Chromatographic pump and control method thereof

Abstract

The invention discloses a chromatographic pump and a control method thereof.The chromatographic pump comprises a plunger system, a hydraulic cylinder system, a pressure detection system and a control system, the plunger system is provided with a magnetorheological damper, the control system comprises a microcontroller, and the microcontroller is provided with an electromagnetic driving unit, a data receiving unit, a data processing unit and a data output unit. And the electromagnetic driving unit is connected with the magnetic excitation coil. The output pressure of the chromatographic pump is monitored in real time through the pressure detection system, a monitored pressure signal is compared with a set value, a difference value is calculated, the current intensity is adjusted by the microcontroller according to the difference value, so that the magnetic field intensity is changed, the viscosity of the magnetorheological damping fluid is changed according to the change of the magnetic field intensity, and the damping effect is improved. By means of closed-loop control, the chromatographic pump can adjust the viscosity of magnetorheological fluid in real time, and it is ensured that the pump outputs constant pressure and accurate flow.

Description

Technical Field

[0001] The present invention relates to the field of chromatographic detection, and particularly to a chromatographic pump and a control method thereof. Background Art

[0002] Ion chromatographs are widely used analytical instruments. By utilizing the differences in the physical and chemical properties of the components in the mixture to be separated, they separate the components to different extents in the mobile phase and the stationary phase, and then conduct quantitative analysis on the separated components. Whether the flow rate of the mobile phase (solvent) is constant and whether the pressure pulsation of the system is stable directly affect the detection results of the liquid chromatograph. Therefore, it is necessary to ensure that the infusion pump system provides a stable pressure and a constant flow rate.

[0003] During the actual use of the infusion pump, the composition of the mobile phase often changes, and even the viscosity and compressibility of the mobile phase change over time. Different solvents have different compression factors, and the degree of volume compression of the solvent is related to its specific compression factor. The volume compression caused by the change in pressure is also different. Therefore, in this case, the change in the pulsation rate cannot be predicted and is not subjectively controllable, and its role in practical applications is very limited.

[0004] When the infusion pump transports the solvent from the solvent bottle to the chromatographic column, the pressure of the solvent rises from one atmosphere to dozens of megapascals. The increase in pressure causes the compression of the solvent volume, resulting in the instability of the solvent (mobile phase) flow rate and pressure.

[0005] The flow pulsation of the infusion pump is caused by the switching of the liquid discharge and liquid suction of the plunger rod, and different mobile phases show different pressure pulsations, which are caused by the compression amount of the fluid, viscosity deviation, and mechanical movement cam wear.

[0006] The flow pulsation rate of the pump gradually decreases as the pressure increases. During the process of the liquid being compressed and released in the pump chamber, due to the compressibility and viscosity of the solid fluid, it will have a certain buffering effect on the flow pressure pulsation and will generate a certain pressure fluctuation. This fluctuation is particularly obvious in cam pumps, resulting in unstable output flow rate of the liquid chromatographic pump, and further affecting the qualitative or quantitative repeatability of chromatography. Usually, cam curve correction is used in chromatographic pumps for pulsation compensation, but this will lead to an increase in processing complexity and cost. Summary of the Invention

[0007] In order to solve the above deficiencies in the prior art, the purpose of the present invention is to provide a chromatographic pump and a control method thereof.

[0008] The technical solution adopted by the present invention to solve its technical problems is: a chromatographic pump, comprising a plunger system, a liquid cylinder system, a pressure detection system, and a control system;

[0009] The plunger system includes a plunger cylinder block and a plunger rod installed in the plunger cylinder block. A magnetorheological damping piston rod is also installed in the plunger cylinder block. The magnetorheological damping piston rod is connected to the plunger rod. Moreover, magnetorheological fluid is provided in the plunger cylinder block, and a magnetic excitation coil is installed on the inner wall of the plunger cylinder block.

[0010] The control system includes a microcontroller, which is provided with an electromagnetic drive unit, a data receiving unit, a data processing unit, and a data output unit. The electromagnetic drive unit is connected to the magnetic excitation coil.

