Liquid level measuring device and liquid level measuring method

Abstract

The invention discloses a liquid level measuring device and a liquid level measuring method, and belongs to the technical field of semiconductor processing, in the liquid level measuring device, an input pipeline is communicated with a gas source, the bottom end of the input pipeline is used for extending below the liquid level of liquid in a container to be measured, and a flow limiting device is installed on the input pipeline; the flow limiting device is used for limiting the pressure of gas input into the liquid by the gas source through the input pipeline to be first preset pressure, the first end of the output pipeline is communicated with the atmosphere, and the second end of the output pipeline extends into the container and is located above the liquid level of the liquid; the input pipeline and the output pipeline are both matched with the pressure measuring device, the controller is used for controlling the pressure measuring device to measure the pressure difference between gas in the input pipeline and the output pipeline, and the controller is further used for determining the height difference between the bottom end of the input pipeline and the liquid level of liquid in the container to be measured based on the pressure difference. The liquid level measuring device can provide a more accurate liquid level measuring function for the semiconductor processing field.

Description

Technical Field

[0001] The present application belongs to the field of semiconductor processing technology, and specifically relates to a liquid level measuring device and a liquid level measuring method. Background Art

[0002] In the field of semiconductor processing technology, liquid reagents provide important uses, and the amount of reagents needs to be accurately controlled. However, the common float-type liquid level gauge is greatly affected by airflow, has poor accuracy, and some reagents are highly corrosive, which will have an adverse effect on the service life of the liquid level gauge and the cleanliness of the reagents. Ultrasonic liquid level gauges are greatly affected by the structure of the container, and capacitive liquid level gauges have high requirements for the conductivity of the liquid and are easily affected by electromagnetic interference. The measurement accuracy is also relatively poor. Therefore, it is urgent to provide a liquid level measurement device for use in the field of semiconductor processing. Summary of the invention

[0003] The purpose of the embodiments of the present application is to provide a liquid level measurement device and a liquid level measurement method to provide a more accurate liquid level measurement function in the semiconductor processing field.

[0004] In a first aspect, an embodiment of the present application discloses a position measurement device, which includes an input pipeline, a current limiting device, an output pipeline, a pressure measurement device and a controller, wherein: The input pipeline is connected to the gas source, the bottom end of the input pipeline is used to extend below the liquid level of the liquid in the container to be tested, the current limiting device is installed on the input pipeline, and the current limiting device is used to limit the pressure of the gas input into the liquid through the gas source through the input pipeline to a first preset pressure, the first end of the output pipeline is connected to the atmosphere, and the second end of the output pipeline extends into the container and is located above the liquid level of the liquid; The input pipeline and the output pipeline are both coordinated with the pressure measuring device. The controller is used to control the pressure measuring device to measure the pressure difference between the gas in the input pipeline and the gas in the output pipeline. The controller is also used to determine the height difference between the bottom end of the input pipeline and the liquid level in the container to be tested based on the pressure difference.

[0005] In a second aspect, an embodiment of the present application discloses a liquid level measurement method, which is applied to the above-mentioned liquid level measurement device. The liquid level measurement method includes: Obtain the pressure difference P between the input pipeline and the output pipeline; Based on the pressure difference P, the height difference H between the bottom end of the input pipeline and the liquid level in the container to be tested is determined.

[0006] The embodiment of the present application discloses a liquid level measuring device, wherein a current limiting device is installed on an input pipeline so that a gas source can deliver a gas of a first preset pressure to the liquid in the container to be measured through the input pipeline, and the space above the liquid level in the container to be measured is also connected to the atmosphere through an output pipeline. By extending the bottom end of the input pipeline below the liquid level in the container to be measured, a corresponding pressure difference exists between the input pipeline and the output pipeline, and the pressure difference is generated by the static pressure generated by the liquid at the required measurement height.

[0007] To this end, in an embodiment of the present application, both the input pipeline and the output pipeline are cooperated with a pressure measuring device. In this case, the controller can control the pressure measuring device to measure the pressure difference between the input pipeline and the output pipeline, and the controller can also determine the height difference between the bottom end of the input pipeline and the liquid level in the liquid based on the measured pressure difference, and then determine the liquid level height in the container to be tested.

[0008] As described above, in the liquid level measuring device disclosed in the embodiment of the present application, except for the input pipeline, other parts of the liquid level measuring device do not directly contact the liquid, and by making the input pipeline and the gas that enters the liquid through the input pipeline use materials that do not physically and chemically react with the liquid, the liquid level measuring device can be prevented from affecting the cleanliness of the liquid. At the same time, since the static pressure value of the liquid is relatively less affected by the airflow that may exist in the container to be measured, the accuracy of the measured liquid level height result can be ensured to be relatively high. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings: Figure 1 A schematic diagram of the structure of a liquid level measuring device disclosed in an embodiment of the present application; Figure 2 This is a flow chart of the liquid level measurement method disclosed in the embodiment of the present application.

