Liquid Feeding Apparatus Preloading Control for Pressure Equilibrium
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Solution Overview
Problem
The existing liquid feeding apparatus for liquid chromatographs experiences pulsating flow due to noise in pressure sensor detection signals, leading to premature termination or incorrect pressure equilibrium between pump chambers, causing inefficiencies in liquid feeding.
Innovation Solution
A liquid feeding apparatus with a preloading operation unit that adjusts the acquisition frequency of pressure sensor signals based on the preloading time determined by the liquid feeding flow rate, ensuring accurate feedback control and reducing noise by optimizing signal acquisition frequency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pressure sensor detection signals are acquired at regular time intervals for feedback control, then the preloading operation can be controlled, but noise in the detection signal causes premature termination or incorrect pressure equilibrium
Solution Approach 1:
The patent applies dynamics by making the signal acquisition frequency variable rather than fixed. The control unit adjusts the acquisition frequency dynamically based on the preloading time determined from the liquid feeding flow rate, allowing the system to adapt to different operating conditions and prevent noise-induced errors while maintaining responsive control.
Solution Approach 2:
The patent changes the parameter of signal acquisition frequency based on the preloading time and liquid feeding flow rate. By adjusting this parameter, the system optimizes the balance between noise reduction and control responsiveness, preventing both premature termination and excessive pressure buildup during the preloading operation.
2Productivity
If the suction and discharge operations are switched immediately after the suction operation is terminated, then the liquid feeding efficiency is improved, but the pressure inside the pump chamber becomes lower than the secondary pump chamber, causing the check valve not to open and producing pulsating flow
Solution Approach 1:
The patent applies preliminary action by performing a preloading operation before the actual discharge operation. The control unit drives the primary pump to the discharge side until the pressure inside the pump chamber becomes substantially equal to the pressure inside the secondary pump chamber, ensuring the check valve is ready to open immediately when discharge begins, thus preventing pulsating flow while maintaining feeding efficiency.
3Speed
If the acquisition frequency of pressure sensor signals is increased for better control responsiveness, then the preloading operation control is improved, but the noise in the detection signal increases
Solution Approach 1:
The system dynamically adjusts the signal acquisition frequency based on the determined preloading time and liquid feeding flow rate, rather than using a fixed high frequency. This dynamic adjustment allows the system to maintain adequate control responsiveness while reducing noise by acquiring signals at the optimal frequency for each operating condition.
Solution Approach 2:
The acquisition frequency parameter is changed according to the preloading time and flow rate conditions. By optimizing this parameter, the system achieves the right balance between control responsiveness and noise reduction, preventing both premature termination and excessive pressure buildup during preloading.
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 approach effectively reduces noise in pressure sensor signals, preventing pulsating flow and ensuring stable pressure equilibrium between pump chambers, thereby maintaining consistent liquid feeding.
Implementation Method 1
a primary side pump and a secondary side pump which perform suction and discharge of liquid by driving a distal end of a plunger in one direction in a pump chamber
Implementation Method 2
When the suction and discharge operations of the primary side pump and the secondary side pump are switched immediately after the suction operation of the liquid using the primary side pump is terminated, the pressure inside a pump chamber of the primary side pump, which has been performing the suction operation just before, becomes lower than the pressure inside a pump chamber of the secondary side pump. Thus, the check valve does not open until the pressure inside the pump chamber of the primary side pump becomes equal to or higher than the pressure inside the pump chamber of the secondary side pump
Implementation Method 3
a pressure sensor for detecting the pressure inside the pump chamber of the primary side pump and the pressure inside the pump chamber of the secondary side pump is provided
Data Source
AI summary
A liquid feeding apparatus has a primary side pump and a secondary side pump, and an outlet part of the primary side pump and an inlet part of the secondary side pump are connected to each other via a check valve. A temporary side pump pressure sensor for detecting the pressure inside the pump chamber of the primary side pump and a secondary side pressure sensor for detecting the pressure inside the pump chamber of the secondary side pump are provided. The signal of the primary side pressure sensor and the signal of the secondary side pressure sensor are acquired after the suction operation of the primary side pump is terminated and before the discharge operation of the secondary side pump is terminated.