Lead Screw Drive Mechanism for Precise Drug Dosing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing drug delivery devices face challenges in providing a reliable and efficient mechanism for delivering precise doses of pharmaceuticals, particularly in reusable and refillable devices, where accurate dosing and easy handling are critical.
Innovation Solution
A drive mechanism comprising a lead screw and lead screw nut with a screw thread and stop features, along with a guide feature, allows for helical rotation and precise control of drug dispensing, enabling easy handling and protection from contaminants, and facilitating reset operations in reusable devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a lead screw and lead screw nut are used for dose delivery, then dosing precision is improved, but the device complexity increases
Solution Approach 1:
The patent combines the lead screw and lead screw nut into an integrated drive mechanism that is coupled to the cartridge assembly, merging multiple functions (dosing control, movement guidance, and mechanical actuation) into a single unified component system. This reduces the number of separate parts while maintaining dosing precision.
Solution Approach 2:
The lead screw mechanism serves multiple functions simultaneously: it controls the precise dosing amount, guides the movement of the cartridge assembly, and provides the mechanical force for drug delivery. This multi-functionality reduces overall device complexity by eliminating the need for separate components for each function.
2Measurement precision
If stop features are added to prevent rotation, then dosing accuracy is improved, but the device complexity increases
Solution Approach 1:
The stop features are integrated directly into the lead screw or lead screw nut structure, combining the rotation prevention function with the existing drive mechanism components. This merging approach maintains dosing accuracy while minimizing additional complexity by avoiding separate independent components.
3Measurement precision
If a guide feature is added to restrict lead screw nut movement, then movement control precision is improved, but the device complexity increases
Solution Approach 1:
The guide feature is merged with the body structure, combining the movement restriction function with the housing. This integration provides precise movement control for the lead screw nut while avoiding the need for separate guide components, thus maintaining low device complexity.
4Ease of operation
If the lead screw is made helically rotatable, then ease of operation is improved, but the device complexity increases
Solution Approach 1:
The lead screw mechanism is designed to convert rotational motion to linear motion automatically through the screw thread geometry, enabling the user to operate the device simply by rotating the lead screw. This self-converting mechanism improves ease of operation while the integrated design keeps complexity low.
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 mechanism ensures accurate and efficient dispensing of drugs, provides mechanical advantage, and offers audible, visual, and tactile feedback, making it suitable for reusable devices like pen injectors, with low part count and cost-effectiveness.
Implementation Method 1
The lead screw and the lead screw nut are provided with a screw thread and a drive feature coupling the lead screw and the lead screw nut, so that the lead screw is helically rotatable in the lead screw nut
Implementation Method 2
The lead screw and the lead screw nut are provided with stop features interfering with a rotation of the lead screw and the lead screw nut relative to one another when a force is applied to the lead screw in the proximal direction
Implementation Method 3
The body has a guide feature restricting a movement of the lead screw nut, and the lead screw nut has a surface area facing the guide feature. This surface area of the lead screw nut has a slope varying around the axis. The screw thread, the slope, and the guide feature interact in such a manner that the lead screw nut rotates in one rotational direction when a force is applied to the lead screw in the proximal direction
Data Source
AI summary
A lead screw (5) with a screw thread (6) is arranged in a body (1) along an axis (4) and coupled to a lead screw nut (7) with a drive feature (8), so that the lead screw is helically rotatable in the lead screw nut. The lead screw and the lead screw nut are provided with stop features (9) interfering with a rotation of the lead screw in the lead screw nut when a force is applied to the lead screw in an axial direction. The lead screw nut has a surface area facing a guide feature (10) of the body. This surface area has a slope (12) varying around the axis. The assembly interacts such that the lead screw nut rotates in one rotational direction when a force is applied to the lead screw in the axial direction.