Highly integrated millimeter wave fmcw radar liquid level gauge

Abstract

The application discloses a kind of high integration millimeter wave FMCW radar liquid level meter, it is related to liquid level meter technical field.The present application includes millimeter wave resonant cavity structure and calibration part;Through millimeter wave resonant frequency drift, liquid level change is accurately measured, without traditional radar echo ranging, improve measurement accuracy and stability;Setting adjustment part accurately adjusts radar angle, ensures that beam is perpendicular to liquid surface;Sealing cover uses high temperature and high pressure wave-transparent material, improves the adaptability of harsh working conditions;Calibration part uses laser reflection mode to monitor liquid level fluctuation in real time, actively check measurement reliability, overall structure is compact, high precision, and strong environmental adaptability.

Description

Technical Field

[0001] This invention relates to the field of liquid level gauge technology, specifically to a highly integrated millimeter-wave FMCW radar liquid level gauge. Background Technology

[0002] In traditional liquid level measurement technology, FMCW radar is widely used for liquid level monitoring in industrial tanks and storage tanks due to its non-contact characteristics. However, existing technologies have revealed a series of shortcomings in practical applications. First, traditional FMCW radar has poor environmental adaptability. In high-temperature, high-pressure, or corrosive liquid environments, the antenna and electronic components are easily damaged, leading to decreased measurement accuracy or even equipment failure. Second, vibration interference is another major problem. When the tank vibrates due to mechanical operation or external factors, liquid level fluctuations can cause interference, reducing the reliability of measurement data. In addition, the measurement accuracy of traditional equipment is limited by the echo ranging principle, and multipath effects and clutter interference make high-precision measurements difficult to achieve. Summary of the Invention

[0003] To overcome the shortcomings of the prior art, the present invention provides the following technical solution: a highly integrated millimeter-wave FMCW radar level gauge, comprising a mounting base, on which a millimeter-wave FMCW radar is mounted via an adjustment section, and a sealing cover is disposed below the millimeter-wave FMCW radar, the sealing cover being fixedly and sealed to the mounting base; two calibration sections arranged perpendicularly to each other are also fixedly mounted on the mounting base, each calibration section including a calibration pool fixedly fitted with the mounting base, and two symmetrically arranged float limit plates are disposed inside the calibration pool, with a float plate disposed between the two float limit plates, the float plate floating on the clear water inside the calibration pool; two light-shielding sealing covers are also fixedly mounted on the calibration pool, the two light-shielding sealing covers and the calibration pool forming a closed, opaque space, and a laser emitter and a light sensor are fixedly mounted between the two light-shielding sealing covers, the light emitted by the laser emitter being reflected onto the light sensor through the float plate.

[0004] Preferably, the millimeter-wave FMCW radar and the container whose liquid level needs to be measured form a millimeter-wave resonant cavity with a resonant frequency of 60GHz~80GHz. Changes in liquid level directly cause changes in the effective length of the resonant cavity, thereby changing the millimeter-wave resonant frequency within the cavity. The resonant frequency depends on the cavity length (resonant frequency = resonant mode order x speed of light / twice the resonant cavity length (as it changes with liquid level)). Therefore, the height of the liquid level change can be accurately calculated by measuring the resonant frequency drift. A high-precision millimeter-wave frequency measurement unit (such as a high-stability phase-locked loop PLL) is used to capture the frequency drift signal in real time. Pure physical signal processing techniques (such as spectrum analysis and physical filtering techniques) are used to ensure the stability of the signal processing. The accurate liquid level is calculated directly from the frequency drift value, eliminating the need for traditional radar echo ranging.

[0005] Preferably, a front reflector and an end reflector are fixedly installed between the two light-shielding sealing covers. The laser emitter emits light towards the floating plate along the inclined direction. The floating plate reflects the light emitted by the laser emitter onto the front reflector. The front reflector reflects the light onto the end reflector. The end reflector reflects the light vertically onto the light sensor.

[0006] Preferably, the sealing cover and the mounting plate are fixed and sealed together in a way that facilitates disassembly. The sealing cover is made of ceramic-based wave-transparent material (such as boron nitride ceramic or alumina ceramic) or high-performance polymer material (such as polytetrafluoroethylene PTFE), which is resistant to high temperature, high pressure, corrosion and pollution, and greatly improves reliability and long-term stability.