[0010] Reference numerals: 100-input pipeline, 110-first pipe section, 120-second pipe section, 200- output pipeline, 210- third pipe section, 220- fourth pipe section, 310-first detection pipeline, 320-second detection pipeline, 330-fixed pipeline, 340-gas supply pipeline, 410-current limiting device, 420-blocking gasket, 500-pressure measuring device, 610-controller, 620-signal conversion device, 630-display device, 640-alarm device, 650-power supply, 900 - Container to be tested. DETAILED DESCRIPTION

[0011] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0012] The terms "first", "second", etc. in the specification and claims of this application are used to distinguish similar objects, and are not used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable under appropriate circumstances, so that the embodiments of the present application can be implemented in an order other than those illustrated or described here, and the objects distinguished by "first", "second", etc. are generally of one type, and the number of objects is not limited. For example, the first object can be one or more. In addition, "and / or" in the specification and claims represents at least one of the connected objects, and the character " / " generally indicates that the objects associated with each other are in an "or" relationship.

[0013] The embodiment of the present application discloses a liquid level measuring device, which can detect the liquid level height of the liquid in the container 900 to be tested. Usually, the container 900 to be tested is a closed structure. Specifically, the container 900 to be tested can be a cylindrical tube structure, or the container 900 to be tested can also be a cubic tube structure. This is not limited herein. Of course, in order to ensure that the container 900 to be tested can cooperate with the liquid level measuring device provided by the present application, a corresponding opening also needs to be provided on the container 900 to be tested.

[0014] like Figure 1 As shown, the liquid level measuring device disclosed in the embodiment of the present application includes an input pipeline 100, a current limiting device 410, an output pipeline 200, a pressure measuring device 500 and a controller 610. Of course, the liquid level measuring device disclosed in the embodiment of the present application may also include a power supply device or wire such as a power supply 650, which will not be introduced one by one in this article.

[0015] The input pipeline 100 and the output pipeline 200 are used to transport gas. The input pipeline 100 is connected to the gas source, and during the operation of the liquid level measuring device, the bottom end of the input pipeline 100 is extended below the liquid level of the liquid in the container 900 to be measured. In this case, it is ensured that the gas input from the gas source through the input pipeline 100 can flow into the liquid in the container 900 to be measured and escape from the bottom end of the input pipeline 100, so as to ensure that the liquid level measurement can be carried out normally.

[0016] It should be noted that, in order to ensure that the measurement accuracy of the liquid level measuring device is relatively high, during the installation of the liquid level measuring device, the bottom end of the input pipeline 100 can be made as close to the bottom of the container 900 to be tested as possible. Of course, it is still necessary to ensure that there is a slit between the bottom end of the input pipeline 100 and the bottom of the container 900 to be tested, so that the gas can escape normally from the bottom end of the input pipeline 100. Based on this, during the installation of the liquid level measuring device, the distance between the bottom end of the input pipeline 100 and the bottom of the container 900 to be tested can be measured and recorded, so that after the liquid level measuring device completes the detection of the height difference between the liquid surface and the bottom end of the input pipeline 100, the actual height of the liquid surface in the container 900 to be tested is determined by accumulating the above-mentioned distance.

[0017] As described above, the bottom end of the input pipeline 100 connected to the gas source extends below the liquid level of the liquid in the container 900 to be tested. Considering that the output gas pressure of the gas source is usually relatively large, and further, in order to minimize the pressure of the gas delivered to the liquid by the input pipeline 100, so as to improve the stability of the pressure of the gas delivered to the liquid by the input pipeline 100 and the liquid level measurement accuracy, in the liquid level measuring device disclosed in the embodiment of the present application, a current limiting device 410 is installed on the input pipeline 100, so as to use the current limiting device 410 to limit the flow rate (i.e., pressure) of the gas delivered to the input pipeline 100 by the gas source. In detail, in the embodiment of the present application, the current limiting device 410 is used to limit the pressure of the gas input into the liquid by the gas source through the input pipeline 100 to a first preset pressure, and the first preset pressure is less than the output pressure of the gas source. Specifically, the flow limiting device 410 can be a tubular structure, which can enable the flow limiting device 410 to have the ability to limit the pressure of the gas delivered to the liquid through the input pipeline 100 by making the cross-sectional area of ​​the flow limiting device 410 smaller than the cross-sectional area of ​​the part of the input pipeline 100 connected to the gas source.

[0018] In order to ensure that the gas delivered to the liquid through the input pipeline 100 can be normally discharged outside the container 900 to be tested, as described above, the liquid level measuring device includes an output pipeline 200, and the first end of the output pipeline 200 is connected to the atmosphere, and the second end of the output pipeline 200 extends into the container and is located above the liquid level. Therefore, during the operation of the liquid level measuring device, the gas input through the input pipeline 100 can be discharged into the atmosphere through the output pipeline 200 after escaping to above the liquid level of the liquid.

[0019] Specifically, in order to make the container 900 to be tested compatible with the liquid level measuring device disclosed in the embodiment of the present application, two openings can be set on the top of the container 900 to be tested, and at the same time, the input pipeline 100 is extended into the container 900 to be tested through one opening, and the bottom end of the input pipeline 100 is as close to the bottom of the container 900 to be tested as possible, and the output pipeline 200 is extended into the container 900 to be tested through the other opening, and the bottom end of the output pipeline 200 is as close to the top of the container 900 to be tested as possible, to ensure that the output pipeline 200 can be reliably located above the liquid level of the liquid in the container 900 to be tested. Of course, in the process of assembling the liquid level measuring device and the container 900 to be tested, it is also necessary to make the input pipeline 100 and the output pipeline 200 both able to seal and cooperate with the corresponding openings to further improve the measurement accuracy.

