Drug Delivery Piston Rod Reset via Gravity and Screw Thread
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Solution Overview
Problem
Existing drug delivery devices, particularly pen-type injectors, face challenges in efficiently resetting the piston rod mechanism after a cartridge is emptied, requiring manual intervention and potential complexity in refilling and reinitialization.
Innovation Solution
A drug delivery device with a mechanism that allows for the guided movement and easy resetting of the piston rod to its initial position using gravitational force, facilitated by a screw thread system and a reset nut with a spiral spring, enabling smooth axial and rotational movement without the need for additional dedicated reset elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If manual resetting of the piston rod is required after cartridge replacement, then the device can maintain simple structure, but the ease of operation deteriorates due to additional manual intervention steps
Solution Approach 1:
The piston rod automatically resets to its initial position through gravitational force when the cartridge is replaced, eliminating the need for manual resetting operations. The system serves itself by using the weight of the piston rod to drive the resetting mechanism without user intervention.
Solution Approach 2:
The resetting mechanism transforms the static piston rod position into a dynamic resetting process. When the cartridge is removed, the piston rod is freed to move dynamically under gravitational influence, rotating the drive sleeve and resetting the mechanism automatically.
2Ease of operation
If a dedicated reset element is added to facilitate piston rod resetting, then the ease of operation improves, but the device complexity increases
Solution Approach 1:
The piston rod serves dual functions: it acts as both the drug delivery actuator and the resetting mechanism driver. The same piston rod that delivers medication also, through its weight and movement, automatically resets the drive mechanism when the cartridge is replaced, eliminating the need for a separate reset element.
Solution Approach 2:
The resetting function is merged with the existing piston rod and drive sleeve mechanism. The piston rod's axial movement is coupled with rotational movement of the drive sleeve through gravitational force, combining delivery and resetting functions into a unified mechanical system.
3Ease of operation
If the piston rod is allowed to move freely for resetting, then the ease of operation improves, but mechanical stress on components increases
Solution Approach 1:
The mechanism is designed to allow the piston rod to move under gravitational force along a controlled path. The drive sleeve and guiding means create a mechanical environment where the piston rod's weight is converted into useful resetting motion without creating excessive stress concentrations or uncontrolled movements.
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
Enables straightforward and efficient refilling and reinitialization of the device, reducing user complexity and mechanical stress on components, ensuring reliable and user-friendly operation for multiple dose administration.
Implementation Method 1
a reset nut with a spiral spring
Implementation Method 2
enabling a reset of the piston rod to a start position
Data Source
AI summary
A mechanism in the body is used to drive a piston rod and comprises means for guiding the movement of the piston rod relatively to the body while delivering the drug. Further means are provided for releasing the piston rod from the means for guiding the movement, thus enabling a reset of the piston rod to a start position, especially after the receptacle has been emptied and is to be refilled. The device is constructed in such a manner that a reset of the piston rod is facilitated.