[0007] Preferably, the calibration unit is used to detect whether there are fluctuations on the liquid surface, and the adjustment unit is used to control the axis angle of the millimeter-wave FMCW radar so that the wave emitted by the millimeter-wave FMCW radar can be perpendicularly irradiated onto the liquid.

[0008] Preferably, the adjustment part includes an outer annular bracket that is fixedly fitted with the mounting plate base. An inner annular bracket is rotatably mounted on the outer annular bracket via two symmetrically arranged outer adjustment pins. The inner annular bracket is fixedly fitted with the outer adjustment pins, and the outer adjustment pins are rotatably fitted with the outer annular bracket.

[0009] Preferably, a radar mounting bracket is rotatably mounted on the inner annular bracket via an inner adjusting pin, wherein the millimeter-wave FMCW radar is fixedly mounted on the radar mounting bracket, the radar mounting bracket is fixedly engaged with the inner adjusting pin, and the inner adjusting pin is rotatably engaged with the inner annular bracket.

[0010] Preferably, an outer adjusting arm is fixedly mounted on the outer adjusting pin, and an outer adjusting electric cylinder is movably mounted on the outer annular bracket. The end of the telescopic rod of the outer adjusting electric cylinder is movably connected to the end of the outer adjusting arm away from the outer adjusting pin.

[0011] Preferably, an inner adjusting arm is fixedly mounted on the inner adjusting pin, and an inner adjusting electric cylinder is movably mounted on the inner annular bracket. The end of the telescopic rod of the inner adjusting electric cylinder is movably connected to the end of the inner adjusting arm away from the inner adjusting pin.

[0012] Preferably, an edge protective cover is provided on the outside of the adjustment section and the calibration section. The bottom end of the edge protective cover is fixedly and sealed on the mounting plate base, and the top end of the edge protective cover is flexibly connected to the outer surface of the millimeter-wave FMCW radar through a flexible cloth.

[0013] Compared with the prior art, the present invention has the following advantages: (1) The present invention uses a sealing cover made of ceramic-based wave-transparent material or high-performance polymer material, which is fixedly and sealed to the mounting plate, and can effectively resist the influence of high temperature, high pressure, corrosive liquid and polluted environment. Compared with the defects of traditional equipment being easily damaged by harsh environment, this design significantly improves the reliability and long-term stability of millimeter wave FMCW radar level gauge, and ensures that it can still operate normally in harsh industrial scenarios; (2) The present invention adopts the resonant cavity frequency drift principle, and accurately measures the liquid level height through the change of millimeter wave frequency, avoiding the instability of traditional radar echo ranging, and providing higher measurement accuracy and reliability. At the same time, combined with high stability phase-locked loop (PLL) and pure physical signal processing technology, the stability and accuracy of measurement results in complex industrial environment are effectively improved; (3) The calibration part of the present invention uses a combination structure of float plate and laser reflection to detect liquid surface fluctuation in real time and actively judge the degree of influence of vibration environment on measurement data; the optical path is extended by refraction of double mirrors, which greatly improves the vibration detection sensitivity and greatly improves the reliability and data credibility of liquid level measurement. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the overall structure of the present invention.

[0015] Figure 2 This is a schematic diagram of the calibration section of the present invention.

[0016] Figure 3 This is a schematic diagram of the adjustment part of the present invention.

[0017] Figure 4 This is a schematic diagram of the sealing cover structure of the present invention.

[0018] Figure 5 This is a schematic diagram of the radar mounting bracket structure of the present invention.

[0019] In the diagram: 101-Mounting plate; 102-Edge protective cover; 103-Millimeter-wave FMCW radar; 104-Calibration cell; 105-Light-shielding sealing cover; 106-End reflector; 107-Front-end reflector; 108-Laser emitter; 109-Light sensor; 110-Float plate limit plate; 111-Float plate; 112-Outer annular bracket; 113-Outer adjusting electric cylinder; 114-Outer adjusting swing arm; 115-Outer adjusting pin; 116-Inner annular bracket; 117-Radar mounting bracket; 118-Inner adjusting pin; 119-Inner adjusting swing arm; 120-Inner adjusting electric cylinder; 121-Sealing cover; 122-Flexible cloth. Detailed Implementation

[0020] The following is in conjunction with the appendix Figures 1-5 The technical solution of the present invention will be further illustrated through specific embodiments.