[0020] In order to determine the height of the liquid level in the container 900 to be tested by using the pressure difference of the gas in the input pipeline 100 and the output pipeline 200, it is necessary to measure the pressure of the gas in the input pipeline 100 and the output pipeline 200. Optionally, the above-mentioned pressure measuring device 500 is installed downstream of the flow limiting device 410 in the input pipeline 100 and in the output pipeline 200, respectively, so as to obtain the pressure of the gas in each of the input pipeline 100 and the output pipeline 200.

[0021] In order to prevent the pressure measuring device 500 from being located in the gas delivery channel and interfering with the measurement accuracy, in another embodiment of the present application, the liquid level measuring device may also include a first detection pipeline 310 and a second detection pipeline 320, wherein the input pipeline 100 is connected to the first detection pipeline 310, and the output pipeline 200 is connected to the second detection pipeline 320, and the first detection pipeline 310 and the second detection pipeline 320 are both coordinated with the pressure measuring device 500, so that the pressure measuring device 500 is located on the branch of the input pipeline 100 and the output pipeline 200, thereby preventing the setting of the pressure measuring device 500 from having an adverse effect on the detection accuracy.

[0022] Specifically, the first detection pipeline 310 and the second detection pipeline 320 can be formed integrally with the input pipeline 100 and the output pipeline 200, respectively. More specifically, the input pipeline 100 and the output pipeline 200 can be formed by blow molding or other methods using corrosion-resistant materials such as glass. During the formation of the two, the first detection pipeline 310 can be formed on one side of the input pipeline 100 and the second detection pipeline 320 can be formed on one side of the output pipeline 200 by hot melting and bonding, so that the first detection pipeline 310 and the second detection pipeline 320 exist as branches of the input pipeline 100 and the output pipeline 200, respectively, to facilitate the pressure measurement device 500 to perform pressure detection. Similarly, in order to ensure relatively high measurement accuracy and prevent the gas input into the liquid from contaminating or damaging the liquid in the container to be tested 900, in the embodiment of the present application, the type of gas delivered through the input pipeline 100 can be selected according to parameters such as the actual type of the liquid contained in the container to be tested 900, so as to ensure that the delivered gas does not react with the liquid in the container to be tested 900. Generally, the aforementioned gas can be nitrogen or an inert gas.

[0023] Based on the above embodiment, a pressure measuring device 500 can be respectively provided at the end of the first detection pipeline 310 and the end of the second detection pipeline 320, or the pressure measuring device 500 can also be a pressure difference detection device. In this case, the pressure measuring device 500 can be connected and matched with both the first detection pipeline 310 and the second detection pipeline 320. In this case, the pressure measuring device 500 can detect the pressure difference between the first detection pipeline 310 and the second detection pipeline 320. Of course, in order to ensure that the signal output by the pressure measuring device 500 can be recognized by the controller 610, in the embodiment of the present application, the pressure measuring device 500 is also connected to the controller 610 through a signal conversion device 620. The signal conversion device 620 can specifically convert the pressure difference obtained by the pressure measuring device 500 into a corresponding voltage parameter, so that the controller 610 can determine the height difference between the bottom end of the input pipeline 100 and the liquid level of the liquid in the container 900 to be tested based on the received voltage parameter.

[0024] As described above, the liquid level measuring device disclosed in the embodiment of the present application includes a controller 610. To this end, during the operation of the liquid level measuring device, the controller 610 can be used to control the pressure measuring device 500 to measure the pressure difference between the gas in the input pipeline 100 and the output pipeline 200, and the controller 610 is also used to determine the height difference between the bottom end of the input pipeline 100 and the liquid level of the liquid in the container 900 to be measured based on the pressure difference.

[0025] Specifically, the pressure difference P is equal to the static pressure value of the liquid column between the bottom end of the input pipeline 100 and the liquid surface of the liquid in the container 900 to be tested, wherein the pressure at the liquid surface of the liquid in the container 900 to be tested can be P 1 When gas begins to escape from the bottom of the input pipeline 100, the pressure at the end of the input pipeline 100 is P 2 The pressure at the end of the output pipeline 200 connected to the atmosphere is P 0 Since the end of the output pipeline 200 located above the liquid level in the test container 900 is also connected to the atmosphere through the output pipeline 200, P 1 =P 0 , and further, P = P 2 -P 1 .

[0026] The static pressure value of the liquid column of the above height is related to the density ρ of the liquid and the gravity acceleration at the location of the liquid level measuring device, that is, H = (P 2 -P 1 ) / ρg= P / ρg, where the density ρ of the liquid in the container 900 to be tested is a known quantity. In order to reduce the difficulty of measurement, the gravity acceleration is taken as the standard value, that is, g≈9.80 m / s². Based on this, after completing the measurement of the pressure difference P, the height difference between the bottom end of the input pipeline 100 and the liquid surface can be determined, thereby determining the liquid level height of the liquid in the container 900 to be tested.

