Peristaltic Pump Control Device Predictive Pressure Regulation
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Solution Overview
Problem
Existing injection devices with peristaltic pumps face challenges in managing pressure pulsations, leading to unnecessary shutdowns and increased injection volumes due to safety intervals that require pressure limits to be set below risk pressures.
Innovation Solution
A control system for peristaltic pumps that regulates the speed of the pump to achieve maximum volume flow without exceeding a specified pressure limit, using a predictive pressure calculation to anticipate pressure maxima within pressure cycles and adjust the pump speed accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a pressure limit is set below the hazard pressure to provide safety intervals, then patient safety is improved, but the maximum achievable volume flow is reduced and injection duration increases
Solution Approach 1:
The control device performs preliminary action by predicting the pressure maximum before it occurs in each pressure cycle. Using the measured pressure from the previous cycle and the known oscillating pressure profile characteristics, the system calculates the expected pressure maximum in advance. This allows the pump speed to be reduced proactively before the pressure limit is reached, preventing unnecessary shutdowns while maintaining safety. The prediction enables the system to operate closer to the hazard pressure without compromising patient safety.
2Stress or pressure
If the pump speed is reduced to avoid exceeding pressure limits, then pressure safety is improved, but the volume flow rate decreases and injection time increases
Solution Approach 1:
The control device applies periodic action by synchronizing speed adjustments with the oscillating pressure cycles. Instead of continuously reducing pump speed, the system modulates the speed periodically in correspondence with each pressure cycle. The pump speed is reduced only during the compression phase when pressure builds up, then restored during the refill phase when pressure drops. This periodic modulation maintains pressure within safe limits while maximizing volume flow during periods when pressure is not critical, thereby preserving injection efficiency.
3Reliability
If pressure limits are set conservatively below hazard pressure, then device safety is improved, but large safety intervals are required which reduce the maximum operating pressure
Solution Approach 1:
The control device implements feedback by continuously measuring the actual pressure in the output line and comparing it with the predicted pressure maximum and the pressure limit. Based on this feedback, the system dynamically adjusts the pump speed in real-time. The feedback mechanism allows the pressure limit to be set closer to the hazard pressure because the system can react immediately when the predicted pressure approaches the limit, reducing pump speed only when necessary. This eliminates the need for large conservative safety intervals while maintaining device safety.
Data Source
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AI summary
The invention relates, inter alia, to a control device (8) for a peristaltic pump (5) that pumps a medium in pulsating pressure cycles, wherein the control device (8) regulates the speed of the peristaltic pump (5) such that a maximum volume flow rate (Qmax) is achieved without exceeding a pressure limit (plimit) in the output line (9). One objective is to keep the actual pressure in the output line (9) as close as possible to the pressure limit (plimit) or to minimize the distance to it. To achieve this, it is proposed to calculate a predictive pressure (pfuture) for each pressure cycle (P) for an expected maximum pressure within the pressure cycle (P) based on at least the pressure (pist) in the output line (9) and to use the predictive pressure to limit the maximum volume flow rate (Qmax) so that the pressure (pist) in the output line (9) does not exceed the pressure limit (plimit) in the pressure cycle (P).The invention also relates to related aspects.