Injection Device Locking Mechanism Prevents Plastic Creeping
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Solution Overview
Problem
Conventional injection devices face challenges due to the direct contact between plastic components and the spring element of the driving mechanism, leading to plastic creeping and reduced shelf life.
Innovation Solution
The injection device incorporates a locking mechanism that retains the driving mechanism in an initial inactive state, preventing direct contact with plastic components and thus avoiding plastic creeping. This design includes a retractable inner sleeve, a removable cap with an engagement mechanism, and a rib to actuate the driving mechanism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the spring element is directly supported by plastic components, then the device structure is simplified, but plastic creeping occurs and shelf life is reduced
Solution Approach 1:
A metal support structure is introduced as an intermediary between the spring element and the plastic housing components. This mediator prevents direct contact between the spring and plastic parts, eliminating the plastic creeping problem while maintaining structural support for the driving mechanism.
2Ease of operation
If the locking mechanism is released to actuate the driving mechanism, then the injection function is enabled, but the plastic components may creep under spring force
Solution Approach 1:
The metal support structure serves as a mediator that bears the spring force during actuation, preventing this force from being transmitted to the plastic components. This allows the driving mechanism to be actuated reliably while protecting the plastic parts from creeping under load.
Solution Approach 2:
The spring force is extracted from the plastic component support function and transferred to the metal support structure. This separation ensures that plastic components only perform their intended functions without bearing the harmful spring load that causes creeping.
Data Source
Figure 1A~1B
Figure 2
Figure 3
AI summary
An injection device comprising: a housing arranged to contain a syringe with a piston for sealing the syringe and displacing the medicament, the housing having a proximal end and a distal end, wherein the distal end is intended to be applied against an injection site; a driving mechanism arranged between the piston and the proximal end of the housing; and a locking mechanism comprising a plate member arranged between the driving mechanism and the piston to retain the driving mechanism to retain the driving mechanism in an initial inactive state in which the driving mechanism cannot be actuated; wherein when the locking mechanism is released, the driving mechanism can be actuated to push the piston towards the distal end of the housing to displace the medicament.