[0027] The embodiment of the present application discloses a liquid level measuring device, wherein a flow limiting device 410 is installed on an input pipeline 100, so that a gas source can deliver a gas of a first preset pressure to the liquid in the container 900 to be measured through the input pipeline 100, and the space above the liquid surface in the container 900 to be measured is also connected to the atmosphere through the output pipeline 200. By extending the bottom end of the input pipeline 100 below the liquid surface of the liquid in the container 900 to be measured, a corresponding pressure difference exists between the input pipeline 100 and the output pipeline 200, and the pressure difference is generated by the static pressure generated by the liquid at the required measurement height.

[0028] To this end, in an embodiment of the present application, the input pipeline 100 and the output pipeline 200 are both cooperated with the pressure measuring device 500. In this case, the controller 610 can control the pressure measuring device 500 to measure the pressure difference between the input pipeline 100 and the output pipeline 200, and the controller 610 can also determine the height difference between the bottom end of the input pipeline 100 and the liquid level in the liquid based on the measured pressure difference, and then determine the liquid level height in the container 900 to be tested.

[0029] As described above, in the liquid level measuring device disclosed in the embodiment of the present application, except for the input pipeline 100, other parts of the liquid level measuring device are not in direct contact with the liquid, and by making the input pipeline 100 and the gas that enters the liquid through the input pipeline 100 adopt materials that do not physically and chemically react with the liquid, the liquid level measuring device can be prevented from affecting the cleanliness of the liquid. At the same time, since the static pressure value of the liquid is relatively less affected by the airflow that may exist in the container 900 to be measured, the accuracy of the measured liquid level height result can be ensured to be relatively high.

[0030] In the above embodiment, the input pipeline 100 can extend obliquely relative to the vertical direction. Based on this, in order to reduce the interference of the pressure generated by the amount of gas retained in the input pipeline 100 between the bottom end of the container 900 to be tested and the liquid surface on the measurement accuracy, in a further embodiment of the present application, the input pipeline 100 includes a first pipe section 110 and a second pipe section 120, one end of the first pipe section 110 is blocked, the other end of the first pipe section 110 is connected to one end of the second pipe section 120, and a part of the second pipe section 120 extends below the liquid surface of the liquid in the container 900 to be tested; the output pipeline 200 includes a third pipe section 210 and a fourth pipe section 220, one end of the third pipe section 210 is connected to the atmosphere, the other end of the third pipe section 210 is connected to one end of the fourth pipe section 220, and the other end of the fourth pipe section 220 extends into the container 900 to be tested and is located above the liquid surface of the liquid. At the same time, the first pipe section 110 and the third pipe section 210 are both extended in the horizontal direction, and the first pipe section 110 is located above the third pipe section 210, and the second pipe section 120 and the fourth pipe section 220 are both extended in the vertical direction. As above, the liquid level measuring device also includes a first detection pipeline 310 and a second detection pipeline 320. In this case, the first detection pipeline 310 can be connected to the bottom of the first pipe section 110, and the second detection pipeline 320 can be connected to the top of the third pipe section 210, and the first detection pipeline 310 and the second detection pipeline 320 are both extended in the vertical direction to reduce the interference degree of the gas volume and gas gravity on the detection accuracy of the pressure measuring device 500, and further improve the detection accuracy of the pressure difference between the input pipeline 100 and the output pipeline 200. Accordingly, the pressure measuring device 500 can be installed between the first detection pipeline 310 and the second detection pipeline 320.

[0031] When the above technical solution is adopted, the second pipe section 120 of the input pipeline 100 extends in the vertical direction, and the pressure of the gas retained therein is equal to or substantially equal to the static pressure value generated by the liquid at the corresponding height in the container 900 to be measured. This can further reduce the factors that interfere with the measurement accuracy in the structural design of the liquid level measuring device, thereby improving the measurement accuracy.

[0032] In order to improve the assembly stability between the liquid level measuring device and the container 900 to be measured and reduce the degree of adverse effects on the measurement accuracy caused by errors in the assembly process, in an embodiment of the present application, the liquid level measuring device may also include a fixed pipeline 330, which extends in a vertical direction and is located upstream of the first detection pipeline 310. One end of the fixed pipeline 330 is fixed and connected to the first pipe section 110, and the other end of the fixed pipeline 330 is fixed and sealed to the third pipe section 210. In this case, during the processing of the input pipeline 100 and the output pipeline 200, the fixed pipeline 330 can be used to connect the input pipeline 100 and the output pipeline 200, as well as the first detection pipeline 310 and the second detection pipeline 320 as a whole, to ensure that the input pipeline 100, the output pipeline 200, the first detection pipeline 310 and the second detection pipeline 320 are in a relatively fixed state, thereby reducing the adverse effect of the assembly error between the input pipeline 100 and the output pipeline 200 on the measurement accuracy during the assembly of the liquid level measuring device and the container 900 to be measured.

