Rainwater measuring equipment based on TDR (time domain reflectometry) technology

Abstract

The utility model discloses rainwater measuring equipment based on a TDR (time domain reflectometry) technology. The device comprises an outer cylinder, the outer cylinder is a hollow cylinder, a water bearing device and a measuring pool are arranged in the outer cylinder, the water bearing device is located above the measuring pool, the bottom of the water bearing device is connected to the top of the measuring pool through a pinch valve, the water bearing device is used for collecting rainwater, and the rainwater is put into the measuring pool through the pinch valve; a water bearing opening is formed in the top of the water bearing device and is parallel to the top of the outer cylinder; the measuring cell is connected with a TDR liquid level sensor, and the TDR liquid level sensor comprises a sensor main body and a probe. According to the utility model, the problems of low precision and high maintenance cost of rainfall measurement equipment in the prior art are solved.

Description

Technical Field

[0001] The utility model relates to the technical field of rainfall measurement, in particular to a rainfall measuring device based on TDR technology. Background Art

[0002] A rain gauge is an instrument used by meteorologists and hydrologists to measure the amount of precipitation in a region over a period of time. The most common types are the siphon type and the tipping bucket type.

[0003] The operation of the siphon rain gauge is cumbersome and the siphon tube is easily blocked. The operation process is relatively cumbersome because the recording paper needs to be replaced on site regularly. In addition, the siphon process is prone to failures, such as siphon interruption, siphon dripping, and pen tip mechanical failure. These are all common problems. Therefore, maintenance must be strengthened during use to ensure the normal operation of the instrument and maintain the integrity and correctness of the automatic recording.

[0004] Since the tipping bucket rain gauge calculates the precipitation by counting each "dumping" operation, the accuracy of the tipping bucket rain gauge is relatively low. For smaller precipitation, the sensitivity that can be detected is also relatively low. During the use of the tipping bucket rain gauge, due to frequent operations, errors are prone to occur.

[0005] With the continuous development of sensor technology, rainfall measurement equipment has begun to adopt more advanced technology. Sensors can sense rainfall conditions in real time and convert the sensed signals into electrical signals or pulse signals for data collection and processing. For example, capacitive sensors, ultrasonic sensors, and pulse output sensors are widely used in rainfall measurement equipment.

[0006] At present, most liquid level rain gauges on the market use a combination of magnetostriction and a float. However, the float in the measured water body will inevitably interfere with the measured water body. Its accuracy and stability are affected not only by the accuracy of the sensor itself, but also by the viscosity between water and the float, the buoyancy of the float, etc.

[0007] In the related art, the technical problems of low accuracy and high maintenance cost of rainfall measurement equipment have not yet been effectively solved. Utility Model Content

[0008] The utility model aims to provide a rainwater measuring device based on TDR technology to solve the problems of low precision and high maintenance cost of rainfall measuring equipment in related technologies.

[0009] In order to achieve the above purpose, the utility model adopts the following technical solutions:

[0010] A rainwater measuring device based on TDR technology comprises: an outer cylinder, which is a hollow cylinder, wherein a water receiver and a measuring pool are arranged inside the outer cylinder, wherein the water receiver is located above the measuring pool, wherein the bottom of the water receiver is connected to the top of the measuring pool via a clamping valve, wherein the water receiver is used to collect rainwater, and the rainwater is put into the measuring pool via the clamping valve; wherein a water receiving port is arranged on the top of the water receiver, and the water receiving port is parallel to the top of the outer cylinder; wherein a TDR liquid level sensor is connected to the measuring pool, and the TDR liquid level sensor comprises a sensor body and a probe.

[0011] It is further configured that a water injection pipe is connected to the bottom of the pinch valve, the pinch valve is used to control the flow of the water injection pipe, and the outlet of the water injection pipe is at the bottom of the measuring pool.

[0012] It is further configured that the sensor body is arranged on the top of the outside of the measuring cell.

[0013] It is further configured that the measuring pool is a hollow cylinder, the probe is arranged at the axis center position of the measuring pool, and the probe is perpendicular to the bottom surface of the measuring pool.

[0014] It is further configured that the root of the probe is parallel to the top of the measuring cell, and the root of the probe is connected to the sensor body through a coaxial cable.

[0015] It is further configured that a drain pipe is provided at the bottom of the measuring pool, a drain valve is provided on the drain pipe, and the drain pipe is used to drain the liquid in the measuring pool.

[0016] Compared with the prior art, the beneficial technical effects of the utility model are:

[0017] (1) TDR technology is used to measure the change of liquid level, and a stable and reliable relationship between the dielectric constant and the change of liquid level is established; currently, most of the liquid level rain gauges on the market use the method of combining magnetostriction with a float, but the float in the measured water body will inevitably interfere with the measured water body, and its accuracy and stability are affected not only by the accuracy of the sensor itself, but also by the viscosity between water and the float, the buoyancy of the float, etc. The utility model does not need to use a float, has little interference with the measured water body, and has high sensitivity.