[0011] The pressure detection system is connected to the data receiving unit. The pressure detection system is arranged at the output end of the hydraulic cylinder system. The pressure detection system collects the output pressure data of the hydraulic cylinder system and transmits the collected data to the data receiving unit. After receiving the output pressure data transmitted by the pressure detection system, the data receiving unit transmits the output pressure data to the data processing unit for processing. After being processed by the data processing unit, an adjustment signal is output to the data output unit. The data output unit outputs an adjustment signal to the electromagnetic drive unit, and the electromagnetic drive unit outputs a current according to the adjustment signal.

[0012] The hydraulic cylinder system is connected to the output end of the plunger system.

[0013] Optionally, the hydraulic cylinder system includes a first hydraulic cylinder and a second hydraulic cylinder, and the first hydraulic cylinder is connected in series with the second hydraulic cylinder.

[0014] The plunger system includes a first plunger system and a second plunger system. The output end of the first plunger system is connected to the first hydraulic cylinder, and the output end of the second plunger system is connected to the second hydraulic cylinder. Moreover, a first one-way valve and a second one-way valve are respectively installed at both ends of the first hydraulic cylinder. Among them, the first one-way valve is a one-way inlet valve, and the second one-way valve is a one-way outlet valve.

[0015] Optionally, the pressure detection system is arranged at the output end of the second hydraulic cylinder. The pressure detection system collects the output pressure data of the second hydraulic cylinder and converts the output pressure data of the second hydraulic cylinder into an electrical signal.

[0016] The pressure detection system outputs the converted electrical signal to the data receiving unit.

[0017] Optionally, after receiving the electrical signal output by the pressure detection system, the data receiving unit preprocesses the electrical signal. The preprocessing steps are as follows:

[0018] Signal conditioning: Amplify, filter, and offset-adjust the received electrical signal.

[0019] Digital conversion: Convert the conditioned electrical signal into a digital signal.

[0020] Optionally, the processing steps of the data processing unit are as follows:

[0021] Data acquisition: Receive the digital signal after digital conversion;

[0022] Signal filtering: Perform digital filtering on the converted digital signal;

[0023] Pressure calculation: Convert the digital signal into the actual pressure value;

[0024] Control signal generation: Generate a PWM signal according to the difference between the actual pressure value and the set pressure value, and transmit the PWM signal to the electromagnetic drive unit.

[0025] Optionally, the electromagnetic drive unit adjusts the output current according to the duty cycle of the PWM signal output by the data processing unit.

[0026] Based on the above technical solutions, the present invention also provides a control method for a chromatographic pump. The output pressure of the chromatographic pump is regulated by a pressure detection system and a microcontroller. The microcontroller is provided with an electromagnetic drive unit, a data receiving unit, a data processing unit, and a data output unit. The steps for regulating the output pressure of the chromatographic pump are as follows:

[0027] Obtain the output pressure data at the output end of the chromatographic pump through the pressure detection system, and transmit the collected data to the data receiving unit;

[0028] After receiving the output pressure data transmitted by the pressure detection system, the data receiving unit transmits the output pressure data to the data processing unit for processing;

[0029] After being processed by the data processing unit, an adjustment signal is output to the data output unit;

[0030] The data output unit outputs an adjustment signal to the electromagnetic drive unit, and the electromagnetic drive unit outputs a current according to the adjustment signal.

[0031] Optionally, after receiving the electrical signal output by the pressure detection system, the data receiving unit preprocesses the electrical signal. The steps of the preprocessing are as follows:

[0032] Signal conditioning: Amplify, filter, and offset-adjust the received electrical signal;

[0033] Digital conversion: Convert the conditioned electrical signal into a digital signal.

[0034] Optionally, the processing steps of the data processing unit are as follows:

[0035] Data acquisition: Receive the digital signal after digital conversion;

[0036] Signal filtering: Perform digital filtering on the converted digital signal;

[0037] Pressure calculation: Convert the digital signal into the actual pressure value;

[0038] Control signal generation: Generate a PWM signal according to the difference between the actual pressure value and the set pressure value, and deliver the PWM signal to the electromagnetic drive unit.

[0039] Optionally, the electromagnetic drive unit adjusts the output current according to the duty cycle of the PWM signal output by the data processing unit.