[0033] Based on the above structure of the liquid level measuring device, the liquid level measuring device may further include an air supply line 340, one end of which is connected to the gas source, and the other end of which is connected to the fixed line 330, and the current limiting device 410 is installed between the fixed line 330 and the first pipe section 110. In this case, the part of the input line 100 that directly contacts the liquid, that is, the second pipe section 120, can be further isolated from the gas source, thereby further reducing the degree of interference of parameters such as the flow rate change of the gas source on the stability of the gas transported by the second pipe section 120 to the liquid. In addition, the pressure and flow rate of the gas source can also be limited to prevent the pressure and flow rate of the gas source from being too large, resulting in relatively large fluctuations in the measurement accuracy. Specifically, the pressure of the gas source can be less than or equal to 20 kPa, and the flow rate can be about 1 L / min.

[0034] As described above, the current limiting device 410 can be a tubular structure with a relatively small diameter. In another embodiment of the present application, the current limiting device 410 can be a gasket-like structure. In detail, the edge of the current limiting device 410 is sealed and connected to the inner wall of the fixed pipeline 330, and the current limiting device 410 is provided with a vent. In this case, the assembly difficulty between the current limiting device 410 and the first pipe section 110 and the fixed pipeline 330 is relatively reduced. Of course, the parameters such as the shape and cross-sectional area of ​​the vent can be flexibly selected according to actual conditions. In a specific embodiment of the present application, the shape of the vent can be circular to reduce the processing difficulty of the current limiting device 410. The current limiting device 410 can ensure that the gas introduced into the liquid inside the container 900 to be tested is at a stable flow rate and pressure, so as to perform pressure measurement in the process of continuously discharging bubbles at the end of the input pipeline 100, ensure that the collected pressure signal is relatively stable, and thus achieve the purpose of accurate measurement.

[0035] In the above-mentioned embodiment of the present application, as described above, the fixed pipeline 330 and the third pipe segment 210 in the output pipeline 200 are fixed and sealed. Optionally, during the processing, the fixed pipeline 330 and the third pipe segment 210 can be filled with materials or the like to form a sealed matching relationship after the fixed connection is completed. In another embodiment of the present application, during the process of connecting the fixed pipeline 330 and the third pipe segment 210, a connecting relationship can be first formed between the fixed pipeline 330 and the third pipe segment 210, and then the connecting opening between the fixed pipeline 330 and the third pipe segment 210 can be sealed by using devices such as a sealing gasket 420, so that a sealing relationship can still be formed between the fixed pipeline 330 and the third pipe segment 210, which can reduce the processing difficulty of the entire liquid level measuring device.

[0036] As described above, the liquid level measuring device disclosed in the embodiment of the present application includes a controller 610. Optionally, the liquid level measuring device also includes a display device 630, and the display device 630 is connected to the controller 610. The display device 630 can display the height difference. In this case, the staff can use the display device 630 to obtain the result of the height difference measured by the liquid level measuring device. Specifically, the display device 630 may include a display screen, which is connected to the controller 610 via a cable. In addition, the display device 630 may also have an interactive capability, so that the staff can control the controller 610 through the display device 630 to improve the convenience of use of the liquid level measuring device.

[0037] In another embodiment of the present application, the liquid level measuring device may further include an alarm device 640, which is connected to the controller 610, and the alarm device 640 can output an alarm signal when the height difference does not meet the preset height range. Specifically, the alarm device 640 may be an audible and visual alarm, and the maximum and minimum values ​​of the aforementioned preset height range may be determined according to actual parameters such as the size of the container 900 to be tested and the installation position of the output pipeline 200 in the container 900 to be tested, which is not limited herein.

[0038] As described above, the embodiment of the present application discloses a liquid level measuring device, and the liquid level measuring device can determine the height difference between the bottom end of the input pipeline and the liquid surface of the liquid in the container to be measured based on the obtained pressure difference, and in the above embodiment, the structure and assembly relationship of the components in the liquid level measuring device can be designed to improve the measurement accuracy of the height difference by improving the structure. Based on the above liquid level measuring device, such as Figure 2 As shown, the embodiment of the present application also discloses a liquid level measurement method, which includes: S1. Obtain the pressure difference P between the input pipeline and the output pipeline; Specifically, as described above, the liquid level measuring device includes a pressure measuring device, and by making the input pipeline and the output pipeline cooperate with the pressure measuring device, the controller can control the pressure measuring device to obtain the pressure difference between the input pipeline and the output pipeline. Of course, the pressure measuring device 500 is also connected to the controller through a signal conversion device to convert the pressure difference into a voltage parameter. In addition, in the above embodiment, the accuracy of the above pressure difference obtained by the pressure measuring device can also be improved by designing the structure of the input pipeline and the output pipeline, as well as the specific installation position of the pressure measuring device.

[0039] Based on the above step S1, the liquid level measurement method disclosed in the embodiment of the present application further includes: S2. Based on the pressure difference P, determine the height difference H between the bottom end of the input pipeline and the liquid level in the container to be tested.

[0040] Specifically, as described above, the height difference is related to the size of the portion of the input pipeline that is below the liquid surface, which is specifically the static pressure value of the liquid column corresponding to the height difference between the bottom end of the input pipeline and the top end of the liquid surface. When the density of the liquid is determined, the height difference H between the bottom end of the input pipeline and the liquid surface can be determined based on the pressure difference P. In this case, the liquid level of the liquid in the container to be tested can be determined by summing the height difference with the known quantity of the distance between the bottom end of the input pipeline and the bottom surface of the container to be tested.

