Dual-Plunger Pump Pressure Feedback for Accurate Solvent Flow
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Solution Overview
Problem
Conventional liquid delivery pumps fail to achieve high flow rate accuracy due to neglecting solvent expansion, pressure-dependent leakage, and flow rate-dependent leakage, which are critical factors affecting the precision required in liquid chromatography.
Innovation Solution
A liquid delivery pump system incorporating a first and second plunger pump, a pressure sensor, and a control unit that adjusts the plungers' speeds based on measured liquid delivery pressure to account for solvent expansion, pressure-dependent leakage, and flow rate-dependent leakage, ensuring high flow rate accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional liquid delivery pump control is used, then device complexity is low, but flow rate accuracy deteriorates due to neglecting solvent expansion, pressure-dependent leakage, and flow rate-dependent leakage
Solution Approach 1:
The control unit receives liquid delivery pressure from a pressure sensor and uses this feedback to calculate and adjust plunger moving speeds. The system continuously monitors pressure and adjusts plunger speeds to compensate for solvent expansion and leakage, achieving high flow rate accuracy through closed-loop control
Solution Approach 2:
The control unit calculates moving speeds of plungers as functions of liquid delivery pressure and target flow rate. By dynamically adjusting plunger speed parameters based on measured pressure, the system compensates for solvent expansion and pressure-dependent leakage, transforming static speed control into dynamic pressure-compensated control
2Measurement precision
If pressure sensor and control unit are added, then flow rate accuracy improves through compensation, but device complexity increases
Solution Approach 1:
The pressure sensor provides real-time feedback on liquid delivery pressure to the control unit, which uses this information to calculate appropriate plunger speeds that compensate for solvent expansion and leakage effects, achieving accurate flow rate control
Solution Approach 2:
The invention replaces complex mechanical flow rate measurement and adjustment mechanisms with a pressure sensor and computational control algorithm. The control unit calculates plunger speeds based on pressure feedback and target flow rate, substituting mechanical complexity with electronic sensing and digital computation
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 system delivers liquids with enhanced precision by correcting for solvent expansion, pressure-dependent leakage, and flow rate-dependent leakage, thereby maintaining consistent flow rates in liquid chromatography applications.
Implementation Method 1
a pressure sensor disposed on a downstream side of the second plunger pump, and configured to measure a liquid delivery pressure that is a pressure of the liquid discharged from the second plunger pump
Implementation Method 2
The solvent is compressed to the load pressure and discharged from the liquid delivery pump. At the detector on the downstream side of the separation column, the pressure of the solvent is approximately at atmospheric pressure. Therefore, the solvent expands in the detector with respect to the state in the liquid delivery pump.
Implementation Method 3
The solvent leakage includes pressure dependent leakage and flow rate dependent leakage.
Data Source
AI summary
A liquid delivery pump delivers a liquid with high flow rate accuracy in consideration of solvent expansion, pressure dependent leakage of the solvent, and flow rate dependent leakage of the solvent. A liquid delivery pump includes first and second plunger pumps connected together, having respective first and second plungers. A pressure sensor measures a liquid delivery pressure (P2) from the second plunger pump, and a controller controls the driving of the first and second plungers. The controller obtains a moving speed (v1) of the first plunger and a moving speed (v2) of the second plunger using a parameter (C1, C0) depending on the liquid delivery pressures (P1, P2), the liquid delivery pressure, and a target flow rate of the liquid. The parameter (C1, C0) is a parameter of an expression representing a relationship between the liquid delivery pressure (P2) and a flow rate (Q0) of the liquid.