Injection Plunger Shock Absorber for Stopper Impact Reduction
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Solution Overview
Problem
During an injection event using an injection device, the initial contact between a plunger and a stopper can cause a shock, leading to syringe breakage, component deformation, and user discomfort, particularly in under-filled syringes with an initial gap between the plunger and the stopper.
Innovation Solution
The injection device incorporates a shock absorber on the plunger rod that contacts the stopper during displacement, reducing the impact force between the plunger rod and the stopper. The shock absorber can be coaxial with the plunger rod, feature a retractable tip with compressible protrusions, or include a spring mechanism, foam plug, or flexible arm to absorb the shock.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a plunger rod directly contacts the stopper during injection, then the injection device structure is simple, but it causes shock leading to syringe breakage, component deformation and user discomfort
Solution Approach 1:
The shock absorber is pre-installed on the plunger rod before the injection process begins. When the plunger rod contacts the stopper, the shock absorber (comprising a retractable tip with deflectable arm and teeth) is already in position to absorb the impact shock, preventing syringe breakage and component deformation while maintaining a relatively simple overall device structure.
Solution Approach 2:
The shock absorber acts as an intermediary component between the plunger rod and the stopper. Instead of direct contact between the rigid plunger rod and stopper, the shock absorber mediates the interaction by absorbing impact shock through its retractable tip mechanism, thereby reducing harmful effects while maintaining the injection function.
2Adaptability or versatility
If there is an initial gap between the plunger and the stopper in under filled syringes, then the syringe can accommodate variable medicament volumes, but it causes increased shock impact during injection
Solution Approach 1:
The shock absorber is pre-positioned on the plunger rod to compensate for the initial gap in under-filled syringes. When injection begins and the plunger rod travels through the gap to contact the stopper, the shock absorber is ready to absorb the impact shock, allowing the system to handle variable medicament volumes while preventing excessive impact forces.
Solution Approach 2:
The shock absorber serves as a mediator that bridges the initial gap between plunger and stopper in under-filled syringes. It absorbs the impact force generated when the plunger rod contacts the stopper after traversing the gap, enabling the system to accommodate variable medicament volumes without suffering from increased shock impact.
3Productivity
If the plunger rod contacts the stopper with high impact force, then the injection can be completed quickly, but it causes syringe breakage, component deformation and user discomfort
Solution Approach 1:
The shock absorber is pre-installed on the plunger rod to cushion the impact during injection. This allows the plunger rod to maintain sufficient speed to complete the injection efficiently while the shock absorber prevents syringe breakage and component deformation by absorbing the impact shock, thus maintaining both productivity and reliability.
Solution Approach 2:
The shock absorber acts as an intermediary that enables the plunger rod to contact the stopper with controlled force. It mediates the interaction to maintain injection speed while preventing excessive impact forces that would compromise syringe integrity, thereby resolving the contradiction between productivity and reliability.
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
The implementation of a shock absorber in the injection device effectively reduces the shock of the plunger contacting the stopper, minimizing the risk of syringe breakage, component deformation, and enhancing user comfort, while ensuring accurate injection.
Implementation Method 1
The one or more teeth may deflect the deflectable arm during retraction of the plunger rod tip, thereby absorbing a shock
Implementation Method 2
The retractable tip may comprise compressible protrusions that are arranged to be compressed as the retractable tip collapses into the plunger rod body
Implementation Method 3
The shock absorber may comprise a spring mechanism
Implementation Method 4
The shock absorber may comprise a foam plug
Data Source
AI summary
The present application relates to shock absorbers for injection devices. According to a first aspect, this specification discloses an injection device including: a medicament container; a stopper translatably disposed within the medicament container; and a plunger rod including: a plunger rod body; and a shock absorber, wherein the plunger rod is operable to displace the stopper; and wherein the shock absorber contacts the stopper during displacement of the stopper by the plunger rod, thereby reducing an impact force between the plunger rod and the stopper.