A quantitative sampling switching valve and a sampling method thereof

Abstract

The application relates to the technical field of valve bodies, in particular to a quantitative sampling switching valve and a sampling method thereof, which comprise a valve head and a shell. The switching valve comprises the valve head and a driving assembly, the valve head comprises a fixed piece and a movable piece which are oppositely arranged and form sealing fitting surfaces. The fixed piece is provided with a first connecting channel, a second connecting channel, a third connecting channel and a fourth connecting channel, and the side of the fixed piece facing the movable piece is provided with a first communication groove and a second communication groove; the side of the movable piece facing the fixed piece is provided with three circumferentially spaced quantitative material storage grooves. The application can improve the detection flux per unit time, reduce pressure pulsation in the switching process, reduce liquid and bubble interference, and improve sampling repeatability and quantitative accuracy.

Description

Technical Field

[0001] This invention relates to the field of valve technology, and more specifically, to a quantitative injection switching valve. Background Technology

[0002] In high-performance liquid chromatography (HPLC), online sample analysis, and high-pressure fluid delivery systems, switching valves are crucial components for sample introduction, quantitative storage, flow path switching, and delivery to the analytical apparatus. Existing switching valves typically use a drive mechanism to rotate a moving plate relative to a stationary plate, altering the fluid connectivity between different channels to complete sample loading and unloading.

[0003] However, existing solutions often still have the following problems in practical applications:

[0004] First, traditional switching valves often employ a single sample loading position alternating with a single sample discharging position, or rely on external quantitative structures for sample injection. This makes it difficult to simultaneously achieve sample filling and discharging, resulting in a discontinuous connection between the injection and detection processes, significant switching gaps in the system, and limited effective detection throughput per unit time. Second, during high-pressure flow path switching, if a significant pressure difference exists between the two working loops to be switched, pressure shocks and flow disturbances can easily occur at the moment the valve core rotates, further leading to bubble generation, flow path instability, peak shape deterioration, and decreased sample quantitative accuracy. Third, in existing structures, the flow paths used for switching are mostly instantaneously open and closed. When the valve position switches, local dead volumes, discontinuous conduction, or cross-contamination can easily occur between the sample chamber, flow path groove, and connecting channels, which is detrimental to high repeatability and high-precision analysis. Fourth, in high-throughput continuous analysis scenarios, the valve core is in a high-frequency switching state for extended periods, gradually exacerbating wear on the dynamic and static sealing surfaces, sample residue, and flow path contamination. If the structural design cannot take into account wear resistance, sealing and continuous conduction characteristics, it will be difficult to maintain stable analytical performance under long-term operation. Summary of the Invention

[0005] The purpose of this invention is to provide a quantitative injection switching valve and its injection method to at least solve the following problems existing in the prior art: sample filling and sample discharge cannot be performed simultaneously, resulting in low detection throughput; pressure pulsation and fluid shock are easily generated during high-pressure flow path switching, affecting injection stability and quantitative accuracy; and cross-contamination, bubbles or sample residue are easily generated during flow path switching, affecting analytical repeatability.

[0006] The present invention adopts the following solution:

[0007] A quantitative injection switching valve includes a valve head and a drive assembly for switching the valve head. The valve head includes a fixed plate and a movable plate that are disposed opposite to each other and form a sealing mating surface; wherein:

[0008] The fixed plate is provided with a first connecting channel, a second connecting channel, a third connecting channel and a fourth connecting channel inside, and a first connecting groove and a second connecting groove are provided on the side of the fixed plate facing the moving plate. The two ends of the first connecting groove are respectively connected to the first connecting channel and the second connecting channel, and the two ends of the second connecting groove are respectively connected to the third connecting channel and the fourth connecting channel.

[0009] The moving plate has three quantitative storage slots on the side facing the fixed plate, and the three quantitative storage slots are arranged at intervals along the circumference of the moving plate.

[0010] The circumferential positions of the first connecting groove and the second connecting groove relative to the three quantitative storage grooves are configured such that, in any stable working phase of the rotation of the moving plate relative to the fixed plate, one of the three quantitative storage grooves is connected to the first connecting groove to form a filling station, another is connected to the second connecting groove to form a sorting station, and the remaining one is not connected to either the first connecting groove or the second connecting groove to form a transition station.

[0011] Furthermore, after the moving plate rotates through a predetermined angle, the three quantitative storage tanks alternate sequentially between the filling station, the discharging station, and the transition station, so that the switching valve can achieve a synchronous working state of filling a certain amount of storage tank and discharging another quantitative storage tank during operation.