[0041] In order to further improve the accuracy of the height difference determined by the liquid level measuring device disclosed in the embodiment of the present application, in a further embodiment of the present application, H=P*K, where K≠0 and K≠±1. Specifically, K=H std / (P std -P 0 ), H std is the preset height difference, P std is the pressure difference detection value obtained when the height difference is the preset height difference, P 0 It is the pressure difference detection value obtained when the altitude difference is zero.

[0042] In detail, in the process of determining the height difference H using the pressure difference P, the embodiment of the present application also uses a sensitivity coefficient K to provide compensation for the height difference, so that the accuracy of the determined height difference is relatively higher. Specifically, since the pressure difference is in direct proportion to the height difference, for this reason, a certain height difference, that is, the ratio between the detected values ​​of the pressure difference obtained under the above-mentioned preset height difference, can be directly used as the aforementioned sensitivity coefficient K, which can improve the measurement accuracy of the liquid level measurement device to a certain extent.

[0043] However, since the principle adopted by the liquid level measuring device disclosed in the embodiment of the present application involves gas pressure, even when the liquid level in the container to be measured is below the bottom of the input pipeline, the pressure difference detected by the liquid level measuring device disclosed in the embodiment of the present application may not necessarily be zero. Therefore, in the above embodiment of the present application, the pressure difference detection value when the height difference is zero can also be introduced to further improve the accuracy of determining the height difference. As mentioned above, H std is the preset height difference, P std is the pressure difference detection value obtained when the height difference is the preset height difference, P 0 is the pressure difference detection value obtained when the height difference is zero. Among them, the height difference between the liquid surface in the liquid contained in the container to be tested and the bottom of the input pipeline can be directly measured by using a measuring tool such as a ruler, so that the height difference between the liquid surface in the container to be tested and the bottom of the input pipeline is H std , of course, the preset height difference H std Specifically, it can be 90% of the volume (or maximum holding height) of the container to be tested; thereafter, when the container to be tested contains liquid with a preset height difference, the pressure difference between the input pipeline and the output pipeline can be obtained by using the liquid level measurement device disclosed in the embodiment of the present application, which is recorded as P std Similarly, when there is no liquid in the container to be tested, or when the liquid level in the container to be tested is below the bottom of the input pipeline, the pressure difference between the input pipeline and the output pipeline is obtained again by using the liquid level measuring device, which is recorded as P 0 .

[0044] Then, using the obtained Pstd and P 0 The value of can be used to determine that the height difference between the bottom of the input pipeline and the liquid level in the container to be tested is the preset height difference H std When the specific value of K corresponding to the measurement is measured, the K value is stored as a preset value in a controller or other device in the liquid level measuring device. When the liquid level measuring device disclosed in the embodiment of the present application is used to measure the liquid level in the container to be measured again, the obtained pressure difference and the K value are multiplied as the height difference determined by the measurement. Accordingly, the height value of the liquid level in the container to be measured can be determined by summing the aforementioned height difference with the distance between the bottom end of the input pipeline and the bottom surface of the container to be measured. This can eliminate as much as possible the adverse effect on the detection accuracy caused by the interference situation that the pressure difference detected by the liquid level measuring device may not necessarily be zero when the liquid level in the container to be measured is below the bottom end of the input pipeline, thereby achieving the purpose of improving the detection accuracy.

[0045] As mentioned above, P 0 is the detection value obtained by using the liquid level measuring device disclosed in the embodiment of the present application when the bottom end of the input pipeline is located above the liquid surface. In order to further improve the accuracy of the determined sensitivity coefficient K, and thus improve the liquid level measurement accuracy output by the liquid level measuring device, in a further embodiment of the present application, when the bottom end of the input pipeline is located above the liquid surface of the liquid in the container to be measured, if within the first preset time length, the measurement value of the pressure measuring device is always within the preset pressure difference range, and the variation range of the measurement value satisfies the preset variation range, the average value of multiple measurement values ​​of the pressure measuring device within the first preset time length is taken as P 0 , wherein the minimum value of the preset pressure difference range is greater than or equal to 0, and the maximum value of the preset pressure difference range is less than the pressure difference detection value obtained when the height difference is the maximum value of the liquid level in the container to be tested.

[0046] When the bottom end of the input pipeline is above the liquid level in the container to be tested, the actual height difference should be 0. In this case, the pressure difference detection values ​​are obtained multiple times, and whether the multiple detection values ​​are within the preset pressure difference range is used as a preliminary judgment, and whether the change range of the detection value meets the preset change range is used as a further judgment to determine the P value that meets the requirements among the multiple detection values. 0 Then, using multiple P 0 The average value of the detection value is taken as P 0 , the accuracy of the determined K can be improved, thereby improving the accuracy of liquid level measurement.

[0047] Of course, in the above-mentioned embodiments of the present application, the range of the preset change amplitude is smaller than the preset pressure difference range. As mentioned above, the maximum value and the minimum value of the preset pressure range are the detection values ​​when the liquid level is the maximum value and 0 of the container to be tested, respectively. For the range of the preset change amplitude, a fixed value close to 0 should be used as the center value, and a relatively small range should be taken on both sides as the preset change amplitude. For example, the difference between the maximum value and the minimum value in the pressure range corresponding to the preset change amplitude should be less than or equal to one tenth of the difference between the maximum value and the minimum value in the preset pressure difference range. In addition, the first preset duration can be flexibly selected according to parameters such as the frequency of obtaining the pressure difference detection value, which is not limited in this article. Generally, the first preset duration can be several minutes, or it can also be less or more time.