[0021] This invention provides a highly integrated millimeter-wave FMCW radar level gauge, including a mounting base 101. A millimeter-wave FMCW radar 103 is mounted on the mounting base 101 via an adjustment mechanism. A sealing cover 121 is disposed below the millimeter-wave FMCW radar 103, and the sealing cover 121 is fixedly and sealingly connected to the mounting base 101. Two calibration parts arranged perpendicularly to each other are also fixedly mounted on the mounting base 101. Each calibration part includes a calibration pool 104 fixedly fitted with the mounting base 101. Two symmetrically arranged calibration pools are disposed inside the calibration pool 104. A float plate 110 is placed between two float plate limiting plates 110, and a float plate 111 is disposed between the two float plate limiting plates 110. The float plate 111 floats on the clean water inside the calibration pool 104. Two light-shielding sealing covers 105 are also fixedly installed on the calibration pool 104. The two light-shielding sealing covers 105 and the calibration pool 104 form a closed and opaque space. A laser emitter 108 and a light sensor 109 are fixedly installed between the two light-shielding sealing covers 105. The light emitted by the laser emitter 108 can be reflected by the float plate 111 onto the light sensor 109. The millimeter-wave FMCW radar 103 and the container to be measured liquid level constitute a millimeter-wave resonant cavity with a resonant frequency of 60GHz~80GHz. The change in liquid level directly causes the effective length of the resonant cavity to change, thereby changing the millimeter-wave resonant frequency in the cavity. The resonant frequency depends on the cavity length (resonant frequency = resonant mode order x speed of light / twice the resonant cavity length (as the liquid level changes)). Therefore, the height of the liquid level change can be accurately calculated by measuring the resonant frequency drift. A high-precision millimeter-wave frequency measurement unit (such as a high-stability phase-locked loop, PLL) is used to capture frequency drift signals in real time. Pure physical signal processing techniques (such as spectrum analysis and physical filtering techniques) are employed to ensure the stability of signal processing. The precise liquid level is calculated directly from the frequency drift value, eliminating the need for traditional radar echo ranging. A front reflector 107 and an end reflector 106 are fixedly installed between two light-shielding sealing covers 105. The laser emitter 108 emits light along an inclined direction towards the float 111. The float 111 reflects the light emitted by the laser emitter 108 onto the front reflector 107, which then reflects the light onto the end reflector 106. The end reflector 106 then reflects the light perpendicularly onto the light sensor 109. The sealing cover 121 and the mounting plate 101 are fixed and sealed together in a manner that facilitates disassembly. The sealing cover 121 is made of a ceramic-based wave-transparent material (such as boron nitride ceramic or alumina ceramic) or a high-performance polymer material (such as polytetrafluoroethylene PTFE), which is resistant to high temperature, high pressure, corrosion and contamination, greatly improving reliability and long-term stability. The calibration section is used to detect whether there are fluctuations on the liquid surface, and the adjustment section is used to control the axis angle of the millimeter-wave FMCW radar 103 so that the wave emitted by the millimeter-wave FMCW radar 103 can be perpendicular to the liquid surface.

[0022] The adjustment unit includes an outer annular bracket 112 fixedly engaged with the mounting plate 101. An inner annular bracket 116 is rotatably mounted on the outer annular bracket 112 via two symmetrically arranged outer adjusting pins 115. The inner annular bracket 116 is fixedly engaged with the outer adjusting pins 115, and the outer adjusting pins 115 are rotatably engaged with the outer annular bracket 112. A radar mounting bracket 117 is rotatably mounted on the inner annular bracket 116 via an inner adjusting pin 118. A millimeter-wave FMCW radar 103 is fixedly mounted on the radar mounting bracket 117. The radar mounting bracket 117 is fixedly engaged with the inner adjusting pin 118, and the inner adjusting pin 118 is rotatably engaged with the inner annular bracket 116. An outer adjusting arm 114 is fixedly mounted on the outer adjusting pin 115. An outer adjusting cylinder 113 is movably mounted on the outer annular bracket 112. The end of the telescopic rod of the outer adjusting cylinder 113 is movably connected to the end of the outer adjusting arm 114 away from the outer adjusting pin 115. An inner adjusting arm 119 is fixedly mounted on the inner adjusting pin 118, and an inner adjusting electric cylinder 120 is movably mounted on the inner annular bracket 116. The end of the telescopic rod of the inner adjusting electric cylinder 120 is movably connected to the end of the inner adjusting arm 119 away from the inner adjusting pin 118. An edge protective cover 102 is sleeved on the outside of the adjusting part and the calibration part. The bottom end of the edge protective cover 102 is fixedly and sealed on the mounting plate 101, and the top end of the edge protective cover 102 is flexibly connected to the outer surface of the millimeter-wave FMCW radar 103 through a flexible cloth 122.

