Helical Piston Rod and Setting Nut for Medication Delivery

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Solution Overview

Problem

Existing medication delivery devices face challenges in providing user comfort, safety, and reducing manufacturing costs while ensuring accurate and single-shot variable-dose delivery.

Innovation Solution

The assembly for a medication delivery device includes a piston rod and setting nut with helical coupling, allowing for rotational dose setting and axial delivery, featuring non-return mechanisms to prevent further use after a dose is delivered, and providing tactile feedback for user guidance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If the piston rod is designed to be rotatable for dose setting, then the ease of operation is improved, but the reliability deteriorates due to risk of accidental rotation during delivery

Engineering Contradiction:

Improveease of dose settingVSAvoidaccuracy of dose delivery

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The device dynamically changes the functional state of the piston rod based on operational phase. During dose setting, the piston rod is rotatable; during dose delivery, it becomes axially movable only. This dynamic state change is achieved through the interaction between the setting nut and the piston rod, where the setting nut's position determines whether the piston rod can rotate or only move axially, thus resolving the contradiction between ease of setting and reliability of delivery.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The setting nut acts as a feedback mechanism that provides tactile and positional information to the user during dose setting. As the piston rod rotates, the setting nut moves axially along the piston rod, providing feedback on the set dose. This feedback system ensures accurate dose setting while the mechanical interaction prevents accidental rotation during delivery, maintaining reliability.

Inventive Principle:

Principle #23Feedback

2Adaptability or versatility

If the device allows repeated dose setting and delivery, then the adaptability is improved, but the safety deteriorates due to risk of accidental re-use

Engineering Contradiction:

Improverepeated dose delivery capabilityVSAvoidrisk of accidental re-use

Core Design Contradiction:

Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The device is designed with a single-shot functionality where the piston rod and setting nut mechanism is configured to allow only one complete cycle of dose setting and delivery. After the first delivery, the setting nut reaches a position where it prevents further rotation of the piston rod, thereby preliminarily disabling any subsequent dose setting or delivery operations. This preliminary action eliminates the risk of accidental re-use while maintaining the adaptability for intended single-use applications.

Inventive Principle:

Principle #10Preliminary action

3Manufacturing precision

If multiple components are used for dose setting and delivery mechanisms, then the manufacturing precision is improved, but the manufacturing cost deteriorates

Engineering Contradiction:

Improveprecision of dose settingVSAvoidmanufacturing cost

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The invention merges the dose setting and delivery functions into a single integrated piston rod and setting nut mechanism. The piston rod serves dual purposes: it rotates to set the dose and then moves axially to deliver the dose. The setting nut is integrated with the piston rod through threading, combining multiple functions (dose setting, dose indication, and delivery control) into a single component system. This merging reduces the number of separate components needed, thereby lowering manufacturing costs while maintaining precise dose setting and delivery capabilities.

Inventive Principle:

Principle #5Merging (Combining)

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

This design enhances user comfort, safety, and reduces manufacturing costs by enabling precise dose setting and delivery while ensuring the device is used only once, preventing accidental re-use and ensuring accurate medication dispensing.

Implementation Method 1

providing tactile feedback for user guidance

Methodology Applied

Scientific EffectTactile feedback: Vibration

Implementation Method 2

piston rod and setting nut with helical coupling, allowing for rotational dose setting and axial delivery

Methodology Applied

Scientific EffectHelical coupling: Screw

Data Source

PatentUS11534555B2Assembly for a medication delivery device and medication delivery device comprising such an assembly

Publication Date: 2022.12.27 NORTON HEALTHCARE LTD

AI summary

An assembly for a medication delivery device having a body, a piston rod and a setting nut. The piston rod is rotatable relative to the body in a dose setting state and is axially movable in a distal direction with respect to the body in a dose delivering state. The setting nut is secured against rotational movement with respect to the body, but is axially movable relative to the body, being helically coupled with the piston rod to axially travel in the proximal direction for setting a dose of a medication due to a helical movement of the setting nut with respect to the piston rod when the piston rod is rotated in the dose setting state, and is able to axially travel in the distal direction for delivering the set dose of the medication when the piston rod is axially moved in the dose delivering state of the assembly.