Liquid dilution device and method
By employing a dual-mode design with a switching valve, the problem of gas interference during the initial liquid aspiration of the liquid dilution device is resolved, achieving precision in liquid dilution and uniformity in mixing, thus ensuring the accuracy of the dilution process.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-04-03
- Publication Date
- 2026-05-29
Smart Images
Figure CN122098359A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of dilution apparatus, and more specifically, to a liquid dilution apparatus and method. Background Technology
[0002] Currently, there are two main technical solutions applicable to liquid dilution: 1. A dilution device consisting of a dilution pipeline and a flow control valve, a flow meter, and an ejector installed sequentially on the dilution pipeline. The liquid dilution device draws the liquid to be diluted into the dilution pipeline through the ejector; and regulates the flow rate of the dilution liquid in the dilution pipeline through the flow meter and the flow control valve, thereby accurately diluting the liquid to be diluted to a specified concentration.
[0003] 2. Two high-precision syringe pumps draw a certain volume of diluent and diluted solution respectively, and then push them together into a three-way valve via a stepper motor for mixing.
[0004] However, none of the above dilution methods take into account the effect of gas in the liquid tubing on liquid aspiration. During the initial aspiration, air in the tubing enters the syringe, resulting in a situation where 5ml of liquid is aspirated, but only 3ml flows into the syringe, leaving the remaining 2ml as air. This makes it impossible to determine the precise volume of liquid to be injected during precise dispensing. Summary of the Invention
[0005] The purpose of this invention is to provide a liquid dilution apparatus and method that can improve the accuracy of liquid dilution.
[0006] The embodiments of the present invention are implemented as follows: In a first aspect, a liquid dilution device according to this embodiment includes: a first conveying device, a second conveying device, a switching valve, a metering structure, and a first container; the first conveying device is connected to the switching valve and is used to convey a first liquid; the second conveying device is connected to the switching valve and is used to convey a second liquid; the metering structure has a set volume and its two ends are respectively connected to different ports of the switching valve; the first container is connected to the switching valve and is used to collect the second liquid and a third liquid; wherein, the concentration of the first liquid is greater than that of the second liquid, and the third liquid is a mixture of the first liquid and the second liquid; The switching valve has at least a first operating mode and a second operating mode; In the first working mode, the first conveying device fills the interior of the quantitative structure with the first liquid, and the second conveying device fills the pipe between the second conveying device and the switching valve, and the pipe between the first container and the switching valve with the second liquid. In the second working mode, the second conveying device pushes all the first liquid inside the quantitative structure into the first container.
[0007] In a possible implementation, the switching valve includes at least a first port, a second port, a third port, a fourth port, a fifth port, and a sixth port; the first conveying device is connected to the first port, the second conveying device is connected to the fourth port, the two ends of the metering structure are respectively connected to the second port and the fifth port, and the first container is connected to the third port; In the first working mode, the first port is also connected to the second port, the third port is connected to the fourth port, and the fifth port is connected to the sixth port; In the second operating mode, the first port is connected to the sixth port, the second port is connected to the third port, and the fourth port is connected to the fifth port.
[0008] In a possible implementation, the switching valve includes a stator structure, a rotor structure, and a drive device; the stator structure is provided with a first port, a second port, a third port, a fourth port, a fifth port, and a sixth port on its periphery; the rotor structure is rotatably disposed within the stator structure and is provided with a first flow channel, a second flow channel, and a third flow channel; the drive device is connected to the rotor structure and is used to drive the rotor structure to rotate. In the first working mode, the two ends of the first flow channel are respectively located at the first port and the second port, the two ends of the second flow channel are respectively located at the third port and the fourth port, and the two ends of the third flow channel are respectively located at the fifth port and the sixth port; In the second operating mode, the two ends of the first flow channel are located at the first port and the sixth port, the two ends of the second flow channel are located at the second port and the third port, and the two ends of the third flow channel are located at the fourth port and the fifth port.