[0048] By adopting the method disclosed in the above embodiment of the present application, the P of determining the sensitivity coefficient K can be improved. 0 In order to further improve the accuracy of the determined sensitivity coefficient K, in a specific embodiment of the present application, the height difference between the bottom end of the input pipeline and the liquid level in the container to be tested is a preset height difference H std When the pressure difference measurement value of the pressure measuring device satisfies the following formula within the second preset time period: H std *(K-ΔK)*U ad ≤P std ≤H std *(K+ΔK)*U ad The multiple pressure difference measurements are qualified measurement values ​​P x The average value of multiple qualified measurements is taken as P std , where ΔK is a preset constant, U ad It is the voltage value output by the pressure measuring device when the height difference between the bottom end of the input pipeline and the liquid surface is a preset height difference.

[0049] As mentioned above, the liquid level measuring device uses the pressure difference between the input pipeline and the output pipeline as the basic data to determine the height difference between the bottom of the input pipeline and the liquid surface in the container to be measured. To this end, based on the physical characteristics of the liquid level measuring device, it can be determined that when the detected value of any pressure difference is not an erroneous value, or the error is too large, the detected value should be within the range of values ​​formed by the allowable error value extending to the left and right sides with the true value of the pressure difference as the center. Among them, when the allowable error is a negative value, the corresponding endpoint value in the aforementioned range is H std *(K-ΔK)*U ad Correspondingly, when the allowable error is positive, the corresponding endpoint value in the above range is recorded as H std *(K+ΔK)*U adTherefore, as long as the detected pressure difference satisfies the aforementioned value range relationship, it is considered that the error of the detection value does not exceed the maximum error, and it can be used as a qualified measurement value.

[0050] To this end, when the height difference between the liquid level in the container to be tested and the bottom end of the input pipeline is a preset height difference, the average value of multiple qualified measurement values ​​is used as P std The detection value of the pressure difference can improve the accuracy of the determined sensitivity coefficient K, thereby further improving the detection accuracy of the liquid level measurement device. In addition, it should be noted that ΔK is the sensitivity change value obtained when the liquid level measurement device is installed in containers of different specifications to be tested, which is a set value. In a specific embodiment of the present application, it is 0.056.

[0051] Based on the above situation, in determining P std and P 0 After calculating their respective values, we can use K=H std / (P std -P 0 ), determine the value of K, and write the above-mentioned value of K into the liquid level measuring device disclosed in the embodiment of the present application. When the liquid level measuring device is used to measure the liquid level height in the future, the accuracy of the height difference obtained can be relatively high, thereby improving the measurement accuracy of the liquid level height.

[0052] In order to further improve the accuracy of the measured liquid level height, optionally, when the container to be tested contains liquid and the distance between the bottom end of the input pipeline and the liquid surface is a preset height difference, a pressure difference P is obtained by using a liquid level measuring device. x ,based on , determine the height difference H y , with H y Taking H' as an example, by judging H' and H std Whether the absolute value of the difference between the two meets the preset difference range, if so, record the obtained P x is a qualified value. Accordingly, by obtaining H' multiple times and judging, multiple qualified P x As P std , and can also improve the accuracy of the obtained K value, thereby improving the accuracy of liquid level measurement.

[0053] In another embodiment of the present application, the height difference H determined by any two adjacent detection processes can also be y The height difference between the two adjacent sides is determined by the absolute value of the difference between the two adjacent sides and the preset height difference. 1 and H 2 For example, H 1 is the height difference determined previously, and accordingly, H2 The height difference determined later, in H 2 The absolute value of the difference from the preset height difference is less than H 1 In the case of the absolute value of the difference between the preset height difference and H 2 The corresponding pressure difference detection value P x2 Give P std , then obtain the pressure difference P again x3 , and based on the assigned formula, determine the height difference H 3 , then judge H 3 Is the absolute value of the difference between the preset height and the height less than H? 2 The absolute value of the difference between the preset height difference and H 3 The corresponding pressure difference detection value P x3 Further assign P std , and obtain the pressure difference P x4 , until the height difference H is determined y If the absolute value of the difference between the pressure difference and the preset height difference meets the allowable error, the pressure difference detection value obtained last time is taken as P std , and determine the value of K. On the contrary, in H 3 The absolute value of the difference from the preset height difference is equal to or greater than H 2 If the absolute value of the difference between the pressure difference and the preset height difference is x3 , continue with P x2 As P std The pressure difference is detected.

[0054] It should be noted that, in this article, the terms "comprise", "include" or any other variant thereof are intended to cover non-exclusive inclusion, so that the process, method, article or device including a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise one..." do not exclude the presence of other identical elements in the process, method, article or device including the element. In addition, it should be pointed out that the scope of the methods and devices in the embodiments of the present application is not limited to performing functions in the order shown or discussed, and may also include performing functions in a substantially simultaneous manner or in reverse order according to the functions involved, for example, the described method may be performed in an order different from that described, and various steps may also be added, omitted, or combined. In addition, the features described with reference to certain examples may be combined in other examples.

