Dose Counter Gear Layout for Accurate Drug Delivery Tracking
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Solution Overview
Problem
Existing drug delivery devices face challenges in providing a compact, reliable, and cost-effective dose counter mechanism that accurately indicates the amount of medicament dispensed or remaining in the device.
Innovation Solution
A drug delivery device with a dose counter mechanism featuring a first unit wheel and a second unit wheel coupled by a gear, where the first unit wheel's continuous rotation is translated into an intermittent rotation of the second unit wheel, utilizing a spur wheel and Geneva mechanisms to ensure accurate and efficient dose tracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a mechanical display with wheels is used to show the amount of medicament or doses remaining, then the display can be read without power, but the device complexity increases
Solution Approach 1:
The dose counter is divided into multiple unit wheels (first unit wheel, second unit wheel, third unit wheel), each displaying a digit. This segmentation allows the counter to display multi-digit doses while keeping each individual wheel simple and manageable, reducing overall complexity while maintaining functionality.
Solution Approach 2:
A common drive shaft acts as an intermediary mechanism that receives rotational input and distributes it to multiple unit wheels through gear connections. This intermediary structure simplifies the control of multiple wheels by using a single drive source, reducing the complexity of controlling each wheel independently.
2Measurement precision
If multiple unit wheels are used to display the dose amount, then the measurement precision improves, but the device complexity increases
Solution Approach 1:
The dose counter displays multiple digits using separate unit wheels (first, second, and third unit wheels), each representing a specific digit position. This segmentation enables precise display of multi-digit dose amounts while maintaining simple individual wheel designs, achieving high measurement precision without excessive complexity.
Solution Approach 2:
Each unit wheel serves multiple functions: it displays a digit, indicates dose remaining, and can be used for dose setting. This multi-functionality reduces the need for separate components, thereby reducing overall device complexity while maintaining precise dose measurement and indication capabilities.
3Measurement precision
If a gear mechanism translates continuous rotation into intermittent rotation, then the dose counter accuracy improves, but the manufacturing precision requirements increase
Solution Approach 1:
A common drive shaft serves as an intermediary that receives continuous rotational motion and distributes it to multiple unit wheels through gear connections. This intermediary mechanism ensures accurate dose tracking by maintaining proper rotational relationships between wheels while simplifying the manufacturing process by using a single drive source that can be manufactured with standard precision.
Solution Approach 2:
The gear mechanisms are pre-assembled and pre-adjusted during manufacturing to ensure accurate rotational relationships between unit wheels. This preliminary action ensures that the continuous rotation is correctly translated into intermittent rotation for each wheel, achieving high dose tracking accuracy while reducing the need for extremely tight manufacturing tolerances on individual components.
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 provides a compact, reliable, and cost-effective dose counter that accurately indicates the amount of medicament dispensed or remaining, enhancing the reliability and ease of assembly of the drug delivery device.
Implementation Method 1
the second unit wheel being coupled to the first unit wheel by means of a gear which translates a continuous rotation movement of the first unit wheel into an intermittent rotation of the second unit wheel
Implementation Method 2
The first unit wheel comprises a spur wheel section on a first face, said spur wheel section having teeth which mesh with a spur wheel
Implementation Method 3
the spur wheel comprising at least one projection which meshes with the thread of the plunger rod
Data Source
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AI summary
The present application relates to a drug delivery device including a housing and a plunger rod with a threaded outer surface. The plunger rod is adapted to advance a piston inside a reservoir containing a medicament in order to dispense the medicament. The plunger rod is arranged parallel to and preferably congruent with a central axis of the housing. The drug delivery device further comprises a drive to move the plunger rod either in rotation or linearly about the central axis. Additionally, the drug delivery device comprises a dose counter to indicate the amount of medicament dispensed from or remaining in the reservoir, said dose counter comprising a first unit wheel and a second unit wheel both arranged next to each other along the central axis of the housing, the second unit wheel being coupled to the first unit wheel by means of a gear which translates a continuous rotation movement of the first unit wheel into an intermittent rotation of the second unit wheel. The first unit wheel comprises a spur wheel section on a first face, said spur wheel section having teeth which mesh with a spur wheel which is arranged concentric around the plunger rod, the spur wheel comprising at least one projection which meshes with the thread of the plunger rod.