An ultra-low temperature magnetic level gauge

Abstract

The present invention relates to the technical field of liquid level measurement equipment, and in particular to an ultra-low temperature magnetic liquid level gauge. The ultra-low temperature magnetic liquid level gauge includes a float, a processor, and a float height monitoring component; a first pressure sensor is installed at the bottom of the outer surface of the float, and a second pressure sensor is installed on the outer surface of the float and above the first pressure sensor; a transmitter electrically connected to the first pressure sensor and the second pressure sensor is also encapsulated inside the float; the transmitter is used to transmit a first pressure signal monitored by the first pressure sensor and a second pressure signal monitored by the second pressure sensor to the processor, and the processor generates a density correction value according to the first pressure signal and the second pressure signal; the float height monitoring component can monitor the distance between the magnet in the float and a preset reference height. The ultra-low temperature magnetic liquid level gauge can accurately monitor the liquid level in the liquid storage container without the need to adjust the weight of the float according to the liquid to be measured.

Description

Technical Field

[0001] The invention relates to the technical field of liquid level measuring equipment, and in particular to an ultra-low temperature magnetic liquid level gauge. Background Art

[0002] The magnetic level gauge is mainly composed of a float, a measuring cylinder, a magnetic turning column, etc. The measuring cylinder is connected to the liquid storage container, so that the liquid level height in the measuring cylinder is equal to the liquid level height in the liquid storage container. The float is set in the measuring cylinder and the height of the float changes with the liquid level height. Therefore, through the interaction between the magnet in the float and the magnetic turning column, the corresponding magnetic turning column is turned over, and then the boundary between the turned magnetic turning column and the non-turned magnetic turning column is the height position of the magnet in the float, that is, the liquid level height position in the liquid storage container.

[0003] However, when the existing magnetic level gauge is used to measure the liquid level, in order to make the height position of the magnet in the float represent the liquid level in the liquid storage container, it is necessary to counterweight the magnetic float according to the density of the measured liquid, so as to ensure that the liquid level and the line of action of the magnetic force of the float (i.e., the height position of the magnet in the float) are in the same horizontal plane during operation (because the "draft" depth of the float will change when the density of the measured liquid is different, and the height position of the magnet in the float will deviate from the liquid level, and it is necessary to adjust the counterweight of the float to keep the "waterline" of the float at the height position of the magnet in the float). The counterweighting process is usually carried out by sampling and measuring the "waterline" position of the float, and then gradually adjusting the weight of the float so that the "waterline" position is flush with the height position of the magnet in the float, or by measuring the density of the liquid to be measured, and then determining the adjustment amount of the counterweight according to the buoyancy formula to achieve adjustment; the above two counterweighting methods are relatively cumbersome. Moreover, for liquid measurements in ultra-low temperature environments (below -150°C) (such as liquid nitrogen, liquid oxygen, liquid argon and other liquids), it is difficult to measure the "waterline" position of the float by sampling (these liquids evaporate rapidly when sampled in a room temperature environment and are no longer in liquid form), and it is also difficult to calculate the density, and thus it is difficult to determine the amount of weight adjustment based on the buoyancy formula.

[0004] In addition, the existing magnetic level meter relies on the flipping of the magnetic column to display the liquid level height, and its graduation value is limited by the size of the magnetic column. The graduation value is usually 10mm or 20mm, and the accuracy is low. Summary of the invention

[0005] The object of the present invention is to provide an ultra-low temperature magnetic level gauge, which can at least partially overcome the above technical problems, thereby accurately monitoring the liquid level of the liquid in the ultra-low temperature environment in the liquid storage container, and there is no need to adjust the weight of the float according to the liquid to be measured.