[0012] The second and third connection channels are configured to be connected to pressure fluids with the same pressure or with a pressure difference within a preset range, so that the quantitative storage tank is in a pressure balance switching state during the process of switching from the filling station to the dispensing station.

[0013] Furthermore, the first connection channel is used to connect to the sample input source, and the fourth connection channel is used to connect to the analysis device; the second connection channel and the third connection channel are configured to be connected to pressure fluids with the same pressure or with a pressure difference within a preset range, so that the quantitative storage tank is in a pressure balance switching state during the process of switching from the filling station to the discharging station.

[0014] Furthermore, the three quantitative storage tanks are distributed at equal angular intervals along the circumference of the moving plate, and the included angle between two adjacent quantitative storage tanks is 120°.

[0015] Furthermore, the three quantitative storage tanks have the same tank depth, tank width, and effective volume, so that the three quantitative storage tanks maintain the same quantitative injection volume during rotation.

[0016] Furthermore, the first connecting groove and the second connecting groove are respectively arc-shaped grooves with asymmetrical volumes, and their respective arc lengths cover the center distance between the openings of the two connecting channels they connect.

[0017] Furthermore, the bottom of the first connecting groove is provided with a first inclined surface, and the bottom of the second connecting groove is provided with a second inclined surface; the first inclined surface makes the groove space on the side of the first connecting groove closer to the first connecting channel larger than the groove space on the side closer to the second connecting channel, and the second inclined surface makes the groove space on the side of the second connecting groove closer to the fourth connecting channel larger than the groove space on the side closer to the third connecting channel, so that the local conductive volume of the quantitative storage groove gradually changes along the switching direction when entering and leaving the corresponding workstation.

[0018] Furthermore, the fixed plate is provided with a pre-balancing flow channel that communicates with the second connecting groove. The pre-balancing flow channel is located between the transition station and the sample dispensing station, and is used to ensure that the quantitative storage tank transferred from the filling station to the sample dispensing station is first connected to the high-pressure side fluid in a controlled manner before being fully connected with the second connecting groove, so as to perform pressure pre-balancing.

[0019] Furthermore, the pre-balancing flow channel is an auxiliary connecting groove disposed on the side of the fixed plate facing the moving plate. One end of the auxiliary connecting groove is connected to the second connecting groove, and the other end is located in the circumferential area corresponding to the transition station. The equivalent conducting cross-sectional area of ​​the pre-balancing flow channel is smaller than the equivalent conducting cross-sectional area of ​​the second connecting groove, so that the quantitative storage tank completes pressure pre-balancing through controlled flow restriction before entering the sampling station.

[0020] Furthermore, the transition station is a necessary station in the process of switching the quantitative storage tank from the filling station to the discharging station. It is located between the filling station and the discharging station. The quantitative storage tank in the transition station is isolated from both the first connecting tank and the second connecting tank to reduce cross-contamination and liquid mixing between adjacent stations.

[0021] The present invention also provides a method for quantitative injection using the aforementioned quantitative injection switching valve, comprising the following steps:

[0022] S1. Connect the first quantitative storage tank to the first connecting tank, thereby placing the first quantitative storage tank in the filling position; simultaneously connect the second quantitative storage tank to the second connecting tank, thereby placing the second quantitative storage tank in the sample discharging position; and place the third quantitative storage tank in the transition position.

[0023] S2. Drive the moving plate to rotate relative to the fixed plate through the predetermined angle position, so that the first quantitative storage tank, the second quantitative storage tank and the third quantitative storage tank are alternately rotated between the filling station, the sampling station and the transition station;

[0024] S3. Repeat steps S1 and S2 to ensure that at any given time, one quantitative storage tank is in the filling station and the other quantitative storage tank is in the sample dispensing station, thereby achieving high-frequency quantitative sample injection.

[0025] During the switching process in step S2, the second connecting channel and the third connecting channel maintain the same pressure or the pressure difference is within a preset range, so that the quantitative storage tank that is transferred from the filling station to the sampling station can complete the switching under pressure balance.

[0026] Beneficial effects:

[0027] First, by setting three quantitative storage tanks on the moving plate and rotating them between the filling station, the sample dispensing station and the transition station, the present invention can simultaneously perform sample filling and sample dispensing at the same time, thereby significantly reducing the switching gap and increasing the effective detection throughput per unit time.

[0028] Secondly, by connecting the second and third connecting channels to pressure fluids with the same or approximately the same pressure, the present invention enables the quantitative storage tank to maintain a pressure balance during switching between different workstations, thereby reducing pressure pulsation during switching, reducing fluid impact, reducing bubble formation, and improving system pressure stability and quantitative accuracy.

