Liquid chromatograph proportional valve control method and system

Abstract

The invention belongs to the technical field of automatic control, and relates to a liquid chromatograph proportional valve control method and system. The method comprises the steps that the opening time and the closing time of each electromagnetic valve in the proportional valve are controlled by adjusting current, so that the opening time of each electromagnetic valve is the same, and the closing time of each electromagnetic valve is the same; the opening current and the holding current are used for driving each electromagnetic valve, and open circuit detection, over-current detection and over-temperature detection are carried out at the same time; through point inspection preventive inspection, when the characteristics of the proportional valve change, the current of the proportional valve is readjusted. According to the invention, the difference between different batches and the difference between different electromagnetic valves of the same proportional valve can be tolerated. The method can also reduce the power of the proportional valve, prolong the service life of the proportional valve, monitor the actual state of the proportional valve and give an alarm in real time.

Description

Technical Field

[0001] The present invention relates to the field of automation control technology, and in particular to a liquid chromatograph proportional valve control method and system. Background Art

[0002] A liquid chromatograph utilizes the principle of chromatographic separation. A high-pressure infusion pump pushes the mobile phase into the system, an injector injects the sample solution into the mobile phase, separation occurs on the chromatographic column, and the detector analyzes the components. The proportional valve in the pump controls the ratio of multiple mobile phases, and the accuracy of the mixing ratio affects the overall test results.

[0003] The traditional control method is voltage control, and the specific control waveform is as follows: Figure 2 As shown. After a period of high level (opening voltage) is maintained and the valve is completely opened, a PWM waveform (holding voltage) is generated to maintain the valve state. ac is the opening time, T fm is the off-time. Experimental verification shows that a higher on-voltage leads to a shorter on-time, while a higher holding voltage leads to a longer off-time. Therefore, traditional voltage control methods cannot accurately control the on-time and off-time of solenoid valves. A current-driven proportional valve control method is needed. Summary of the Invention

[0004] In response to the above technical problems, a method and system for controlling a proportional valve of a liquid chromatograph is provided. The present invention mainly utilizes a spot inspection unit and a control unit to control the opening current and holding current of the solenoid valve through current drive, thereby controlling the opening time and closing time of the solenoid valve.

[0005] The technical means adopted in the present invention are as follows:

[0006] A method for controlling a proportional valve of a liquid chromatograph, comprising:

[0007] By adjusting the current, the opening time and closing time of each solenoid valve in the proportional valve are controlled so that the opening time of each solenoid valve is the same and the closing time of each solenoid valve is the same;

[0008] The opening current and holding current are used to drive each solenoid valve, and open circuit detection, overcurrent detection and overtemperature detection are performed at the same time;

[0009] During preventive inspections, if the proportional valve characteristics change, readjust the proportional valve current.

[0010] Furthermore, the opening and closing of the proportional valve is controlled by current driving.

[0011] Furthermore, the control of the opening time and closing time of each solenoid valve in the proportional valve by adjusting the current specifically includes:

[0012] By adjusting the turn-on current I d , control the opening time T of each solenoid valve a Same; by adjusting the holding current I ef , control the closing time T of each solenoid valve b The same, so that the opening time T a ≥ Turn-off time T b , record the opening current, holding current, opening time and closing time of each solenoid valve, and calculate the delay time T a -T b Furthermore, the on-time and off-time of each solenoid valve driven by the on-current and the holding current specifically include:

[0013] The opening current, holding current, opening time, closing time and delay time of each solenoid valve recorded in the adjustment results are analyzed, and the proportional valve is driven according to the control signal received. The control signal is used to control the opening current, holding current and delay time of the solenoid valve; whether the solenoid valve is working is judged based on the actual current situation.

[0014] Furthermore, when the characteristics of the proportional valve change, each solenoid valve in the proportional valve is readjusted, and the holding current and opening current of the solenoid valve and the delay time are readjusted to control the opening time and closing time of the solenoid valve so that the proportional valve can work normally.

[0015] The present invention also provides a liquid chromatograph proportional valve control system based on the liquid chromatograph proportional valve control method, comprising: a spot inspection unit and a control unit;

[0016] The spot inspection unit is used to control the opening time and closing time of each solenoid valve in the proportional valve by adjusting the current when it is used for the first time, so that the opening time of each solenoid valve is the same and the closing time of each solenoid valve is the same; through preventive inspection, when the characteristics of the proportional valve change, the current of the proportional valve is readjusted.