[0006] The ultra-low temperature magnetic liquid level gauge provided by the present invention comprises a float and a measuring cylinder, wherein the measuring cylinder is vertically installed and communicated with a liquid storage container, and the float is installed in the measuring cylinder; a first pressure sensor is fixedly installed at the bottom of the outer surface of the float, and a second pressure sensor is fixedly installed on the outer surface of the float and at a first preset distance above the first pressure sensor; a transmitter is also encapsulated inside the float, and the first pressure sensor and the second pressure sensor are both electrically connected to the transmitter; the ultra-low temperature magnetic liquid level gauge also comprises: a processor, the transmitter is electrically connected to the processor, and the transmitter is used to transmit a first pressure signal monitored by the first pressure sensor and a second pressure signal monitored by the second pressure sensor to the processor, and the processor can generate a density correction value for correcting the liquid level height in the liquid storage container according to the first pressure signal and the second pressure signal; a float height monitoring component, and the float height monitoring component can monitor the distance between the magnet in the float and a preset reference height.

[0007] Furthermore, the float is cylindrical, and the processor generates the density correction value in the following manner:

[0008] ,

[0009] in, X 1 is the density correction, m is the mass of the float, g is the gravitational acceleration at the location of the liquid storage container, ∆h is the first preset distance, P 1 is the pressure value corresponding to the first pressure signal, P 2 is the pressure value corresponding to the second pressure signal, A is the cross-sectional area of ​​the float, h 0 is the distance from the magnet in the float to the bottom of the float.

[0010] Furthermore, the processor corrects the distance between the magnet in the float and the preset reference height monitored by the float height monitoring component according to the density correction amount, including:

[0011] ,

[0012] in, H is the corrected liquid level height, H c The float height monitoring component monitors the distance between the magnet in the float and the preset reference height.

[0013] In view of the fact that the existing magnetic level gauge uses a magnetic column to display the liquid level height, the accuracy is poor. Therefore, in the ultra-low temperature magnetic level gauge provided by the present invention:

[0014] The magnet is cylindrical and has a vertical axis. The float height monitoring component includes a plurality of Hall sensors evenly distributed along the vertical direction, and each of the Hall sensors is electrically connected to the processor. The processor can generate a magnetic field strength monitoring value corresponding to each Hall sensor in response to an output signal of each Hall sensor.

[0015] Further, at least one Hall sensor is lower than the lower end of the measuring cylinder, and at least one Hall sensor is higher than the upper end of the measuring cylinder.

[0016] Furthermore, the height values ​​of the Hall sensors are recorded in ascending order as H 1 ,H 2 , H 3 ,…,H n , the magnetic field intensity monitoring value corresponding to each Hall sensor is recorded as B 1 ,B 2 ,B 3 ,…,B n The processor can obtain the distance between the magnet and the preset reference height based on each of the magnetic field strength monitoring values, including: traversing the generated magnetic field strength monitoring values, obtaining the maximum monitoring value B i ;

[0017] exist In the case of ,

[0018] exist In the case of ,

[0019] in, H i The maximum monitoring value B i The corresponding height value of the Hall sensor, H c The float height monitoring component monitors the distance between the magnet in the float and the preset reference height.

[0020] Further, the processor obtains the distance between the magnet and a preset reference height based on each of the magnetic field intensity monitoring values, and further includes:

[0021] exist In the case of

[0022] ,

[0023] exist In the case of

[0024] ,

[0025] in, ∆H is the distance between two adjacent Hall sensors.

[0026] Furthermore, the ultra-low temperature magnetic level gauge further comprises a magnetic shielding box body, and the measuring cylinder and each of the Hall sensors are packaged in the magnetic shielding box body.

[0027] For a container, the height of the liquid level inside it is usually not too high or too low. For this reason, the ultra-low temperature magnetic level gauge provided in the present invention also has a liquid level alarm function. In particular, the alarm liquid level can be set below the waterline when the float touches the bottom, or above the waterline when the float touches the top.

[0028] The ultra-low temperature magnetic liquid level gauge also includes a liquid level alarm component electrically connected to the processor, and the liquid level alarm component can send a first alarm signal when the liquid level height is lower than a first preset height, and / or send a second alarm signal when the liquid level height is higher than a second preset height.

[0029] Further, the processor controls the liquid level warning component to send out a first warning signal when the pressure value corresponding to the first pressure signal gradually decreases, and / or, the processor controls the liquid level warning component to send out a second warning signal when the pressure value corresponding to the first pressure signal gradually increases.

