Injection Device Threaded Part Dose Control
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Solution Overview
Problem
Existing injection apparatuses lack intuitive operation and clear dose control, making it difficult for patients to understand and manage the injection process, especially in correcting inadvertently set doses.
Innovation Solution
A novel injection apparatus design featuring a threaded part that is rotatable for dose-setting but not during injection, utilizing a combination of rotary and axial motions to set and deliver the dose, with a ratchet mechanism for dose correction and audible feedback for setting doses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the threaded part is rotatable during injection operation, then the patient can adjust the dose during injection, but the patient cannot have clear control over the injection process and understand what is happening
Solution Approach 1:
The threaded part is designed to be rotatable during dose-setting operation but locked during injection operation. This dynamic change in mobility allows the patient to adjust the dose before injection by rotating the threaded part, while preventing rotation during injection to ensure clear control and understanding of the injection process.
2Ease of operation
If the threaded part is prevented from rotating during injection operation, then the patient has clear control over the injection process, but the patient cannot correct an inadvertently set dose
Solution Approach 1:
The threaded part transitions from a locked state during injection to an unlocked state for dose correction. After injection, the threaded part can be rotated again to allow dose correction, providing the necessary adaptability while maintaining control clarity during the actual injection process.
Solution Approach 2:
The ratchet mechanism is engaged during dose-setting to prevent the threaded part from rotating back, ensuring the set dose is maintained. After injection, the ratchet can be disengaged to allow rotation for dose correction, providing preliminary prevention during setting and subsequent correction capability.
3Reliability
If a ratchet mechanism is used to prevent rotation during injection, then dose control is maintained, but the device complexity increases
Solution Approach 1:
The ratchet mechanism automatically engages when the threaded part is rotated during dose-setting, preventing rotation in the wrong direction without requiring additional control mechanisms. The spring-loaded pawl automatically interacts with the ratchet teeth, providing self-regulating dose control that minimizes the need for complex additional mechanisms.
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 apparatus provides intuitive and easy-to-understand operation, allowing patients to accurately set and correct doses, ensuring intuitive control over the injection process and clear feedback during use.
Implementation Method 1
a threaded part (122) is in engagement with a thread (100) on a piston rod (98), the threaded part (122) being rotatable during a dose-setting operation but not during an injection operation
Data Source
AI summary
An injection apparatus has a barrel (50) that is adapted to receive a container (108) with injection fluid (110). It further comprises a piston rod (98), provided with a thread (100), for expelling injection fluid (110) from such a container (108), which piston rod (98) is guided relative to the barrel (50) in the axial direction (112, 114). Additionally provided is a threaded part (122) whose thread (120) is in engagement with the thread (100) of the piston rod (98), which threaded part (122) is rotatable relative to the piston rod (98) and relative to the barrel (50) in order to set an injection dose, and, during an injection operation, is prevented from rotating relative to the piston rod (98).