Spring-Driven Drive Mechanism for Drug Delivery
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Solution Overview
Problem
Existing drug delivery devices face challenges with user-friendly dose setting and delivery, particularly with manual and motor-driven devices, where users may struggle to exert sufficient force for injection, leading to inconsistent dosing and increased complexity with electronic components.
Innovation Solution
A spring-supported drive mechanism with a gear-based system that allows for easy dose setting and delivery, utilizing a floating gear and flat torsion spring to store energy for distal movement of the piston rod, reducing the required injection trigger force and providing consistent dosing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a manual drive mechanism is used where the user exerts force directly on the piston rod, then the device structure is simple, but the user cannot provide sufficient force and displacement for high-dose injection (e.g., 120 IU of U300 insulin)
Solution Approach 1:
The patent replaces the direct manual mechanical push with a spring-driven mechanical system. The spring member stores energy during dose setting and automatically provides the force for dose delivery, eliminating the need for the user to exert high force directly on the piston rod while maintaining mechanical simplicity.
Solution Approach 2:
The spring member is pre-loaded during the dose setting phase when the user rotates the dosage selector. This preliminary action stores energy that is then automatically released during dose delivery, providing the necessary injection force without requiring additional user effort during the critical injection phase.
2Ease of operation
If a motor-driven device is used to provide automated dose delivery, then the injection force and consistency are improved, but the device weight increases and requires batteries and electronic control systems
Solution Approach 1:
The patent replaces the motor-driven electronic system with a purely mechanical spring-driven system. The spring member provides automated force delivery through mechanical energy storage and release, eliminating the need for motors, batteries, and electronic control systems while maintaining automated dose delivery functionality.
Solution Approach 2:
The patent extracts and eliminates the heavy electronic components (motors, batteries, control systems) from the device, retaining only the essential mechanical elements (spring member, gears, piston rod) needed to achieve automated dose delivery, thereby significantly reducing device weight.
3Device complexity
If the button is placed on the end opposite to the needle and moved along the cartridge axis, then the dose setting mechanism is simple, but users find it difficult to extend their thumb to the button position and exert required force
Solution Approach 1:
The patent changes the button movement direction from the longitudinal axis (distal-proximal direction) to a transverse dimension (rotational movement). The dosage selector rotates perpendicular to the cartridge axis, bringing the button within easy reach of the user's thumb and improving ergonomics while maintaining mechanical simplicity.
4Reliability
If the spring member is always engaged with the drive member, then the dose delivery is consistent, but the user cannot set the dose during the delivery state
Solution Approach 1:
The patent makes the engagement between the dose setting member and drive member dynamic rather than static. The floating gear can move axially to engage or disengage from the drive gear based on the operational state, allowing the system to switch between dose setting mode (disengaged) and dose delivery mode (engaged), thereby achieving both reliability and adaptability.
5Adaptability or versatility
If a floating gear is used to allow disengagement during dose setting, then the user can set dose freely, but the gear alignment and engagement precision become more difficult to control
Solution Approach 1:
The patent introduces a lever arm as an intermediary mechanism that controls the axial movement of the floating gear. The lever arm translates the user's rotational input into precise axial positioning of the floating gear, ensuring accurate engagement and disengagement while maintaining manufacturing feasibility.
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 spring-loaded drive mechanism simplifies dose setting and delivery, reducing user effort and ensuring consistent dosing, while eliminating the need for complex electronic components and heavy motors, thus enhancing usability and reducing environmental impact.
Implementation Method 1
a spring member (21) coupled to the dose setting member (19, 35) in such a manner that the movement of the dose setting member (19, 35) in a setting direction loads the spring member (21) in the dose setting state, the spring force of the loaded spring member driving the dose setting member (19, 35) in the drive direction in the dose delivery state
Implementation Method 2
the spring force of the loaded spring member driving the dose setting member (19, 35) in the drive direction in the dose delivery state
Data Source
Figure 1
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AI summary
A drive mechanism (11) for a delivery device comprising a drive member (17) for driving a piston rod (13); a moveable dose setting member (19, 35) being disengaged from the drive member (17) in a dose setting state and being moveable in a drive direction in a dose delivery state, wherein the dose setting member (19, 35) engages with the drive member (17) in the dose delivery state in such a manner that the movement of the dose setting member (19, 35) in the drive direction is transferred to the drive member (17); and a spring member (21) being coupled to the dose setting member (19, 35) in such a manner that the movement of the dose setting member (19, 35) in a setting direction loads the spring member (21) in the dose setting state, the spring force of the loaded spring member (21) driving the dose setting member (19, 35) in the drive direction in the dose delivery state.