Handheld Injection Device Release Clutch Dynamics
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Solution Overview
Problem
Existing drug delivery devices face challenges in providing accurate and compact designs for variable dose administration, particularly for users who are visually impaired, and often require components to protrude during dose setting, which complicates integration with electronic counters and increases the risk of dose inaccuracy.
Innovation Solution
A handheld injection device with a rotatable dose setting member, a power reservoir, and a release clutch that remains axially stationary during both dose setting and injection, utilizing a torsion spring for energy storage and release, along with a gauge element for visual dose indication without translation, and a locking arm for easy access by electronic counters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If components protrude during dose setting to facilitate electronic counter integration, then ease of operation is improved, but device complexity increases and compactness is compromised
Solution Approach 1:
The drive member is designed to dynamically change its engagement state with the release clutch during operation. During dose setting, the drive member remains axially stationary while allowing rotational movement. During injection, the release clutch axially displaces to engage the drive member, enabling energy release. This dynamic engagement mechanism eliminates the need for permanently protruding components while maintaining operational ease.
Solution Approach 2:
The device separates the dose setting function and injection function into distinct operational phases with different mechanical configurations. The release clutch acts as a segmented component that can independently axially disengage during dose setting and engage during injection, allowing each phase to optimize its own requirements without compromising the other.
2Ease of operation
If the drive member axially moves during dose setting, then ease of operation is improved, but manufacturing precision deteriorates due to potential unintended piston rod movement
Solution Approach 1:
The release clutch provides dynamic axial movement control: it remains axially engaged during dose setting to prevent unintended drive member and piston rod movement, ensuring precision. During injection, it axially disengages to allow drive member rotation and energy release. This dynamic control resolves the contradiction between operational ease and manufacturing precision.
Solution Approach 2:
The release clutch acts as an intermediary component between the drive member and housing. It mediates the axial movement requirement by providing controlled axial displacement only when needed for injection, while maintaining axial constraint during dose setting. This intermediary function protects the precision of piston rod positioning while enabling ease of operation.
3Device complexity
If the device is designed to be compact without protruding components, then device complexity is reduced, but ease of operation for electronic counter integration deteriorates
Solution Approach 1:
The release clutch provides dynamic axial movement: it remains axially retracted during dose setting to maintain a compact profile for electronic counter integration. During injection, it axially displaces to engage the drive member. This dynamic positioning allows the device to be compact when needed while providing mechanical engagement when required, resolving the contradiction between compactness and operational ease.
4Power
If the release clutch axially displaces during injection, then power delivery is improved, but reliability deteriorates due to potential misalignment
Solution Approach 1:
The release clutch incorporates a cam surface that provides geometric feedback during axial displacement. The cam surface guides the axial movement and ensures proper alignment between the release clutch and drive member teeth during engagement. This geometric feedback mechanism ensures reliable alignment while enabling the axial displacement needed for power delivery, resolving the contradiction between power 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
The solution enhances dose accuracy, maintains a compact device size without protruding components, facilitates easy integration with electronic counters, and provides tactile and visual feedback for dose setting and dispensing, particularly benefiting visually impaired users.
Implementation Method 1
a power reservoir, wherein energy is stored in the power reservoir during rotation of the rotatable dose setting member and the drive member releases the stored energy in the power reservoir when the release clutch is in its second axial position
Data Source
AI summary
A handheld injection device includes a housing, a rotatable dose setting member and a power reservoir coupled to the dose setting member. Energy is stored in the power reservoir during rotation of the dose setting member. The injection device also includes a release member for receiving a force from a user and a rotatably arranged drive member engaging with a drive track of a piston rod. The device further includes a release clutch rotationally constrained to the housing and releasably engaging the drive member. The release clutch is positionable in a first axial position when the release member is in a dose setting position and in a second axial position when the release member is in a dose injection position. The axial position of the drive member within the housing remains constant when the release member is in its dose setting position and in its dose injection position.