Capacitive liquid level sensor

Abstract

The utility model belongs to the field of liquid level sensors, and particularly relates to a capacitive liquid level sensor which is particularly suitable for being used in an LNG tank body. A capacitive liquid level sensor comprises an inner sleeve, an outer sleeve and a separation assembly, the inner sleeve is embedded in the outer sleeve, a gap exists between the inner sleeve and the outer sleeve, the separation assembly comprises a protruding piece and an isolation film, the protruding piece is fixedly arranged on the outer wall of the inner sleeve, and the isolation film is arranged on the outer wall of the inner sleeve. The protruding piece comprises a limiting part and a connecting part which are fixedly connected, the connecting part is used for being fixedly arranged on the outer wall of the inner sleeve, and the limiting part is arranged on the side, away from the inner sleeve, of the connecting part; and the isolating membrane is coated on the outer walls of the convex piece and the inner sleeve. The liquid level type capacitive sensor solves the problem that an existing liquid level type capacitive sensor is prone to short circuit.

Description

Technical Field

[0001] The utility model belongs to the field of liquid level sensors, and specifically relates to a capacitive liquid level sensor, and in particular to a capacitive liquid level sensor suitable for use in LNG tanks. Background Art

[0002] Liquid level sensors are widely used in various industrial fields, for example, to measure and monitor the height of liquids in tanks, containers, and other containers. In liquefied natural gas (LNG) storage tanks, the low temperature environment and the low dielectric constant of LNG require liquid level sensors with high sensitivity.

[0003] In existing technology, capacitive level sensors for LNG tanks typically employ a dual-cylinder structure, consisting of an inner and outer cylinder connected to different electrodes (one connected to the positive electrode, the other to the negative electrode). Liquid level is calculated by measuring the capacitance change caused by the liquid to be measured entering the gap between the inner and outer cylinders, thus ensuring a gap between the inner and outer cylinders. However, due to the typical height of LNG tanks, the level sensor is relatively long. Furthermore, to ensure measurement accuracy, the gap between the inner and outer cylinders is typically close. Furthermore, external pressure can cause the inner and outer cylinders to bend, potentially causing the gap to change or even connect, leading to a short circuit in the entire level sensor. Utility Model Content

[0004] In view of the above-mentioned shortcomings of the prior art, the purpose of the present invention is to provide a capacitive liquid level sensor to solve the problem that the prior capacitive liquid level sensor is prone to short circuit.

[0005] To achieve the above-mentioned purpose, the present invention adopts the following technical solution: a capacitive liquid level sensor, comprising an inner sleeve, an outer sleeve and a partition assembly, the inner sleeve being embedded in the outer sleeve, and there being a gap between the inner sleeve and the outer sleeve, the partition assembly comprising a protrusion and an isolation membrane, the protrusion being fixedly arranged on the outer wall of the inner sleeve, the protrusion comprising a fixedly connected limiting portion and a connecting portion, the connecting portion being fixedly arranged on the inner wall of the inner sleeve, the limiting portion being arranged on the side of the connecting portion away from the inner sleeve; the isolation membrane being covered on the outer wall of the protrusion and the inner sleeve.

[0006] As an embodiment of the present invention, the connecting portion is mechanically fixed to the inner sleeve, and a mounting hole matching the protrusion is provided on the inner sleeve, and the inner sleeve is fixed to the protrusion through the mounting hole.

[0007] Wherein, the size of the limiting portion close to the mounting hole is larger than the size of the mounting hole.

[0008] As an embodiment of the present invention, the mounting hole is a non-through hole provided on the outer wall of the inner sleeve, and the connecting portion is clamped and fixed to the outer wall of the inner sleeve through the non-through hole.

[0009] As an embodiment of the present invention, the mounting hole is a through hole, and the connecting portion is riveted and fixed to the inner sleeve through the through hole.

[0010] As an implementation manner of the present invention, the inner sleeve and the protruding piece are bonded and fixed.

[0011] As an embodiment of the present invention, the inner sleeve and the protruding piece are connected by hot melting.

[0012] As an embodiment of the present invention, the limiting portion is a structure with a trapezoidal cross section, and the oblique side of the limiting portion is arranged in the length direction of the inner sleeve.