[0009] In a possible implementation, both the stator structure and the rotor structure are cylindrical structures; the first port, the second port, the third port, the fourth port, the fifth port, and the sixth port are all located at equal angles on the outer periphery of the stator structure; the first flow channel, the second flow channel, and the third flow channel are all arc-shaped of equal length and are respectively located at equal angles on the outer periphery of the rotor; when switching between the first operating mode and the second operating mode, the driving device drives the rotor structure to rotate 60°.
[0010] In a possible implementation, the first conveying device is provided with a first output valve port and a plurality of first input valve ports, the first output valve port being connected to the first port, and each of the first input valve ports being used to connect to a first liquid storage device containing the first liquid.
[0011] In a possible implementation, the second conveying device is provided with a second output valve port and a plurality of second input valve ports, the second output valve port being connected to the fourth port, and each of the second input valve ports being used to connect to a second liquid storage device containing the second liquid.
[0012] In possible implementations, it also includes: The second container, connected to the sixth port, is used to collect the first liquid discharged in the first operating mode; A third conveying device is connected to the first container and the second container respectively, and is used to pump the second liquid discharged into the first container in the first working mode to the second container.
[0013] Secondly, a liquid dilution method according to this embodiment is applied to the above-mentioned liquid dilution apparatus, the method comprising: Action 1: Control the switching valve to switch to the first working mode; Action 2: Control the second conveying device to convey the second liquid until it fills the pipe between the second conveying device and the switching valve, and the pipe between the first container and the switching valve; Action 3: Control the first conveying device to deliver the first liquid until the metering structure is filled; Action 4: Control the switching valve to switch to the second working mode; Action 5: Control the second conveying device to convey the second liquid, so that all the first liquid inside the metering structure is pushed into the first container. Repeat this action until the set volume of the second liquid is reached. Complete the dilution process.
[0014] In a possible implementation, controlling the switching valve to switch to the first operating mode and controlling the first delivery device to deliver the first liquid until the metering structure is filled includes: Determine whether the first liquid is flowing out of the pipe between the sixth port and the second container; If so, determine that the first liquid fills the quantitative structure; If not, control the first conveying device to continue conveying the first liquid.
[0015] In a possible implementation, controlling the second delivery device to deliver the second liquid until it fills the conduit between the second delivery device and the switching valve, and the conduit between the first container and the switching valve, includes: Determine whether the second liquid is flowing out of the pipe between the third port and the first container; If so, confirm that the second liquid fills the pipe between the second delivery device and the switching valve, and the pipe between the first container and the switching valve; If not, control the second conveying device to continue conveying the second liquid.
[0016] The beneficial effects of the embodiments of the present invention are: The switching valve has two preset operating modes. In the first mode, a first liquid is delivered via a first delivery device, with over-sampling, until the metering structure is completely filled with the first liquid. Simultaneously, in this mode, a second liquid is delivered via a second delivery device, with over-sampling, filling the pipes between the first delivery device and the switching valve, and between the switching valve and the first container, with the second liquid. This removes air from the pipes, preventing it from affecting the accuracy of subsequent dilution processes. Then, switching to the second mode, the second delivery device delivers the second liquid to the switching valve. This second liquid pushes the first liquid from the metering structure into the first container. Since air was removed from the pipes in the first mode, the dilution accuracy is not affected, and the pushing process also achieves mixing between the first and second liquids. Attached Figure Description
[0017] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.
[0018] Figure 1 This is an overall schematic diagram of the liquid dilution device according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the switching valve in the first working mode according to an embodiment of the present invention; Figure 3 This is a schematic diagram of the switching valve in the second working mode according to an embodiment of the present invention.
[0019] Icons: 1. First conveying device; 2. Second conveying device; 3. Switching valve; 31. First port; 32. Second port; 33. Third port; 34. Fourth port; 35. Fifth port; 36. Sixth port; 4. Quantitative structure; 5. First container; 6. Second container; 7. Third conveying device; 8. First liquid storage device; 9. Second liquid storage device. Detailed Implementation
[0020] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.
