Injection Device Drive Coupling for Syringe Protection
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Solution Overview
Problem
Automatic injection devices face issues with syringe breakage and inconsistent dose delivery due to high forces required for viscous liquids and deep injections, particularly because existing designs rely on radial tags that generate friction and risk damage to the syringe barrel and rear flange.
Innovation Solution
An automatic injection device design where the syringe barrel and rear flange are immobilized within a housing, allowing forces to be evenly distributed and bypassing the rear flange, reducing the risk of breakage and enabling more forceful injections without modifying the syringe, with a syringe housing that clamps onto the barrel to distribute axial forces and protect the delicate rear flange.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If radial tags are used to engage the plunger and barrel to transmit driving force, then the plunger can be driven forward to dispense liquid, but friction is generated between the tags and the inner wall of the outer housing, requiring greater force to drive the inner housing forward
Solution Approach 1:
The harmful radial tags that generate friction are removed from the system. Instead of using radial tags to engage the plunger and barrel, the patent employs a drive coupling arrangement with a drive coupling part that selectively transmits force without creating frictional contact between moving parts, thereby eliminating the energy loss associated with friction.
Solution Approach 2:
The mechanical friction-based engagement system (radial tags scraping against the inner wall) is replaced with a non-frictional drive coupling mechanism. The drive coupling arrangement uses a selective force transmission mechanism that avoids frictional contact, substituting the old mechanical friction-based system with a newer non-frictional approach.
2Force
If radial tags directly engage the rear flange to drive the barrel forward, then the barrel can be advanced for injection, but the rear flange is susceptible to breakage due to large forces and frictional resistance
Solution Approach 1:
The direct engagement between radial tags and the rear flange is removed. The drive coupling arrangement eliminates the need for the radial tags to directly engage the rear flange, thereby removing the source of high forces that cause breakage in the fragile rear flange and syringe barrel.
Solution Approach 2:
The drive coupling arrangement provides a protective mechanism that prevents excessive forces from being transmitted to the rear flange before breakage can occur. By using a selective force transmission mechanism, the system cushions or protects the vulnerable rear flange from the large forces that would otherwise be applied during barrel advancement.
3Adaptability or versatility
If clearance is introduced between the radial tags and the rear flange to accommodate syringe position variation, then different syringe sizes can be used, but a greater driving force is required to overcome the gap and engage the flange
Solution Approach 1:
The clearance gap problem is resolved by removing the radial tag engagement system entirely. The drive coupling arrangement provides a mechanism that works regardless of the position of the syringe barrel, eliminating the need to overcome a gap between tags and flange, thereby maintaining adaptability without the increased force requirement.
Solution Approach 2:
The drive coupling arrangement provides a universal force transmission mechanism that works with different syringe sizes and positions without requiring adjustment. The selective force transmission capability allows the same mechanism to accommodate various configurations, providing multi-functionality that eliminates the need for additional force to overcome gaps.
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
This design reduces the risk of syringe breakage, allows for more viscous liquids to be dispensed and deeper injections, and provides a more reliable and controlled delivery mechanism by distributing forces effectively and protecting the syringe barrel.
Implementation Method 1
the syringe housing clamps onto the barrel to distribute axial forces and protect the delicate rear flange
Implementation Method 2
a drive coupling arrangement between said driving means and said plunger, said drive coupling arrangement comprising at least first and second parts which are configurable such that a driving force can be selectively transmitted or not transmitted between them in use
Data Source
AI summary
An injection device including a syringe having a needle, a barrel and a plunger. The device is configured to provide an automatic injection cycle and includes a drive coupling arrangement between a driving spring and the syringe. In operation, a drive force can be selectively transmitted between the respective first and second parts of the drive coupling arrangement depending upon their relative rotational positions such that, when the first and second parts are in a first relative rotational position during the dispensing stage, a driving force is transmitted to the plunger to drive the plunger into the barrel, and, when the first and second parts are in a second relative rotational position during the retraction stage, no force is transmitted to the plunger to allow the plunger and the syringe to retract.