[0013] As an embodiment of the present invention, the isolation membrane is connected to the inner sleeve by thermoplastic connection.

[0014] As an embodiment of the present invention, a surface texture or microstructure is provided on the surface of the isolation membrane on the side close to the inner sleeve to adapt to the deformation of the inner sleeve.

[0015] As an embodiment of the present invention, there are multiple protrusions, and the multiple protrusions are arranged along the circumference and axial direction of the inner sleeve, wherein the multiple axially arranged protrusions are evenly distributed along the length direction of the inner sleeve.

[0016] As an embodiment of the present invention, the size of the limiting portion of the protrusion close to the bottom of the inner sleeve is larger than the size of the limiting portion arranged in the middle of the inner sleeve.

[0017] To sum up, compared with the prior art, the present invention includes at least one of the following beneficial technical effects: through the solution provided by the present invention, by fixing a partition assembly on the outer wall of the inner sleeve, the isolation of the inner sleeve and the outer sleeve can be well achieved, so that the entire capacitive liquid level sensor can be better adapted to the environment in which LNG is located. Even if the inner sleeve and the outer sleeve change due to environmental changes, the inner and outer sleeves will not contact each other, thereby avoiding the short circuit of the capacitive liquid level sensor.

[0018] In addition, by configuring the separation component as a protrusion and an isolation membrane, the protrusion is fixedly arranged on the outer wall of the inner sleeve, and the isolation membrane is coated on the inner sleeve and the protrusion, double isolation can be achieved, thereby more effectively avoiding contact between the inner and outer sleeves, thereby improving the stability and service life of the entire capacitive liquid level sensor.

[0019] At the same time, by providing the surface of the isolation membrane with a surface texture or microstructure, the isolation membrane and the inner sleeve can be better matched when the inner sleeve is deformed in an ultra-low temperature environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0021] Figure 1 It is a structural schematic diagram of a capacitance liquid level sensor provided in a specific embodiment of the utility model.

[0022] Description of reference numerals:

[0023] 100, inner sleeve; 110, mounting hole;

[0024] 200, outer sleeve;

[0025] 300, separation component; 310, protruding member; 311, limiting portion; 312, connecting portion; 320, isolation membrane. DETAILED DESCRIPTION

[0026] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention. In addition, it should be understood that the specific implementation methods described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention. In the present invention, unless otherwise specified, the directional words used, such as "up", "down", "left", "right", "front", and "back", generally refer to the up, down, left, and right of the device in actual use or working state, specifically the drawing direction in the accompanying drawings.

[0027] It should be noted that the order of description of the following embodiments does not limit the preferred order of the embodiments of the present invention. In addition, in the following embodiments, the description of each embodiment has its own focus. For parts not described in detail in one embodiment, please refer to the relevant description of other embodiments.

[0028] Reference Figure 1 , Figure 1A capacitive liquid level sensor is shown, comprising an inner sleeve 100, an outer sleeve 200, and a separator assembly 300. The inner sleeve 100 is sleeved within the outer sleeve 200, with a certain gap between the inner sleeve 100 and the outer sleeve 200, so that the inner sleeve 100 and the outer sleeve 200 serve as the positive electrode and the outer sleeve 200, respectively. The liquid to be measured is accommodated between the inner sleeve 100 and the outer sleeve 200, making the inner sleeve 100 and the outer sleeve 200 electrically conductive. The capacitance value formed by the gap between the inner sleeve 100 and the outer sleeve 200 is used to measure the height of the liquid to be measured between the inner sleeve 100 and the outer sleeve 200, thereby achieving height measurement of the liquid to be measured. The separator assembly 300 is disposed between the inner sleeve 100 and the outer sleeve 200 and is relatively fixed to the outer wall of the inner sleeve 100. It is insulated from the inner sleeve 100 and the outer sleeve 200, thereby achieving isolation of the inner sleeve 100 from the outer sleeve 200.

[0029] Specifically, the separation assembly 300 includes a protrusion 310 and an isolation membrane 320. Multiple protrusions 310 are arranged at intervals on the outer wall of the inner sleeve 100 and are fixedly connected to the outer wall of the inner sleeve 100, so that the protrusions 310 are at least partially protruded on the outer wall of the inner sleeve 100, thereby realizing a fixed connection between the protrusions 310 and the outer wall of the inner sleeve 100.

