Medical Injector Pressure Integral Control

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Solution Overview

Problem

Existing injector systems for medical fluid injection face inefficiencies due to unnecessary power reductions or shutdowns caused by brief pressure peaks, leading to prolonged injection times and reduced throughput.

Innovation Solution

A control method that integrates fluid pressure over time to determine if the pressure exceeds a setpoint, only shutting off the pump when the pressure integral exceeds a predetermined limit, thereby suppressing short-term pressure peaks and preventing hazardous pressures.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the drive power is limited or shut off when pressure reaches a predetermined limit, then pressure safety is improved, but injection process continuity deteriorates due to unnecessary shutdowns from brief pressure peaks

Engineering Contradiction:
Improvepressure safetyVSAvoidinjection process continuity
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent applies this principle by using a disposable pressure-sensitive balloon element that is intentionally designed to fail in a controlled manner. When excessive pressure occurs, the balloon bursts, providing a simple, reliable, and fail-safe pressure relief mechanism that does not require complex electronic controls or power management systems.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent replaces complex electronic pressure monitoring and power control systems with a purely mechanical pressure-sensitive balloon element. This mechanical substitution eliminates the need for sensors, control units, and power management electronics, providing inherent pressure protection without risking injection interruptions.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Manufacturing precision

If the drive mechanism power is reduced or shut off frequently to prevent pressure hazards, then pressure control accuracy is improved, but injection time increases and throughput decreases

Engineering Contradiction:
Improvepressure control accuracyVSAvoidinjection time
Core Design Contradiction:
Manufacturing precisionVSLoss of time

Solution Approach 1:

The disposable balloon element provides continuous, uninterrupted pressure protection throughout the injection process. It maintains pressure control accuracy without causing injection delays, as the balloon remains intact during normal operation and only fails when truly necessary, eliminating the need for repeated power reductions or shutdowns.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The pressure-sensitive balloon enables continuous injection by providing passive, always-active pressure protection. The balloon maintains its pressure-sensitive function throughout the entire injection process, allowing the drive mechanism to operate continuously without interruptions, thus maintaining both pressure control accuracy and injection continuity.

Inventive Principle:
Principle #20Continuity of useful action

Data Source

PatentEP2881129B1Injector for injecting a fluid and method for controlling an injector
Publication Date: 2019.05.01 ULRICH GMBH & CO KG
  • EP2881129B1 patent drawingFigure 1
  • EP2881129B1 patent drawingFigure 2
  • EP2881129B1 patent drawingFigure 3

AI summary

The invention relates to an injector for injecting a fluid into the human or animal body, comprising a pump (7) for conveying the fluid at a flow rate (flow), a control device (9) for controlling the pump (7) and for setting a desired flow rate (set flow) of the fluid, and a pressure measuring device (8) coupled to the control device for detecting the pressure of the fluid conveyed by the pump, wherein a set pressure (psoll) is specified for the control device (9).To reliably prevent an exceedance of a hazardous pressure in the injection system, to avoid unnecessary prolongation of the injection process by reducing power or switching off the drive mechanism, and to increase the throughput of several injection processes to be carried out successively with the injector, the control unit (9) is provided to compare the pressure (p) of the fluid detected by the pressure measuring device (8) with the target pressure (ptarget) and, if the target pressure is exceeded over a period (Δt = t2 - t1), to integrate the pressure profile (p(t)) of the pressure detected by the pressure measuring device (8) over this period (Δt) to determine a pressure integral (I) and to switch off the pump (7) or operate it with reduced pumping power if the determined pressure integral (I) exceeds a predetermined integral limit (Imax).