Liquid level sensor based on ultrasonic ranging principle
Patent Information
- Application Number
- CN202522484554.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-21
- Publication Date
- 2026-10-27
- Estimated Expiration
- 2035-11-21
AI Technical Summary
[0002]相关技术中，汽车领域的各种液位高度一般通过液位高度传感器进行检测，例如玻璃水、冷却液和润滑油等，通过将液位高度传感器安装在液体容器上，采用发射超声波并接收液面回波实时测量和输出液体高度信息；现有的液位高度传感器通常采用分体组合结构，导致整体零件层级多、配合面多，进而导致轴向尺寸大、装配公差链长，使得整体产品结构复杂
[0003]本实用新型旨在至少在一定程度上解决上述技术中的技术问题之一。为此，本实用新型的一个目的在于提出一种基于超声波测距原理的液位高度传感器，采用测量管进行回波导向，并将电路板一体注塑封装于法兰内，从而使得结构简单可靠，且大大提升测量效果。
Smart Images
Figure CN224906090U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of sensor technology, and in particular to a liquid level height sensor based on the ultrasonic ranging principle. Background Technology
[0002] In related technologies, various liquid levels in the automotive field are generally detected by liquid level sensors, such as those for windshield washer fluid, coolant, and lubricating oil. By installing the liquid level sensor on the liquid container, it uses ultrasonic waves to transmit and receive the liquid surface echo to measure and output liquid level information in real time. Existing liquid level sensors usually adopt a split assembly structure, resulting in many layers of parts and many mating surfaces, which in turn leads to large axial dimensions and long assembly tolerance chains, making the overall product structure complex. Utility Model Content
[0003] This invention aims to at least partially solve one of the technical problems in the aforementioned technologies. Therefore, one objective of this invention is to provide a liquid level sensor based on the principle of ultrasonic ranging, which uses a measuring tube for echo guidance and integrates the circuit board into a flange via injection molding, thereby achieving a simple and reliable structure and significantly improving measurement performance.
[0004] To achieve the above objectives, a first aspect of this utility model proposes a liquid level sensor based on the ultrasonic ranging principle, comprising: a flange with a connecting portion; a measuring tube connected to the connecting portion, and a connecting structure ensuring that the liquid level inside and outside the measuring tube is consistent; and a circuit board integrally injection molded into the flange, wherein an ultrasonic transceiver is provided on the circuit board, the ultrasonic transceiver guiding the received and transmitted ultrasonic waves through the measuring tube, and calculating the liquid level based on the received ultrasonic wave time; thereby achieving both structural simplification and improved measurement performance.
[0005] In addition, the liquid level sensor based on the ultrasonic ranging principle proposed in the above embodiments of this utility model may also have the following additional technical features:
[0006] Optionally, the first opening of the flange is provided with an external thread for connection to a container storing the liquid to be tested.
[0007] Optionally, the flange is further provided with a sealing groove, and a sealing ring is provided in the sealing groove to seal the liquid to be tested.
[0008] Optionally, the measuring tube is laser-welded to the flange connection.
[0009] Optionally, the measuring tube is provided with a through hole to communicate with the liquid to be measured through the through hole.
[0010] Optionally, the diameter of the through hole is 3 mm.
[0011] Optionally, the flange is made of thermosetting material and integrally molded to enclose the circuit board inside, so as to isolate the liquid to be tested from the circuit board.
[0012] Optionally, the circuit board also includes a temperature sensor to measure the temperature of the liquid to be tested. Attached Figure Description
[0013] Figure 1 This is a schematic diagram of the structure of a liquid level height sensor based on the ultrasonic ranging principle according to an embodiment of this utility model;
[0014] Figure 2 This is a cross-sectional structural diagram of a liquid level height sensor based on the ultrasonic ranging principle according to an embodiment of this utility model.
[0015] Figure 3 This is an exploded structural diagram of a liquid level height sensor based on the ultrasonic ranging principle according to an embodiment of the present invention.
[0016] Figure 4 This is a circuit structure block diagram of the circuit board according to an embodiment of the present utility model.
[0017] Label Explanation
[0018] Flange 10, connection part 101, external thread 102, sealing groove 103;
[0019] Measuring tube 11, through hole 110;
[0020] Circuit board 12, ultrasonic transceiver 120;
[0021] Sealing ring 13. Detailed Implementation
[0022] The embodiments of this utility model are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this utility model, and should not be construed as limiting this utility model.
[0023] To better understand the above technical solutions, exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art.
[0024] To better understand the above technical solutions, the following will provide a detailed explanation of the technical solutions in conjunction with the accompanying drawings and specific implementation methods.
[0025] like Figure 1-3 As shown in the figure, the liquid level sensor based on the ultrasonic ranging principle of this utility model includes a flange, a measuring tube, and a circuit board.
