Injection Device Axial Coupling for Simpler Piston Resetting
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Solution Overview
Problem
Existing drug delivery devices, particularly pen-type devices, require complex operations for resetting the piston rod due to the need for translating rotational movements into axial movements during cartridge replacement, leading to increased component complexity and assembly effort.
Innovation Solution
An injection device with a simplified resetting mechanism that utilizes axial movements of the cartridge holder to engage and disengage the coupling sleeve with the piston rod sleeve, reducing the number of components and assembly complexity by eliminating the need for rotational translations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a rotation-to-axial movement translation mechanism is used during cartridge replacement, then the piston rod can be reset, but the device complexity and assembly effort increase
Solution Approach 1:
The patent extracts the rotation-to-axial movement translation function from the cartridge holder assembly and relocates it to the threaded sleeve insert. This separation allows the cartridge holder to simply perform axial movement while the threaded sleeve insert independently handles the rotational translation, reducing overall system complexity and assembly requirements
Solution Approach 2:
The threaded sleeve insert acts as an intermediary component between the cartridge holder and the piston rod sleeve. It receives rotational input from the cartridge holder and converts it to axial movement of the piston rod sleeve, eliminating the need for complex integrated mechanisms
2Reliability
If a rotation-to-axial movement translation mechanism is used during cartridge replacement, then the piston rod can be reset, but the assembly effort increases
Solution Approach 1:
The mechanism is segmented into distinct functional components: the cartridge holder performs axial movement, the threaded sleeve insert performs rotation-to-axial translation, and the piston rod sleeve receives the axial movement. This segmentation allows each component to be manufactured and assembled independently, reducing overall assembly effort
Solution Approach 2:
The complex translation mechanism is extracted from the cartridge holder and placed in the threaded sleeve insert, simplifying the cartridge holder assembly and reducing the skill level required for assembly operations
Data Source
AI summary
The present disclosure refers to an injection device comprising a housing, a cartridge holder having a first attachment member, a threaded sleeve insert axially and rotationally constrained to the housing, the threaded sleeve insert having a second attachment member for releasable attachment with the first attachment member, and a metering mechanism. The metering mechanism comprises an actuating element, a piston rod, a piston rod sleeve in which the piston rod can be non-rotatably connected in the piston rod sleeve, and a coupling element coupling the actuating element and the piston rod sleeve. The piston rod can be non-rotatably connected to the piston rod sleeve by a coupling sleeve. The cartridge holder is attached to the threaded sleeve insert by axially moving cartridge holder with respect to the threaded sleeve insert and the housing to engage the coupling sleeve with the piston rod sleeve.