Positive Displacement Pump Linkages for Smaller Drug Delivery Footprints

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Solution Overview

Problem

Conventional drug delivery systems have a large footprint due to the design of the pump mechanism, which includes a leadscrew that needs to extend into and behind the reservoir, increasing the overall size of the device.

Innovation Solution

A positive displacement pump mechanism using a scissor linkage, magnetic linkage, or flexible tether linkage to drive the plunger within the reservoir, reducing the overall size footprint by eliminating the need for a leadscrew that extends beyond the reservoir.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a leadscrew driven plunger system is used, then the plunger can be effectively driven within the reservoir, but the total footprint of the reservoir and drive mechanism is greater than the length of the reservoir by up to 2 times

Engineering Contradiction:

Improveplunger driving effectivenessVSAvoidfootprint of pump mechanism

Core Design Contradiction:

Ease of operationVSArea of stationary object

Solution Approach 1:

The drive mechanism is integrated within the reservoir housing, merging the previously separate components into a unified structure. The motor assembly, leadscrew, and reservoir are combined such that the drive mechanism occupies space within the reservoir's overall envelope rather than extending beyond it, reducing the footprint to approximately 1.5 times the reservoir length instead of 2 times.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The leadscrew is positioned within the reservoir such that it nests within the available space. The drive mechanism components are nested within the reservoir housing, with the leadscrew extending into the reservoir only as needed to engage the plunger, minimizing the external footprint while maintaining functional effectiveness.

Inventive Principle:

Principle #7Nested doll (Nesting)

2Reliability

If the leadscrew extends the full length of the reservoir to reach the plunger when empty, then complete plunger engagement is achieved, but the footprint increases significantly

Engineering Contradiction:

Improveplunger engagement completenessVSAvoidleadscrew length

Core Design Contradiction:

ReliabilityVSLength of stationary object

Solution Approach 1:

The leadscrew length is made variable through a telescoping or adjustable mechanism. When the reservoir is empty, the leadscrew extends to its full length to ensure complete plunger engagement. When the reservoir is full, the leadscrew retracts to occupy minimal space, dynamically adapting its length to the operational requirements rather than maintaining a fixed maximum length throughout.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The drive mechanism is pre-positioned and configured to engage the plunger at the optimal point before the reservoir filling process begins. This preliminary positioning allows the leadscrew to achieve complete engagement without requiring maximum extension throughout the entire operational cycle, reducing the necessary leadscrew length while maintaining reliability.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentEP4304676B1Improved drive mechanisms for positive displacement pumps

Publication Date: 2026.04.22 INSULET CORP

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Figure 3A~3B

AI summary

A novel embodiment of a pump system, for example, of the type that would be used in a wearable drug delivery system, comprises, in a preferred embodiment, a reservoir, a plunger, disposed within the reservoir and driven by a scissor mechanism connected to a drive mechanism through a linkage, such that a force imparted by the drive mechanism in causes the scissor mechanism to expand thereby causing the plunger move within the reservoir to force a liquid drug contained within the reservoir through a fluid port to a patient.