Lockable Syringe Plunger with Cam Mechanism
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Solution Overview
Problem
Existing syringe assemblies lack a reliable mechanism to lock the plunger at a desired position, which limits their ability to maintain negative gauge pressure for efficient fluid withdrawal in medical applications.
Innovation Solution
A syringe assembly with a locking mechanism comprising partial rings and cam surfaces that allow selective restriction or permission of plunger movement based on rotational position, enabling the plunger to be locked at any position along the barrel and maintain negative gauge pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a locking mechanism is added to the syringe assembly, then the ability to maintain negative gauge pressure and secure fluid withdrawal is improved, but the device complexity increases
Solution Approach 1:
The locking mechanism is nested within the syringe barrel, with the cam surface integrated into the barrel wall and the plunger head interacting with this internal cam structure. The locking components are contained within the existing syringe geometry, adding functionality without significantly increasing external dimensions or overall complexity.
Solution Approach 2:
The cam surface and plunger head interaction creates a self-locking mechanism where the plunger's own movement and geometry engage with the cam surface to automatically lock at the desired position. The mechanism uses the plunger's longitudinal movement to trigger the locking action through the cam profile, eliminating the need for separate actuating components.
2Adaptability or versatility
If a locking mechanism with cam surface is implemented, then the plunger can be locked at any position along the barrel, but the manufacturing precision requirements increase
Solution Approach 1:
Instead of adding complex locking features to the plunger, the invention places the cam surface on the stationary barrel and allows the moving plunger head to interact with it. This inversion means the precision requirements are applied to the stationary barrel component rather than the moving plunger, simplifying manufacturing tolerances for the dynamic part.
Solution Approach 2:
The cam surface serves multiple functions: it guides the plunger movement, provides the locking action, and allows positioning at any location along the barrel. This multi-functionality reduces the need for separate positioning mechanisms, thereby reducing overall manufacturing precision requirements while maintaining versatility.
3Ease of operation
If the locking mechanism allows rotation-based locking, then the ease of operation is improved, but the device complexity increases
Solution Approach 1:
The cam surface utilizes a curved, arcuate geometry that naturally guides the plunger head through a rotational motion to engage the locking position. This curved surface transforms a simple rotational input into the desired locking action, providing intuitive operation while keeping the mechanism geometry relatively simple and manufacturable.
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 locking mechanism allows for secure locking of the plunger, facilitating the maintenance of negative gauge pressure and efficient fluid withdrawal, enhancing the usability of the syringe assembly in medical procedures.
Implementation Method 1
The first partial ring comprises a cam surface disposed on an inner surface of the first partial ring... The cam surface of the first partial ring is operably connected to the plunger and configured to restrict or allow longitudinal movement of the plunger based on the rotational position of the plunger
Implementation Method 2
the plunger may comprise a raised surface that applies the radial force to the cam surface of the first partial ring when in the locked configuration and wherein the raised surface may apply a minimal radial force to the cam surface of the first partial ring when in the unlocked configuration
Data Source
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AI summary
The embodiments disclosed herein relate to lockable syringe assemblies and related devices and methods. The syringe assembly may include a barrel, a plunger, and a locking mechanism. In some arrangements, the locking mechanism is an elastomeric locking ring or a rigid partial ring. The plunger may include a plurality of ribs and is longitudinally moveable within the barrel. Once the plunger is disposed at a desired longitudinal location, the plunger can be axially rotated and locked in such a way that further longitudinal movement is restricted.