[0029] Third, by setting up a transition station and isolating the quantitative storage tank in the transition station from both connecting tanks, the present invention helps to reduce liquid cross-contamination and cross-polluting during the station switching process.

[0030] Fourth, by setting up a pre-balancing flow channel between the transition station and the sample dispensing station, the quantitative storage tank to be switched is controlled to be connected to the high-pressure side fluid before being fully connected to the second connecting tank, thereby gradually bringing its internal pressure closer to the sample dispensing side pressure. This further reduces pressure pulsation and fluid impact during high-pressure switching, reduces bubble interference and sample disturbance, and improves the stability, repeatability, and analytical stability of the quantitative injection process.

[0031] Fifth, inclined surfaces are provided in the first and second connecting channels to create an asymmetrical local spatial distribution at both ends of the connecting channels. This structural design allows the local conductive volume of the quantitative storage tank to gradually change along the switching direction when entering and leaving the corresponding station, thereby further reducing instantaneous impact and pressure fluctuations during flow path switching. Simultaneously, the inclined surfaces reduce the local space within the channel near the high-pressure side, which helps reduce local dead volume and residual liquid retention, minimizing sample backmixing, cross-contamination, and bubble interference; and relatively increases the local space near the sample input and analysis output sides, facilitating a smooth transition of the sample during filling and discharge. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the installation structure of a quantitative injection switching valve according to an embodiment of the present invention;

[0033] Figure 2 This is a schematic diagram of the valve head cross-sectional structure of a quantitative injection switching valve according to an embodiment of the present invention;

[0034] Figure 3 This is an exploded view of the valve head structure of a quantitative injection switching valve according to an embodiment of the present invention;

[0035] Figure 4 This is a schematic diagram of the fixed plate structure of the valve head of a quantitative injection switching valve according to an embodiment of the present invention;

[0036] Figure 5 This is a schematic diagram of the moving plate structure of the valve head of a quantitative injection switching valve according to an embodiment of the present invention;

[0037] Figure 6 This is a schematic diagram showing the switching position of the moving plate and the fixed plate of the valve head of a quantitative injection switching valve according to an embodiment of the present invention.

[0038] Figure 7 This is another schematic diagram of the fixed plate structure of the valve head of a quantitative injection switching valve according to an embodiment of the present invention;

[0039] Reference numerals: 1. Valve head; 2. Housing; 3. Moving plate; 4. Fixed plate; 5. Top cover; 6. First connecting channel; 7. Second connecting channel; 8. Third connecting channel; 9. Fourth connecting channel; 10. First connecting groove; 11. Second connecting groove; 12. Circular protrusion; 13. Quantitative storage tank; 14. Control panel; 15. Display screen device; 16. Operation button module; 17. Positioning pin; 18. Connection port; 19. Pre-balancing flow channel. Detailed Implementation

[0040] Combination Figures 1 to 6As shown, this embodiment provides a quantitative injection switching valve, which includes a valve head 1 and a housing 2. The housing 2 serves as the supporting base for the entire device and the cavity for housing internal components. Its material can be a high-strength and corrosion-resistant metal or a high-strength engineering plastic. The valve head 1 is bolted to the housing 2. The valve head 1 includes a moving plate 3, a fixed plate 4, and a drive motor for driving the moving plate 3 to rotate. The body of the drive motor is fixed inside the housing 2 by a motor bracket, and its output shaft is mechanically connected to the moving plate 3 through a rotating shaft, thereby transmitting torque and driving the moving plate 3 to perform precise circumferential rotation.

[0041] Combination Figures 1 to 3 As shown, the fixed plate 4 is positioned above the movable plate 3, and a sealing contact surface is formed between the fixed plate 4 and the movable plate 3. To prevent fluid leakage under high pressure, the contact surface between the fixed plate 4 and the movable plate 3 is optically smoothed. A first connecting channel 6, a second connecting channel 7, a third connecting channel 8, and a fourth connecting channel 9 are internally disposed on the fixed plate 4. A first connecting groove 10 and a second connecting groove 11 are provided on the side of the fixed plate 4 facing the movable plate 3. The two ends of the first connecting groove 10 communicate with the bottom openings of the first connecting channel 6 and the second connecting channel 7, respectively. The two ends of the second connecting groove 11 communicate with the bottom openings of the third connecting channel 8 and the fourth connecting channel 9, respectively. In this embodiment, the first connecting groove 10 and the second connecting groove 11 respectively adopt an arc-shaped groove structure with asymmetric volume, and the arc length of each covers the center distance of the openings of the corresponding two connecting channels, so that when the quantitative storage groove enters the corresponding station and leaves the corresponding station, the conduction area gradually changes along the rotation direction, avoiding instantaneous changes.