[0030] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0031] 1. The ultra-low temperature magnetic liquid level gauge provided by the embodiment of the present disclosure, by setting a first pressure sensor and a second pressure sensor, and then using the pressure difference and height difference of the two pressure sensors and the mass of the float to obtain the "displacement" of the float floating in the liquid to be measured of unknown density, and then obtain the "waterline" of the float and the height deviation of the magnet in the float (i.e., the density correction amount), thereby, the distance between the magnet in the float and the preset reference height monitored by the float height monitoring component can be corrected by the density correction amount, and then the accurate liquid level height in the liquid storage container can be obtained; the cumbersome process of adjusting the weight of the float is avoided, so that the ultra-low temperature magnetic liquid level gauge can adapt to the liquid level measurement of liquids of different densities without adjusting the weight and can ensure the measurement accuracy;

[0032] 2. The ultra-low temperature magnetic level meter provided in the embodiment of the present disclosure measures the height position of the magnet in the float through the Hall sensor array, and then obtains the distance between the magnet in the float and the preset reference height. Compared with displaying the height position of the float by flipping the magnetic flip column, the graduation value is smaller, and the accuracy of the monitoring result is greatly improved; and the maintenance trouble caused by repeated flipping and wear of the magnetic flip column is avoided; in addition, the embodiment of the present disclosure monitors the height position of the float through the Hall sensor array. H c Combined with the aforementioned density correction, the liquid level in the liquid storage container can be accurately obtained;

[0033] 3. The ultra-low temperature magnetic liquid level gauge provided in the embodiment of the present disclosure can, through the liquid level alarm component, give an alarm when the first preset height is lower than the magnet height when the float touches the bottom (that is, the lower limit of the alarm liquid level of the first alarm signal is extended to below the magnet height when the float touches the bottom), and correspondingly, it can also give an alarm when the second preset height is higher than the magnet height when the float touches the top (that is, the upper limit of the alarm liquid level of the second alarm signal is extended to above the magnet height when the float touches the bottom. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The drawings described herein are used to provide a further understanding of the embodiments of the present invention, constitute a part of this application, and do not constitute a limitation of the embodiments of the present invention. In the drawings:

[0035] Figure 1 It is a schematic diagram of the three-dimensional structure of the ultra-low temperature magnetic liquid level gauge installed on the liquid storage container according to an embodiment of the present invention;

[0036] Figure 2 Based on Figure 1 A longitudinal sectional view showing the ultra-low temperature magnetic level gauge installed on a liquid storage container;

[0037] Figure 3It is a longitudinal cross-sectional view of a float according to an embodiment of the present invention.

[0038] Marks and corresponding parts names in the attached drawings:

[0039] 1- float; 11- first pressure sensor; 12- second pressure sensor; 13- transmitter; 14- magnet; 2- measuring tube; 3- processor; 41- Hall sensor; 5- magnetic shielding box; 9- liquid storage container. DETAILED DESCRIPTION

[0040] In order to make the purpose, technical scheme and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments and drawings. The schematic implementation modes and descriptions of the present invention are only used to explain the present invention and are not intended to limit the present invention. It should be noted that the present invention is already in the actual development and use stage.

[0041] When the existing magnetic level gauge is used to measure the liquid level, it is necessary to adjust the float by weight so that the "waterline" of the float and the height position of the magnet in the float are aligned. The weight adjustment process is cumbersome, and for the liquid to be measured with unknown density, it is usually necessary to adjust repeatedly to achieve the result that the "waterline" of the float and the height position of the magnet in the float are aligned. The adjustment process is relatively cumbersome. Especially for the measurement of liquid in ultra-low temperature environment (below -150°C), it is difficult to determine the weight of the weight by sampling and measuring the "waterline" position of the float, and it is difficult to ensure that the "waterline" of the float and the height position of the magnet in the float are aligned; in addition, when the existing magnetic level gauge is used to measure the liquid level, the measurement result is displayed by the flipping of the magnetic flip column, and the measured graduation value is limited by the size of the magnetic flip column, and the graduation value is usually 10mm or 20mm, with low accuracy.

