Pump Drive Mechanism With Zig-Zag Slider for Low-Force Actuation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional automatic drug delivery systems face challenges in minimizing size and power consumption due to the large footprint of existing pump mechanisms and high SMA wire actuation forces, which hinder the reduction of overall device size and energy requirements.
Innovation Solution
A novel drive mechanism for a positive displacement pump using a cylindrically-shaped slider element with a zig-zag track, where interface elements like pegs or ball bearings move along the track to impart rotational motion to a header element connected to a gear train, allowing for longitudinal translation of the plunger and efficient drug delivery with reduced energy consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a conventional ratcheting mechanism is used to drive the pump, then the pump can be actuated by SMA wires, but the mechanism occupies a relatively large volume and requires relatively large SMA wire actuation force
Solution Approach 1:
The patent replaces the conventional ratcheting mechanism with a novel drive mechanism that uses a flexural pivot instead of rigid mechanical joints. The flexural pivot uses elastic deformation to achieve the same mechanical function, eliminating the need for complex ratchet teeth and springs, thereby reducing volume and actuation force requirements
Solution Approach 2:
The patent changes the mechanical parameters of the drive mechanism by using a flexural pivot with specific geometric parameters (arm length, thickness, width) that optimize the trade-off between torque generation and actuation force. The dimensions are carefully selected to reduce both volume and force requirements
2Ease of operation
If a conventional ratcheting mechanism is used to drive the pump, then the pump can be actuated, but the mechanism occupies a relatively large volume inside the housing
Solution Approach 1:
The patent replaces the bulky ratcheting mechanism with a compact flexural pivot-based drive mechanism that achieves the same pump actuation function. The flexural pivot eliminates the need for large ratchet wheels and springs, significantly reducing the volume occupied by the drive mechanism while maintaining full pump actuation capability
Solution Approach 2:
The patent implements a nested arrangement where the flexural pivot is positioned coaxially with the reservoir, and the drive mechanism components are arranged in a compact, space-efficient configuration that minimizes the volume occupied within the housing
3Productivity
If a conventional ratcheting mechanism is used, then the pump can deliver liquid drug, but the device requires relatively large energy to operate
Solution Approach 1:
The patent replaces the high-energy ratcheting mechanism with a low-energy flexural pivot system. The elastic deformation of the flexural pivot requires significantly less energy than the mechanical engagement and disengagement of ratchet teeth, reducing overall device energy consumption while maintaining liquid drug delivery capability
Solution Approach 2:
The patent optimizes the geometric parameters of the flexural pivot (arm length, thickness, width) to minimize the energy required for each actuation cycle while ensuring sufficient torque is generated to drive the pump and deliver the required liquid drug volume
4Use of energy by moving object
If the SMA wire actuation force is reduced, then energy consumption decreases, but the pump mechanism becomes harder to actuate
Solution Approach 1:
The patent carefully selects and optimizes the geometric parameters of the flexural pivot (arm length L, thickness t, width w) to achieve the optimal balance between required actuation force and ease of operation. The dimensions are designed to provide sufficient mechanical advantage while keeping the SMA wire actuation force low, making the pump easy to actuate with minimal energy input
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 new drive mechanism enables a smaller form factor and lower energy consumption, allowing for a more compact drug delivery device with reduced battery requirements and the ability to deliver different volumes of liquid using the same motion, enhancing the overall efficiency and usability of wearable drug delivery devices.
Implementation Method 1
a back and forth longitudinal motion of the slider element along its radial axis causes movement of the one or more interface elements along the track through the channel, thus providing a movement of the interface elements around the circumference of the slider element. The movement of the one or more interface elements through the channel imparts a rotational motion to a header element
Data Source
AI summary
A novel embodiment of a drive mechanism for use in a pump, for example, of the type that would be used in a wearable drug delivery system, comprises, a cylindrically-shaped slider element configured with a channel on a circumferential surface thereof defining one or more zig-zag-shaped tracks therethrough. One or more pegs are engaged within the tracks, such that a back and forth longitudinal motion of the slider element along a radial axis of the cylinder causes movement of the pegs along one of the tracks through the channel, thus providing a movement of the pegs around the circumference of the cylinder which imparts a rotational motion to a header element disposed co-axially with the slider. The header element is in turn connected to a gear train, for example, a planetary gear box, which is coupled to the pump via a linkage or other type of mechanism.