[0042] In a preferred embodiment, the bottom of the first connecting channel 10 is provided with a first inclined surface, and the bottom of the second connecting channel 11 is provided with a second inclined surface; the first and second inclined surfaces are linearly distributed, with an inclination angle between 15° and 30°. Specifically, the first inclined surface makes the internal space of the first connecting channel 10 near the first connecting channel 6 larger than the internal space near the second connecting channel 7, and the second inclined surface makes the internal space of the second connecting channel 11 near the fourth connecting channel 9 larger than the internal space near the third connecting channel 8, so that the local conductive volume of the quantitative storage tank 13 gradually changes along the switching direction when entering and leaving the corresponding station. For the first connecting channel 10, the space near the first connecting channel 6 is larger, forming a larger buffer / acceptance space on the sample input side, which is beneficial for the sample to enter the quantitative storage tank 13 more smoothly, reducing local impact and turbulence on the inlet side. At the same time, because the space near the second connecting channel 7 is smaller, it can also reduce the direct disturbance of the high-pressure side to the filling end, reducing the dilution, reverse crosstalk, or local turbulence of the sample during the filling process. For the second connecting channel 11, the space near the fourth connecting channel 9 is larger and the space near the third connecting channel 8 is smaller, which is beneficial for the sample to transition to the analytical device side during the sample dispensing stage. In other words, when the high-pressure fluid pushes the sample from the third connecting channel 8 side, the local cavity on the source side is smaller and less residual liquid is retained; while the space near the fourth connecting channel 9 is larger, which is more conducive to the smooth release and transition of the sample clump to the analytical device side.

[0043] Therefore, through the design of the first and second inclined surfaces, the local volumes at both ends of the two connecting channels are gradually distributed within their respective channels. When the quantitative storage tank 13 rotates relative to the connecting channel, the volume of the local cavity involved in the connection gradually changes, making the switching process smoother and reducing local instantaneous impacts, eddies, and pressure peaks. At the same time, since the second connecting channel 7 and the third connecting channel 8 become relatively small local cavities, the smaller volume on the high-pressure fluid source side results in less residual liquid retention space and makes it less likely to form a "liquid reservoir" or mixing retention area on the high-pressure side. Therefore, it is beneficial to reduce the residue of old samples, backmixing of high-pressure fluid, and interference of residual fluid after switching on the next quantitative measurement.

[0044] A circular protrusion 12 is provided at the center of one end face of the movable piece 3 facing the fixed piece 4. The upper surface of the circular protrusion 12 serves as the main body of the dynamic seal, forming a tight sealing pair with the bottom surface of the fixed piece 4 to reduce frictional resistance. Three quantitative storage grooves 13 are formed on the upper surface of the circular protrusion 12. The three quantitative storage grooves 13 are centrally symmetrical and evenly distributed along the circumference of the movable piece 3, and the included angle between each quantitative storage groove 13 is 120 degrees. The depth and width of the quantitative storage grooves 13 are set according to a preset sampling amount, so that the volume of each quantitative storage groove 13 remains highly consistent. The movable piece 3 rotates around the central axis under the drive of the drive motor. When rotating to a specific phase, two of the three quantitative storage grooves 13 are axially aligned and connected with the first connecting groove 10 and the second connecting groove 11, respectively. Preferably, the depth, width and effective volume of each quantitative storage tank 13 are kept consistent to ensure that the amount of sample entering the sampling station each time during the rotation process is basically the same.

[0045] The top end of the first connecting channel 6 is connected to the sample input source via a pipe. The top end of the second connecting channel 7 is connected to the first high-pressure mobile phase source via a pipe. The top end of the third connecting channel 8 is connected to the second high-pressure mobile phase source via a pipe. The top end of the fourth connecting channel 9 is connected to the analytical device via a pipe. Preferably, the pressure values ​​of the fluids such as pure water provided by the first high-pressure mobile phase source and the second high-pressure mobile phase source are kept equal, or the pressure difference between the two is controlled within a preset range, so as to maintain pressure balance during station switching. For example, the preset range is controlled in the form of an absolute pressure difference ≤ 1.0 MPa and a relative pressure difference ≤ 2%. Through the bridging effect of the first connecting groove 10 and the second connecting groove 11, a first fluid loop is formed between the first connecting channel 6 and the second connecting channel 7, and a second fluid loop is formed between the third connecting channel 8 and the fourth connecting channel 9. Throughout the rotation switching process, the first fluid loop and the second fluid loop are always in a state of pressure balance, eliminating the influence of pressure fluctuations on the flow path.

