The patent uses flexible tabs made of elastic material that engage with the toothing elements. These flexible elements provide the necessary compliance and reliability for short stroke actuation without requiring complex mechanical linkages, multi-stage mechanisms, or precision-adjustable components. The flexibility itself provides the robustness needed for reliable counting.
Solution Approach 2:
The flexible tabs automatically adapt their engagement with the toothing based on the actual actuation stroke length. The system self-adjusts to the available distance without requiring external calibration or complex control mechanisms. The elastic deformation of the tabs provides inherent tolerance compensation, making the mechanism inherently reliable without added complexity.
3Ease of manufacture
If the counter mechanism is simplified to reduce manufacturing complexity, then ease of manufacture is improved, but the ability to guarantee accurate counting independent of actuation stroke length deteriorates
Solution Approach 1:
The flexible tabs provide a simple yet effective solution that is easy to manufacture while ensuring reliable counting. The elastic material and simple geometry of the tabs allow for straightforward fabrication without complex machining or assembly steps, yet they provide the necessary adaptability to maintain counting accuracy across varying stroke lengths.
Solution Approach 2:
The flexible tabs can be made from inexpensive elastic materials that are easy to manufacture and replace if needed. This approach prioritizes functional reliability and ease of manufacture over using expensive, precision-machined components, aligning with the goal of simplifying the overall device while maintaining counting accuracy.
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 ensures reliable and accurate counting of doses, preventing under-counting and over-counting, while simplifying the mechanism and reducing manufacturing complexity, ensuring the counter always actuates before dose dispensing.
Implementation Method 1
by being resiliently biased towards its rest position by a resilient element, such as a spring
Implementation Method 2
said first and second flexible tabs being disposed radially outside of said first toothing and being resiliently biased radially inward into contact with said first toothing
Data Source
AI summary
A counter having an actuating element (20) and a counting element (30) with toothing (32), the actuating element axially movable along an axis (X) between a rest position and an actuation position, the counting element mounted to rotate on an axis perpendicular to the axis (X). The actuating element has a first flexible tab (21) engaging the toothing to rotate the counting element in a counting direction when the actuating element moves into its actuation position, and a second flexible tab (22) engaging the toothing to rotate the counting element in the counting direction when the actuation element returns to its rest position. The first and second flexible tabs are resiliently biased radially inward into contact with the first toothing. The counter has a stop element (19) which engages the second flexible tab limiting radially inward movement thereof when the actuating element moves into and out of its actuation position.