Multi-Dose Injector Rack-and-Pinion Dosing With Lockout
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Solution Overview
Problem
Existing injection devices require frequent refilling and are not user-friendly for self-administration of multiple doses of liquid medicaments, particularly for treatments requiring regular administration over extended periods.
Innovation Solution
A dispensing mechanism with a housing, ram, and user-operable push button, featuring a crank arm and ratchet gear system that allows for repeated, controlled administration of medicament doses without refilling, including an anti-reverse mechanism for one-directional movement and a lockout feature to ensure proper operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single-dose injection device is used, then the device is simple to manufacture, but the device requires frequent refilling and multiple trips to the doctor's office
Solution Approach 1:
The injection device is segmented into a reusable body housing containing the dosing mechanism and a replaceable cartridge containing the medicament reservoir. This allows the complex multi-dose mechanism to be manufactured once and reused, while only the simpler cartridge needs frequent replacement, resolving the contradiction between manufacturing simplicity and reduced refilling trips.
Solution Approach 2:
The device is pre-filled with multiple doses of medicament in the cartridge during manufacturing. This preliminary action allows patients to self-administer multiple doses at home without returning to the doctor's office, eliminating the time loss from frequent trips while the reusable body housing amortizes the manufacturing complexity over multiple uses.
2Loss of time
If a multi-dose injection device is used, then the frequency of doctor visits is reduced, but the device complexity increases
Solution Approach 1:
By segmenting the device into a reusable body housing with the complex dosing mechanism and a disposable pre-filled cartridge, the complexity is confined to the housing that is manufactured once. The cartridge remains simple and is merely replaced, not reset, reducing overall system complexity while enabling multi-dose usage without frequent doctor visits.
Solution Approach 2:
The device incorporates a self-contained dosing mechanism with a ram, ratchet gear, and lockout feature that automatically controls medicament delivery. This self-service capability allows the device to precisely meter and administer multiple doses without external intervention, reducing doctor visit frequency while the modular design keeps the complexity manageable through the reusable housing.
3Measurement precision
If a complex dosing mechanism is implemented, then precise dose control is achieved, but the ease of operation for self-administration is reduced
Solution Approach 1:
The dosing mechanism is designed as a self-contained system where the ram, driven by the ratchet gear and spring, automatically delivers the precise dose without requiring the patient to manually control the dosing parameters. The patient simply activates the device, and the self-service mechanism ensures precise dose delivery, resolving the contradiction between precision and ease of operation.
Solution Approach 2:
The cartridge is pre-filled with the exact amount of medicament needed for the prescribed number of doses during manufacturing. This preliminary action eliminates the need for the patient to measure or calculate doses, simplifying operation while ensuring precise dose control is maintained by the pre-configured dosing mechanism in the reusable housing.
4Reliability
If a lockout feature is added to prevent improper use, then usage safety is improved, but the device complexity increases
Solution Approach 1:
The lockout feature is designed to preemptively prevent improper operation by mechanically blocking the activation mechanism after the prescribed number of doses are administered. This preliminary anti-action stops the device from being misused before improper use can occur, improving reliability while the lockout mechanism integrates into the existing ratchet gear system, minimizing the increase in overall device complexity.
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 easy, self-administration of precise and repeated medicament doses, reducing the need for frequent refilling and ensuring correct usage, suitable for a wide range of drugs including hazardous agents.
Implementation Method 1
a ratchet gear having a first set of teeth releasably engageable with the pawl tooth and a second set of teeth releaseably engageable with the ram, wherein engagement of the pawl tooth with the first set of teeth of the ratchet gear causes the ratchet gear to rotate, causing the ram to distally advance relative to the housing
Implementation Method 2
a flexible column integrally formed extending from a distal portion of the push button, the flexible column having a flexible column protrusion at a proximal end thereof, wherein as the push button moves along the proximal-distal axis, the flexible column protrusion slides between the integrally formed ratchets on both housing parts and engages the housing ratchets and restricts movement of the push button to one direction during a resetting motion
Implementation Method 3
a crank arm having pawl tooth, a pivot point, and a crank arm protrusion slideably engageable with the slot such that movement of the push button causes the crank arm protrusion to move along the slot, causing rotation of the crank arm about the pivot point
Data Source
AI summary
A dispensing mechanism for delivering a dosage of medicament including a housing, a push button, a crank arm that is slideably engageable with the push button, a ram, and a ratchet gear releasably engageable with the crank arm and ram, translation of the push button along an axis causing the crank arm to engage and rotate the ratchet gear which causes the ram to distally advance relative to the housing.