[0040] Adopting the above technical solution, the present invention monitors the output pressure of the chromatographic pump in real time through the pressure detection system, compares the monitored pressure signal with the set value, calculates the difference, and according to the difference, the microcontroller adjusts the current intensity, thereby changing the magnetic field intensity. The magnetorheological fluid damper then changes its viscosity according to the change of the magnetic field intensity, so as to realize the compensation of the pump output pressure. Through closed-loop control, the chromatographic pump of the present invention can adjust the viscosity of the magnetorheological fluid in real time to ensure a constant pressure and accurate flow rate of the pump output. Description of the Drawings

[0041] Figure 1 is a schematic structural diagram of the system of the present invention. Detailed Embodiments

[0042] The following further describes the present application in detail with reference to the drawings and embodiments. It can be understood that the specific embodiments described herein are only used to explain the related invention, rather than limiting the invention. Additionally, it should be noted that for the sake of description, only the parts related to the invention are shown in the drawings.

[0043] It should be noted that, without conflict, the embodiments in the present application and the features in the embodiments can be combined with each other. The following will describe the present application in detail with reference to the drawings and embodiments.

[0044] As Figure 1 shown, the present invention discloses a chromatographic pump, which includes a structural part and a control part. Among them, the structural part includes a plunger system and a cylinder system, and the control part includes a pressure detection system and a control system. The control part is connected to the plunger system, and precisely controls the movement speed and displacement of the plunger rod in the plunger system by adjusting parameters such as the current magnitude and energization duration of the plunger system.

[0045] In the structural part, the plunger system includes a plunger cylinder 1 and a plunger rod installed in the plunger cylinder 1. A magnetorheological damper piston rod 2 is also installed in the plunger cylinder 1. The magnetorheological damper piston rod 2 is connected to the plunger rod, and magnetorheological fluid is provided in the plunger cylinder 1. A magnetic excitation coil is installed on the inner wall of the plunger cylinder 1. The magnetic excitation coil can generate a magnetic field after being energized, and the intensity of the magnetic field can adjust the viscosity of the magnetorheological fluid, thereby adjusting the damping effect of the magnetorheological fluid.

[0046] In the present invention, a chromatographic pump generally includes two sets of plunger systems, where one set of plunger system serves as the main pump and the other set of plunger system serves as the auxiliary pump, and the main pump and the auxiliary pump alternately and cyclically extract the mobile phase. Therefore, the plunger system of the present invention includes a first plunger system and a second plunger system. Correspondingly, the liquid cylinder system also includes a first liquid cylinder 3 and a second liquid cylinder 4. The first liquid cylinder 3 and the second liquid cylinder 4 are connected in series. The output end of the first plunger system is connected to the first liquid cylinder 3, and the output end of the second plunger system is connected to the second liquid cylinder 4. And a first one-way valve 5 and a second one-way valve 6 are respectively installed at both ends of the first liquid cylinder 3. Among them, the first one-way valve 5 is a one-way inlet valve, and the second one-way valve 6 is a one-way outlet valve.

[0047] In the control part, the pressure detection system includes a pressure collector 7. The pressure collector 7 is arranged at the output end of the second liquid cylinder 4 and is used for collecting the output pressure of the second liquid cylinder 4. At the same time, the pressure collector 7 is connected to the control system 8 and is used for outputting the collected pressure data to the control system 8.

[0048] In the present invention, the control system 8 includes a microcontroller. The microcontroller is provided with an electromagnetic drive unit, a data receiving unit, a data processing unit and a data output unit. The electromagnetic drive unit is connected to the magnetic excitation coil. Among them, the pressure collector 7 is connected to the data receiving unit and transmits the collected data to the data receiving unit. After receiving the output pressure data transmitted by the pressure collector 7, the data receiving unit transmits the output pressure data to the data processing unit for processing. After being processed by the data processing unit, an adjustment signal is output to the data output unit. The data output unit outputs an adjustment signal to the electromagnetic drive unit, and the electromagnetic drive unit outputs a current according to the adjustment signal.

[0049] The electromagnetic drive system includes an electromagnetic component one and an electromagnetic component two. The electromagnetic component one and the electromagnetic component two are respectively installed with an electromagnetic positioning device one and an electromagnetic positioning device two. The electromagnetic component one is connected to the magnetorheological damping piston rod of the first plunger system, and the electromagnetic component two is connected to the magnetorheological damping piston rod of the second plunger system. The magnetorheological damping piston rod drives the first plunger system and the second plunger system to perform alternating reciprocating motions respectively under the drive of the electromagnetic component one and the electromagnetic component two.

