Capacitive liquid level sensor

Abstract

The utility model relates to the technical field of liquid level sensors, in particular to a capacitive liquid level sensor. Through a mounting plate and an outer electrode tube fixedly mounted on the mounting plate, an inner electrode is mounted in the outer electrode tube, a tube cavity of the outer electrode tube is divided into a first tube cavity and a second tube cavity, the inner electrode comprises a first metal wire and a second metal wire, the first metal wire is positioned and mounted in the first tube cavity through a first protective sleeve, and the second metal wire is positioned and mounted in the second tube cavity through a second protective sleeve. The second metal wire is positioned and mounted in the second pipe cavity through the second protective sleeve; and the upper ends of the first metal wire and the second metal wire penetrate out of the mounting plate to form leading-out ends of the inner electrode. Through the structure, the first metal wire and the first pipe cavity as well as the second metal wire and the second pipe cavity form two cylindrical capacitors, so that the measured data is more stable and accurate, and the long-time use of the liquid level sensor can be ensured.

Description

Technical Field

[0001] The utility model relates to the technical field of liquid level sensors, in particular to a capacitive liquid level sensor. Background Art

[0002] The principle of capacitive liquid level sensor is to use the capacitance formed by the liquid medium filled between the positive and negative probes to change linearly with the liquid level, and convert the change in capacitance (that is, the change in liquid level) into a standard electrical signal output.

[0003] In the existing technology, the most common liquid level sensors are single-stage and multi-stage liquid level sensors. The structural principles of the two are similar. Both consist of a long metal tube as the outer electrode. A metal tube rod or carbon tube covered with one or more sections of copper is installed inside the metal tube to serve as the inner electrode. The microcontroller in the signal processing device then processes the obtained liquid level signal and sends it to the client or display screen.

[0004] This type of capacitance level gauge can eventually be simplified into a long cylindrical capacitor. When performing liquid level detection, the detection result of a cylindrical capacitor has a large error, and the measurement is relatively unstable after long-term use. Utility Model Content

[0005] In response to the above problems, the present invention provides a capacitive liquid level sensor to solve the problem in the prior art that a long cylindrical capacitor liquid level sensor has large detection error during use and unstable measurement results after long-term use.

[0006] The utility model is realized by using the following technical scheme: a capacitive liquid level sensor, comprising a mounting plate and an outer electrode tube fixedly mounted on the mounting plate, an inner electrode mounted inside the outer electrode tube, the lumen of the outer electrode tube being divided into a first lumen and a second lumen, the inner electrode comprising a first metal wire and a second metal wire, the first metal wire being positioned and mounted in the first lumen through a first protective sleeve, the second metal wire being positioned and mounted in the second lumen through a second protective sleeve, the upper ends of the first metal wire and the second metal wire both passing through the mounting plate to form lead-out ends of the inner electrode.

[0007] Through the above structure, the first metal wire and the first tube cavity, and the second metal wire and the second tube cavity form two cylindrical capacitors, making the measurement data more stable and accurate, and ensuring the long-term use of the liquid level sensor.

[0008] Furthermore, a limit centering post is fixedly mounted at the bottom end of the outer electrode tube, and a tension spring is disposed within the second tube cavity. The bottom end of the first protective tube bypasses the limit centering post and is fixedly connected to the bottom of the tension spring, while the bottom end of the second protective tube is fixedly connected to the top of the tension spring. The tension spring ensures that the first and second protective tubes remain taut, thereby maintaining the two metal wires in a taut, self-centering state and preventing irregular metal displacement toward the inner wall of the tube cavity due to factors such as vibration.

[0009] Furthermore, the first protective sleeve and the second protective sleeve are formed into a complete hose, which makes it easier to achieve consistent measurement, thereby improving production efficiency and reducing production costs.

[0010] Furthermore, the outer electrode tube cavity also includes a process cavity. The process cavity provides mechanical stability, dual-cavity liquid level balance, and production process structure intervention. A temperature sensor can also be inserted into this cavity to measure the medium temperature.

[0011] Furthermore, the process lumen, the first lumen, and the second lumen are connected to each other.

[0012] Furthermore, a sealing plug is inserted into the top of the outer electrode tube. The bottom shape of the sealing plug matches the process tube cavity, the first tube cavity, and the second tube cavity. The tops of the first and second protective tubes pass through the sealing plug. The sealing plug prevents liquid from leaking from the top of the outer electrode tube and also serves to position the two metal wires.

[0013] Furthermore, a fixing clip is fixedly installed on the top of each of the first and second protective sleeves, and the fixing clip is located above the sealing plug. The setting of the fixing clip makes it more convenient to adjust the length of the metal wire in the outer electrode tube.

