Cam-Sleeve Plunger Engagement for Reliable Syringe Coupling
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Solution Overview
Problem
Existing powered fluid injectors lack reliable and robust syringe plunger engagement mechanisms that facilitate secure connection and disconnection with the syringe plunger for reciprocal movement, which is essential for precise fluid delivery in medical procedures.
Innovation Solution
A plunger engagement mechanism featuring a cam sleeve with movable pins and an actuator, such as a rotary electric motor, that allows reversible movement between disengaged and engaged positions, enabling secure connection and disconnection with the syringe plunger through tracks on the piston head.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a simple plunger engagement mechanism is used, then the device complexity is reduced, but the reliability of connection and disconnection with the syringe plunger deteriorates
Solution Approach 1:
The engagement mechanism employs a cam sleeve that can dynamically change its radial position between extended and retracted states. This dynamic transformation allows the mechanism to provide robust engagement when needed while maintaining simplicity when disengaged, resolving the contradiction between reliability and complexity
Solution Approach 2:
The engagement mechanism is divided into distinct functional components: the cam sleeve, pins, and actuator. This segmentation allows each component to perform its specific function efficiently, with the cam sleeve providing engagement, pins providing connection points, and actuator controlling movement, thereby achieving reliable connection without excessive overall complexity
2Reliability
If a robust engagement mechanism with movable pins and cam sleeve is implemented, then the reliability of plunger connection is improved, but the device complexity increases
Solution Approach 1:
The cam sleeve integrates multiple functions into a single component: it houses the pins, provides the cam surface for actuation, and controls the radial movement of pins. This merging reduces the number of separate parts needed, achieving reliable engagement while limiting the increase in overall device complexity
3Ease of operation
If an actuator is added to control the cam sleeve movement, then the ease of operation for engagement and disengagement is improved, but the device complexity increases
Solution Approach 1:
The engagement mechanism is designed to be self-actuating through the cam sleeve's interaction with the syringe plunger geometry. The cam surface automatically translates the plunger's linear movement into radial pin movement, eliminating the need for separate actuators and reducing complexity while maintaining ease of operation
Data Source
AI summary
A fluid injector system has at least one reciprocally operable piston having a piston head, and a plunger engagement mechanism associated with the piston head. The plunger engagement mechanism has a cam sleeve disposed within the piston head and movable relative to the piston head, the cam sleeve having one or more tracks defining a cam surface. The plunger engagement mechanism further has an actuator operatively connected to the cam sleeve for moving the cam sleeve relative to the piston head, and one or more pins disposed within the cam sleeve. The one or more pins are movable within the one or more tracks with movement of the cam sleeve between a first or withdrawn position, wherein the one or more pins are radially withdrawn into the piston head and a second or extended position, wherein the one or more pins protrude radially outward relative to an outer surface of the piston head.