[0017] The control unit is used to drive each solenoid valve using the opening current, holding current, and delay time recorded by the spot inspection unit, and simultaneously perform open circuit detection, overcurrent detection, and overtemperature detection. Compared with the prior art, the present invention has the following advantages:

[0018] The present invention provides a method and system for controlling a proportional valve in a liquid chromatograph. Using a spot inspection unit and a control unit, the system controls the holding current and opening current of the solenoid valve through current drive, thereby controlling the valve's opening and closing times. This method can tolerate differences between batches and between different solenoid valves within the same proportional valve. Furthermore, the method reduces the power consumption of the proportional valve, extending its lifespan, and monitors the valve's actual status, providing real-time alarms.

[0019] Based on the above reasons, the present invention can be widely promoted in fields such as automation control. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0021] Figure 1 This is a flow chart of the liquid chromatograph proportional valve control method of the present invention.

[0022] Figure 2 This is a waveform diagram of the voltage control method in the prior art.

[0023] Figure 3 This is a pipeline connection diagram of a liquid chromatograph in the prior art.

[0024] Figure 4 This is a schematic diagram of the structure of a quaternary pump using a proportional valve in the prior art.

[0025] Figure 5 It is a schematic diagram of the structure of the proportional valve control system of the liquid chromatograph in the present invention.

[0026] Figure 6 Schematic diagram of the turn-on current, holding current, turn-on time, and turn-off time in the present invention.

[0027] Figure 7 Schematic diagram of control time and actual time in an embodiment of the present invention.

[0028] Figure 8 This is a schematic diagram of the control time and compensation time for reducing the alternation time in an embodiment of the present invention. DETAILED DESCRIPTION

[0029] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments of the present invention can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0030] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is in no way intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0031] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0032] Unless otherwise specified, the relative arrangement of the parts and steps, numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present invention. At the same time, it should be clear that, for ease of description, the sizes of the various parts shown in the accompanying drawings are not drawn according to actual proportional relationships. The technology, methods and equipment known to those of ordinary skill in the relevant art may not be discussed in detail, but in appropriate cases, the technology, methods and equipment should be considered as a part of the specification. In all examples shown and discussed here, any specific value should be interpreted as being merely exemplary, rather than as a limitation. Therefore, other examples of the exemplary embodiments can have different values. It should be noted that similar numbers and letters represent similar items in the following drawings, and therefore, once an item is defined in an accompanying drawing, it does not need to be further discussed in subsequent drawings.

[0033] like Figure 1 As shown, the present invention provides a liquid chromatograph proportional valve control method, comprising:

[0034] Control the opening and closing of the proportional valve, and perform open circuit detection, overcurrent detection and overtemperature detection;

[0035] In specific implementation, as a preferred embodiment of the present invention, a current driving method is adopted to control the opening and closing of the proportional valve.

[0036] By adjusting the current, the opening time and closing time of each solenoid valve in the proportional valve are controlled so that the opening time of each solenoid valve is the same and the closing time of each solenoid valve is the same;

[0037] In a specific implementation, as a preferred embodiment of the present invention, the closing time and opening time of each solenoid valve in the proportional valve are controlled by adjusting the current, specifically including:

[0038] By adjusting the turn-on current I d , control the opening time T of each solenoid valve a Same; by adjusting the holding current I ef , control the closing time T of each solenoid valve b The same, so that the opening time T a ≥ Turn-off time T b , record the opening current, holding current, opening time and closing time of each solenoid valve, and calculate the delay time T a -T b During implementation, if the on-time or off-time cannot be guaranteed to be exactly the same, the control error range is within milliseconds.

[0039] Use the opening current and holding current to drive the opening time and closing time of each solenoid valve;

[0040] In specific implementation, as a preferred embodiment of the present invention, the opening time and closing time of each solenoid valve are driven by the opening current and the holding current, specifically including:

[0041] Analyze the opening current, holding current, opening time, closing time and delay time of each solenoid valve recorded in the adjustment results, and drive the proportional valve according to the control signal received. The control signal is used to control the opening current, holding current and delay time of the solenoid valve; judge whether the solenoid valve is working based on the actual current situation.

[0042] During preventive inspections, if the proportional valve characteristics change, readjust the proportional valve current.

[0043] In specific implementation, as a preferred embodiment of the present invention, when the characteristics of the proportional valve change, each solenoid valve in the proportional valve is readjusted, and the proportional valve is made to work normally by readjusting the opening current, holding current and delay time of the solenoid valve.

