Fluid Dispenser Dose Indicator Safety Mechanism
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Solution Overview
Problem
Fluid dispensers, particularly those for pharmaceuticals, face challenges in accurately counting doses to prevent under-counting, which can lead to safety risks due to incomplete or interrupted dispensing cycles, and require mechanisms to ensure the dose indicator device is actuated correctly during both actuation and return strokes.
Innovation Solution
A fluid dispenser with a dose indicator device featuring a first safety system that actuates the indicator upon a predetermined incomplete actuation stroke and a second safety system that blocks further dispensing until a predetermined incomplete return stroke is completed, ensuring accurate counting and preventing under-counting by using a combination of gears and abutment means to manage the counter element's axial and rotational displacement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the dispenser allows actuation during the return stroke before completing a predetermined incomplete return stroke, then the ease of operation is improved, but the reliability of dose counting deteriorates due to potential under-counting
Solution Approach 1:
The patent applies preliminary anti-action by implementing a blocking mechanism that prevents actuation during the return stroke until a predetermined incomplete return stroke is completed. This blocking mechanism (comprising blocking means on the counter element and abutment means on the body) proactively stops potential harmful under-counting events before they can occur, ensuring that only valid actuations are counted while still allowing normal operation after the return stroke completes.
2Reliability
If the dose indicator device counts incomplete actuation strokes, then the reliability of dose counting is improved, but the manufacturing precision requirements worsen due to the need for precise gear tooth positioning
Solution Approach 1:
The patent applies preliminary action by designing the gear teeth with predetermined positions that are established during manufacturing. The stationary gear and counter element gear are configured with specific tooth positions that automatically engage at the correct moment to initiate counting. This preliminary configuration ensures that the system is pre-set to reliably count incomplete strokes without requiring complex real-time adjustments, balancing manufacturing precision requirements with improved counting reliability.
3Reliability
If the dispenser blocks further actuation during the return stroke, then the reliability of dose counting is improved, but the productivity deteriorates due to extended blocking time
Solution Approach 1:
The patent applies partial action by implementing a blocking mechanism that only blocks actuation for a specific portion of the return stroke (until a predetermined incomplete return stroke is completed), rather than blocking the entire return stroke. This partial blocking approach maintains reliability by preventing under-counting during the critical phase while minimizing the blocking duration, thus preserving productivity by allowing actuation to resume as soon as the incomplete return stroke is achieved.
Data Source
AI summary
A fluid dispenser comprising a body (1), a fluid reservoir (2), a dispenser member, such as a pump or a valve, mounted on said reservoir (2), and a dose indicator device for indicating the number of doses of fluid that have been dispensed or that remain to be dispensed from said reservoir, the dispenser being characterized in that said dose indicator device includes a first safety system for actuating the dose indicator device once the dispenser has performed a predetermined incomplete actuation stroke, even if the dispenser does not perform the complete actuation stroke.