[0055] The embodiments of the present application are described above in conjunction with the accompanying drawings, but the present application is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the guidance of the present application, ordinary technicians in this field can also make many forms without departing from the purpose of the present application and the scope of protection of the claims, all of which are within the protection of the present application.

Claims

1. A liquid level measuring device, characterized in that: It includes an input pipeline, a current limiting device, an output pipeline, a pressure measuring device and a controller, wherein: The input pipeline is connected to the gas source, the bottom end of the input pipeline is used to extend below the liquid level of the liquid in the container to be tested, the current limiting device is installed on the input pipeline, and the current limiting device is used to limit the pressure of the gas input into the liquid through the gas source through the input pipeline to a first preset pressure, the first end of the output pipeline is connected to the atmosphere, and the second end of the output pipeline extends into the container and is located above the liquid level of the liquid; The input pipeline and the output pipeline are both coordinated with the pressure measuring device. The controller is used to control the pressure measuring device to measure the pressure difference between the gas in the input pipeline and the gas in the output pipeline. The controller is also used to determine the height difference between the bottom end of the input pipeline and the liquid level in the container to be tested based on the pressure difference.

2. The liquid level measuring device according to claim 1, characterized in that: It also includes a first detection pipeline and a second detection pipeline, the input pipeline is connected to the first detection pipeline, the output pipeline is connected to the second detection pipeline, and the pressure measuring device is installed between the first detection pipeline and the second detection pipeline.

3. The liquid level measuring device according to claim 2, characterized in that: The first detection pipeline and the second detection pipeline both extend in a vertical direction.

4. The liquid level measuring device according to claim 1, characterized in that: The input pipeline includes a first pipe section and a second pipe section, one end of the first pipe section is sealed, the other end of the first pipe section is connected to one end of the second pipe section, and a part of the second pipe section extends below the liquid level in the container to be tested; the output pipeline includes a third pipe section and a fourth pipe section, one end of the third pipe section is connected to the atmosphere, the other end of the third pipe section is connected to one end of the fourth pipe section, the other end of the fourth pipe section extends into the container to be tested and is located above the liquid level of the liquid; the first pipe section and the third pipe section both extend in the horizontal direction, and the first pipe section is located above the third pipe section, and the second pipe section and the fourth pipe section both extend in the vertical direction.

5. The liquid level measuring device according to claim 4, characterized in that: It also includes a fixed pipeline and an air supply pipeline, wherein the fixed pipeline extends in a vertical direction, and one end of the fixed pipeline is fixed and connected to the first pipe section, and the other end of the fixed pipeline is fixed and sealed to the third pipe section, one end of the air supply pipeline is connected to an air source, and the other end of the air supply pipeline is connected to the fixed pipeline, and the current limiting device is installed between the fixed pipeline and the first pipe section.

6. The liquid level measuring device according to claim 5, characterized in that: The edge of the flow limiting device is sealedly connected to the inner wall of the fixed pipeline, and the flow limiting device is provided with a vent hole.

7. The liquid level measuring device according to claim 1, characterized in that: It also includes an alarm device, which is connected to the controller and is used to output an alarm signal when the height difference does not meet a preset height range.

8. A liquid level measurement method, applied to the liquid level measurement device according to any one of claims 1 to 7, characterized in that: The liquid level measurement method comprises: Obtain the pressure difference P between the input pipeline and the output pipeline; Based on the pressure difference P, the height difference H between the bottom end of the input pipeline and the liquid level in the container to be tested is determined.

9. The liquid level measurement method according to claim 8, characterized in that: H=P*K, where K≠0 and K≠±1, K=H std / (P std -P0), H std is the preset height difference, P std is the pressure difference detection value obtained when the height difference is the preset height difference, and P0 is the pressure difference detection value obtained when the height difference is zero.

10. The liquid level measurement method according to claim 9, characterized in that: In the case where the bottom end of the input pipeline is located above the liquid level in the container to be tested, if within a first preset time period, the measurement value of the pressure measuring device is always within a preset pressure difference range, and the change amplitude of the measurement value satisfies the preset change amplitude, the average value of multiple measurement values ​​of the pressure measuring device within the first preset time period is taken as P0, wherein the minimum value of the preset pressure difference range is greater than or equal to 0, and the maximum value of the preset pressure difference range is less than the pressure difference detection value obtained when the height difference is the liquid level of the liquid in the container to be tested is the maximum value, and the range of the preset change amplitude is less than the preset pressure difference range.

11. The liquid level measurement method according to claim 9, characterized in that: The height difference between the bottom end of the input pipeline and the liquid level in the container to be tested is the preset height difference H std When, within the second preset time period, the pressure difference measurement value of the pressure measuring device satisfies the following formula: H std *(K-ΔK)*U ad ≤P std ≤H std *(K+ΔK)*U ad The plurality of pressure difference measurements are qualified measurement values ​​P x The average value of multiple qualified measurement values ​​is taken as P std , where ΔK is a preset constant, U ad It is the voltage value output by the pressure measuring device when the height difference between the bottom end of the input pipeline and the liquid surface is a preset height difference.

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