[0044] The present invention also includes a liquid chromatograph proportional valve control system based on the liquid chromatograph proportional valve control method, comprising: a spot inspection unit and a control unit;

[0045] When the spot inspection unit is used for the first time, it controls the opening time and closing time of each solenoid valve in the proportional valve by adjusting the current, so that the opening time of each solenoid valve is the same and the closing time of each solenoid valve is the same; through preventive inspection, when the characteristics of the proportional valve change, the current of the proportional valve is readjusted.

[0046] The control unit is used to drive each solenoid valve using the opening current, holding current and delay time recorded by the inspection unit, and simultaneously perform open circuit detection, overcurrent detection and overtemperature detection, and issue an alarm when the proportional valve is in an abnormal working state.

[0047] Example

[0048] like Figure 2 As shown in FIG, the voltage control method used in the prior art cannot accurately control the opening and closing time of the solenoid valve. Figure 3 As shown in the figure, the high-pressure infusion pump pushes the mobile phase into the system, the injector injects the sample solution into the mobile phase, the chromatographic column forms a separation, and the detector performs the analysis of each component. The control of the proportional valve affects the ratio of the multi-channel mobile phase, such as Figure 4 The structure of the proportional valve control system of the liquid chromatograph in the present invention is as shown in FIG. Figure 5 As shown, the method of the present invention uses the current of the controlled proportional valve to accurately control the opening time and closing time of the solenoid valve.

[0049] In order to make the opening time of the solenoid valve and the opening time of the control valve the same, the control unit needs to delay (T1a-T1b) before shutting down after receiving the shut-off signal. If T1a=T1b, no delay compensation is required. Figure 7 For example, T1a is the opening time of chA, and T1b is the closing time of chA. In order to reduce the vacuum time when the two valves are alternating, it is required that T1a = T2a, where T2a is the opening time of chB, that is, the opening time of the two valves must be equal, such as Figure 8 shown.

[0050] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A liquid chromatograph proportional valve control method, characterized in that: include: By adjusting the current, the opening time and closing time of each solenoid valve in the proportional valve are controlled so that the opening time of each solenoid valve is the same and the closing time of each solenoid valve is the same; The opening current and holding current are used to drive each solenoid valve, and open circuit detection, overcurrent detection and overtemperature detection are performed at the same time; During preventive inspections, if the proportional valve characteristics change, readjust the proportional valve current.

2. The liquid chromatograph proportional valve control method according to claim 1, characterized in that: The opening and closing of the proportional valve is controlled by a current driving method.

3. The liquid chromatograph proportional valve control method according to claim 1, characterized in that: The method of controlling the opening and closing time of each solenoid valve in the proportional valve by adjusting the current specifically includes: By adjusting the turn-on current I d , control the opening time T of each solenoid valve a Same; by adjusting the holding current I ef , control the closing time T of each solenoid valve b The same, so that the opening time T a ≥ Turn-off time T b , and record the opening current, holding current, opening time and closing time of each solenoid valve, and calculate the delay time T a -T b .

4. The liquid chromatograph proportional valve control method according to claim 1, characterized in that: The use of the opening current and the holding current to drive the opening time and the closing time of each solenoid valve specifically includes: The opening current, holding current, opening time, closing time and delay time of each solenoid valve recorded in the adjustment results are analyzed, and the proportional valve is driven according to the control signal received. The control signal is used to control the opening current, holding current and delay time of the solenoid valve; whether the solenoid valve is working is judged based on the actual current situation.

5. The liquid chromatograph proportional valve control method according to claim 1, characterized in that: When the characteristics of the proportional valve change, each solenoid valve in the proportional valve is readjusted, and the opening current and holding current of the solenoid valve and the delay time are readjusted to control the opening time and closing time of the solenoid valve so that the proportional valve can work normally.

6. A liquid chromatograph proportional valve control system implemented based on the liquid chromatograph proportional valve control method according to any one of claims 1 to 5, characterized in that: include: Inspection unit and control unit; When the spot inspection unit is used for the first time, it controls the opening time and closing time of each solenoid valve in the proportional valve by adjusting the current, so that the opening time of each solenoid valve is the same and the closing time of each solenoid valve is the same; During preventive inspections, if the proportional valve characteristics change, readjust the proportional valve current. The control unit is used to drive each solenoid valve using the opening current, holding current and delay time recorded by the inspection unit, and simultaneously perform open circuit detection, overcurrent detection and overtemperature detection, and issue an alarm when the proportional valve is in an abnormal working state.

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