Injection Device Interchangeable Drive Coupling Noise Reduction
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Solution Overview
Problem
Existing injection devices require high force drive springs, resulting in noise and vibration during syringe extension and retraction, particularly when the syringe fill volume is low, which can startle patients.
Innovation Solution
The injection device employs a fixed-length drive coupling combined with an interchangeable drive coupling of varying length, which is inversely proportional to the syringe contents, and an interchangeable release element to minimize noise and vibration by optimizing the length of the drive coupling and release mechanism based on the syringe volume.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a high force drive spring is used to reliably empty the syringe before retraction, then the syringe can be extended and discharged in time, but noise and vibration increase significantly
Solution Approach 1:
The drive coupling length is made variable rather than fixed, allowing the system to dynamically adjust the drive characteristics. By selecting different drive coupling lengths based on syringe fill volume, the system optimizes the balance between reliable syringe emptying and minimization of noise/vibration, resolving the contradiction between reliability and harmful factors.
Solution Approach 2:
The invention changes the parameter of drive coupling length to adapt to different syringe fill volumes. For smaller fill volumes, a longer drive coupling is used to reduce the force required and minimize recoil noise, while for larger fill volumes, a shorter drive coupling provides sufficient force. This parameter adjustment resolves the contradiction by tailoring the drive characteristics to the actual load.
2Device complexity
If a fixed drive coupling length is used, then the device structure is simpler, but noise and recoil cannot be minimized across different syringe fill volumes
Solution Approach 1:
The drive coupling is segmented into multiple interchangeable components of different lengths rather than using a single fixed-length coupling. This segmentation allows selection of the appropriate length for each syringe fill volume, minimizing noise and recoil while maintaining relative structural simplicity through modular design.
Solution Approach 2:
The interchangeable drive coupling system provides multi-functionality, where a set of standard-length drive couplings can be used across different syringe fill volumes. This universal approach allows a single mechanism design to handle various scenarios optimally, reducing noise and recoil adaptively without requiring complex active control systems.
3Object-generated harmful factors
If the drive coupling length is increased to reduce spring force for small fill volumes, then noise and vibration decrease, but the syringe extension time increases
Solution Approach 1:
By changing the drive coupling length parameter based on syringe fill volume, the system achieves optimal balance between extension speed and noise reduction. For small fill volumes, a longer drive coupling reduces spring force and noise while still achieving timely extension. For large fill volumes, a shorter drive coupling provides higher force and faster extension, maintaining the contradiction resolution across different operating conditions.
Data Source
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AI summary
An injection device (110) comprises a housing (112) adapted to receive a syringe (116) having a discharge nozzle (118) and a dispensing piston (114) movable in the syringe to expel the contents of the syringe through the discharge nozzle. There is also a drive (130) adapted to act on the syringe to advance it from a retracted position in which the discharge nozzle is contained within the housing to an extended position in which the discharge nozzle extends from the housing. A drive coupling (134) extends from the drive to the dispensing piston of the syringe so as to transfer movement of the drive to the piston. The drive coupling comprises a fixed-length drive coupling and an interchangeable drive coupling. There is also a method of manufacturing an injection device by assembling a first sub-assembly (210) and second sub-assembly (220) .