[0014] Furthermore, a threaded sleeve is fixedly mounted on the bottom of the mounting plate. The sleeve is fitted over the outer surface of the outer electrode tube and securely connected to it. This arrangement makes it easier to install the mounting plate on the liquid tank. It also prevents damage, deformation, and breakage at the base of the overly long liquid level sensor caused by stress concentration during intense acceleration, sudden deceleration during a vehicle accident, or vibration.

[0015] Furthermore, a mounting groove is provided at the bottom of the mounting plate, so that the mounting structure of the liquid box is more closely fitted and the sealing performance is improved.

[0016] Furthermore, a signal processor is fixedly mounted on the top of the mounting plate, and the outer electrode tube, the first metal wire, and the second metal wire are all electrically connected to the signal processor. The arrangement of the signal processor makes the processing of the liquid level sensor more convenient.

[0017] In summary, the beneficial effects of the present invention are:

[0018] 1. By setting a first lumen and a second lumen inside the outer electrode tube, and placing the first metal wire in the first lumen and the second metal wire in the second lumen, the two metal wire electrodes are automatically centered under the action of spring tension through a closed U-shaped pressure-resistant insulating sleeve, so that the capacitive liquid level sensor forms two cylindrical capacitors that can withstand extremely high pressure, which makes the measurement of liquids more accurate and stable, and can measure a wider range of liquids.

[0019] 2. By setting the tension spring, the first metal wire and the second metal wire always maintain a vertical automatic centering state, thereby avoiding the irregular deviation of the metal wire toward the inner wall of the lumen due to factors such as vibration and stress release, fundamentally solving the problem of unreliable measurement of long-rod capacitance sensors during long-term use, and further increasing the measurement stability of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the overall structure of the utility model;

[0021] Figure 2 This is a schematic diagram of the structure of the utility model without the signal processing device;

[0022] Figure 3 Schematic diagram of the matching between the pressure cap and the sealing plug

[0023] Figure 4 is a cross-sectional view of the outer electrode tube;

[0024] Figure 5 Schematic diagram of the internal structure of the outer electrode tube (the outer electrode tube and the sealing plug are cut away);

[0025] Figure 6 Schematic diagram of the structure of the sealing plug;

[0026] Figure 7 for Figure 5 A partial enlarged view of the “A” area in the middle;

[0027] Figure 8 for Figure 5 A partial enlarged view of the "B" area in the middle;

[0028] Figure 9 Schematic diagram of the structure of the limiting column.

[0029] In the figure: 1-mounting plate; 11-signal processing device; 12-signal output interface; 13-mounting groove; 14-threaded sleeve; 15-sealing boss; 2-external electrode tube; 21-limiting and centering column; 22-sealing plug; 23-fixing block; 24-process tube cavity; 25-first tube cavity; 26-second tube cavity; 27-pressure cap; 28-limiting groove; 3-first protective sleeve; 31-first metal wire; 32-second metal wire; 33-second protective sleeve; 34-aluminum sleeve; 4-tension spring. DETAILED DESCRIPTION

[0030] The following embodiments are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0031] In the description of this application, it should be understood that the terms "center", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on this application.

[0032] The following is a description of preferred embodiments of the present invention with reference to the accompanying drawings.

[0033] like Figure 1 As shown, the utility model provides a capacitive liquid level sensor, including an aluminum special-shaped outer electrode tube 2, and an inner electrode is installed inside the outer electrode tube 2. A disc-shaped mounting plate 1 is fixedly installed on the top of the outer electrode tube 2, and a threaded sleeve 14 is fixedly installed on the bottom of the mounting plate 1. The threaded sleeve 14 is sleeved on the outer surface of the outer electrode tube 2 and fixedly connected to the outer electrode tube 2. A signal processing device 11 is fixedly installed on the top of the mounting plate 1. By directly mounting the signal processing device 11 on the mounting plate 1, signal processing is made more convenient. The inner electrode and the outer electrode tube 2 are both electrically connected to the signal processing device 11. The signal processing device 11 processes the signals transmitted by the inner and outer electrodes through a single-chip microcomputer and sends them to the user end. A signal output interface 12 for connecting the signal output line is provided on the signal processing device 11.

[0034] like Figures 2 to 4As shown, the outer electrode tube 2 comprises a first lumen 25, a second lumen 26, and a process lumen 24. The first lumen 25 and the second lumen 26 are symmetrically arranged and interconnected. The inner electrode comprises a first metal wire 31 and a second metal wire 32. The first metal wire 31 is positioned and mounted within the first lumen 25 via a first protective sleeve 3, while the second metal wire 32 is positioned and mounted within the second lumen 26 via a second protective sleeve 33. The upper ends of the first metal wire 31 and the second metal wire 32 extend through the mounting plate to form the lead-out ends of the inner electrode. The first metal wire 31, the second metal wire 32, and the outer electrode tube 2 are all electrically connected to the signal processing device 11.