[0042] In order to overcome the defects of the above-mentioned existing magnetic liquid level meters, the present invention provides an ultra-low temperature magnetic liquid level meter, which can accurately monitor the liquid level in the liquid storage container and does not require the float to be weighted according to the liquid to be measured. It is particularly suitable for liquid level monitoring of liquid in an ultra-low temperature environment.

[0043] Embodiment 1:

[0044] like Figures 1 to 3 As shown, this embodiment provides an ultra-low temperature magnetic level gauge, comprising a float 1 and a measuring tube 2, wherein the measuring tube 2 is vertically installed and communicated with a liquid storage container 9, and the float 1 is installed in the measuring tube 2;

[0045] A first pressure sensor 11 is fixedly installed on the bottom of the outer surface of the float 1, and a second pressure sensor 12 is fixedly installed on the outer surface of the float 1 and at a first preset distance above the first pressure sensor 11;

[0046] A transmitter 13 is also encapsulated inside the float 1, and the first pressure sensor 11 and the second pressure sensor 12 are both electrically connected to the transmitter 13;

[0047] The ultra-low temperature magnetic level gauge also includes:

[0048] The processor 3, the transmitter 13 is electrically connected to the processor 3, the transmitter 13 is used to transmit the first pressure signal monitored by the first pressure sensor 11 and the second pressure signal monitored by the second pressure sensor 12 to the processor 3, and the processor 3 can generate a density correction value for correcting the liquid level height in the liquid storage container 9 according to the first pressure signal and the second pressure signal;

[0049] A float height monitoring component is provided, wherein the float height monitoring component is capable of monitoring the distance between the magnet 14 in the float 1 and a preset reference height.

[0050] Specifically, the float 1 is cylindrical, and the processor 3 generates the density correction value in the following manner:

[0051] ,

[0052] in, X 1 is the density correction, m is the mass of float 1, g is the gravitational acceleration at the location of the liquid storage container 9, ∆h is the first preset distance, P 1 is the pressure value corresponding to the first pressure signal, P 2 is the pressure value corresponding to the second pressure signal, A is the cross-sectional area of ​​float 1, h 0 is the distance from the magnet 14 in the float 1 to the bottom of the float 1 .

[0053] It should be understood that the columnar configuration of the float 1 is a preferred solution for making the draft and displacement of the float 1 proportional, with the purpose of simplifying the calculation process of the density correction amount.

[0054] The processor 3 corrects the distance between the magnet 14 in the float 1 and the preset reference height obtained by the float height monitoring component according to the density correction value, including:

[0055] ,

[0056] in, H is the corrected liquid level height, H c The distance between the magnet 14 in the float 1 and a preset reference height is monitored by the float height monitoring assembly.

[0057] Accordingly, the ultra-low temperature magnetic liquid level gauge provided in the present embodiment, by setting a first pressure sensor 11 and a second pressure sensor 12, further utilizes the pressure difference and height difference of the two pressure sensors and the mass of the float 1 to obtain the "displacement" of the float 1 floating in the liquid to be tested of unknown density (when the float 1 is columnar, the draft of the float 1 can be easily obtained), and then obtains the "waterline" of the float 1 and the height deviation of the magnet 14 in the float 1 (i.e., the density correction amount). Thus, the distance between the magnet 14 in the float 1 and the preset reference height monitored by the float height monitoring component can be corrected by the density correction amount, thereby obtaining the accurate liquid level height in the liquid storage container 9.

[0058] The ultra-low temperature magnetic liquid level meter provided in this embodiment avoids the tedious process of adjusting the counterweight of the float 1 by means of error correction, so that the ultra-low temperature magnetic liquid level meter can adapt to the liquid level measurement of liquids of different densities without counterweight adjustment and can ensure the measurement accuracy. Based on this feature, the ultra-low temperature magnetic liquid level meter is particularly suitable for liquid level monitoring of liquids in ultra-low temperature environments.

