A 5-segment split capacitive liquid level sensor
By designing the capacitive liquid level sensor in a split configuration, separating the sensor body from the circuit board, the issues of detection accuracy and cost in low-temperature environments are resolved, enabling normal operation and high-precision measurement under low-temperature conditions.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- HENAN RUNHAO INTERNET OF THINGS RESEARCH INSTITUTE CO LTD
- Filing Date
- 2025-10-20
- Publication Date
- 2026-07-21
AI Technical Summary
Conventional capacitive sensors are affected by low-temperature environments, especially in cryogenic liquid containers and LNG tank trucks, where electronic components cannot function properly, affecting detection accuracy and increasing costs.
Design a 5-segment split capacitive liquid level sensor, separating the sensor body from the transmitter. The sensor body extends into the cryogenic liquid, while the circuit board is located outside the transmitter and connected by cables and connectors to avoid the circuit board being affected by the low temperature.
This enables the sensor to operate normally in low-temperature environments, maintain detection accuracy, and reduce costs.
Smart Images
Figure CN224535179U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of capacitive liquid level sensor technology, specifically to a 5-segment split capacitive liquid level sensor. Background Technology
[0002] Instruments and meters are crucial tools for monitoring equipment operation, and level gauges, as instruments for measuring the level of liquid media in containers, hold an irreplaceable and vital position. Current level gauge types are mainly classified into magnetic levitation, pressure, and ultrasonic types. Among them, capacitive level gauges work by converting changes in the position of the measured object into capacitance for measurement, offering advantages such as high resolution and fast dynamic response. For example, the utility model patent CN 216954555 U discloses a segmented capacitive sensor that uses a single encapsulation structure, changing the traditional separate encapsulation of the detection capacitor and detection circuit. It integrates the fixed encapsulation unit and the detection unit into a single structure. The detection unit includes a detection board and a logic circuit module, with the detection board connected to the logic circuit module and connected to the detection electrode via external connecting lines. This capacitive sensor is suitable for use in general containers, but it is particularly useful in special environments such as cryogenic environments where the liquid being measured is at a low temperature, such as when measuring liquid nitrogen, and in applications like LNG tank trucks. Ordinary circuit boards can only work normally within a certain temperature range; otherwise, some electronic components will not work properly, affecting the final detection accuracy. If multiple high-end electronic components are used to cope with low-temperature environments, the cost will be relatively high. Utility Model Content
[0003] The purpose of this invention is to provide a 5-segment split capacitive liquid level sensor to solve the problem that low temperature affects the measurement results when conventional capacitive sensors are used in low-temperature environments.
[0004] To achieve the above objectives, the present invention adopts the following technical solution: A 5-segment split capacitive liquid level sensor includes a sensor body and a transmitter. The sensor body includes an upper end, an outer tube, an inner core, and a lower end. The inner core and the outer tube are coaxially fitted together. The upper end is connected to the upper part of the outer tube, and the lower end is connected to the lower part of the outer tube. The inner core includes an inner tube, five copper foil segments located on the outer periphery of the inner tube, and an outermost insulating tube. Each copper foil segment is connected to a lead wire. The upper end is connected to a cable, and five conductive wires at one end of the cable are connected to each lead wire. The other end of the cable is provided with a male connector or a female connector. The transmitter includes a female connector or a male connector, the female connector being connected to the male connector, and a housing containing a circuit board.
[0005] Furthermore, the inner tube is made of fiberglass, and the copper foil in each section is equally spaced.
[0006] Furthermore, the insulating tube is made of PTFE.
[0007] Furthermore, the lower end includes a lower connector and a plug. The lower connector is fixedly connected to the outer tube and has a positioning center hole for the lower end of the insulating tube to be inserted. The plug is threadedly connected to the outer tube and is used to support the lower end of the inner core.
[0008] Furthermore, the lower end of the outer tube is provided with a radially penetrating through hole for liquid inlet, and there are two sets of through holes.
[0009] Furthermore, the upper end includes an insert cylinder and a wiring cylinder. The insert cylinder is for inserting the upper end of the inner core. A hollow screw is threaded into the insert cylinder. The insert cylinder has a positioning step, and an O-ring is provided between the hollow screw and the positioning step.
[0010] Furthermore, the junction box is connected to a waterproof connector, and one end of the cable passes through the waterproof connector.
[0011] Furthermore, a nylon washer is provided between the hollow screw and the O-ring.
