Drug Delivery Dose Reset Ratchet Mechanism
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Solution Overview
Problem
Existing drug delivery devices with spring-driven mechanisms do not allow users to accurately decrease a set dose without expelling the entire dose, leading to wastage of medication and inefficiency.
Innovation Solution
A drug delivery device featuring a resettable dose setting mechanism with a releasable one-way ratchet mechanism, allowing users to both set and reduce a dose by rotating a dose setting member, which engages and disengages ratchet parts to adjust the dose incrementally, utilizing a drive spring and bias means for precise control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a wind-up device with a one-way ratchet mechanism is used, then the device allows dose setting and storage, but the user cannot decrease the set dose without expelling the entire dose
Solution Approach 1:
The invention inverts the traditional one-way ratchet mechanism by making the ratchet engagement reversible. The ratchet arm can be actively pulled out of engagement with the toothed ring, allowing the drive member to rotate in both directions. This enables the user to both increase and decrease the set dose by rotating the dose setting member, while still preventing unintended rotation through the ratchet locking mechanism.
2Adaptability or versatility
If a flexible ratchet arm mechanism is used for dial-down, then the set dose can be reduced, but the ratchet arm must be actively pulled out of engagement requiring complex control
Solution Approach 1:
The invention merges the dose setting function and the ratchet control function into a single integrated mechanism. The dose setting member is directly connected to the ratchet arm, so that rotating the dose setting member automatically controls the ratchet arm's engagement and disengagement from the toothed ring. This eliminates the need for separate control mechanisms and simplifies the overall device structure.
3Adaptability or versatility
If the ratchet mechanism allows bidirectional rotation, then dose can be adjusted both up and down, but the mechanism becomes more complex
Solution Approach 1:
The invention makes the ratchet mechanism dynamic by allowing the ratchet arm to transition between engaged and disengaged states based on the direction of rotation. The ratchet arm is biased by a spring to maintain engagement in the normal dose-setting direction, but can be actively disengaged when the user rotates the dose setting member in the opposite direction. This dynamic behavior enables bidirectional adjustment without requiring a completely different mechanism for each direction.
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 accurate, reliable, and cost-effective adjustment of drug doses, preventing medication wastage by allowing users to decrease set doses without expelling the entire amount, thus improving user control and device efficiency.
Implementation Method 1
a spring which is strained during dose setting, the stored energy subsequently being used to expel the set dose of drug from a cartridge
Implementation Method 2
the spring is strained and maintained in this strained position until the user releases the set dose by activating the latch provided on the side of the housing
Implementation Method 3
a releasable one-way ratchet mechanism allowing the drive member to be rotated in the first direction
Implementation Method 4
bias means for axially biasing the first and second ratchet parts into engagement with each other
Data Source
AI summary
Drug delivery device adapted to expel a set dose, comprising an expelling mechanism with a drive spring, a dose setting mechanism with first and second dose setting ratchet parts, a bias spring as well as control means. The control means is adapted to rotate the second ratchet part in a first direction to thereby set a dose when rotating the dose setting member in the first direction, and move the ratchet parts axially out of engagement with each other when the dose setting member is rotated in the opposite direction. When the first and second ratchet parts have been axially disengaged, the drive spring will rotate the second ratchet part in the second direction to thereby reduce the set dose, the bias spring moving the ratchet parts axially into engagement with each other again, this resulting in the set dose being reduced corresponding to one tooth of the ratchet mechanism.