[0030] Naturally, the protrusion 310 can be connected to the inner sleeve 100 by mechanical fixing, chemical bonding, or thermal welding. Preferably, mechanical fixing is used. The advantage of such a setting is that the mechanical bonding can ensure the stability of the connection between the protrusion 310 and the inner sleeve 100 under various temperature changes and environments as much as possible, thereby ensuring the stability and life of the entire capacitive liquid level sensor.

[0031] It is understood that the present invention is not limited to mechanical fixation for the protrusion 310 and the inner sleeve 100. In an alternative embodiment, the protrusion 310 and the inner sleeve 100 are chemically fixed by selecting a high-strength epoxy resin or other industrial adhesive that is compatible with the materials of the inner sleeve 100 and the protrusion 310. Preferably, the surface of the inner sleeve 100 is pre-treated before bonding, such as by polishing or chemical cleaning, to enhance the bonding effect.

[0032] In another preferred alternative embodiment, a hybrid fixing method combining mechanical and chemical fixing is used to secure the protruding member 310 to the inner sleeve 100. For example, mechanical fixing can be used to first position the protruding member 310, and then adhesive or heat welding can be applied to enhance the connection strength. This combination of methods has the advantage of providing a more reliable fixing effect in certain high-pressure or high-vibration environments. In yet another alternative embodiment, the protruding member 310 and the inner sleeve 100 are secured by heat welding.

[0033] The following further describes the mechanical connection between the protrusion 310 and the inner sleeve 100. At this time, the inner sleeve 100 is provided with a mounting hole 110 matching the protrusion 310 at the position where the protrusion 310 is mounted.

[0034] In a preferred embodiment, the mounting hole 110 is a through hole, that is, the mounting hole 110 is provided through the inner sleeve 100. This arrangement has the advantage of facilitating processing and reducing manufacturing costs during the manufacture of the inner sleeve 100. For example, a through hole arrangement has the advantage of allowing two holes to be made at once (i.e., radially through the sidewall of the inner sleeve 100), while blind holes or grooves can only make one hole at a time, thus improving manufacturing efficiency.

[0035] For example, when the mounting hole 110 is a through hole, the protrusion 310 is preferably a rivet, which is riveted to the inner sleeve 100 through the mounting hole 110. The rivet is preferably made of a low-temperature-resistant insulating material. This arrangement has the advantage of ensuring that the rivet will not deform or be damaged in a low-temperature environment, and will not conduct electricity, thereby preventing the inner and outer sleeves from being connected. On the other hand, riveting is also more convenient for installing the protrusion because it is inserted into the inner sleeve, thus ensuring reliability and preventing it from loosening or even falling off during use.

[0036] Of course, in another preferred embodiment, the mounting hole 110 is preferably a non-through hole (e.g., a groove), that is, the mounting hole 110 is provided on the outer wall of the inner cylinder but does not penetrate the inner wall. In this case, preferably, the bottom of the protrusion 310 is provided with a snap structure, which can directly snap into a pre-machined groove on the surface of the inner sleeve 100. The advantage of this arrangement is that it can easily and quickly complete the fixing of the protrusion 310 and the inner sleeve 100 by the operator, and also facilitates subsequent maintenance and replacement.

[0037] Please continue reading Figure 1 , the protrusion 310 includes a fixed limiting portion 311 and a connecting portion 312, which are preferably integrally arranged. The connecting portion 312 is used to connect and fix with the mounting hole 110 on the inner sleeve 100. As mentioned above, the mounting hole 110 can be a through hole that passes through the inner sleeve 100, or it can be a mounting hole 110 that is not set through the outer wall of the inner sleeve 100 (that is, the above-mentioned non-through hole). When the mounting hole 110 is a non-through hole set on the outer wall of the inner sleeve 100, the connecting portion 312 is preferably fixed to the outer wall of the inner sleeve 100 through the mounting hole 110. When the mounting hole 110 is a through hole, the connecting portion 312 is fixed to the inner sleeve 100 by riveting. Figure 1 In this specific embodiment, the mounting hole 110 is a through hole, and the connecting portion 312 passes through the mounting hole 110 and is detachably fixed to the inner sleeve 100 .