[0059] Embodiment 2:

[0060] This embodiment is based on Embodiment 1, except that, in this embodiment:

[0061] The magnet 14 is cylindrical and has a vertical axis. The float height monitoring assembly includes a plurality of Hall sensors 41 evenly distributed along the vertical direction, and each of the Hall sensors 41 is electrically connected to the processor 3;

[0062] The processor 3 can generate a magnetic field intensity monitoring value corresponding to each Hall sensor 41 in response to an output signal of each Hall sensor 41 .

[0063] Specifically, at least one Hall sensor 41 is lower than the lower end of the measuring cylinder 2 , and at least one Hall sensor 41 is higher than the upper end of the measuring cylinder 2 .

[0064] The height values ​​of the Hall sensors 41 are recorded in ascending order as H 1 ,H 2 ,H3 ,…,H n , the magnetic field intensity monitoring value corresponding to each Hall sensor 41 is recorded as B 1 ,B 2 ,B 3 ,…,B n ;

[0065] The processor 3 can obtain the distance between the magnet 14 and a preset reference height based on each of the magnetic field intensity monitoring values, including:

[0066] Traverse the generated magnetic field strength monitoring values ​​to obtain the maximum monitoring value B i ;

[0067] exist In the case of ,

[0068] exist In the case of ,

[0069] in, H i The maximum monitoring value B i The corresponding height value of the Hall sensor 41, H c The distance between the magnet 14 in the float 1 and a preset reference height is monitored by the float height monitoring assembly.

[0070] It should be understood that the magnetic field intensity monitoring value of each Hall sensor 41 is B 1 ,B 2 ,B 3 ,…,B n After being arranged in sequence, it presents a single-peak characteristic. The above two formulas are to express that if there are two equal maximum values ​​in the magnetic field intensity monitoring values ​​of each of the Hall sensors 41 (obviously they should correspond to two adjacent Hall sensors 41), then the height position of the magnet 14 in the float 1 is flush with the height position of the midpoint of the line connecting the two adjacent Hall sensors 41.

[0071] The processor 3 obtains the distance between the magnet 14 and a preset reference height based on each of the magnetic field intensity monitoring values, and further includes:

[0072] exist In the case of

[0073] ,

[0074] exist In the case of

[0075] ,

[0076] in, ∆H is the distance between two adjacent Hall sensors 41 .

[0077] Accordingly, the ultra-low temperature magnetic level meter provided in this embodiment measures the height position of the magnet 14 in the float 1 through the Hall sensor 41 array, and then obtains the distance between the magnet 14 in the float 1 and the preset reference height. Compared with displaying the height position of the float 1 by flipping the magnetic flip column, the graduation value is smaller, and the accuracy of the monitoring result is greatly improved; and the maintenance trouble caused by repeated flipping and wear of the magnetic flip column is avoided; in addition, the embodiment monitors the height position of the float 1 through the Hall sensor 41 array H c Combined with the aforementioned density correction value, the liquid level height in the liquid storage container 9 can be accurately obtained.

[0078] By obtaining the distance between the magnet 14 and the preset reference height based on each of the magnetic field strength monitoring values ​​by the processor 3, the number of required Hall sensors 41 can be reduced while ensuring the required measurement accuracy, thereby reducing the cost of the ultra-low temperature magnetic level meter.

[0079] Preferably, the ultra-low temperature magnetic level gauge further includes a magnetic shielding box 5, in which the measuring tube 2 and each of the Hall sensors 41 are encapsulated. Accordingly, by providing the magnetic shielding box 5, it is possible to effectively prevent the external magnetic field from interfering with each of the Hall sensors 41, thereby ensuring that each of the Hall sensors 41 accurately senses the magnetic field strength of the magnet 14, which is conducive to ensuring the accuracy of the monitoring results. It should be understood that the material of the magnetic shielding box 5 is selected from ferromagnetic materials with high magnetic permeability, such as soft iron, silicon steel, and Permalloy.

[0080] Preferably, the ultra-low temperature magnetic liquid level gauge further comprises a display, which is located at the position of the liquid storage container 9, and the display is electrically connected to the processor 3, and the display can display the corrected liquid level height in real time.

