Segmented Piston Plunger for Compact Infusion Device
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Solution Overview
Problem
Existing infusion devices are bulky due to the length of medicament containers and plunger rods, and rely on electric power for infusion speed control, which can lead to device failure if batteries deplete, complicating the addition of mechanisms like automatic stop and constant infusion speed.
Innovation Solution
A compact infusion device with interconnectable piston plunger segments and a mechanical drive system using a flat spiral spring, allowing for a compact design and purely mechanical speed control through a centrifugal brake, eliminating the need for electric power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If a flexible plunger rod is used to reduce device length, then the overall length is reduced, but the device becomes bulky in other dimensions and access to the drive spring is blocked
Solution Approach 1:
The plunger rod is divided into multiple telescopic segments that can extend and retract relative to each other. When retracted, the segments occupy minimal space allowing compact device design. When extended, they provide the necessary plunger rod length for medication delivery without increasing the device's overall volume when not in use.
Solution Approach 2:
The plunger rod transitions from a static structure to a dynamic telescopic mechanism that adapts its length based on operational requirements. The segments can extend during medication delivery and retract to a compact configuration during storage and transport, solving both the length and volume constraints simultaneously.
2Ease of operation
If electric motors are used for infusion speed control, then infusion speed can be controlled, but the device becomes dependent on electric power and batteries
Solution Approach 1:
The patent replaces electric motor-based speed control with a purely mechanical constant speed control mechanism. This mechanism uses mechanical elements such as cam profiles, gear ratios, or friction-based regulation to maintain constant infusion speed without requiring electric power, thereby eliminating battery dependency and improving device reliability for critical medications.
3Length of moving object
If the plunger rod is made shorter to reduce device length, then device length is reduced, but the plunger rod cannot provide sufficient force for medication delivery
Solution Approach 1:
The plunger rod is segmented into telescopic sections that can extend to provide sufficient stroke length for forceful medication delivery, then retract to maintain compact device dimensions. The segmented structure allows the plunger rod to achieve both short stored length and long extended length with adequate force generation capability.
Solution Approach 2:
The telescopic segments utilize composite material structures that provide high strength-to-weight ratios, enabling the plunger rod to generate sufficient delivery force while maintaining a compact, lightweight design when retracted. The composite construction allows for both structural integrity during forceful delivery and compactness during storage.
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 device achieves a compact and reliable infusion mechanism with constant speed control, avoiding battery dependency and reducing bulkiness, while enabling intuitive operation and safe needle handling.
Implementation Method 1
a flat spiral spring, allowing for a compact design and purely mechanical speed control
Implementation Method 2
enabling intuitive operation and safe needle handling... mechanical drive system using a flat spiral spring, allowing for a compact design and purely mechanical speed control through a centrifugal brake
Data Source
AI summary
The present invention relates to an infusion device comprising a housing; a compartment inside said housing for positioning a medicament container, an infusion needle arranged to said housing, being connectable to said medicament container for delivering a dose of medicament, a piston plunger arranged in said housing capable of acting on said medicament container for delivering a dose of medicament, mechanical drive means capable of acting on said piston plunger for delivering a dose of medicament. The invention is characterised in that said piston plunger comprises a number of distinct segments being inter-connectable to each other for forming an elongated piston plunger.