[0026] The flange 10 is provided with a connecting part 101; the measuring tube 11 is connected to the connecting part 101, and the height of the liquid to be measured inside and outside the measuring tube 11 is consistent through the connecting structure; the circuit board 12 is integrally injection molded and encapsulated in the flange 10, and an ultrasonic transceiver 120 is provided on the circuit board 12. The ultrasonic transceiver 120 guides the received and transmitted ultrasonic waves through the measuring tube 11, and obtains the height of the liquid to be measured based on the received ultrasonic waves.
[0027] It should be noted that liquid level sensors are generally installed at the bottom of the container containing the liquid to be measured. Based on the principle of communicating vessels, when the bottoms of two containers are connected and filled with the same liquid, and the air pressure at the top of the liquid inside and outside is equal, the height of the liquid inside and outside is the same. At this time, the liquid level height actually measured by the liquid level sensor in the measuring tube is equal to the actual height of the medium inside the container.
[0028] As an example, the flange 10 has an external thread 102 on its connection part 101 for connection to a container storing the liquid to be tested.
[0029] As an example, the flange 10 is also provided with a sealing groove 103, and a sealing ring 13 is provided in the sealing groove 103 to seal the liquid to be tested through the sealing ring 13.
[0030] It should be noted that after the liquid level sensor is fixedly connected to the bottom of the container of liquid to be measured through the external thread 102, the liquid to be measured is sealed by the sealing ring 13 to prevent leakage of the liquid to be measured.
[0031] As an example, the measuring tube 11 is laser welded to the connection portion 101 of the flange 10.
[0032] It should be noted that the measuring tube 11 and the flange 10 are laser welded to form a continuous fusion line. The weld itself serves as a seal, preventing liquid from seeping in from the interface between the tube wall and the flange 10.
[0033] As an example, the measuring tube 11 is provided with a through hole 110 to communicate with the liquid to be measured through the through hole 110.
[0034] As an example, the diameter of the through hole 110 is 3 mm.
[0035] It should be noted that the through-hole 110 is located at the bottom of the measuring tube 11, with a diameter of only 3mm. Liquid can only enter the internal cavity of the measuring tube, while a molded flange separates the measuring tube 11 from the circuit board 12. The surface of the ultrasonic transducer on the circuit board 12 is covered with plastic and does not directly contact the liquid. The small exchange through-hole 110 at the bottom slows down the exchange speed of the internal and external liquids, preventing large fluctuations in the liquid surface inside the measuring tube 11 during aggressive driving, thus avoiding impact on the measurement results. Furthermore, the measuring tube 11 guides the echo signal, ensuring that most of the echo energy is received by the ultrasonic transceiver 120, guaranteeing the reliability of the measurement.
[0036] As an example, the flange 10 is made of thermosetting material and is integrally molded to enclose the circuit board 12 inside, so as to isolate the liquid to be tested from the circuit board 12.
[0037] It should be noted that flange 10 is made of thermosetting materials, such as thermosetting plastics or thermosetting resins, and is integrally molded to completely enclose the circuit board (PCBA) inside the material, isolating the liquid to be tested from the PCBA, so as to prevent the leaked liquid from corroding the electronic components and ensure the smooth communication of the product.
[0038] As an example, such as Figure 4 As shown, circuit board 12 also includes a temperature sensor to measure the temperature of the liquid to be tested.
[0039] It should be noted that the ultrasonic transceiver function is based on the piezoelectric effect, with the carrier component being a piezoelectric ceramic that can convert mechanical energy into electrical energy. Ultrasonic transmission: When a high-frequency alternating voltage is applied across the piezoelectric ceramic, the ceramic generates corresponding high-frequency vibrations through the reverse piezoelectric effect. These high-frequency vibrations transmit energy outwards in the form of sound waves; when the vibration frequency exceeds 20kHz, ultrasonic waves are emitted. Ultrasonic reception: After the ultrasonic echo signal is received by the piezoelectric ceramic, it generates mechanical stress, and through the direct piezoelectric effect, a corresponding induced voltage is generated across the piezoelectric ceramic. By processing the induced voltage, the transmission path of the ultrasonic wave can be determined.
[0040] In addition, such as Figure 4As shown, the circuit board also includes a crystal oscillator with a frequency of 18.75MHz for timing. The chip's built-in oscillator records the propagation time of the ultrasonic signal. To ensure a liquid level height measurement accuracy of ±2mm, the chip oscillator's design frequency tolerance is ±1.5%. The liquid level height compensation algorithm is as follows:
[0041] Compensation level height = Measurement height [mm] * 18.75 * 10^6 [Hz] / Baud rate [bit / s] / OLS_CNT
[0042] Final measured liquid level = measured height + compensation liquid level height
[0043] The LIN communication baud rate is 19.2 kbps, and OLS_CNT is the measured oscillator frequency of the conversion, which is 966 to 987. In addition, the temperature sensor measures the temperature through a PTC thermistor because it has good linearity in the range of -40℃ to 160℃.