[0021] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.
[0022] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.
[0023] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this invention is in use. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention. In addition, the terms "first," "second," "third," etc., are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.
[0024] Furthermore, terms such as "horizontal" and "vertical" do not imply that components must be absolutely horizontal or suspended, but rather that they can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," not that the structure must be completely horizontal, but can be slightly tilted.
[0025] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.
[0026] First Embodiment Please refer to Figures 1 to 3 This embodiment provides a liquid dilution device, including: a first delivery device 1, a second delivery device 2, a switching valve 3, a metering structure 4, and a first container 5. The first delivery device 1 is connected to the switching valve 3 and is used to deliver a first liquid to the switching valve 3. The second delivery device 2 is connected to the switching valve 3 and is used to deliver a second liquid to the switching valve 3. The concentration of the first liquid is greater than the concentration of the second liquid; that is, the first liquid is the liquid to be diluted, such as a high-concentration standard liquid or reagent concentrate, and the second liquid is the diluent, such as deionized water, buffer solution, or solvent. The metering structure 4 can be a metering loop, which has a set volume that can be flexibly selected according to the target dilution factor. The switching valve 3 has two preset working modes. When switched to the first working mode, the first liquid is delivered through the first delivery device 1 and oversampled until the metering structure 4 is filled with the first liquid. Simultaneously, in this operating mode, the second liquid is delivered via the second delivery device 2, and an over-sample is taken, filling the pipes between the first delivery device 1 and the switching valve 3, and between the switching valve 3 and the first container 5, with the second liquid. This removes air from the pipes, preventing it from affecting the accuracy of the subsequent dilution process. Then, switching to the second operating mode, the second delivery device 2 delivers the second liquid to the switching valve 3. At this time, the second liquid pushes the first liquid inside the metering structure 4 to the first container 5. Since the air inside the pipes was removed in the first operating mode, the accuracy of the dilution is not affected. Furthermore, the pushing process also achieves mixing between the first and second liquids.
[0027] Furthermore, to prevent the second liquid discharged into the first container 5 in the first working mode from affecting the accuracy of subsequent dilution, this portion of liquid needs to be drained from the first container 5. In this embodiment, this can be done manually or automatically by a delivery device (such as various pumps). Optionally, both the first delivery device 1 and the second delivery device 2 can be quantitative pumps, precision plunger pumps, or high-precision peristaltic pumps, and the volume can be selected using syringes of 5ml, 10ml, or 25ml to accurately extract different volumes of liquid, thus achieving precise liquid sampling. If, in actual online use, the sample cell is far from the dilution device, and the intermediate pipeline is long, the volume obtained by a single aspiration by the syringe pump may not be able to fill the quantitative structure 4. In this case, the volume specifications of the first delivery device 1 and the second delivery device 2 can be increased, and multiple sampling actions can be performed to ensure that the sample to be diluted fills the quantitative loop. Therefore, this device can guarantee accurate quantitative extraction of the diluent under any conditions.
[0028] In an optional embodiment, the switching valve 3 may be a six-way valve, including a first port 31, a second port 32, a third port 33, a fourth port 34, a fifth port 35 and a sixth port 36; the first conveying device 1 is connected to the first port 31, the second conveying device 2 is connected to the fourth port 34, the two ends of the metering structure are connected to the second port 32 and the fifth port 35 respectively, and the first container 5 is connected to the third port 33.
[0029] In the first operating mode, the first port 31 is also connected to the second port 32, the third port 33 is connected to the fourth port 34, and the fifth port 35 is connected to the sixth port 36. At this time, two independent and parallel flow paths are formed in the system. The first flow path fills the quantitative structure 4 with a quantitative amount of the first liquid, and the second flow path discharges the air inside the pipe between the second conveying device 2 and the fourth port 34, as well as the pipe between the third port 33 and the first container 5.