[0050] The pressure collector 7 can collect the pressure data at the output end of the second liquid cylinder 4 in real time and feed the pressure data back to the control system 8. When the pressure data is different from the set value, the control system changes the current in the magnetic excitation coil, thereby changing the magnetic field intensity. After the magnetorheological fluid senses the change in the magnetic induction intensity, its compression or tensile modulus and shear modulus will increase rapidly. The time for the entire change process is several milliseconds. The magnetorheological damping piston rod makes a reverse damping movement under the action of the magnetic field, compensating for the pressure, so that the pressure of the mobile phase in the chromatographic pump system is maintained at a constant value. Through this closed-loop control, the chromatographic pump system can adjust the viscosity of the magnetorheological fluid in real time to ensure that the chromatographic pump outputs a constant pressure. In the present invention, the magnetorheological fluid has a two-way damping effect, that is, adjustable damping forces of different magnitudes and directions can be generated during the pushing and pulling processes of the magnetorheological damping piston rod, so that the pressure pulsation is instantaneously compensated.

[0051] The following will make a detailed description of the data feedback and output process of the control part of the present invention.

[0052] S1. The pressure collector 7 collects the output pressure data of the second liquid cylinder 4, converts the output pressure data of the second liquid cylinder into an electrical signal, and then the pressure collector 7 outputs the converted electrical signal to the data receiving unit.

[0053] S2. After receiving the electrical signal output by the pressure collector 7, the data receiving unit preprocesses the electrical signal. Among them, the content of the preprocessing includes:

[0054] S21. Signal conditioning: Amplify, filter, and offset-adjust the received electrical signal;

[0055] S22. Digital conversion: Convert the conditioned electrical signal into a digital signal through the A / D conversion module.

[0056] Through the above preprocessing process, it is ensured that the signal is within the A / D conversion input range of the microcontroller and the noise interference is reduced.

[0057] S3. The data receiving unit transports the preprocessed data to the data processing unit for processing. The processing steps of the data processing unit are as follows:

[0058] S31. Data acquisition: Receive the digital signal after digital conversion.

[0059] S32. Signal filtering: Numerically filter the converted digital signal to further reduce noise

[0060] S33. Pressure calculation: Convert the digital signal into an actual pressure value according to the characteristics and calibration data of the pressure collector 7.

[0061] S34. Control signal generation: Generate a PWM signal according to the difference between the actual pressure value and the set pressure value, and deliver the PWM signal to the electromagnetic drive unit.

[0062] S4. The electromagnetic drive unit adjusts the output current according to the duty cycle of the PWM signal output by the data processing unit and the control strategy of the current regulator. The current regulator usually features fast response and stable output, and can ensure that the output current is proportional to the duty cycle of the PWM signal.

[0063] The above description is only the preferred embodiment of the present application and the explanation of the applied technical principles. Those skilled in the art should understand that the scope of the invention involved in the present application is not limited to the technical solution formed by the specific combination of the above technical features, and should also cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the inventive concept. For example, the technical solutions formed by mutually replacing the above features with the technical features (but not limited to) having similar functions disclosed in the present application.

[0064] Except for the technical features described in the specification, the remaining technical features are known to those skilled in the art. To highlight the innovative features of the present invention, the remaining technical features will not be elaborated herein.

Claims

1. A chromatographic pump, characterized in that, It includes a plunger system, a hydraulic cylinder system, a pressure detection system, and a control system; The plunger system includes a plunger cylinder block and a plunger rod installed in the plunger cylinder block. A magnetorheological damping piston rod is also installed in the plunger cylinder block. The magnetorheological damping piston rod is connected to the plunger rod. Moreover, magnetorheological fluid is provided in the plunger cylinder block, and a magnetic excitation coil is installed on the inner wall of the plunger cylinder block; The control system includes a microcontroller, which is provided with an electromagnetic drive unit, a data receiving unit, a data processing unit, and a data output unit. The electromagnetic drive unit is connected to the magnetic excitation coil; The pressure detection system is connected to the data receiving unit. The pressure detection system is arranged at the output end of the hydraulic cylinder system. The pressure detection system collects the output pressure data of the hydraulic cylinder system and transmits the collected data to the data receiving unit. After receiving the output pressure data transmitted by the pressure detection system, the data receiving unit transmits the output pressure data to the data processing unit for processing. After the data processing unit processes it, it outputs an adjustment signal to the data output unit. The data output unit outputs an adjustment signal to the electromagnetic drive unit, and the electromagnetic drive unit outputs a current according to the adjustment signal; The hydraulic cylinder system is connected to the output end of the plunger system.