[0035] like Figure 2 、 Figure 4 、 Figure 6 、 Figure 7 As shown, a limiting centering post 21 is fixedly mounted at the bottom of the outer electrode tube 2. A tension spring 4 is disposed within the second lumen 26. The top end of the first protective sleeve 3 extends into the signal processing device 11. The bottom end of the first protective sleeve 3 bypasses the limiting centering post 21 and is fixedly connected to the bottom of the tension spring 4. The bottom end of the second protective sleeve 33 is fixedly connected to the top of the tension spring 4, and the top end of the second protective sleeve 33 also extends into the signal processing device 11. After bypassing the limiting centering post 21, the first protective sleeve 3 forms an overall "J" shape. The second protective sleeve 33 is a straight line. The first metal wire 31 and the second metal wire 32 are both vertically straight lines. However, the length of the first metal wire 31 within the first lumen 25 is from the top of the first lumen 25 to the limiting centering post 21, while the length of the second metal wire 32 is from the tension spring 4 to the top of the second lumen 26. The two lengths are different, with the length of the second metal wire 32 being approximately 0.6 times the length of the first metal wire 31.

[0036] like Figure 4 、 Figure 6As shown, the first and second protective sleeves 3, 33 are integrally formed into a single, "U"-shaped hose. A retaining groove 28 is provided at the bottom of the retaining post 21, with the bottom of the "U"-shaped hose locked within the retaining groove 28. This prevents the first and second protective sleeves 3, 33 from shifting axially along the retaining post 21, further ensuring that the first and second metal wires 31, 32 remain stable within the outer electrode tube 2. This integrated design ensures reliable operation of the sensor in various extreme environments, significantly improving production consistency and efficiency. The first and second protective sleeves 3, 33 utilize soft polymer ultra-high voltage insulation. This structure enables the device to detect the level of conductive or non-conductive elemental liquids (such as diesel, gasoline, water, and chemical liquids) at room temperature and pressure (solutions that uniformly dissolve without precipitation). It can also be used for reliable and precise level measurement of low-temperature, pressurized (LNG), high-pressure, or ultra-high-pressure (liquid hydrogen) liquids. That is, the bottom end of the first protective sleeve 3 extends from the first lumen 25 to the second lumen 26, then is wrapped around one end of the tension spring 4 and passes through the center of the tension spring 4. After passing through the tension spring 4, it is connected to the second protective sleeve 33 wrapped around the other end of the tension spring 4 to form a whole. Figure 6 As shown, after the first protective sleeve 3 passes around the tension spring 4 , the second protective sleeve 33 passes around the tension spring 4 , and both are compressed and fixed by the aluminum sleeve 34 .

[0037] like Figure 2 、 Figure 5 As shown, a sealing plug 23 is inserted into the top of the outer electrode tube 2. The shape of the bottom of the sealing plug 23 matches the shapes of the first lumen 25, the second lumen 26, and the process lumen 24, ensuring that the sealing plug 23, when inserted from the top of the outer electrode tube 2, precisely blocks all three lumens of the outer electrode tube 2. The first protective sleeve 3 and the second protective sleeve 33 both pass through the sealing plug 23 and extend toward the signal processor 11. A copper cap 27 is also threadedly fixed to the top of the outer electrode tube 2. The cap 27's primary function is to compress the sealing plug 23, thereby further improving the stability of the device.

[0038] The sealing plug 23 has two functions: one is to seal the outer electrode tube 2 to prevent liquid from leaking from the top of the outer electrode tube 2; the other is to cooperate with the limiting centering column 21 to determine the overall position of the first protective sleeve 3 and the second protective sleeve 33, which is equivalent to the principle of two-point positioning, so that the first metal wire 31 and the second metal wire 32 are respectively located in the center of the second tube cavity 26 of the first tube cavity 25.

[0039] As a further illustration of this embodiment, a fixing clamp 23 is fixedly mounted above the sealing plug 23. The fixing clamp 23 can adjust the length of the inner electrode within the outer electrode tube 2. The fixing clamp 23 is constructed of an internally threaded tube and a bolt. The internally threaded tube is provided with a hole through which the first and second protective sleeves 3, 33 slide. The bolt squeezes and secures the tube in place and seals the tube. The fixing clamp 23 is conventional technology and will not be described in detail here.

[0040] As a further illustration of this embodiment, a mounting groove 13 cooperating with the liquid box is further provided at the bottom of the mounting plate 1 .

[0041] As a further illustration of this example, a sealing boss 15 cooperating with the signal processing device 11 is provided on the top of the mounting plate 1. The sealing boss 15 can be snapped into the signal processing device 11, further strengthening the fixation of the signal processing device 11 and the mounting plate 1.