[0030] In the second operating mode, the first port 31 is connected to the sixth port 36, the second port 32 is connected to the third port 33, and the fourth port 34 is connected to the fifth port 35. At this time, the system forms a push-mixing flow path, through which the second liquid sequentially passes through the fourth port 34, the fifth port 35, the metering structure 4, the second port 32, and the third port 33. During this process, the second liquid pushes the first liquid inside the metering structure 4, and the two are mixed.
[0031] In an optional embodiment, the switching valve 3 is a metering valve, comprising a stator structure, a rotor structure, and a drive device; the stator structure is provided with a first port 31, a second port 32, a third port 33, a fourth port 34, a fifth port 35, and a sixth port 36 on its periphery; the rotor structure is rotatably disposed within the stator structure and is provided with a first flow channel, a second flow channel, and a third flow channel; the drive device is connected to the rotor structure and is used to drive the rotor structure to rotate; In the first working mode, the two ends of the first flow channel are located at the first port 31 and the second port 32, respectively; the two ends of the second flow channel are located at the third port 33 and the fourth port 34, respectively; and the two ends of the third flow channel are located at the fifth port 35 and the sixth port 36, respectively. In the second working mode, the two ends of the first flow channel are located at the first port 31 and the sixth port 36, the two ends of the second flow channel are located at the second port 32 and the third port 33, and the two ends of the third flow channel are located at the fourth port 34 and the fifth port 35.
[0032] Furthermore, both the stator structure and the rotor structure are cylindrical structures; the first port 31, the second port 32, the third port 33, the fourth port 34, the fifth port 35, and the sixth port 36 are all located at equal angles on the outer periphery of the stator structure; the first flow channel, the second flow channel, and the third flow channel are all arc-shaped with equal lengths and are located at equal angles on the outer periphery of the rotor; when switching between the first working mode and the second working mode, the driving device drives the rotor structure to rotate 60°.
[0033] In an optional embodiment, the first conveying device 1 is provided with a first output valve port and a plurality of first input valve ports, such as a six-way valve. The first output valve port is connected to the first port 31. There are five first input valve ports. Each first input valve port is used to connect to a first liquid storage device 8 containing the first liquid. The specifications of the first liquid storage device 8 connected to each first output valve port can be different or different.
[0034] In an optional embodiment, the second conveying device 2 is provided with a second output valve port and a plurality of second input valve ports, such as a six-way valve. The second output valve port is connected to the fourth port 34. There are five second input valve ports. Each second input valve port is used to connect to a second liquid storage device 9 containing the second liquid. The specifications of the first liquid storage device 8 connected to each first output valve port can be different.
[0035] In an optional embodiment, the system further includes a second container 6 and a third conveying device 7. The second container 6 is connected to the sixth port 36 and is used to collect the first liquid discharged in the first operating mode. The third conveying device 7 is connected to both the first container 5 and the second container 6 and is used to draw the second liquid discharged into the first container 5 in the first operating mode into the second container 6, thereby preventing the first liquid discharged into the first container 5 in the first mode from affecting the subsequent dilution accuracy.
[0036] For example, the second delivery device 2 extracts the volume of the second liquid according to the specifications of the metering structure 4 and the dilution factor. For instance, if the metering loop is 200 μL and the dilution factor is 200 times, then the second delivery device 2 needs to deliver 39.8 ml of the second liquid. If the second delivery device is a precision syringe pump equipped with a 25 ml syringe, the second delivery device 2 extracts 25 ml of the second liquid at full capacity. Since the inside of the tube is full of the second liquid, the second delivery device 2 can push 25 ml of the second liquid. After pushing 25 ml of the second liquid, the second delivery device extracts and pushes another 14.8 ml of the second liquid, achieving precise delivery of 39.8 ml of the second liquid, thereby achieving precise dilution of the first liquid.
[0037] Second Embodiment This embodiment also provides a dilution method, including the following steps: Step S1: Control the second conveying device 2 to convey the second liquid until it fills the pipe between the second conveying device 2 and the switching valve 3, and the pipe between the first container 5 and the switching valve 3.
