Injector Clutch Arrangement for Dose Setting Isolation
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Solution Overview
Problem
Existing injector devices require users to exert sufficient grip to rotate the dose setting knob against a spring bias, making it difficult for those with limited dexterity, and complicate the design with bi-directional ratchets or disconnection mechanisms to allow dose reversal.
Innovation Solution
A clutch arrangement isolates the dose setting element from the drive spring's force during dose setting, allowing easy rotation and potential reverse movement, and a preloaded or separately energized drive spring provides motive force without user input.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the drive spring is connected to the dose setting element during dose setting, then the spring can provide continuous drive force for multiple doses, but the user must exert sufficient grip to rotate the dose setting knob against spring bias
Solution Approach 1:
The drive mechanism is segmented into two operational states: during dose setting, the clutch disengages to isolate the dose setting element from the drive spring, allowing easy rotation; during dose delivery, the clutch engages to transmit spring force to the plunger. This segmentation resolves the contradiction by separating the dose setting function from the drive force transmission.
Solution Approach 2:
The clutch arrangement dynamically transitions between engaged and disengaged states based on operational phase. During dose setting, the clutch is disengaged to eliminate spring resistance; during dose delivery, it engages to transmit drive force. This dynamic behavior allows the system to adapt its mechanical connection according to the current operation, resolving the contradiction between continuous drive force and ease of setting.
2Stability of the object's composition
If a ratchet mechanism is used to prevent dose setting reversal, then the dose setting position is maintained, but the device complexity increases with bi-directional ratchets or disconnection mechanisms
Solution Approach 1:
The clutch arrangement extracts the function of preventing unintended dose setting reversal from the dose setting element itself. By isolating the dose setting element from the drive mechanism during setting, the system inherently prevents reverse movement without requiring additional ratchet or disconnection mechanisms on the dose setting element, thereby reducing device complexity.
Solution Approach 2:
The clutch acts as an intermediary between the dose setting element and the drive spring. During dose setting, the clutch disengages to allow free rotation; during dose delivery, it engages to transmit force. This intermediary mechanism provides controlled connection and disconnection without requiring complex bi-directional ratchets, simplifying the overall device structure.
3Productivity
If the drive spring is preloaded to deliver multiple doses, then continuous drive force is available, but users with limited dexterity cannot easily rotate the dose setting knob against spring bias
Solution Approach 1:
The operational sequence is segmented into distinct phases: dose setting phase where the clutch is disengaged to eliminate spring resistance, and dose delivery phase where the clutch is engaged to utilize spring force. This segmentation allows users with limited dexterity to set doses easily without fighting spring bias, while still enabling multiple dose delivery through the preloaded spring.
Solution Approach 2:
The dynamic engagement and disengagement of the clutch allows the system to adapt to different operational requirements. During dose setting, the disengaged state eliminates mechanical resistance, making the device accessible to users with limited dexterity. During dose delivery, the engaged state provides the necessary drive force for multiple doses, resolving the contradiction between productivity and ease of operation.
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 easier dose setting and reversal for users with limited dexterity, allowing a more powerful spring to be used and reducing the need for user-wound mechanisms, while maintaining efficient delivery of multiple doses.
Implementation Method 1
a drive mechanism releasable to advance said plunger in respective predetermined increments of magnitude to express said successive selected doses; characterised in that said drive mechanism includes a drive spring for applying expulsion drive movement directly or indirectly to said plunger
Implementation Method 2
said drive mechanism further including a clutch arrangement operable during said dose setting routine to isolate said dose setting element from the force of said drive spring
Data Source
AI summary
An injector apparatus includes a housing (101, 102) for a cartridge or syringe, a plunger (40) for cooperating in use with the cartridge or syringe to express successive doses, a dose setting arrangement (16, 20) to select a dose volume, and a drive mechanism (22, 24) releasable to advance the plunger in respective predetermined increments of magnitude to express the successive doses. The drive mechanism includes a drive spring (22) for imparting movement directly or indirectly to the plunger (40), and the dose setting arrangement includes a dose setting element (16) moveable in a dose setting routine to define a magnitude of an increment of movement of the plunger for a given dose. The drive mechanism further includes a clutch arrangement (56) operable during the dose setting routine to inhibit forward movement of the plunger and/or to isolate the dose setting element from the force of the drive spring.