Fixed Dose Injection Device Using Rotational Coupling
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Solution Overview
Problem
Existing injection devices for delivering fixed doses of liquid drugs are complex, cumbersome to operate, and require multiple steps for dose setting and ejection, making them difficult for users to manage effectively.
Innovation Solution
A simplified injection device design featuring a base member, a piston rod, and two tubular members that allow for a two-step dose setting and ejection cycle, where the first tubular member rotates to set the dose and advances non-rotationally to eject it, ensuring only the predetermined fixed dose is delivered without the need for complex clutch arrangements or rotational decoupling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a clutch arrangement is used to prevent piston rod rotation during dose setting while allowing rotation during injection, then the device can differentiate between setting and injection modes, but the device complexity increases and manufacturing becomes more difficult
Solution Approach 1:
The invention removes the clutch arrangement entirely from the system. Instead of using a complex switching mechanism to differentiate between dose setting and injection modes, the patent extracts this function and replaces it with a simpler mechanical constraint system where the piston rod is prevented from rotating during dose setting through direct mechanical coupling, and rotation is allowed during injection through a different mechanical configuration, eliminating the need for a clutch mechanism
Solution Approach 2:
The invention segments the dose setting and injection functions into distinct mechanical phases. During dose setting, the piston rod is mechanically constrained to rotate only with the drive mechanism. During injection, the mechanical constraints are released to allow the piston rod to rotate independently. This segmentation eliminates the need for a clutch arrangement by using separate mechanical pathways for each function
2Reliability
If a four-step dose setting and ejection procedure is used, then the device can deliver fixed doses, but the ease of operation decreases and the procedure becomes cumbersome
Solution Approach 1:
The invention merges the dose setting and ejection operations into a single continuous action. By integrating the mechanical constraints and release mechanisms, the user performs one unified operation that both sets the dose and initiates ejection, eliminating the need for separate four-step procedures and making the device easier to operate while maintaining fixed dose delivery reliability
Solution Approach 2:
The invention incorporates preliminary mechanical constraints that automatically prepare the device for dose setting before the user action begins. The mechanical coupling is pre-configured to prevent piston rod rotation during the dosing phase, and the system is pre-prepared to automatically transition to the ejection phase, reducing the number of user steps required
3Adaptability or versatility
If multiple mechanical components and clutch arrangements are used, then the device can control dose setting and injection modes, but the ease of manufacture decreases
Solution Approach 1:
The invention extracts the clutch arrangement and associated complex mechanical components from the system. By removing these difficult-to-manufacture elements and replacing them with simpler mechanical constraints that can be integrated into the basic structure, the patent maintains mode control capability while significantly improving ease of manufacture
Solution Approach 2:
The invention makes the basic mechanical components multi-functional. The piston rod and drive mechanism serve dual purposes: they rotate together during dose setting and allow independent rotation during injection, without requiring separate specialized components for each function. This universality reduces the total number of parts and simplifies manufacturing
Data Source
AI summary
An injection device for delivering a predetermined fixed dose of liquid drug, comprising a base member, a piston rod a first tubular member, and a second tubular member.