[0012] The beneficial effects of this utility model are: This utility model discloses a 5-segment split-type capacitive liquid level sensor. The sensor body, responsible for detecting the liquid level, is connected to the transmitter via a cable using a connector for easy connection. The sensor body extends into the cryogenic liquid to be measured, but no circuitry is housed within it. The circuit board is placed within the transmitter, which can be flexibly positioned externally on the container being measured, thus ensuring the circuit board's operation is unaffected by the low-temperature environment. The 5-segment split-type capacitive liquid level sensor, with its five equally divided segments, provides a basis for designing an automatic calibration function. Attached Figure Description
[0013] Figure 1 This is a schematic diagram of the structure of the 5-segment split capacitive liquid level sensor of this utility model; Figure 2 This is a cross-sectional view of the sensor body of the 5-segment split capacitive liquid level sensor of this utility model. Figure 3 This is a partially cut-out three-dimensional structural view of the main body of the sensor; Figure 4 This is a schematic diagram of a female connector.
[0014] 1. Outer tube; 11. Through hole; 2. Inner core; 21. Inner tube; 22. Copper foil; 23. Insulating tube; 3. Upper end; 31. Wiring cylinder; 32. Insert cylinder; 33. Cap; 4. Lower end; 41. Hollow screw; 42. Nylon washer; 43. O-ring seal; 5. Cable; 6. Female connector; 7. Transmitter; 71. Male connector; 72. Housing; 8. Waterproof connector; 91. Lower connector; 92. Plug. Detailed Implementation The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present utility model are within the protection scope of the present utility model.
[0015] Embodiments of this utility model: like Figure 1 As shown, a 5-segment split capacitive liquid level sensor includes a sensor body and a transmitter 7. The sensor body includes an upper end 3, an outer tube 1, an inner core 2, and a lower end 4. The inner core 2 is coaxially sleeved with the outer tube 1. The upper end 3 is connected to the upper part of the outer tube 1, and the lower end 4 is connected to the lower part of the outer tube 1. The transmitter 7 is connected to the transmitter 7 via a cable 5.
[0016] like Figure 2 As shown, the inner core 2 includes an inner tube 21, five copper foil segments 22 located around the outer periphery of the inner tube 21, and an outermost insulating tube 23. The inner tube 21 is made of fiberglass with an outer diameter of 7.6 mm. The copper foil segments 22 are equally spaced, each segment being attached to the outer periphery of the inner tube 21, with adjacent segments spaced apart. The five copper foil segments 22 are located on the effective measurement section of the sensor, with no copper foil segments at either end; for example, the lowest copper foil segment 22 is located above the lower end. Each copper foil segment 22 is connected to a lead wire, which is welded together. The lead wires extend upwards from the upper part of the inner core 2. Holes can be drilled in the copper foil segments, allowing the lead wires to pass upwards from inside the tube.
[0017] The insulating tube 23 is made of PTFE and has an outer diameter of 10mm.
[0018] The upper end 3 is connected to a cable 5. The five conductive wires at one end of the cable 5 are connected to each lead wire, and the connection position is inside the upper end 3. The other end of the cable 5 is provided with a female connector 6, which is used to connect to the transmitter 7. In other embodiments, the other end of the cable can also use a male connector.
[0019] like Figure 2 and 3As shown, the upper end 3 has an unequal diameter structure. Functionally, it includes a cartridge body 32 and a wiring body 31. The inner diameter of the cartridge body 32 is smaller than that of the wiring body 31, and the two are connected. Due to the different diameters, the cartridge body 32 has a positioning step. The cartridge body 32 is for the upper end of the inner core 2 to be inserted. A hollow screw 41 is threaded into the cartridge body 32. A nylon washer 42 and an O-ring seal 43 are provided between the lower end of the hollow screw 41 and the positioning step. The inner diameter of the hollow screw 41 is slightly larger than the outer diameter of the inner core 2. After the nylon washer 42 is tightened by the hollow screw 41, the nylon washer 42 can play a positioning role in clamping the inner core 2.
[0020] The junction box 31 is threaded with a waterproof connector 8. One end of the cable 5 passes through the waterproof connector 8, which is existing technology and secures the cable 5 while providing waterproofing. The portion of the cable 5 located inside the junction box 31 has its shielding layer stripped, and the five conductive wires are soldered to their respective leads. The shielding layers of the five conductive wires are then twisted together and crimped together using wire lugs, soldering them into the inner cavity of the junction box 31. The cable 5 is an RG316 coaxial cable, and the appropriate length is selected according to the actual layout requirements.