[0081] Embodiment 3:

[0082] This embodiment is based on Embodiment 1, except that, in this embodiment:

[0083] The ultra-low temperature magnetic liquid level gauge also includes a liquid level alarm component electrically connected to the processor 3, and the liquid level alarm component can send a first alarm signal when the liquid level height is lower than a first preset height, and / or send a second alarm signal when the liquid level height is higher than a second preset height.

[0084] Specifically, when the pressure value corresponding to the first pressure signal gradually decreases, the processor 3 controls the liquid level warning component to send out a first warning signal, and / or,

[0085] When the pressure value corresponding to the first pressure signal gradually increases, the processor 3 controls the liquid level warning component to send out a second warning signal.

[0086] Compared to the method of comparing the liquid level height obtained by monitoring with the first preset height and the second preset height and then issuing an alarm, the ultra-low temperature magnetic liquid level gauge provided in this embodiment identifies the state of the float 1 (floating, touching the bottom or touching the top) by the change in the pressure value corresponding to the first sensor, and can thus issue an alarm when the first preset height is lower than the height of the magnet 14 when the float 1 touches the bottom (that is, the lower limit of the alarm liquid level of the first alarm signal is extended to below the height of the magnet 14 when the float 1 touches the bottom), and accordingly, can also issue an alarm when the second preset height is higher than the height of the magnet 14 when the float 1 touches the top (that is, the upper limit of the alarm liquid level of the second alarm signal is extended to above the height of the magnet 14 when the float 1 touches the bottom).

[0087] Preferably, the processor 3 controls the liquid level warning component to issue a first warning signal when the pressure value corresponding to the first pressure signal gradually decreases to a first preset percentage of the pressure value when the pressure starts to decrease (for example, when the pressure value gradually decreases to 50% of the pressure value when the pressure starts to decrease, the first warning signal is issued, indicating that the warning liquid level of the first warning signal is 50% of the "draft" of the float 1 when the liquid level drops again after the float 1 touches the bottom); similarly, the processor 3 controls the liquid level warning component to issue a second warning signal when the pressure value corresponding to the first pressure signal gradually increases to a second preset percentage of the pressure value when the pressure starts to increase (for example, when the pressure value gradually increases to 30% of the pressure value when the pressure starts to increase, the second warning signal is issued, indicating that the warning liquid level of the second warning signal is 30% of the "draft" of the float 1 when the liquid level rises again after the float 1 touches the top).

[0088] It should be understood that, when the float 1 is in a floating state, the draft of the float 1 is expressed as:

[0089] ,

[0090] in, h cIt is the draft of the float 1 in the floating state.

[0091] Therefore, after the ultra-low temperature magnetic level gauge is fixedly installed on the predetermined liquid storage container 9, the liquid level heights when the float 1 touches the bottom and the top are known. After obtaining the draft of the float 1 in the floating state, the warning liquid level of the first alarm signal can be conveniently adjusted down to the target distance. Similarly, the warning liquid level of the second alarm signal can be conveniently adjusted up to the target distance.

[0092] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. An ultra-low temperature magnetic level gauge, comprising a float (1) and a measuring tube (2), wherein the measuring tube (2) is vertically installed and communicated with a liquid storage container (9), and the float (1) is installed in the measuring tube (2); characterized in that: A first pressure sensor (11) is fixedly mounted on the bottom of the outer surface of the float (1), and a second pressure sensor (12) is fixedly mounted on the outer surface of the float (1) and located at a first preset distance above the first pressure sensor (11); A transmitter (13) is also encapsulated inside the float (1), and the first pressure sensor (11) and the second pressure sensor (12) are both electrically connected to the transmitter (13); The ultra-low temperature magnetic level gauge also includes: A processor (3), wherein the transmitter (13) is electrically connected to the processor (3), and the transmitter (13) is used to transmit a first pressure signal monitored by the first pressure sensor (11) and a second pressure signal monitored by the second pressure sensor (12) to the processor (3), and the processor (3) is capable of generating a density correction value for correcting the liquid level height in the liquid storage container (9) according to the first pressure signal and the second pressure signal; A float height monitoring component is provided, wherein the float height monitoring component is capable of monitoring the distance between a magnet (14) in the float (1) and a preset reference height.