[0042] The device operates as follows: The device is inserted into a liquid tank, such as an oil tank. When the outer electrode tube 2 is inserted, the oil in the tank flows into the three chambers. At this point, the first metal wire 31 and the inner wall of the first tube cavity 31, and the second metal wire 32 and the inner wall of the second tube cavity 33, form two long cylindrical capacitors, generating two correlated signal outputs with a certain ratio. Through comparative calculation, errors are offset, resulting in more accurate and reliable automatic adaptive detection of the liquid level of any medium in the oil tank or pressure vessel. The detected information is transmitted as an electrical signal to the signal processing device 11, which processes the information and transmits the resulting data to the user through the signal output interface 12.

[0043] To sum up, the capacitive liquid level sensor provided by the present invention is configured to form a first tubular cavity 25 and a second tubular cavity 26 inside the outer electrode tube 2, and place the first metal wire 31 in the first tubular cavity 25, and the second metal wire 32 in the second tubular cavity 33, so that the capacitive liquid level sensor forms two self-centering long cylindrical capacitors, which makes the measurement of liquid more accurate and stable, and the contrast offset adaptive algorithm of the single-chip microcomputer enables the device to measure a wider range of liquids; through the setting of the tension spring 4, the first metal wire 31 and the second metal wire 32 are always kept in a vertical state, thereby avoiding the irregular deviation of the metal wire toward the inner wall of the lumen due to factors such as vibration and stress release, and further increasing the measurement stability of the device.

[0044] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and replacements can be made without departing from the technical principles of the present invention. These improvements and replacements should also be regarded as the scope of protection of the present invention.

Claims

1. A capacitive liquid level sensor, comprising a mounting plate (1) and an outer electrode tube (2) fixedly mounted on the mounting plate (1), wherein an inner electrode is mounted inside the outer electrode tube (2), characterized in that: The lumen of the outer electrode tube (2) is divided into a first lumen (25) and a second lumen (26); the inner electrode comprises a first metal wire (31) and a second metal wire (32); the first metal wire (31) is positioned and installed in the first lumen (25) through a first protective sleeve (3); the second metal wire (32) is positioned and installed in the second lumen (26) through a second protective sleeve (33); the upper ends of the first metal wire (31) and the second metal wire (32) both pass through the mounting plate to form the lead-out ends of the inner electrode.

2. The capacitive liquid level sensor according to claim 1, characterized in that: A limiting centering column (21) is fixedly mounted on the bottom end of the outer electrode tube (2), a tension spring (4) is provided in the second tube cavity (26), the bottom end of the first protective sleeve (3) bypasses the limiting centering column (21) and is fixedly connected to the bottom of the tension spring (4), and the bottom end of the second protective sleeve (33) is fixedly connected to the top end of the tension spring (4).

3. The capacitive liquid level sensor according to claim 2, characterized in that: The first protective sleeve (3) and the second protective sleeve (33) are a complete hose, and the first protective sleeve (3) and the second protective sleeve (33) as a whole form a "U"-shaped tube.

4. The capacitive liquid level sensor according to claim 1, characterized in that: The lumen of the outer electrode tube (2) further includes a process lumen (24).

5. The capacitive liquid level sensor according to claim 4, characterized in that: The process lumen (24), the first lumen (25), and the second lumen (26) are in communication with each other.

6. The capacitive liquid level sensor according to claim 5, characterized in that: A sealing plug (22) is also inserted into the top of the outer electrode tube (2), and the bottom shape of the sealing plug (22) matches the process tube cavity (24), the first tube cavity (25), and the second tube cavity (26); the tops of the first protective sleeve (3) and the second protective sleeve (33) both pass through the sealing plug (22).

7. The capacitive liquid level sensor according to claim 6, characterized in that: A fixing clip (23) is fixedly mounted on the top of each of the first protective sleeve (3) and the second protective sleeve (33), and the fixing clip (23) is located above the sealing plug (22).

8. The capacitive liquid level sensor according to claim 1, characterized in that: A threaded sleeve (14) is also fixedly mounted on the bottom of the mounting plate (1), and the threaded sleeve (14) is sleeved on the outer surface of the outer electrode tube (2) and fixedly connected to the outer electrode tube (2).

9. The capacitive liquid level sensor according to claim 1, characterized in that: The bottom of the mounting plate (1) is also provided with a mounting groove (13).

10. The capacitive liquid level sensor according to any one of claims 1 to 9, characterized in that: A signal processor (11) is also fixedly mounted on the top of the mounting plate (1), and the outer electrode tube (2), the first metal wire (31), and the second metal wire (32) are all electrically connected to the signal processor (11).

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