[0038] The limiting portion 311 is disposed on a side of the connecting portion 312 away from the inner sleeve 100. The limiting portion 311 is preferably larger in size on the side closer to the mounting hole 110 than the mounting hole 110, so that the limiting portion 311 can at least partially fit against the outer wall of the inner sleeve 100 and does not enter the gap in the mounting hole 110. Preferably, the limiting portion 311 is configured as a protrusion similar to a trapezoidal structure, with the hypotenuse of the trapezoidal structure disposed in the longitudinal direction of the capacitive liquid level sensor. This configuration has the advantage of better facilitating fitting with the isolation membrane 320 described later, thereby preventing damage to the isolation membrane 320 during the fitting process that would otherwise impair the isolation effect.

[0039] It is naturally understandable that the limiting portion 311 of the protrusion 310 is preferably composed of a non-conductive material, and the connecting portion 312 can be composed of a conductive material or a non-conductive material, and the present invention does not impose any restrictions on this.

[0040] Please continue reading Figure 1 A plurality of protrusions 310 are fixedly mounted on the outer wall of the inner sleeve 100. Preferably, the plurality of protrusions 310 are respectively arranged in the circumferential direction and the axial direction of the inner sleeve 100. The specific number of protrusions 310 can be selected according to actual needs, and the present invention does not limit this.

[0041] In a preferred embodiment, non-uniform distribution is adopted according to specific design requirements, for example, multiple protrusions 310 are arranged in a spiral shape to avoid the inner sleeve 100 from contacting the outer sleeve 200 in all directions as much as possible.

[0042] In another preferred embodiment, the sizes of the limiting portion 311 of the protrusion 310 at different length positions of the inner sleeve 100 are different. For example, the size of the limiting portion 311 of the protrusion 310 arranged near the bottom of the inner sleeve 100 is larger than the size arranged in the middle of the inner sleeve 100, and / or the stiffness of the limiting portion 311 of the protrusion 310 arranged near the bottom of the inner sleeve 100 is greater than the stiffness arranged in the middle of the inner sleeve 100. The advantage of such a setting is that it can ensure that the inner and outer sleeves are always in an isolated state under greater external environmental fluctuations and external pressures, thereby avoiding short circuits and ensuring measurement accuracy.

[0043] Please continue reading Figure 1 The isolation film 320 covers the inner sleeve 100 with the protrusion 310. The isolation film 320 preferably covers the protrusion 310 by heat-sealing. The advantage of heat-sealing is that, in certain circumstances, the isolation film 320 can be pre-shaped around the protrusion 310 using thermoforming technology to better fit the protrusion 310 and the inner sleeve 100.

[0044] More preferably, the surface of the isolation membrane 320 on the side close to the inner sleeve 100 is provided with a surface texture or microstructure manufactured by molding, etching or other surface treatment techniques. The advantage of such a setting is that when the capacitive liquid level sensor of the present invention is used in an LNG tank, due to the low temperature of the LNG, for example, at -160°C, the inner and outer cylinders will be deformed. At this time, the surface texture structure provided can well ensure that when the inner sleeve 100 expands and contracts, the isolation membrane 320 still maintains a relatively good covering effect to achieve insulation.

[0045] Therefore, through the solution provided by the present invention, by fixing the separation component 300 on the outer wall of the inner sleeve 100, the isolation of the inner sleeve 100 and the outer sleeve 200 can be well achieved, so that the entire capacitive liquid level sensor can be better adapted to the environment in which LNG is located. Even if the inner sleeve 100 and the outer sleeve 200 change due to environmental changes, it will not cause the inner and outer sleeves to contact, thereby avoiding the short circuit of the capacitive liquid level sensor.

[0046] In addition, by setting the separation component 300 as a protrusion 310 and an isolation membrane 320, the protrusion 310 is fixedly set on the outer wall of the inner sleeve 100, and the isolation membrane 320 is coated on the inner sleeve 100 and the protrusion 310, double isolation can be achieved, thereby more effectively avoiding contact between the inner and outer sleeves 200, thereby improving the stability and service life of the entire capacitive liquid level sensor.

[0047] At the same time, by providing the surface of the isolation membrane 320 with a surface texture or microstructure, the isolation membrane 320 and the inner sleeve 100 can be better matched when the inner sleeve is deformed in an ultra-low temperature environment.

