Injection Dosing System With Dynamic Coupling-Sleeve Locking
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Solution Overview
Problem
Existing injection apparatuses require high force for dose dispensing due to reverse rotation locks that increase friction, and these locks are ineffective for injection devices with axially displaced dosing sleeves.
Innovation Solution
A dosing device with a holding element that allows the coupling sleeve to be displaced relative to the housing, ensuring it is rotationally fixed during dose setting and correction, and released for dispensing, eliminating the need for additional friction-causing mechanisms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a reverse rotation lock is used to prevent unintentional movement of the piston rod, then reliability is improved, but the force required for dose dispensing increases due to increased friction
Solution Approach 1:
The locking mechanism is segmented into two independent parts: a ratchet wheel fixed to the piston rod and a separate locking element that can engage or disengage from the ratchet teeth. This allows the locking function to be activated only when needed (during dose setting) and disengaged during dose dispensing, eliminating continuous friction resistance.
Solution Approach 2:
The locking element is designed to be dynamically switchable between engaged and disengaged states. During dose setting, the locking element engages with the ratchet teeth to prevent reverse rotation. During dose dispensing, the locking element is disengaged, allowing free rotation without friction resistance from the locking mechanism.
2Reliability
If a reverse rotation lock with biasing is used to ensure the lock functions properly, then reliability is improved, but device complexity increases due to additional components and mechanisms
Solution Approach 1:
The locking element combines multiple functions into a single component: it provides the locking action through engagement with ratchet teeth, provides the necessary biasing force through its own elastic deformation, and enables easy disengagement through axial movement. This eliminates the need for separate springs and complex actuating mechanisms.
Solution Approach 2:
The locking element is made of elastic material that generates its own biasing force through deformation. When engaged, the elastic deformation provides the necessary force to maintain locking. When disengaged, the elastic recovery facilitates easy return to the locked position, eliminating the need for external spring mechanisms.
3Measurement precision
If the coupling sleeve is rotationally fixed during dose setting, then dose control precision is improved, but the force required for dispensing increases due to friction from locking mechanisms
Solution Approach 1:
The coupling sleeve's rotational constraint is made dynamic rather than static. During dose setting, the locking element engages to provide rotational constraint. During dose dispensing, the locking element disengages, transforming the constraint into freedom of rotation, thereby eliminating friction resistance during the high-force dispensing operation.
Data Source
AI summary
A dosing system for an injection device for dispensing a dose of a product includes a housing having a longitudinal axis, a dose-setting element, a holding element and a coupling sleeve for driving a driving device for dispensing the dose. The dose-setting element, holding element, and coupling sleeve may be accommodated in the housing. To set and correct the dose, the dose-setting element and the coupling sleeve move in the direction of the longitudinal axis relative to the housing, and the coupling sleeve may be held the holding element rotationally fixed by relative to the housing. To dispense the dose, the coupling sleeve may rotate relative to the housing, the dosing system including a guide in the housing, in which guide the holding element may be displaced in the direction of the longitudinal axis relative to the housing and be guided in a rotationally fixed manner relative to the housing.