Dual Plunger Pump Pulsation Reduction via Phase Shift
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Solution Overview
Problem
Conventional liquid chromatograph pumps fail to effectively reduce pulsations, particularly when the ejection flow rate changes, due to factors like backlash, manufacturing accuracy, and vibration, leading to fluctuations in solvent flow and detection accuracy.
Innovation Solution
A pump system comprising a first and second plunger pump connected in series or parallel, with a pump controller that alternately performs intake and compression actions at constant cycles, sets one pressurizing chamber to a higher pressure than the other, and adjusts lift amounts to control flow rates, ensuring constant cycle pulsations regardless of ejection flow rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional pump structures with cam mechanisms are used to drive plunger pumps in series or parallel, then coordinated operations can be achieved to reduce pulsations, but cyclic pulsations occur due to backlash, dimensional looseness, manufacturing accuracy issues, and vibration during speed changes
Solution Approach 1:
The pump system is divided into multiple independent plunger pumps (first plunger pump and second plunger pump) that operate in parallel. Each pump has its own plunger, pressurizing chamber, and drive mechanism, allowing independent control of their respective drive cycles. This segmentation enables the system to distribute the pumping action across multiple units, reducing the impact of pulsations from any single pump while maintaining overall flow stability.
Solution Approach 2:
The invention employs periodic drive cycles for each plunger pump, where the first and second plunger pumps operate with different drive cycle periods. By adjusting the drive cycle parameters (such as the ratio of compression stroke time to total cycle time) of each pump differently, the system creates a composite flow pattern where pulsations from individual pumps cancel each other out, achieving reduced overall pulsation while maintaining stable flow rate.
2Productivity
If the ejection flow rate is changed by adjusting pump operation, then flow rate control is achieved, but pulsations of all cycles cannot be reduced because the pump is configured to control ejection flow rate by changing drive cycle
Solution Approach 1:
The invention dynamically adjusts the drive cycle parameters of each plunger pump based on the desired flow rate. Instead of using a fixed drive cycle, the system modifies the compression stroke time, intake stroke time, and overall cycle period of each pump in real-time. This dynamic adjustment allows the pumps to maintain optimal pulsation-reducing operation across a range of flow rates, adapting to changing operational requirements while suppressing pulsations.
Solution Approach 2:
The system changes multiple drive cycle parameters simultaneously (compression stroke time, intake stroke time, cycle period, and the ratio between compression and intake times) to achieve both flow rate control and pulsation reduction. By coordinating parameter changes across multiple pumps with different drive characteristics, the system maintains effective pulsation suppression even when the overall ejection flow rate is adjusted, overcoming the limitation of fixed drive cycle configurations.
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 configuration reduces pulsations in liquid chromatograph pumps, maintaining flow stability and improving detection accuracy by synchronizing pulsation cycles with plunger actions, even during changes in ejection flow rates.
Implementation Method 1
a first plunger pump and a second plunger pump connected in series or in parallel, and a pump controller. The embodiment is characterized in that the pump controller: causes the first plunger pump and the second plunger pump, which are connected in series or in parallel, to perform intake and compression actions alternately at substantially constant cycles
Implementation Method 2
at least sets a pressurizing chamber of one of the plunger pumps to a state of a higher pressure than a pressurizing chamber of the other plunger pump
Data Source
AI summary
A pump controller causes a first plunger pump and a second plunger pump connected in series or in parallel to perform intake and compression actions alternately at substantially constant cycles, sets a pressurizing chamber of one of the plunger pumps to a state of a higher pressure than the pressurizing chamber of the other plunger pump, and performs flow rate control by adjusting lift amounts of the first plunger and the second plunger. Thus, it is possible to provide a pump for liquid chromatograph, and a liquid chromatograph, which are capable of reducing pulsations even when an ejection flow rate is changed.