Injection Pen Drive Train With Ratchet Torque Peak Damping
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Solution Overview
Problem
Existing wind-up injection devices experience torque peaks and discontinuities during dose setting and dispensing, leading to a less than optimal user experience and potential inaccuracies in dosage selection.
Innovation Solution
A drive train mechanism incorporating visco-elastic and visco-frictional dampening elements to smooth rotational torque transmission, utilizing components like O-rings and friction rings to reduce torque peaks and improve handling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a ratchet mechanism is used to maintain discrete angular positions, then the rotatable element is held securely against torque load, but torque peaks and discontinuities occur during rotation
Solution Approach 1:
A dampening element is introduced into the drive train to cushion and absorb the torque peaks and discontinuities generated by the ratchet mechanism during rotation. This element is positioned to dampen vibrations and torque fluctuations before they propagate through the drive train, thereby maintaining secure holding accuracy while significantly improving rotational smoothness and user experience.
2Ease of operation
If friction means are added to dampen ratchet arm movement, then smooth movement during dialling is achieved, but device complexity increases
Solution Approach 1:
The dampening function is merged with existing components in the drive train rather than adding separate dedicated dampening mechanisms. The dampening element is integrated into the rotational path between the user handle and the ratchet mechanism, combining the functions of torque transmission and vibration dampening in a single integrated solution, thereby achieving smooth dialling without proportionally increasing device complexity.
3Ease of operation
If visco-elastic dampening elements are introduced, then torque peaks are reduced and handling is smoothed, but energy transfer efficiency may be reduced
Solution Approach 1:
The dampening element is strategically positioned at specific locations in the drive train where torque peaks and vibrations have the greatest impact on user experience, rather than uniformly dampening throughout the entire drive train. This localized approach allows selective dampening of harmful torque fluctuations while minimizing energy loss in critical power transmission paths, thereby maintaining handling smoothness without significantly compromising energy transfer efficiency.
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 mechanism provides a smoother and more precise user experience by dampening torque fluctuations, enhancing dosage selection accuracy and reducing rattling, while maintaining efficient energy transfer.
Implementation Method 1
The drive train is adapted to dampen torque peaks visco-elastically
Implementation Method 2
The drive train is adapted to dampen torque peaks visco-frictionally
Data Source
Figure 1
Figure 2
Figure 3~5
AI summary
A drive train (T) for a wind-up injection device (1) for injecting a liquid drug comprises a torsional energy storage (9) adapted to be loaded or unloaded by a rotatable element (6), a rotatable user handle (8), a rotationally driveable expelling mechanism (5) adapted to expel the liquid drug and a clutch element (12) coupled with the torsional energy storage (9) via the rotatable element (6) and comprising a ratchet (12.4) for maintaining the rotatable element (6) at one of a number of discrete angular positions against the torque of the torsional energy storage (9). The clutch element (12) is adapted to transmit a torque from the user handle (8) via the rotatable element (6) to the torsional energy storage (9) or alternatively from the torsional energy storage (9) via the rotatable element (6) to the expelling mechanism (5), wherein the ratchet (12.4) is switchable from one position to an adjacent position by a torque transmitted from the user handle (8) to the torsional energy storage (9). The drive train (T) is adapted to dampen torque peaks visco-elastically and/or visco-frictionally.