2. The ultra-low temperature magnetic level gauge according to claim 1, characterized in that: The float (1) is cylindrical, and the processor (3) generates the density correction value in the following manner: ， in, X 1 is the density correction, m is the mass of the float (1), g is the gravitational acceleration at the location of the liquid storage container (9), ∆ h is the first preset distance, P 1 is the pressure value corresponding to the first pressure signal, P 2 is the pressure value corresponding to the second pressure signal, A is the cross-sectional area of ​​the float (1), h 0 is the distance from the magnet (14) in the float (1) to the bottom of the float (1).

3. The ultra-low temperature magnetic level gauge according to claim 2, characterized in that: The processor (3) corrects the distance between the magnet (14) in the float (1) and a preset reference height obtained by monitoring the float height monitoring component according to the density correction value, including: ， in, H is the corrected liquid level height, H c The distance between the magnet (14) in the float (1) and a preset reference height is monitored by the float height monitoring component.

4. The ultra-low temperature magnetic level gauge according to claim 1, characterized in that: The magnet (14) is cylindrical and has a vertical axis. The float height monitoring component comprises a plurality of Hall sensors (41) evenly distributed in the vertical direction. Each of the Hall sensors (41) is electrically connected to the processor (3). The processor (3) is capable of generating a magnetic field intensity monitoring value corresponding to each Hall sensor (41) in response to an output signal of each Hall sensor (41).

5. The ultra-low temperature magnetic level gauge according to claim 4, characterized in that: At least one Hall sensor (41) is lower than the lower end of the measuring cylinder (2), and at least one Hall sensor (41) is higher than the upper end of the measuring cylinder (2).

6. The ultra-low temperature magnetic level gauge according to claim 5, characterized in that: The height values ​​of the Hall sensors (41) are recorded in ascending order as H 1 ,H 2 ,H 3 ,…,H n , the magnetic field intensity monitoring value corresponding to each Hall sensor (41) is recorded as B 1 ,B 2 ,B 3 ,…,B n ; The processor (3) is capable of obtaining the distance between the magnet (14) and a preset reference height based on each of the magnetic field intensity monitoring values, including: Traverse the generated magnetic field strength monitoring values ​​to obtain the maximum monitoring value B i ; exist In the case of , exist In the case of , in, H i The maximum monitoring value B i The corresponding height value of the Hall sensor (41), H c The distance between the magnet (14) in the float (1) and a preset reference height is monitored by the float height monitoring component.

7. The ultra-low temperature magnetic level gauge according to claim 6, characterized in that: The processor (3) obtains the distance between the magnet (14) and a preset reference height based on each of the magnetic field intensity monitoring values, and further comprises: exist In the case of ， exist In the case of ， in, ∆H is the distance between two adjacent Hall sensors (41).

8. The ultra-low temperature magnetic level gauge according to claim 4, characterized in that: The ultra-low temperature magnetic liquid level gauge further comprises a magnetic shielding box body (5), and the measuring cylinder (2) and each of the Hall sensors (41) are both packaged in the magnetic shielding box body (5).

9. The ultra-low temperature magnetic level gauge according to claim 1, characterized in that: The ultra-low temperature magnetic liquid level gauge further comprises a liquid level warning component electrically connected to the processor (3), wherein the liquid level warning component is capable of sending a first warning signal when the liquid level is lower than a first preset height, and / or sending a second warning signal when the liquid level is higher than a second preset height.

10. The ultra-low temperature magnetic level gauge according to claim 9, characterized in that: The processor (3) controls the liquid level warning component to send out a first warning signal when the pressure value corresponding to the first pressure signal gradually decreases, and / or The processor (3) controls the liquid level warning component to send out a second warning signal when the pressure value corresponding to the first pressure signal gradually increases.

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