[0046] Combination Figure 7 As shown, in a preferred embodiment, a pre-balancing flow channel 19 is further provided on the side of the stationary plate 4 facing the moving plate 3. The pre-balancing flow channel 19 is an auxiliary connecting groove provided on the side of the stationary plate facing the moving plate 3, with one end connected to the second connecting groove 11 and the other end extending to the circumferential area corresponding to the transition station, so that the quantitative storage tank 13 transferred from the filling station to the sampling station is first connected to the high-pressure side fluid in a controlled manner via the pre-balancing flow channel 19 before it is fully connected to the second connecting groove 11.

[0047] The width, depth, and / or equivalent conductive cross-sectional area of ​​the pre-balanced flow channel 19 are smaller than the width, depth, and / or equivalent conductive cross-sectional area of ​​the second connecting channel 11, so that the high-pressure side fluid first enters the quantitative storage tank 13 to be switched at a smaller flow rate to pre-balance its internal pressure, and then the quantitative storage tank 13 is fully connected to the second connecting channel 11 and enters the sample dispensing station.

[0048] During the rotation and switching process of the moving plate 3 relative to the fixed plate 4, the quantitative storage tank 13, which was originally in the filling station, first disengages from the first connecting channel 10 and then enters a transition station that is not connected to either the first connecting channel 10 or the second connecting channel 11. When the moving plate 3 continues to rotate, the quantitative storage tank 13 first partially connects with the pre-balancing channel 19, so that its internal pressure gradually approaches the pressure on the sample discharge side. After the pre-balancing is completed, it then fully connects with the second connecting channel 11 and, under the push of high-pressure fluid, sends the loaded sample to the analysis device through the fourth connecting channel 9.

[0049] By setting the pre-balancing flow channel 19, the quantitative storage tank 13, which is transitioning from the transition station to the sampling station, first forms a controlled micro-connection with the high-pressure side fluid before fully connecting with the second connecting channel 11. This allows the internal pressure of the quantitative storage tank 13 to gradually approach the sampling side pressure, which helps to further reduce the pressure difference shock and pressure pulsation at the moment of switching and improve the smoothness of high-pressure flow path switching. At the same time, since the equivalent conduction cross-sectional area of ​​the pre-balancing flow channel 19 is smaller than that of the second connecting channel 11, the high-pressure side fluid enters the quantitative storage tank 13 to be switched at a smaller flow rate during the pre-balancing stage. This helps to avoid the sample being subjected to a sudden large flow shock before entering the sampling station, further reducing the risk of local disturbance, bubble formation, and sample cluster dispersion, and helps to maintain peak shape stability and quantitative repeatability. It should be noted that each time the driving component drives the moving plate 3 to rotate and switch phases, one of the quantitative storage tanks 13 is located at the transition station and is not connected to the pre-balancing channel 19. Only when the quantitative storage tank 13 switches from the transition station to the second connecting tank 11 will it gradually connect to the pre-balancing channel 19, so as not to affect the accuracy of quantitative measurement.

[0050] Combination Figure 1As shown, a control panel 14 is provided on the housing 2. The control panel 14 integrates a display screen 15 and several operation button modules 16. A control system is fixedly installed in the internal cavity of the housing 2. The control system includes a microprocessor circuit, a motor drive circuit, and a signal acquisition circuit. The control system is electrically connected to the drive motor, the display screen 15, and the operation button modules 16. A counting module is integrated inside the control system. The counting module accumulates the number of rotations of the moving plate 3 in real time by sensing the rotation cycle of the moving plate 3, or it can be monitored by an encoder. The display screen 15 can display the values ​​counted by the counting module and the current speed of the drive motor. The operation button modules 16 include speed adjustment buttons and start / stop control buttons. The control system receives the electrical signals sent by the operation button modules 16 and adjusts the input current frequency of the drive motor through the motor drive circuit, thereby controlling the rotation speed and on / off state of the drive motor. When the count reaches a set value, a replacement is prompted to prevent excessive wear of the moving plate from causing leakage.

[0051] The upper side of the fixed plate 4 is connected to the upper cover 5 via a locating pin 17. The upper cover 5 is fastened to the lower housing of the valve head with bolts. The locating pin 17 precisely limits the relative position of the upper cover 5 and the fixed plate 4, preventing displacement under fluid pressure. The upper cover 5 has four through-hole connection ports 18 inside. The four connection ports 18 correspond axially to the first connection channel 6, the second connection channel 7, the third connection channel 8, and the fourth connection channel 9 inside the fixed plate 4, respectively, and maintain fluid communication. The inner wall of the connection port 18 is provided with internal threads for connecting to the connector of the external fluid pipeline, ensuring the sealing of the pipeline connection.

