Multi-start lead screw for fluid delivery precision
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Solution Overview
Problem
Existing fluid delivery devices using single-start lead screws are limited in precision, engagement surface, and versatility, making them less efficient for fluid dispensing and priming compared to multi-start lead screws.
Innovation Solution
A fluid delivery device employing a multi-start lead screw with various drive mechanisms, including worm drives and shape memory alloy (SMA) wires, to provide enhanced precision, engagement, and variable fill capabilities, with features like a ratchet gear and clutch mechanism for controlled fluid dispensing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a single-start lead screw is used, then the device structure is simple, but the precision and engagement surface are limited
Solution Approach 1:
The lead screw is divided into multiple starts (multiple threads wrapped around the screw body), where each start acts as an independent engagement surface. This segmentation allows the tube nut to engage with multiple thread starts simultaneously, increasing the total engagement surface area and distributing the load across multiple contact points, thereby improving precision and reducing wear without significantly increasing overall device complexity
2Length of moving object
If a single-start lead screw is used, then the device is easy to manufacture, but the travel distance per rotation is limited
Solution Approach 1:
By creating multiple starts on the lead screw, each start contributes to the total axial travel distance. When the tube nut rotates once, it engages with multiple thread starts simultaneously, effectively multiplying the travel distance per rotation by the number of starts. This segmentation approach increases the functional length without requiring a proportionally longer screw body, maintaining manufacturability while enhancing performance
3Adaptability or versatility
If a single-start lead screw is used, then the device complexity is low, but the versatility and drive mechanism options are limited
Solution Approach 1:
The multi-start lead screw configuration provides universal compatibility with various drive mechanisms including worm drives, gear drives, and direct motor coupling. The multiple engagement surfaces and increased rotational capability per unit rotation enable the same lead screw to work with different actuator types, enhancing the device's versatility and adaptability to various fluid delivery requirements without requiring a complete redesign of the drive system
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 multi-start lead screw design allows for more precise and efficient fluid dispensing, enabling greater surface engagement and travel distance with each rotation, improving the device's load capacity and versatility in fluid delivery systems.
Implementation Method 1
In some embodiments, the actuator may comprise an ortho-planar spring and a shape memory alloy (SMA) wire. In some of these embodiments, a finger may be actuated by the SMA wire.
Implementation Method 2
In some embodiments, the actuator may comprise a worm drive and a ratchet gear.
Implementation Method 3
A ratchet wheel may interface with the finger. A locking mechanism may be fixed to an internal face of the ortho-planar spring and may include a plurality of teeth configured to mate with the ratchet wheel.
Data Source
AI summary
A device for delivering fluid to a user may include a reservoir that holds the fluid and a plunger received in the reservoir. As the plunger is driven into the reservoir, the fluid is driven out; similarly, as the reservoir is filled, the plunger is driven out of the reservoir. The plunger may be moved into or out of the reservoir by the action of a lead screw. The lead screw may include multiple starts.