[0038] In step S1, the switching valve 3 is kept in the first operating mode, and the second delivery device 2 is started to deliver the second liquid. The total amount of the second liquid delivered must be sufficient to fill the entire pipeline space from the pump outlet through the switching valve 3 to the first container 5.
[0039] The system detects whether the second liquid is flowing out of the pipe between the third port 33 and the first container 5. When the second liquid is detected flowing out of the pipe at the inlet end of the first container 5, it is determined that the target pipe has been completely filled with the second liquid (i.e., the air has been expelled), and then the delivery is stopped or the process proceeds to the next step.
[0040] This step uses a diluent to pre-purge air from the pipes, preventing air from disrupting the continuity of the liquid column and thus improving the accuracy of dilution.
[0041] Step S2: Control the switching valve 3 to switch to the first working mode, and control the first conveying device 1 to convey the first liquid until the metering structure 4 is filled.
[0042] In step S2, the system controller instructs the drive device to rotate the switching valve 3 to the angle corresponding to the first operating mode. Subsequently, the first conveying device 1 is started to convey the first liquid at a set flow rate. To ensure that the metering structure 4 is completely and bubble-free, the total amount of the first liquid conveyed will exceed the volume of the metering structure 4.
[0043] The system continuously or at the endpoint detects whether the first liquid is flowing out of the pipe between the sixth port 36 and the second container 6. When liquid outflow is detected (e.g., by an optical or conductive sensor), it is determined that the quantitative structure 4 and its upstream flow path are indeed filled with the first liquid, and the first delivery device 1 is stopped. If no outflow is detected, delivery continues. This achieves accurate and residue-free quantification of the sample, ensuring that the exact same volume of the first liquid is retained each time.
[0044] Step S3: Control the switching valve 3 to switch to the second working mode, and control the second conveying device 2 to convey the second liquid until the first liquid inside the metering structure 4 and the required second liquid calculated according to the dilution ratio are all pushed to the first container 5.
[0045] In step S3, the switching valve 3 rotates to the second operating mode. The second conveying device 2 delivers a second liquid, pushing out a measured amount of the first liquid from inside the metering structure 4. The volume of the second liquid delivered is calculated based on the volume of the metering structure and the dilution factor. The second liquid serves both as the pushing force and as the dilution medium. During the pushing process, the first and second liquids mix within the pipe, ensuring uniform mixing and accurate proportions.
[0046] If the dilution factor or final volume does not meet the requirements in a single step, the system can automatically repeat the S2 to S3 cycle. Each cycle adds a fixed amount of the first liquid and a corresponding volume of the second liquid (determined by the amount pushed in step S3) to the first container 5. For example, a large volume of trace standard liquid can be prepared by adding trace amounts of sample multiple times, or different stepwise dilutions can be achieved by varying the volume of the second liquid pushed in each step.
[0047] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.
Claims
1. A liquid dilution device, characterized in that, include: The system comprises a first conveying device, a second conveying device, a switching valve, a metering structure, and a first container; the first conveying device is connected to the switching valve for conveying a first liquid; the second conveying device is connected to the switching valve for conveying a second liquid; the metering structure has a set volume and its two ends are respectively connected to different ports of the switching valve; the first container is connected to the switching valve for collecting the second liquid and a third liquid; wherein the concentration of the first liquid is greater than that of the second liquid, and the third liquid is a mixture of the first liquid and the second liquid; The switching valve has at least a first operating mode and a second operating mode; In the first working mode, the first conveying device fills the interior of the quantitative structure with the first liquid, and the second conveying device fills the pipe between the second conveying device and the switching valve, and the pipe between the first container and the switching valve with the second liquid. In the second working mode, the second conveying device pushes all the first liquid inside the quantitative structure into the first container.
