Syringe Safety Device Locking Element Prevents Plug Migration
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Solution Overview
Problem
Syringes experience contamination due to the migration of sealing plugs caused by pressure loss during transport, which compromises the sterility of the medium inside the syringe cylinder.
Innovation Solution
A syringe design featuring a safety device with a locking element that engages with the plunger to prevent the sealing plug from sliding back, utilizing a tilting locking element with a pretensioning force to ensure the sealing plug remains in place, and an optional unlocking mechanism for controlled displacement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a sealing plug is used to seal the syringe cylinder, then the medium can be contained and discharged, but the sealing plug may migrate under pressure loss causing contamination
Solution Approach 1:
The locking element is positioned to preemptively prevent the sealing plug from migrating before pressure loss occurs. The locking element engages with the plunger in advance, creating a mechanical barrier that counteracts the harmful effect of pressure loss and prevents contamination without requiring active intervention.
Solution Approach 2:
The locking element acts as an intermediary component between the sealing plug and the syringe cylinder wall. It translates the sealing plug's movement into engagement with the locking element, which then provides the restraining force through cooperation with the plunger, effectively mediating the interaction to prevent migration.
2Reliability
If a locking element is added to prevent sealing plug migration, then sterility is maintained, but the device complexity increases
Solution Approach 1:
The locking element is integrated into the safety device structure that already includes the sealing plug and plunger mechanism. By merging the locking function with the existing sealing mechanism, the patent avoids adding a completely separate complex system, thereby limiting the increase in device complexity while achieving the reliability goal.
Solution Approach 2:
Instead of adding a complex active locking mechanism that requires engagement and disengagement operations, the patent inverts the approach by using a passive locking element that automatically engages with the plunger through the existing movement dynamics, simplifying the overall device structure.
3Reliability
If the locking element is made tilting with pretensioning force, then the sealing plug is securely locked, but the manufacturing precision requirements increase
Solution Approach 1:
The locking element is pre-positioned and pre-oriented during manufacturing so that it automatically engages with the plunger in the correct orientation when the syringe is assembled and used. This preliminary positioning action eliminates the need for high-precision active control during operation, reducing the manufacturing precision requirements for the locking mechanism itself.
Solution Approach 2:
The locking element's geometry and positioning parameters are designed to create a self-aligning mechanism that tolerates certain variations in manufacturing precision. By optimizing the angular and positional parameters of the locking element relative to the plunger, the system achieves reliable locking without requiring extremely tight manufacturing tolerances.
Data Source
AI summary
A syringe includes a syringe cylinder, a sealing plug movably disposed within the syringe cylinder, and with a plunger cooperating with the sealing plug. A safety device prevents a sliding back of the sealing plug within the syringe cylinder in any position the sealing plug assumes within the syringe cylinder. The safety device has a locking element which engages at the plunger in any position the plunger assumes within the syringe cylinder. The locking element is attached to a retaining fixture and protrudes from the retaining fixture same such that an attachment point of the locking element is closer to the sealing plug at the retaining fixture than the free end of the locking element opposite of the attachment point.