[0052] In any stable operating phase, one of the three quantitative storage tanks 13 is connected to the first connecting channel 10, forming a filling station; another is connected to the second connecting channel 11, forming a sample discharging station; and the remaining one is not connected to either the first connecting channel 10 or the second connecting channel 11, forming a transition station. The quantitative storage tank 13 in the filling station is used to receive samples from the sample input source; the quantitative storage tank 13 in the sample discharging station is used to send the loaded sample to the analytical device via the fourth connecting channel 9 under the impetus of the high-pressure mobile phase; the quantitative storage tank 13 in the transition station is isolated from the two connecting channels, used to complete the waiting and isolation before and after the station change, reducing cross-contamination and liquid mixing.

[0053] When the drive assembly drives the moving piece 3 to continue rotating at a predetermined angle, the quantitative storage tank 13, which was originally in the filling station, moves to the transition station and then further to the sorting station. The quantitative storage tank 13, which was originally in the sorting station, moves to the transition station, and the quantitative storage tank 13, which was originally in the transition station, moves to the filling station. Through this cyclical rotation, multiple quantitative storage tanks 13 sequentially complete the state changes of "filling - transition - sorting".

[0054] As the moving plate 3 continues to rotate, the quantitative storage tank 13, originally in the filling station, first undergoes a transitional station where it is not connected to either of the two connecting channels before entering the dispensing station, and then becomes connected to the second connecting channel 11. Since the second connecting channel 7 and the third connecting channel 8 are respectively connected to pressure fluids with the same or approximately the same pressure, the internal pressure environment of the quantitative storage tank 13 changes little during the switching process from the filling station to the dispensing station, thus forming a pressure balance switching state. This reduces pressure differential shocks and pressure pulsations during traditional high-pressure switching processes, improves quantitative repeatability, and reduces bubble interference.

[0055] In the specific workflow, the quantitative injection switching valve operates according to the following steps:

[0056] The operator sets the target speed of the drive motor via the operation button module 16. The control system receives the setting signal and controls the motor drive circuit to output a corresponding pulse width modulation signal, causing the drive motor to start rotating at the preset speed. At this time, the display screen 15 displays the currently set speed value, which is in revolutions per minute.

[0057] The moving plate 3 rotates to the first phase under drive, causing the first quantitative storage tank of the three quantitative storage tanks 13 to physically coincide with the first connecting channel 10. The sample from the sample input source enters the first quantitative storage tank under pressure for filling. Simultaneously, the second quantitative storage tank of the three quantitative storage tanks connects to the second connecting channel 11. The second high-pressure mobile phase source forces the pre-stored sample in the second quantitative storage tank out through the fourth connecting channel and finally delivers it to the analytical device for detection. In this embodiment, the angular position of each rotation can be 120°.

[0058] The moving plate 3 continues to rotate to the next phase under the rapid rotation of the drive motor. The first quantitative storage tank disengages from the first connecting groove and rotates to a position communicating with the second connecting groove 11. At this time, the second high-pressure mobile phase source forces the sample out of the first quantitative storage tank. Simultaneously, the third quantitative storage tank 13 of the three quantitative storage tanks rotates to a position communicating with the first connecting groove for sample filling. The counting module counts this switching action and updates the value on the display device 15, which is displayed cumulatively in units of tens of thousands. This process is repeated.

[0059] For the sealing structure of the moving plate 3 and the stationary plate 4, the circular protrusion 12 can be made of high-hardness alumina ceramic or silicon carbide ceramic to ensure wear resistance during frequent rotation. The cross-sections of the first connecting groove 10 and the second connecting groove 11 are arc-shaped, and their arc length covers the center distance between the openings of the two adjacent channels. The inner wall of the quantitative storage tank 13 is mirror-polished to reduce sample adsorption residue in the tank.

[0060] In one embodiment, when the accumulated count value of the counting module in the control system reaches a preset maintenance threshold, the control system emits a flashing signal or a buzzer alarm signal through the display screen device 15 to prompt the operator to replace the moving plate 3 or the fixed plate 4. The speed adjustment of the drive motor is performed in steps using the up and down adjustment buttons in the operation button module 16.

[0061] In practical applications, when this switching valve assembly is used for high-performance liquid chromatography (HPLC) analysis, the sample input source connected to the first connection channel 6 provides the sample solution to be tested. The first high-pressure mobile phase source connected to the second connection channel 7 provides the high-pressure eluent. The second high-pressure mobile phase source connected to the third connection channel 8 provides the eluent at the same pressure. Since the first connecting channel 10 and the second connecting channel 11 divide the four channels into two relatively independent isobaric loops, when the moving plate 3 rotates to switch, the quantitative storage tank 13 moves from one loop to another under constant pressure. This pressure-free switching technology effectively avoids the pressure pulsation generated during switching in traditional switching valves, ensuring the stability of the chromatographic column pressure, thereby improving the repeatability and quantitative accuracy of the chromatographic peaks.