[0044] Temperature signals play an important role in product applications, including: (1) providing high-temperature alarms to protect hardware from permanent damage; and (2) characterizing the current temperature of the liquid medium. Liquids expand and contract at high and low temperatures, and measuring the liquid temperature can compensate for measurement deviations caused by liquid volume expansion. Liquid density changes with temperature, resulting in changes in the propagation rate of ultrasonic signals. By measuring the current liquid temperature, the software can adjust the ultrasonic rate to compensate for deviations in calculating the measured liquid level.
[0045] Therefore, the circuit board 12 of this application, as an embedded component, is used to encapsulate and injection molded flange 10. A sealing ring 13 is press-fitted into the sealing groove 103 of the flange, and finally, the measuring tube 11 is laser-welded to the flange 10. The flange 10 is fixed to the container storing the liquid via external threads 102, and the liquid is sealed by the sealing ring 13 to prevent leakage. The circuit board 12 includes an ultrasonic transceiver 120 and corresponding data storage and processing circuitry, and is integrally injection molded within the flange 10. The measuring tube 11 communicates with the external liquid level through a small hole at the bottom, and a top opening ensures there is no pressure difference between the inner and outer liquid surfaces. During operation, the ultrasonic transceiver 120 on the circuit board 12 emits ultrasonic waves into the measuring tube 11. When the ultrasonic waves contact the liquid and air surfaces inside the measuring tube 11, they generate near-total reflection echoes. The circuit board 12 receives these echoes via the ultrasonic transceiver 120 and uses hardware and software to determine the validity of the echoes and calculate the echo propagation time. Finally, based on the medium temperature measured by the PTC on circuit board 12, the liquid medium height is corrected and output to the host computer via a LIN signal.
[0046] In summary, the liquid level sensor based on the ultrasonic ranging principle according to this utility model embodiment directly embeds a circuit board with an ultrasonic transceiver, temperature compensation, and signal processing circuit into a thermosetting flange, forming a one-time sealed and non-removable composite module. The measuring tube and the flange are laser-welded into a communicating vessel structure, and the small hole at the bottom slows down the exchange speed of the internal and external liquids. The circuit board measures the liquid-gas interface distance in the tube in real time through the bottom transceiver surface. At the same time, the built-in PTC corrects the sound velocity and thermal expansion and contraction deviations caused by temperature. After crystal oscillator frequency calibration, the liquid level measurement result with an accuracy of ±2mm is output through the LIN bus. Thus, with the fewest parts and the simplest structure, automotive-grade liquid level detection with temperature resistance and vibration resistance is achieved.
[0047] In the description of this utility model, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this utility model and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model.
[0048] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this utility model, "a plurality of" means two or more, unless otherwise explicitly specified.
[0049] In this utility model, unless otherwise explicitly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; 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; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.
[0050] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.
[0051] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms should not be construed as necessarily referring to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. In addition, those skilled in the art can combine and integrate the different embodiments or examples described in this specification.
[0052] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.
Claims
1. A liquid level height sensor based on the ultrasonic ranging principle, characterized in that, include: Flange, wherein the flange is provided with a connecting part; A measuring tube is connected to the connecting part, and the measuring tube is connected to make the height of the liquid to be measured inside and outside the measuring tube the same through a connecting structure; The circuit board is integrally injection molded and encapsulated within the flange. An ultrasonic transceiver is provided on the circuit board. The ultrasonic transceiver guides the received and transmitted ultrasonic waves through the measuring tube and obtains the liquid height to be measured based on the received ultrasonic wave time.
2. The liquid level sensor based on ultrasonic ranging principle as described in claim 1, characterized in that, The flange connection is provided with an external thread for connection to a container storing the liquid to be tested.
3. The liquid level sensor based on ultrasonic ranging principle as described in claim 2, characterized in that, The flange is also provided with a sealing groove, and a sealing ring is provided in the sealing groove to seal the liquid to be tested.
4. The liquid level sensor based on ultrasonic ranging principle as described in claim 1, characterized in that, The measuring tube is laser-welded to the flange connection.
5. The liquid level sensor based on ultrasonic ranging principle as described in claim 1, characterized in that, The measuring tube is provided with a through hole to communicate with the liquid to be measured.
6. The liquid level sensor based on ultrasonic ranging principle as described in claim 5, characterized in that, The diameter of the through hole is 3mm.
7. The liquid level sensor based on ultrasonic ranging principle as described in claim 1, characterized in that, The flange is made of thermosetting material and is integrally molded to enclose the circuit board inside, thereby isolating the liquid to be tested from the circuit board.
8. The liquid level sensor based on ultrasonic ranging principle as described in claim 1, characterized in that, The circuit board also includes a temperature sensor to measure the temperature of the liquid to be tested.