Liquid Chromatograph Pump Precompression Control

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Solution Overview

Problem

Conventional liquid chromatographs using resin materials for pumps face issues with delayed mobile phase ejection due to pressure deficiency and discrepancies in low-pressure gradient control, as resin materials deform under pressure, affecting the timing of solvent switching and mixture ratios.

Innovation Solution

A liquid chromatograph with a liquid-sending unit that includes a pump with a check valve and a pressure application controller, which adjusts the plunger's position and speed based on input information about the mobile phase's compressibility and the pump chamber's inner volume change, ensuring the pressure reaches the check-valve-opening pressure for timely ejection, and a solvent supplier with a switching mechanism controlled by the passage-switching controller to maintain target mixture ratios.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If resin material is used for pump components, then metal ion dissolution is prevented, but ejection timing is delayed due to pressure deficiency

Engineering Contradiction:

Improvemetal ion dissolutionVSAvoidejection timing delay

Core Design Contradiction:

Object-affected harmful factorsVSLoss of time

Solution Approach 1:

The system performs precompression by advancing the plunger before the check valve opens, pre-storing pressure energy in the compressed mobile phase. This preliminary action ensures that when the check valve finally opens, ejection occurs at the correct timing without delay, resolving the timing issue while maintaining resin material benefits

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system dynamically adjusts the precompression amount based on the compressibility of the mobile phase. By changing the compression parameter according to mobile phase composition, the system compensates for resin material compliance and ensures consistent ejection timing across different mobile phases

Inventive Principle:

Principle #35Parameter changes

2Device complexity

If precompression amount is fixed, then pump structure is simple, but ejection timing varies with mobile phase compressibility

Engineering Contradiction:

Improvepump structureVSAvoidejection timing accuracy

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The system transitions from fixed precompression to dynamic precompression control. The control unit adjusts the precompression amount in real-time based on mobile phase compressibility, ensuring accurate ejection timing while maintaining relatively simple pump hardware structure

Inventive Principle:

Principle #15Dynamics

3Adaptability or versatility

If resin pump is used, then material compatibility is improved, but volume change under pressure affects gradient control accuracy

Engineering Contradiction:

Improvematerial compatibilityVSAvoidgradient control accuracy

Core Design Contradiction:

Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The system uses feedback control where the control unit monitors mobile phase compressibility and adjusts precompression accordingly. This closed-loop approach compensates for resin volume changes under pressure, maintaining gradient control accuracy while benefiting from resin material compatibility

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

This solution ensures accurate and timely ejection of the mobile phase and precise solvent mixing ratios, regardless of the material used, by accounting for the compressibility and volume changes in the pump chamber, thus improving the performance of the liquid chromatograph.

Implementation Method 1

when the operational phase changes from the phase for suctioning the mobile phase to the phase for ejecting the same, the check value will not open until the pressure within the pump becomes equal to or higher than a certain value

Methodology Applied

Scientific EffectPressure threshold opening: Valve

Implementation Method 2

in which the pressure of the mobile phase within the pump is increased beforehand after the completion of the suction and before the beginning of the ejection of the mobile phase

Methodology Applied

Scientific EffectCompression: Compression

Implementation Method 3

The compressibility of the mobile phase varies depending on the component of the mobile phase. Therefore, the amount of change in inner volume during the precompression (the travel distance of the plunger) should be determined for each mobile phase to be used

Methodology Applied

Scientific EffectCompressibility: Compression

Data Source

PatentUS12174159B2Liquid chromatograph

Publication Date: 2024.12.24 SHIMADZU CORP

AI summary

A liquid chromatograph (1) includes a liquid-sending unit (20) for sending a mobile phase from a reservoir (11) to a column (14) through a tube (12) at a predetermined pressure. The unit (20) includes a pump (21) having a suction port (211) connected to the reservoir and an ejection port (212) connected to the tube directly or via another pump. A check valve (232) is provided for the ejection port. For the precompression process for opening this valve, a pressure application controller (27) controls the pressure applied to the mobile phase within the pump, based on the compressibility of the mobile phase and the amount of compression of the inner wall of the pump resulting from the pressure application, so as to reach the pressure at which the check valve opens before the mobile phase suctioned from the suction port is to be ejected from the ejection port.