2. The liquid dilution apparatus according to claim 1, characterized in that, The switching valve includes at least a first port, a second port, a third port, a fourth port, a fifth port, and a sixth port; the first conveying device is connected to the first port, the second conveying device is connected to the fourth port, the two ends of the metering structure are respectively connected to the second port and the fifth port, and the first container is connected to the third port; In the first working mode, the first port is also connected to the second port, the third port is connected to the fourth port, and the fifth port is connected to the sixth port; In the second operating mode, the first port is connected to the sixth port, the second port is connected to the third port, and the fourth port is connected to the fifth port.
3. The liquid dilution apparatus according to claim 2, characterized in that, The switching valve includes a stator structure, a rotor structure, and a drive device; the stator structure is provided with a first port, a second port, a third port, a fourth port, a fifth port, and a sixth port on its periphery; the rotor structure is rotatably disposed within the stator structure and is provided with a first flow channel, a second flow channel, and a third flow channel; the drive device is connected to the rotor structure and is used to drive the rotor structure to rotate. In the first working mode, the two ends of the first flow channel are respectively located at the first port and the second port, the two ends of the second flow channel are respectively located at the third port and the fourth port, and the two ends of the third flow channel are respectively located at the fifth port and the sixth port; In the second operating mode, the two ends of the first flow channel are located at the first port and the sixth port, the two ends of the second flow channel are located at the second port and the third port, and the two ends of the third flow channel are located at the fourth port and the fifth port.
4. The liquid dilution apparatus according to claim 3, characterized in that, Both the stator structure and the rotor structure are cylindrical; the first port, the second port, the third port, the fourth port, the fifth port, and the sixth port are all located at equal angles on the outer periphery of the stator structure; the first flow channel, the second flow channel, and the third flow channel are all arcs of equal length and are located at equal angles on the outer periphery of the rotor; when switching between the first working mode and the second working mode, the driving device drives the rotor structure to rotate 60°.
5. The liquid dilution apparatus according to claim 2, characterized in that, The first conveying device is provided with a first output valve port and a plurality of first input valve ports. The first output valve port is connected to the first port, and each of the first input valve ports is used to connect to a first liquid storage device containing the first liquid.
6. The liquid dilution apparatus according to claim 2, characterized in that, The second conveying device is provided with a second output valve port and a plurality of second input valve ports. The second output valve port is connected to the fourth port, and each of the second input valve ports is used to connect to a second liquid storage device containing the second liquid.
7. The liquid dilution apparatus according to claim 2, characterized in that, Also includes: The second container, connected to the sixth port, is used to collect the first liquid discharged in the first working mode; A third conveying device is connected to the first container and the second container respectively, and is used to pump the second liquid discharged into the first container in the first working mode to the second container.
8. A liquid dilution method, characterized in that, The method, applied to the liquid dilution apparatus as described in any one of claims 1 to 7, comprises: Action 1: Control the switching valve to switch to the first working mode; Action 2: Control the second conveying device to convey the second liquid until it fills the pipe between the second conveying device and the switching valve, and the pipe between the first container and the switching valve; Action 3: Control the first conveying device to deliver the first liquid until the metering structure is filled; Action 4: Control the switching valve to switch to the second working mode; Action 5: Control the second conveying device to convey the second liquid, so that all the first liquid inside the metering structure is pushed into the first container. Repeat this action until the set volume of the second liquid is reached. Complete the dilution process.
9. The liquid dilution method according to claim 8, characterized in that, The control of switching the switching valve to the first operating mode and controlling the first delivery device to deliver the first liquid until the metering structure is filled includes: Determine whether the first liquid is flowing out of the pipe between the sixth port and the second container; If so, determine that the first liquid fills the quantitative structure; If not, control the first conveying device to continue conveying the first liquid.
10. The liquid dilution method according to claim 8, characterized in that, The control of the second conveying device to convey the second liquid until it fills the pipe between the second conveying device and the switching valve, and the pipe between the first container and the switching valve, includes: Determine whether the second liquid is flowing out of the pipe between the third port and the first container; If so, confirm that the second liquid fills the pipe between the second delivery device and the switching valve, and the pipe between the first container and the switching valve; If not, control the second conveying device to continue conveying the second liquid.