Injection Pen Cartridge Coupling for Piston Rod Reset
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Solution Overview
Problem
Existing injection devices require complex operations for resetting the piston rod, involving multiple component parts and movements, which complicates the process of replacing cartridges and increases production costs.
Innovation Solution
An injection device with a simplified mechanism that uses axial movements of the cartridge holder to couple and decouple the coupling sleeve with the piston rod, reducing the number of components and simplifying the assembly process by eliminating the need for translating rotational movements into axial movements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a complex mechanism with multiple component parts is used to couple and decouple the coupling sleeve, then reliable operation for resetting the piston rod is ensured, but the device complexity and number of components increase
Solution Approach 1:
The patent combines the coupling sleeve with the piston rod by providing a coupling element that integrally connects these two components. This merging eliminates the need for separate coupling mechanisms while ensuring reliable transmission of the resetting movement from the cartridge holder to the piston rod, thereby reducing component count without sacrificing operational reliability.
Solution Approach 2:
The coupling sleeve is designed to perform multiple functions: it guides the piston rod during dose discharge, transmits the resetting movement during cartridge replacement, and provides structural support. This multi-functionality reduces the need for additional specialized components while maintaining reliable operation across different operational modes.
2Reliability
If multiple component parts and movements are used for resetting the piston rod, then reliable operation is ensured, but production costs and assembly effort increase
Solution Approach 1:
By integrating the coupling element between the coupling sleeve and piston rod, the patent reduces the total number of parts that need to be manufactured and assembled. This merging of components directly lowers production costs and simplifies assembly procedures while maintaining the reliability of piston rod resetting operation.
Solution Approach 2:
The patent extracts and eliminates unnecessary intermediate components from the resetting mechanism. By directly coupling the cartridge holder to the piston rod through a simplified coupling element, it removes redundant parts that would otherwise increase manufacturing complexity and assembly effort.
3Ease of operation
If rotational movements are translated into axial movements through multiple components, then coupling and decoupling is achieved, but device complexity increases
Solution Approach 1:
The patent merges the rotational-to-axial movement conversion function directly into the coupling element itself. The coupling element is designed with features that automatically convert the rotational movement of the cartridge holder into axial movement of the piston rod during resetting, eliminating the need for separate mechanical conversion components.
Solution Approach 2:
The coupling element acts as an intermediary between the cartridge holder and piston rod, mediating the movement conversion process. It receives rotational input from the cartridge holder and transforms it into axial output for the piston rod, simplifying the overall mechanism by providing a direct mediation path without additional conversion components.
Data Source
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AI summary
The present invention refers to an injection device comprising a housing (6, 21), a cartridge holder (18) for receiving a cartridge (19) containing a medicament, the cartridge holder (18) having a first attachment member (18a), a threaded sleeve insert (12) axially and rotationally constrained to the housing (6, 21), threaded sleeve insert (12) having a second attachment member (12a) for releasable attachment of the cartridge holder (18) by means of interaction with the first attachment member (18a), and a metering mechanism. The metering mechanism comprises an actuating element (1) for setting or discharging a dose, a piston rod (2) for producing an advance movement for dispensing a dose, a piston rod sleeve (3) in which the piston rod (2) is accommodated such that the piston rod (2) can be non-rotatably connected to the piston rod sleeve (3), and a coupling element (4) with which the actuating element (1) and the piston rod sleeve (3) can be coupled for discharge of the dose set with the actuating element (1) in such a way that a dispensing movement of the actuating element (1) is transmitted to the piston rod (2) by way of the piston rod sleeve (3) connected to the piston rod (2). The piston rod (2) can be non-rotatably connected to the piston rod sleeve (3) by means of a coupling sleeve (7) wherein the coupling sleeve (7) can be in engagement with the piston rod sleeve (3) to form a non-rotatable connection between the piston rod (2) and the coupling sleeve (7) and wherein the coupling sleeve (7) can be out of engagement with the piston rod sleeve (3) such that the piston rod (2) is rotatable relative to the piston rod sleeve (3). According to the invention, attachment of the cartridge holder (18) to the threaded sleeve insert (12) includes an axial movement of the cartridge holder (18) with respect to the threaded sleeve insert (12) and the housing (6, 21), which axial movement brings the coupling sleeve (7) in engagement with the piston rod sleeve (3).