2. The chromatographic pump according to claim 1, wherein The hydraulic cylinder system includes a first hydraulic cylinder and a second hydraulic cylinder, and the first hydraulic cylinder and the second hydraulic cylinder are connected in series; The plunger system includes a first plunger system and a second plunger system. The output end of the first plunger system is connected to the first hydraulic cylinder, and the output end of the second plunger system is connected to the second hydraulic cylinder. Moreover, a first one-way valve and a second one-way valve are respectively installed at both ends of the first hydraulic cylinder. Among them, the first one-way valve is a one-way inlet valve, and the second one-way valve is a one-way outlet valve.

3. The chromatographic pump according to claim 2, characterized in that, The pressure detection system is arranged at the output end of the second hydraulic cylinder. The pressure detection system collects the output pressure data of the second hydraulic cylinder and converts the output pressure data of the second hydraulic cylinder into an electrical signal; The pressure detection system outputs the converted electrical signal to the data receiving unit.

4. The chromatographic pump according to claim 3, wherein After receiving the electrical signal output by the pressure detection system, the data receiving unit performs preprocessing on the electrical signal. The steps of the preprocessing are as follows: Signal conditioning: Amplify, filter, and offset-adjust the received electrical signal; Digital conversion: Convert the conditioned electrical signal into a digital signal.

5. The chromatographic pump according to claim 4, characterized in that, The processing steps of the data processing unit are as follows: Data acquisition: Receive the digital signal after digital conversion; Signal filtering: Perform digital filtering on the converted digital signal; Pressure calculation: Convert the digital signal into an actual pressure value; Control signal generation: Generate a PWM signal according to the difference between the actual pressure value and the set pressure value, and transmit the PWM signal to the electromagnetic drive unit.

6. The chromatographic pump according to claim 5, characterized in that, The electromagnetic drive unit adjusts the output current according to the duty cycle of the PWM signal output by the data processing unit.

7. A control method for a chromatographic pump, characterized in that, The output pressure of the chromatographic pump is regulated by the pressure detection system and the microcontroller. The microcontroller is provided with an electromagnetic drive unit, a data receiving unit, a data processing unit, and a data output unit. The steps for regulating the output pressure of the chromatographic pump are as follows: Obtain the output pressure data at the output end of the chromatographic pump through the pressure detection system, and transmit the collected data to the data receiving unit; After receiving the output pressure data transmitted by the pressure detection system, the data receiving unit transmits the output pressure data to the data processing unit for processing; After being processed by the data processing unit, an adjustment signal is output to the data output unit; The data output unit outputs an adjustment signal to the electromagnetic drive unit, and the electromagnetic drive unit outputs a current according to the adjustment signal.

8. The control method of the chromatographic pump according to claim 7, characterized in that, After receiving the electrical signal output by the pressure detection system, the data receiving unit preprocesses the electrical signal. The steps of the preprocessing are as follows: Signal conditioning: Amplify, filter, and offset-adjust the received electrical signal; Digital conversion: Convert the conditioned electrical signal into a digital signal.

9. The control method of the chromatographic pump according to claim 8, wherein, The processing steps of the data processing unit are as follows: Data acquisition: Receive the digital signal after digital conversion; Signal filtering: Perform digital filtering on the converted digital signal; Pressure calculation: Convert the digital signal into an actual pressure value; Control signal generation: Generate a PWM signal according to the difference between the actual pressure value and the set pressure value, and transmit the PWM signal to the electromagnetic drive unit.

10. The control method of the chromatographic pump according to claim 9, characterized in that, The electromagnetic drive unit adjusts the output current according to the duty cycle of the PWM signal output by the data processing unit.

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