Coupled Volume Pumping Apparatus for High Pressure Force Balancing

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Solution Overview

Problem

High-performance liquid chromatography (HPLC) systems face challenges in delivering liquids at high pressures (up to 2000 bar) while managing liquid compressibility, which requires efficient and cost-effective pumping solutions that balance force requirements and dynamic behavior.

Innovation Solution

A pumping apparatus with a piston reciprocating in a chamber having two volumes, where the volumes are coupled to balance forces, allowing for smaller and less costly drive systems, and featuring a pressure ratio between effective areas to optimize pressure increase and force compensation, with control units and sensors for precise pressure management.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stress or pressure

If a single-volume pump chamber is used to deliver liquid at high pressure, then the pump can achieve high outlet pressure, but the drive system requires large force and becomes more complex and costly

Engineering Contradiction:
Improveoutlet pressureVSAvoidforce requirement on drive
Core Design Contradiction:
Stress or pressureVSForce

Solution Approach 1:

The pump working chamber is divided into two separate volumes (first volume and second volume) that are coupled together. The piston reciprocates between these two volumes, with each volume having its own effective area on the piston. This segmentation allows the force requirements to be distributed and balanced across the two volumes, reducing the peak force requirement on the drive system while maintaining the capability to achieve high outlet pressure through the pressure proportion relationship between the two volumes.

Inventive Principle:
Principle #1Segmentation

2Force

If the first effective area of the piston is increased to reduce force requirements, then the force compensation improves, but the achievable outlet pressure decreases

Engineering Contradiction:
Improveforce compensationVSAvoidachievable outlet pressure
Core Design Contradiction:
ForceVSStress or pressure

Solution Approach 1:

The invention utilizes parameter changes by establishing a specific pressure proportion P between the first and second volumes that corresponds to the area proportion A of the piston effective areas. By controlling the inlet pressure and maintaining the relationship P ≈ A, the system can achieve both force compensation and high outlet pressure. The control unit adjusts the inlet pressure to maintain this proportion, allowing the piston to operate with reduced force requirements while still achieving the desired outlet pressure through the coupled volume pressure relationship.

Inventive Principle:
Principle #35Parameter changes

3Measurement precision

If a high pressure pump system is designed to deliver liquid at controlled flow rates, then measurement precision is improved, but the device complexity increases due to additional control mechanisms

Engineering Contradiction:
Improveflow rate control precisionVSAvoidcontrol system complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The invention incorporates a control unit that monitors and adjusts the inlet pressure to maintain the pressure proportion P in relation to the area proportion A of the piston effective areas. This feedback mechanism ensures that the outlet pressure follows the desired pressure proportion relationship, enabling precise flow rate control. The coupling between the first and second volumes, combined with the controlled inlet pressure, creates a self-regulating system that improves measurement precision without requiring overly complex control mechanisms.

Inventive Principle:
Principle #23Feedback

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 solution enables efficient high-pressure liquid delivery with reduced force requirements on the drive system, improved dynamic behavior, and higher accuracy in flow rates, achieving pressures up to 2000 bar with inlet pressures around 600 bar, while maintaining cost-effectiveness and precision.

Implementation Method 1

The first and second volumes are coupled to each other as long as a pressure in the first volume exceeds a pressure in the second volume

Methodology Applied
Scientific EffectPascal's Law: Pascal's Law

Implementation Method 2

A movement of the piston into a first direction decreases the first volume and increases the second volume

Methodology Applied
Scientific EffectHydraulic pressure transmission: Hydraulic Press

Implementation Method 3

The coupling of the first and second volumes of the pump working chamber allows balancing forces onto the piston

Methodology Applied
Scientific EffectForce balance through pressure differential: Pressure Gradient

Data Source

PatentEP1795749B1High pressure pumping apparatus with coupled volumes in a pump working chamber
Publication Date: 2009.03.04 AGILENT TECHNOLOGIES INC
  • EP1795749B1 patent drawingFigure 1
  • EP1795749B1 patent drawingFigure 2
  • EP1795749B1 patent drawingFigure 3~5

AI summary

A pumping apparatus (10), for delivering liquid at a high pressure at which compressibility of the liquid becomes noticeable, comprises a piston (20) adapted for reciprocation in a pump working chamber (30), wherein a movement of the piston (20) into a first direction (40) decreases a first volume (V1) in the pump working chamber (30) and increases a second volume (V2) in the pump working chamber (30), and a movement of the piston (20) into a second direction (50) opposite to the first direction (40) increases the first volume (V1) and decreases the second volume (V2). A coupling (70, 80, 90, 100) is provided for coupling the first volume (V1) with the second volume (V2) as long as a pressure (Psup) in the first volume (V1) exceeds a pressure in the second volume (V2). An outlet valve (120) is provided for coupling the second volume (V2) with an outlet (110) of the pumping apparatus (10) as long as a pressure in the second volume (V2) exceeds a pressure (Psys) at the outlet (110).