Dose Reset Mechanism With Ratchet Locking For Medicament Devices
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Solution Overview
Problem
Existing medicament delivery devices require excessive rotation and multiple interacting components to reset a dose, leading to reliability issues and user inconvenience, particularly due to wear and tear in dial-down mechanisms.
Innovation Solution
A dose reset mechanism featuring a ratchet connection between the dose setting member and drive member, with a tensioned drive spring and interactive elements allowing controlled dose adjustment and reset through a single incremental movement of the dose setting knob, utilizing radial ledges and flexible arms for secure locking and easy reset.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the dose setting knob is rotated past maximum value and back to zero for resetting, then the dose can be reset, but excessive rotation is required and multiple components interact causing complexity and wear
Solution Approach 1:
The patent extracts the reset function from the continuous rotation mechanism by introducing a distinct reset member that can be actuated independently. This separates the dose setting function (continuous rotation) from the reset function (discrete action), reducing the interaction complexity between components during normal operation while maintaining reliable resetting capability.
Solution Approach 2:
The patent introduces a reset member as an intermediary component between the user and the dose setting mechanism. This reset member engages with the gear mechanism to provide controlled resetting without requiring the user to manipulate multiple components simultaneously, thereby reducing operational complexity while maintaining reliability.
2Ease of operation
If the arm slides over teeth in a dial-down mechanism, then dose reduction is achieved, but the arm wears down over time reducing locking reliability
Solution Approach 1:
Instead of having the flexible arm slide over stationary teeth (which causes wear), the patent inverts the mechanism so that stationary ledges on the gear engage with flexible arms. This reverses the wear pattern, allowing the flexible arms to flex against the ledges in a controlled manner that maintains locking reliability while preserving ease of dose adjustment.
Solution Approach 2:
The patent employs different material properties for the gear ledges and flexible arms, creating a composite system where the rigid ledges provide structural stability and the flexible arms provide compliant engagement. This material differentiation reduces wear on critical locking surfaces while maintaining ease of operation.
3Adaptability or versatility
If a curved profile is used for teeth and connecting member, then the dial-down mechanism functions, but wear and reduced locking force occur over time
Solution Approach 1:
The patent applies different geometric profiles to different parts of the mechanism: radial ledges on the gear for reliable engagement, and specifically designed flexible arm geometries for controlled flexing. This local optimization ensures that each component has the appropriate shape for its specific function, maintaining both adaptability and reliability.
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
Enables reliable, intuitive, and cost-effective dose resetting with minimal component interaction, improving user experience and device longevity by allowing precise, controlled dose adjustments and resets with reduced wear and tear.
Implementation Method 1
a drive spring having a first end connected to the connection member and a second end connected to a fixed point of said housing such that said drive spring is tensioned when said dose setting member and said connection member are rotated for setting a dose
Implementation Method 2
said connection member and said drive member are interconnected by ratchet means such that said connection member is also rotated when said dose setting knob is rotated for setting a dose but locked by the ratchet means from being moved in the opposite direction
Implementation Method 3
generally radial outwardly protruding ledges arranged on flexible arms extending in the circumferential direction of the connection member
Data Source
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AI summary
The invention relates to a dose reset mechanism to be used in a medicament delivery device, wherein the dose reset mechanism comprises a dose setting member (10) arranged in a housing for setting a dose when it is rotated and for resetting a dose when it is rotated in the opposite direction. A drive member (38) is connected to plunger rod (41) such that when said drive member is rotated, the plunger rod is axially moved, acting on a container for expelling the medicament. A connection member (26) is arranged between the dose setting member and the drive member. The connection member and the drive member are interconnected by ratchet means (34,44) such that the connection member is also rotated when the dose setting member is rotated but locked by the ratchet means from being moved in the opposite direction. The dose setting member further comprises at least one dose reset member (18) and at least one supporting element (17) interactively connected to said ratchet means such that the interconnection between the connection member and the drive member is released when the dose setting member is turned in the opposite direction.