[0062] This embodiment constructs a highly efficient fluid distribution structure by setting three circumferentially evenly distributed quantitative storage tanks 13 on the moving plate 3, and cooperating with two connecting slots on the fixed plate 4. This structure ensures that, at any rotation phase, there are always two quantitative storage tanks 13 in the filling state and the discharging state, respectively. This spatial layout achieves physical synchronization between sample injection and storage and sample output detection, significantly improving the detection throughput per unit time. By simultaneously connecting high-pressure flowing phases of equal pressure to the second connecting channel 7 and the third connecting channel 8, both the first fluid circuit and the second fluid circuit are in an equal high-pressure environment. Throughout the entire rotation and switching process of the moving plate 3, there is no pressure difference between the flow paths within the valve body, achieving smooth sample injection without impact, ensuring the accuracy of sample quantification, and effectively eliminating air bubble interference in the flow path. In addition, by integrating the valve head 1, control panel 14, and integrated counting control system into the same housing 2, integrated control and monitoring are achieved. Operators can adjust the switching speed and visually observe the number of valve head 1 switching cycles through the control panel 14, thereby accurately judging the service life of the valve core based on the displayed values, greatly improving the maintenance convenience and operational reliability of the equipment.

[0063] This embodiment achieves high-frequency quantitative sample injection by setting multiple circumferentially distributed quantitative storage tanks on the moving plate and forming a periodic alternation relationship between the filling station, sample dispensing station, and transition station with the two connecting tanks on the stationary plate. At the same time, by introducing pressure fluids with the same or approximately the same pressure in the two working loops, the quantitative storage tanks are kept in a pressure balance state when switching between different stations, thereby improving detection throughput, reducing pressure pulsation, reducing cross-contamination and bubble interference, and improving quantitative repeatability and analytical stability.

[0064] Example 2

[0065] This embodiment provides a sample injection method based on the above-mentioned quantitative injection switching valve, including the following steps:

[0066] Step S1: Connect the first quantitative storage tank 13 to the first connecting tank 10, so that the first quantitative storage tank 13 is in the filling position; at the same time, connect the second quantitative storage tank 13 to the second connecting tank 11, so that the second quantitative storage tank 13 is in the sampling position; and put the third quantitative storage tank 13 in the transition position.

[0067] In step S2, the driving plate 3 rotates relative to the fixed plate 4 through a predetermined angle position, so that the first quantitative storage tank 13, the second quantitative storage tank 13 and the third quantitative storage tank 13 alternate between the filling station, the sample dispensing station and the transition station in sequence.

[0068] Step S3: Repeat steps S1 and S2 so that at any given time, one quantitative storage tank 13 is in the filling position and the other quantitative storage tank 13 is in the dispensing position, thereby achieving high-frequency quantitative injection.

[0069] During the station switching process in step S2, the second connecting channel 7 and the third connecting channel 8 maintain the same pressure or the pressure difference is within a preset range, so that the quantitative storage tank 13, which is transferred from the filling station to the sampling station, completes the switching under pressure balance.

[0070] The switching frequency can be adjusted by regulating the speed of the drive motor, and the structure is simpler and more stable.

[0071] It should be understood that the above are merely preferred embodiments of the present invention, and the scope of protection of the present invention is not limited to the above embodiments. All technical solutions that fall within the scope of the present invention are within the scope of protection of the present invention.

[0072] The accompanying drawings used in the above embodiments only illustrate certain embodiments of the present invention and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained from these drawings without creative effort.

Claims

1. A quantitative injection switching valve, characterized in that, The valve head includes a valve head and a drive assembly for switching the valve head. The valve head includes a fixed plate and a movable plate that are disposed opposite to each other and form a sealing mating surface; wherein: The fixed plate is provided with a first connecting channel, a second connecting channel, a third connecting channel and a fourth connecting channel inside, and a first connecting groove and a second connecting groove are provided on the side of the fixed plate facing the moving plate. The two ends of the first connecting groove are respectively connected to the first connecting channel and the second connecting channel, and the two ends of the second connecting groove are respectively connected to the third connecting channel and the fourth connecting channel. The moving plate has three quantitative storage slots on the side facing the fixed plate, and the three quantitative storage slots are arranged at intervals along the circumference of the moving plate. The circumferential positions of the first connecting groove and the second connecting groove relative to the three quantitative storage grooves are configured such that, in any stable working phase of the rotation of the moving plate relative to the fixed plate, one of the three quantitative storage grooves is connected to the first connecting groove to form a filling station, another is connected to the second connecting groove to form a sorting station, and the remaining one is not connected to either the first connecting groove or the second connecting groove to form a transition station. Furthermore, after the moving plate rotates through a predetermined angle, the three quantitative storage tanks alternate sequentially between the filling station, the discharging station, and the transition station, so that the switching valve can achieve a synchronous working state of filling a certain amount of storage tank and discharging another quantitative storage tank during operation. The second and third connection channels are configured to be connected to pressure fluids with the same pressure or with a pressure difference within a preset range, so that the quantitative storage tank is in a pressure balance switching state during the process of switching from the filling station to the dispensing station.

