Syringe Pump Cam Mechanism for Lead Screw Runout
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Solution Overview
Problem
Syringe pumps used in medical applications face challenges in efficiently delivering precise amounts of medications over extended periods, with existing systems lacking flexibility in accommodating different syringe sizes and types, and often experiencing issues with lead screw runout and occlusion detection.
Innovation Solution
A syringe pump design featuring a modular architecture that allows interchangeability between syringe and peristaltic pumps, incorporating a sliding block assembly with a cam mechanism for engaging and disengaging from a lead screw, and redundant sensors for fail-safe operation, along with a method for mitigating lead screw runout and occlusion detection using pressure sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a syringe pump uses a lead screw mechanism for plunger actuation, then precise medication delivery is achieved, but lead screw runout occurs causing delivery inaccuracies
Solution Approach 1:
The patent implements feedback control by using a linear encoder to continuously monitor the actual position of the plunger and comparing it with the commanded position. The controller adjusts the motor output based on the position error to compensate for lead screw runout, ensuring accurate medication delivery despite mechanical imperfections in the lead screw mechanism.
Solution Approach 2:
The patent replaces direct mechanical coupling with a field-based sensing and control system. Instead of relying solely on the mechanical integrity of the lead screw, the system uses a linear encoder (electromagnetic/optical field) to sense position and a controller to regulate motor torque, substituting mechanical precision requirements with electronic control and feedback.
2Ease of manufacture
If the syringe pump is designed with fixed architecture, then manufacturing simplicity is maintained, but flexibility to accommodate different syringe sizes and types is reduced
Solution Approach 1:
The patent implements a dynamic, reconfigurable pump chamber design where the volume definition is not fixed but can be adjusted based on the syringe being used. The system can dynamically adapt its operational parameters and physical configuration to match different syringe sizes and types, allowing a single pump platform to serve multiple applications without sacrificing manufacturing simplicity.
Solution Approach 2:
The patent creates a universal pump platform that can accommodate various syringe types and sizes through standardized interfaces and programmable control. The single device performs multiple functions by adapting to different syringe configurations, eliminating the need for multiple specialized pump designs while maintaining ease of manufacture through modular, standardized components.
3Device complexity
If the syringe pump operates without redundant sensors, then device complexity is reduced, but reliability during extended infusion is compromised
Solution Approach 1:
The patent implements beforehand cushioning by incorporating redundant sensors that detect potential failures (such as occlusions or sensor malfunctions) before they compromise the infusion. The system proactively monitors for anomalies and can alert operators or automatically adjust operation to prevent delivery errors, ensuring reliability during extended infusions without significantly increasing complexity.
4Device complexity
If occlusion detection is not implemented, then device complexity is minimized, but medication delivery accuracy deteriorates during extended operation
Solution Approach 1:
The patent uses feedback control for occlusion detection by continuously monitoring the relationship between motor current, plunger position, and expected flow rate. When an occlusion is detected (indicated by abnormal current draw or position deviations), the system provides feedback to the controller to adjust motor output or alert the operator, maintaining delivery accuracy during extended operation without requiring complex dedicated occlusion sensing hardware.
Data Source
AI summary
A syringe pump includes a lead screw, a cam, and an assembly having first and second arms each having a first end and a second end. The second ends of the first and second arms are configured to engage with the lead screw. The first ends of the first and second arms are configured to engage with the cam such that actuation of the cam toward the assembly causes the second ends of the first and second arms to pivotally approach each other. The second ends of the first and second arms each includes threads to engage the lead screw when the second ends of the first and second arms approach each other. The plunger head coupled to the assembly and operative to drive a plunger of a syringe into a barrel of the syringe.