[0048] Preferably, the isolation membrane 320 is made of FEP or PTFE. The advantage of choosing this material is that it needs to be used in LNG tanks, which have high requirements for its low-temperature resistance. FEP or PTFE, a low-temperature resistant plastic material, can well meet this requirement.

[0049] Furthermore, in order to further reduce manufacturing costs, the isolation film 320 is preferably made of FEP material.

[0050] The above is a detailed introduction to the scheme of the present invention. Specific examples are used in this article to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as a limitation on the present invention.

[0051] Reference throughout this specification to "one embodiment," "an embodiment," or "a specific embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention, and not necessarily in all embodiments. Thus, various appearances of the phrases "in one embodiment," "in an embodiment," or "in a specific embodiment" in different places throughout this specification are not necessarily referring to the same embodiment. Furthermore, the particular features, structures, or characteristics of any specific embodiment of the invention may be combined with one or more other embodiments in any suitable manner. It should be understood that other variations and modifications of the embodiments of the invention described and illustrated herein are possible in light of the teachings herein and are considered part of the spirit and scope of the invention.

[0052] It should also be understood that one or more of the elements shown in the figures may also be implemented in a more separate or more integrated manner, or even removed because they are inoperable in certain circumstances or provided because they may be useful depending on the application.

[0053] In addition, unless otherwise expressly indicated, any marking arrows in the drawings should be regarded as illustrative only and not limiting. Furthermore, unless otherwise indicated, the term "or" as used herein is generally intended to mean "and / or." Where a term is unclear in providing separation or combination capabilities, the combination of components or steps will also be considered as indicated.

Claims

1. A capacitive liquid level sensor, characterized in that: It includes an inner sleeve, an outer sleeve and a separation component. The inner sleeve is embedded in the outer sleeve, and there is a gap between the inner sleeve and the outer sleeve. The separation component includes a protrusion and an isolation membrane. The protrusion is fixedly arranged on the outer wall of the inner sleeve, and the protrusion includes a limiting portion and a connecting portion that are fixedly connected. The connecting portion is fixedly arranged on the outer wall of the inner sleeve, and the limiting portion is arranged on a side of the connecting portion away from the inner sleeve; The isolation membrane is coated on the outer wall of the protruding part and the inner sleeve.

2. The capacitive liquid level sensor according to claim 1, characterized in that: The connecting portion is mechanically fixed to the inner sleeve, and a mounting hole matching the protrusion is provided on the inner sleeve, and the inner sleeve is fixed to the protrusion through the mounting hole, wherein The size of the limiting portion close to the mounting hole is larger than the size of the mounting hole.

3. The capacitive liquid level sensor according to claim 2, characterized in that: The mounting hole is a non-through hole provided on the outer wall of the inner sleeve, and the connecting portion is clamped and fixed to the outer wall of the inner sleeve through the non-through hole.

4. The capacitive liquid level sensor according to claim 2, characterized in that: The mounting hole is a through hole, and the connecting portion is riveted and fixed to the inner sleeve through the through hole.

5. The capacitive liquid level sensor according to claim 1, characterized in that: The inner sleeve and the protruding piece are fixed by hot-melt connection, thermoplastic connection or bonding.

6. The capacitive liquid level sensor according to any one of claims 1 to 5, characterized in that: The limiting portion is a structure with a trapezoidal cross section, and the oblique side of the limiting portion is arranged in the length direction of the inner sleeve.

7. The capacitive liquid level sensor according to claim 6, characterized in that: A surface texture or microstructure is provided on the surface of the isolation membrane on the side close to the inner sleeve to adapt to the deformation of the inner sleeve.

8. The capacitive liquid level sensor according to claim 6, characterized in that: The isolation film is made of FEP.

9. The capacitive liquid level sensor according to any one of claims 1 to 5, characterized in that: There are multiple protrusions, and the multiple protrusions are arranged along the circumference and axial direction of the inner sleeve, wherein the multiple axially arranged protrusions are evenly distributed along the length direction of the inner sleeve.

10. The capacitive liquid level sensor according to claim 9, characterized in that: The size of the limiting portion of the protrusion close to the bottom of the inner sleeve is larger than the size of the middle portion of the inner sleeve.

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