2. The quantitative injection switching valve according to claim 1, characterized in that, The first connection channel is used to connect to the sample input source, and the fourth connection channel is used to connect to the analysis device; the second connection channel and the third connection channel are configured to connect to pressure fluids with the same pressure or with a pressure difference within a preset range, so that the quantitative storage tank is in a pressure balance switching state during the process of switching from the filling station to the discharging station.

3. The quantitative injection switching valve according to claim 2, characterized in that, The three quantitative storage tanks are distributed at equal angular intervals along the circumference of the moving plate, and the included angle between two adjacent quantitative storage tanks is 120°.

4. The quantitative injection switching valve according to claim 3, characterized in that, The three quantitative storage tanks have the same tank depth, tank width and effective volume, so that the three quantitative storage tanks maintain the same quantitative injection volume during rotation.

5. The quantitative injection switching valve according to claim 2, characterized in that, The first connecting groove and the second connecting groove are arc-shaped grooves with asymmetrical volumes, and their respective arc lengths cover the center distance between the openings of the two connecting channels they connect.

6. The quantitative injection switching valve according to claim 5, characterized in that, The bottom of the first connecting groove is provided with a first inclined surface, and the bottom of the second connecting groove is provided with a second inclined surface; The first inclined surface makes the space inside the first connecting groove near the first connecting channel larger than the space inside the groove near the second connecting channel, and the second inclined surface makes the space inside the second connecting groove near the fourth connecting channel larger than the space inside the groove near the third connecting channel, so that the local conductive volume of the quantitative storage tank gradually changes along the switching direction when entering and leaving the corresponding workstation.

7. The quantitative injection switching valve according to claim 6, characterized in that, The fixed plate is provided with a pre-balancing flow channel that communicates with the second connecting groove. The pre-balancing flow channel is located between the transition station and the sample dispensing station. It is used to ensure that the quantitative storage tank transferred from the filling station to the sample dispensing station is first connected to the high-pressure side fluid in a controlled manner before it is fully connected to the second connecting groove, so as to perform pressure pre-balancing.

8. The quantitative injection switching valve according to claim 7, characterized in that, The pre-balancing channel is an auxiliary connecting groove located on the side of the fixed plate facing the moving plate. One end of the auxiliary connecting groove is connected to the second connecting groove, and the other end is located in the circumferential area corresponding to the transition station. The equivalent conducting cross-sectional area of ​​the pre-balancing channel is smaller than that of the second connecting groove, so that the quantitative storage tank can complete the pressure pre-balancing through a controlled flow restriction method before entering the sampling station.

9. The quantitative injection switching valve according to claim 1, characterized in that, The transition station is a necessary station in the process of switching the quantitative storage tank from the filling station to the sampling station. It is located between the filling station and the sampling station. The quantitative storage tank in the transition station is isolated from both the first connecting tank and the second connecting tank to reduce cross-contamination and liquid mixing between adjacent stations.

10. A method for quantitative injection using the quantitative injection switching valve according to any one of claims 1 to 9, characterized in that, Includes the following steps: S1. Connect the first quantitative storage tank to the first connecting tank, thereby placing the first quantitative storage tank in the filling position; simultaneously connect the second quantitative storage tank to the second connecting tank, thereby placing the second quantitative storage tank in the sample discharging position; and place the third quantitative storage tank in the transition position. S2. Drive the moving plate to rotate relative to the fixed plate through the predetermined angle position, so that the first quantitative storage tank, the second quantitative storage tank and the third quantitative storage tank are alternately rotated between the filling station, the sorting station and the transition station; S3. Repeat steps S1 and S2 to ensure that at any given time, one quantitative storage tank is in the filling station and the other quantitative storage tank is in the dispensing station, thereby achieving quantitative sample injection. During the switching process in step S2, the second connecting channel and the third connecting channel maintain the same pressure or the pressure difference is within a preset range, so that the quantitative storage tank that is transferred from the filling station to the sampling station can complete the switching under pressure balance.

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