[0021] The other end of cable 5 is connected to female connector 6. The five conductive wires are connected to pins 1-5 respectively. The shielding layer is twisted together and then soldered to pin 6. Figure 4 A schematic diagram of the female connector 6 is shown.
[0022] like Figure 2 As shown, a cap 33 is threadedly connected to the upper part of the wiring sleeve 31.
[0023] like Figure 2 As shown, the lower end includes a lower connector 91 and a plug 92. The lower connector 91 is fixedly connected to the outer tube 1, which can be made of stainless steel, and the two are welded together. The lower connector 91 has a positioning center hole for inserting the lower end of the insulating tube 23. The plug 92 is threadedly connected to the outer tube 1 and is used to support the lower end of the inner core 2. When installing the inner core, the prefabricated structure with the insulating tube 23 is inserted into the outer tube together, and then plugged in with the plug 92.
[0024] like Figure 1 and 2 As shown, the lower end of the outer tube 1 has a radially penetrating through hole 11 for liquid inlet. There are two sets of through holes 11. In this embodiment, it is mainly for measuring the liquid level at low temperatures and is non-conductive. The through hole 11 is located above the lower end.
[0025] Transmitter 7 includes a male connector 71 that connects to a female connector 6. Transmitter 7 also includes a housing 72, which houses a circuit board. The leads of each pin of the 6-pin male connector 71 are connected to designated locations on the circuit board. The power supply and output signals of the circuit board are led out through the RVV 4X0.3mm² transmitter 7 leads, which pass through the inner hole of a waterproof connector on the other side of the housing 72.
[0026] This utility model's 5-segment split-type capacitive liquid level sensor measures the capacitance formed between the inner core 2 and the outer tube 1 during operation. When the liquid level of the measured medium in the container changes, the liquid level between the insulating tube 23 and the outer tube 1 also changes, causing a change in the capacitance value between the positive and negative electrodes. The sensor uses an internal algorithm to convert the real-time acquired measured capacitance value into a liquid level height signal for output; this algorithm is existing technology.
[0027] It should be noted that, where there is no conflict, the embodiments and features in the embodiments of this utility model can be combined with each other.
[0028] In the description of this utility model, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this utility model is in use, or the orientation or positional relationship commonly understood by those skilled in the art. They are only used for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model. In addition, the terms "first," "second," etc., are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.
[0029] In the description of this utility model, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.
[0030] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A 5-segment split-type capacitive liquid level sensor, characterized in that: The sensor body includes a sensor body and a transmitter. The sensor body includes an upper end, an outer tube, an inner core, and a lower end. The inner core and the outer tube are coaxially fitted together. The upper end is connected to the upper part of the outer tube, and the lower end is connected to the lower part of the outer tube. The inner core includes an inner tube, five copper foil segments located on the outer periphery of the inner tube, and an outermost insulating tube. Each copper foil segment is connected to a lead wire. The upper end is connected to a cable, and five conductive wires at one end of the cable are connected to each lead wire. The other end of the cable is equipped with a male connector or a female connector. The transmitter includes a female connector or a male connector, the female connector being connected to the male connector, and a housing containing a circuit board.
2. The 5-segment split-type capacitive liquid level sensor according to claim 1, characterized in that: The inner tube is made of fiberglass, and the copper foil in each section is equally spaced.
3. The 5-segment split-type capacitive liquid level sensor according to claim 2, characterized in that: The insulating tube is made of PTFE.
4. The 5-segment split-type capacitive liquid level sensor according to claim 1, characterized in that: The lower end includes a lower connector and a plug. The lower connector is fixedly connected to the outer tube and has a positioning center hole for the lower end of the insulating tube to be inserted. The plug is threadedly connected to the outer tube and is used to support the lower end of the inner core.
5. The 5-segment split-type capacitive liquid level sensor according to claim 1, characterized in that: The lower end of the outer tube is provided with a radially penetrating through hole for liquid inlet, and there are two sets of through holes.
6. The 5-segment split-type capacitive liquid level sensor according to claim 1, characterized in that: The upper end includes a insert cylinder and a wiring cylinder. The insert cylinder is for inserting the upper end of the inner core. A hollow screw is threaded into the insert cylinder. The insert cylinder has a positioning step. An O-ring is provided between the hollow screw and the positioning step.
7. The 5-segment split-type capacitive liquid level sensor according to claim 6, characterized in that: The junction box is connected to a waterproof connector, and one end of the cable passes through the waterproof connector.
8. The 5-segment split-type capacitive liquid level sensor according to claim 6, characterized in that: A nylon washer is provided between the hollow screw and the O-ring, and the inner core passes through the nylon washer.