Transversal Clock Spring Medicament Delivery Device
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Solution Overview
Problem
Existing medicament delivery devices with transversal strip clock springs face challenges such as increased device diameter and activation button placement issues, which affect usability and durability due to high tensioning requirements.
Innovation Solution
A medicament delivery device with a tubular housing, a rotatable dose setting member, a transversal clock spring, and a hold and release mechanism, allowing the activation button to be placed at the distal end, with ratchets for one-directional dose setting and resetting, and resilient members for tension management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a strip clock spring is arranged transversal in relation to the longitudinal direction of the device, then the spring can produce higher forces for high viscosity medicament delivery, but the device diameter increases significantly
Solution Approach 1:
The clock spring is nested within the tubular housing structure, with the spiral windings contained within the longitudinal axis of the device. The spring's spiral path is routed through the hollow interior of the tubular housing, allowing the spring to generate high forces without increasing the external device diameter significantly.
Solution Approach 2:
The clock spring is oriented with its spiral plane perpendicular to the longitudinal axis of the device, utilizing the radial dimension for spring windings while keeping the spring's overall envelope within the device's longitudinal boundaries. This dimensional reorientation allows high force generation without excessive diameter increase.
2Device complexity
If the activation button is placed at the proximal end of the device to accommodate the clock spring, then the device structure is simplified, but the usability is reduced for certain patient groups
Solution Approach 1:
Instead of placing the activation button at the proximal end as in conventional designs, the activation button is inverted to the distal end of the device. This reversal of the activation interface location improves ergonomics and accessibility for patients with limited hand dexterity while the clock spring mechanism is reconfigured to accommodate this change.
Solution Approach 2:
The connection between the activation button and the clock spring is made flexible through a linkage mechanism that allows the button to be positioned at the distal end while still effectively tensioning and releasing the spring. This dynamic connection enables independent optimization of button location and spring mechanism.
3Ease of operation
If the clock spring is tensioned by turning a knob at the distal end, then the force member is tensioned just prior to medicament dose delivery, but the device must be stored in a highly tensioned state increasing risk of damage
Solution Approach 1:
The clock spring is pre-configured and pre-positioned within the housing before use, with the dose setting mechanism ready to tension the spring immediately upon activation. This eliminates the need to store the device in a highly tensioned state, as the spring only reaches high tension momentarily during dose delivery rather than during storage and transport.
Solution Approach 2:
The device is designed to release the stored energy in the clock spring completely after each dose delivery, returning the spring to its relaxed state. This cycling between tensioned and relaxed states allows the device to be stored in a low-energy state, reducing the risk of material fatigue and damage from prolonged high tension.
4Force
If multiple windings of the clock spring are used to generate sufficient force, then the spring can deliver adequate medicament doses, but the device diameter increases further
Solution Approach 1:
The clock spring mechanism replaces the need for large-volume compression springs or complex mechanical advantage systems. The spiral geometry of the clock spring provides mechanical advantage through its winding structure, generating high expulsion forces with a compact form factor that fits within the device's longitudinal axis without requiring excessive diameter.
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 intuitive and safe dose setting with the activation button at the distal end, reduces device diameter, and minimizes material creep-related damage by managing spring tension effectively, enhancing user experience and device durability.
Implementation Method 1
a clock spring arranged transversal in relation to the longitudinal direction of the device and having a first end connected to the dose setting member and a second end connected to a drive member which is interactively connected to the plunger rod, such that the clock spring is tensioned upon rotation of the dose setting member
Implementation Method 2
resilient members for tension management
Data Source
AI summary
A medicament delivery device has a housing for a medicament container; a dose setting member rotatable in relation to the housing; a plunger rod acting on a stopper inside the medicament container; a driver that converts rotation of the dose setting member into translation of the plunger rod; a transversal clock spring connected to the dose setting member and to a drive member connected to the plunger rod, such that rotating the dose setting member tensions the spring; a spring hold and release member releasably connected to the drive member; and an activator having a distal end protruding through a distal passage of the dose setting member and connected to the hold and release member. Pushing the activator proximally moves the hold and release member proximally, releasing the spring from its tensioned state and forcing the drive member to rotate.