[0023] The working principle of the highly integrated millimeter-wave FMCW radar level gauge disclosed in this invention is as follows: The mounting plate 101 is installed on the top of the tank whose liquid level needs to be measured. (Through the adjustment mechanism, the axis of the millimeter-wave FMCW radar 103 is controlled to be perpendicular to the liquid surface. Specifically, the swing of the millimeter-wave FMCW radar 103 can be controlled by adjusting the extension and retraction of the outer adjusting cylinder 113 and the inner adjusting cylinder 120. The extension and retraction of the inner adjusting cylinder 120 drives the inner adjusting arm 119 to swing, which in turn drives the inner adjusting pin 118 to swing, which in turn drives the radar...) Mounting bracket 117 and millimeter-wave FMCW radar 103 swing. The extension rod of the outer adjusting electric cylinder 113 drives the outer adjusting arm 114 to swing, which in turn drives the outer adjusting pin 115 to swing. The outer adjusting pin 115 then drives the inner annular bracket 116 and the millimeter-wave FMCW radar 103 on it to swing until the axis of the millimeter-wave FMCW radar 103 is perpendicular to the liquid surface (when the distance between the millimeter-wave FMCW radar 103 and the liquid surface reaches its minimum). Depending on the sealing conditions, the sealing cover 121 may or may not be installed. During use, the electromagnetic waves emitted by the millimeter-wave FMCW radar 103 enter the tank interior (resonant cavity) and are continuously reflected on the inner wall of the tank (the cavity size and the electromagnetic wave wavelength satisfy a certain relationship (the length is an integer multiple of half the wavelength). The electromagnetic waves will produce constructive interference, forming a stable standing wave. At a specific frequency, the amplitude of the electromagnetic field in the resonant cavity is significantly enhanced, which is called the resonant state). Changes in liquid level directly lead to changes in the length of the cavity. After the cavity length changes, its resonant frequency will drift slightly but precisely. By accurately measuring this resonant frequency drift, the amount of change in liquid level can be measured very accurately, thus achieving high-precision liquid level detection.

[0024] When the measurement environment vibrates, the liquid surface being measured will fluctuate. This will affect the measurement accuracy of the millimeter-wave FMCW radar 103. Therefore, it is necessary to detect whether there is fluctuation in the liquid surface and perform a self-check of the measurement data of the millimeter-wave FMCW radar 103. Specifically, when vibrations occur in the environment, the water inside the calibration pool 104 will fluctuate, causing the float 111 to oscillate. This results in the upper surface of the float 111 no longer being parallel to the horizontal plane (the upper surface of the float 111 has a reflective surface). The light emitted by the laser emitter 108, passing through the tilted float 111, causes a change in the angle of the reflected light. This, in turn, changes the position of the light reflected from the float 111 onto the front reflector 107, then onto the end reflector 106, and finally onto the light sensor 109. The light sensor 109 detects these changes. The front and end reflectors 107 and 106 are used to extend the light propagation path as much as possible within a limited space, improving measurement sensitivity. For example, if the light reflected from the end reflector 106 onto the light sensor 109 exceeds the sensor's sensing range, it indicates that the vibration amplitude is too large. Therefore, the liquid level data measured by the millimeter-wave FMCW radar 103 is inaccurate at this time.

