Telescoping Screw Plunger Drive With Anti-Rotation for Compact Patch Pumps
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing drug delivery patch pump designs face challenges in achieving small size, low power consumption, accurate delivery, high reliability, and low manufacturing costs while ensuring biocompatibility with drug quality, as materials contacting the delivered fluid can impact drug quality.
Innovation Solution
A novel nesting telescopic screw design for a syringe barrel-type reservoir with an anti-rotation mechanism, using nested telescoping screws and a plunger driver assembly that minimizes device size and ensures biocompatibility, featuring a plunger with an elliptical cross-section and a pusher with keying features to prevent rotation, along with a thrust bearing feature to manage axial thrust loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a lead screw drive mechanism is used, then accurate delivery and high reliability are achieved, but device size increases
Solution Approach 1:
The patent implements a nested telescopic screw mechanism where multiple screws are arranged concentrically. The outermost drive screw rotates to advance inner screws through threaded engagement, allowing the plunger driver assembly to extend and retract within a compact cylindrical space. This nesting arrangement achieves the long stroke length required for accurate delivery while minimizing the overall device footprint.
Solution Approach 2:
The patent transitions from a conventional linear screw arrangement to a multi-dimensional nested configuration. By arranging screws in concentric cylinders and using telescopic extension, the mechanism utilizes radial and axial dimensions simultaneously, allowing the plunger to achieve sufficient travel distance without proportionally increasing the device's external dimensions.
2Object-affected harmful factors
If a syringe barrel-type reservoir is used, then biocompatibility is improved, but the reservoir volume is reduced
Solution Approach 1:
The patent divides the reservoir into two functional zones: a large-volume storage chamber that maintains biocompatibility through syringe barrel-type material selection, and a smaller fluid chamber where the plunger operates. The plunger driver assembly is configured to operate within this segmented space, allowing the reservoir to maintain its biocompatible characteristics while providing sufficient volume for the required fluid delivery.
3Volume of moving object
If nested telescoping screws are used, then device size is minimized, but manufacturing complexity increases
Solution Approach 1:
The patent combines multiple functions into the nested screw assembly: the outermost drive screw provides both the driving rotation and the telescopic extension mechanism, while inner screws are pre-threaded to engage with the outer screw's threads. This merging of functions reduces the number of separate components and simplifies the manufacturing process compared to conventional multi-component telescopic mechanisms.
Solution Approach 2:
The nested screw mechanism is designed to be self-advancing through threaded engagement. When the outermost drive screw rotates, it automatically advances inner screws through the threaded interface without requiring additional actuators or complex control mechanisms. This self-service characteristic simplifies manufacturing by eliminating the need for additional driving components.
4Volume of moving object
If plunger driver assembly is made fully retractable, then device size is reduced, but reliability decreases
Solution Approach 1:
The plunger driver assembly is nested within the reservoir structure, with the outermost drive screw capable of rotating and retracting completely into the reservoir. The inner screws are pre-threaded to engage with the outer screw, ensuring that when the outer screw retracts, the inner screws remain properly positioned and engaged. This nested arrangement maintains reliability by ensuring proper alignment and engagement of all components during retraction.
Solution Approach 2:
The inner screws are pre-threaded and pre-positioned within the outermost drive screw during manufacturing. This preliminary action ensures that when the mechanism is assembled and operated, the inner screws automatically engage with the outer screw's threads without requiring additional alignment procedures or complex control mechanisms, thereby maintaining reliability despite full retraction capability.
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 design achieves a compact form factor, high reliability, and accurate drug delivery while maintaining biocompatibility, utilizing a syringe barrel-type container that is drug-friendly, and allows for precise control of fluid delivery without affecting drug quality.
Implementation Method 1
a plunger driver assembly mounted at a proximal end of the reservoir that comprises a plurality of nested, telescoping screws that, when an outermost drive screw is rotated, move from a nested configuration that does not extend into the reservoir to an extended configuration that extends from the proximal end of the reservoir into the reservoir
Implementation Method 2
The plurality of nested, telescopic screws comprises an innermost screw that is connected to the plunger and constrained from rotation by an anti-rotation mechanism
Data Source
AI summary
A fluid delivery device has a syringe barrel-type reservoir with plunger and plunger driver assembly comprising nested, telescopic screws comprising an innermost screw keyed to a first side of the plunger or intermediate pusher to prevent rotation. In a fully retracted position, the nested screws do not extend into the reservoir. The nested screws all have right handed threads and employ the same pitch in their respective inner thread and outer thread designs. The outermost screw is connected to a motor for controllable rotation. The decreasing torque ratios from the outermost to innermost screw member and anti-rotation feature allows the innermost screw to advance the plunger into the reservoir before the adjacent concentric screw member commences rotating and advancing within its corresponding screw, and so on, to translate the plunger and expel fluid in a fluid chamber defined on the other, second side of the plunger.