Claims

1. A high-integration millimeter-wave FMCW radar liquid level gauge, characterized in that: The installation disc seat (101) is provided with a millimeter wave FMCW radar (103) through an adjusting part, and a sealing cover (121) is arranged below the millimeter wave FMCW radar (103). Two calibration parts arranged perpendicularly are further fixedly installed on the installation disc seat (101), and the calibration parts are used for detecting whether the liquid surface is fluctuated, and the calibration part comprises a calibration pool (104) fixedly matched with the installation disc seat (101), two symmetrically arranged floating plate limiting sheets (110) are arranged in the calibration pool (104), and a floating plate (111) is arranged between the two floating plate limiting sheets (110) and floats on the clean water in the calibration pool (104). Two light shielding sealing covers (105) are further fixedly installed on the calibration pool (104), the two light shielding sealing covers (105) form a closed and light-proof space with the calibration pool (104), a laser emitter (108) and a light sensor (109) are fixedly installed between the two light shielding sealing covers (105), and the light emitted by the laser emitter (108) can be reflected on the light sensor (109) through the floating plate (111). The millimeter wave FMCW radar (103) and a container required to measure a liquid surface form a millimeter wave resonant cavity, the resonant frequency is 60GHz-80GHz, the change of the liquid level directly leads to the change of the effective length of the resonant cavity, so that the millimeter wave resonant frequency in the cavity is changed, and the front end mirror sheet (107) and the end mirror sheet (106) are fixedly installed between the two light shielding sealing covers (105), the laser emitter (108) emits light along an inclined direction to the floating plate (111), the floating plate (111) reflects the light emitted by the laser emitter (108) on the front end mirror sheet (107), the front end mirror sheet (107) reflects the light on the end mirror sheet (106), and the end mirror sheet (106) reflects the light vertically on the light sensor (109).

2. A high integration millimeter wave FMCW radar liquid level meter according to claim 1, characterized in that: The sealing cover (121) and the installation disc seat (101) are fixedly and sealingly matched in a detachable manner.

3. A high integration millimeter wave FMCW radar liquid level meter according to claim 2, characterized in that: The adjusting part is used for controlling the axis angle of the millimeter wave FMCW radar (103), so that the wave emitted by the millimeter wave FMCW radar (103) can be vertically irradiated on the liquid.

4. A high integration millimeter wave FMCW radar liquid level meter according to claim 3, characterized in that: The adjusting part comprises an outer ring-shaped support (112) fixedly matched with the installation disc seat (101), an inner ring-shaped support (116) is rotatably installed on the outer ring-shaped support (112) through two symmetrically arranged outer adjusting pin shafts (115), the inner ring-shaped support (116) is fixedly matched with the outer adjusting pin shaft (115), and the outer adjusting pin shaft (115) is rotatably matched with the outer ring-shaped support (112).

5. A highly integrated millimeter wave FMCW radar liquid level meter according to claim 4, characterized in that: The radar mounting frame (117) is rotatably mounted on the inner side annular support (116) by an inner side adjusting pin shaft (118), wherein the millimeter wave FMCW radar (103) is fixedly installed on the radar mounting frame (117), the radar mounting frame (117) is fixedly matched with the inner side adjusting pin shaft (118), and the inner side adjusting pin shaft (118) is rotatably matched with the inner side annular support (116).

6. A high-integration millimeter-wave FMCW radar liquid level gauge according to claim 5, characterized in that: The outer side adjusting swing arm (114) is fixedly installed on the outer side adjusting pin shaft (115), the outer side annular support (112) movably installs the outer side adjusting electric cylinder (113), and the telescopic rod end of the outer side adjusting electric cylinder (113) is movably connected with one end of the outer side adjusting swing arm (114) away from the outer side adjusting pin shaft (115).

7. A highly integrated millimeter wave FMCW radar liquid level meter according to claim 6, characterized in that: The inner side adjusting swing arm (119) is fixedly installed on the inner side adjusting pin shaft (118), the inner side annular support (116) movably installs the inner side adjusting electric cylinder (120), and the telescopic rod end of the inner side adjusting electric cylinder (120) is movably connected with one end of the inner side adjusting swing arm (119) away from the inner side adjusting pin shaft (118).

8. A high integration millimeter wave FMCW radar liquid level meter according to claim 7, characterized in that: The edge protection cover (102) is sleeved outside the adjusting part and the calibration part, the bottom end of the edge protection cover (102) is fixedly and sealingly installed on the mounting disc seat (101), and the top end of the edge protection cover (102) is flexibly connected with the outer surface of the millimeter wave FMCW radar (103) through the flexible cloth (122).

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