[0018] (2) TDR technology is used to measure the water surface and convert the liquid level change. The dielectric constant of water is 81, which has a large attenuation on electromagnetic waves. The reflection of the water surface is obtained by measuring the air segment. The dielectric constant of air is 1, and the attenuation of electromagnetic waves in air is small. This method can also avoid the measurement error caused by the influence of water temperature on the dielectric constant of water.

[0019] (3) Algorithm filtering mechanism: Since the measuring pool is a closed container and the well is in a high humidity environment for a long time, it is inevitable that water will adhere to the probe surface, which will affect the accuracy of the sensor to a certain extent. The surface treatment process can be used to avoid continuous water droplets on the probe, which will affect the measurement accuracy. At the same time, in view of the influence of the dielectric constant in the high temperature environment, high-frequency filtering is used to distinguish and identify the water-gas interface (that is, although there is some liquid water on the part of the probe that is not in the water, it can be identified because it is not completely covered and is discontinuous). BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the specific implementation methods of the utility model or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0021] Figure 1 The utility model discloses a flow chart of a rainwater measurement method based on TDR technology;

[0022] Figure 2 It is a schematic diagram of a rainwater measuring device based on TDR technology disclosed in the utility model;

[0023] Figure 3 This is the TDR trace diagram measured by the TDR liquid level sensor in the utility model.

[0024] Figure numerals: 1, water receiving port; 2, water receiving vessel; 3, water filling pipe; 4, clamp valve; 5, drain pipe; 6, drain valve; 7, probe; 8, measuring cell; 9, sensor body. DETAILED DESCRIPTION

[0025] The technical solution of the utility model will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0026] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying 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 limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0027] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0028] Example

[0029] Reference Figure 1 , is a rainwater measurement method based on TDR technology used in the utility model, comprising:

[0030] Step S101, obtaining measurement data, the measurement data including the bottom radius of the measurement pool 8 and the dielectric constant of air;

[0031] Step S102, obtaining a first time point and a second time point according to the electromagnetic wave signal emitted by the TDR liquid level sensor, wherein the first time point is the time point when the electromagnetic wave signal is transmitted to the top of the measuring pool 8 and is reflected, and the second time point is the time point when the electromagnetic wave signal is transmitted to the water surface and is reflected;

[0032] Specifically, the electromagnetic wave signal is emitted from the TDR liquid level sensor and transmitted along the cable. When it reaches the top of the transmission measuring pool 8, the first reflection occurs due to impedance mismatch. The electromagnetic wave signal is transmitted along the cable to the receiver, and the receiver captures it. The time at this time is recorded as t1. The electromagnetic wave with the remaining energy continues to be transmitted along the measuring pool 8. When it reaches the water surface, the impedance changes, resulting in a second reflection. The reflected signal is reflected along the cable to the receiver, and the time of the reflected electromagnetic wave is recorded as t2. Thus, the transmission time of the electromagnetic wave in the air segment can be obtained. When the rainwater capacity is 3.14mL, it means that there is 0.1mm deep precipitation on the ground.

[0033] Step S103, calculating the volume of rainwater in the measuring pool 8 according to the measurement data, the first time point and the second time point, and obtaining the precipitation according to the rainwater volume.

[0034] Optionally, the liquid level of rainwater in the measuring tank 8 is calculated using the following formula: W =HL, Among them, L W is the liquid level height, C is the speed of light, Δt is the time it takes for the probe to transmit the electromagnetic wave signal in the air, Ka is the dielectric constant of the air, H is the height of the measuring cell 8, and L is the height from the liquid level to the top of the measuring cell 8.

[0035] Optionally, the time for the probe 7 to transmit the electromagnetic wave signal in the air is calculated using the formula △t=t2-t1, where t1 is the first time point and t2 is the second time point. The time for the electromagnetic wave to be transmitted on the probe 7 can be calculated by the difference between the first time point and the second time point.

[0036] Optionally, the volume of rainwater is calculated using the formula: V = π × r 2 ×L W , V is the volume of rainwater, r is the bottom radius of the measuring pool 8, L W is the liquid level height.

[0037] This solution should also use precision conversion, assuming that the time accuracy is 30ps, that is, the minimum time interval is 3×10 -11 seconds, the dielectric constant of air is 1, according to Minimum L = 3 × 10 8 ×3×10 -11 ÷2=0.0015 meters. If the diameter of the water sensor is 30 mm, the minimum volume that can be measured is V=π×r 2 ×L,V=3.1415926×(0.015) 2 ×0.0015=0.00000106028 (cubic meters)=0.

[0038] 00106028 (liters) = 1.06028 (milliliters), which converts to a rainfall amount of 0.0332930 mm.

[0039] Reference Figure 2, is a rainwater measuring device based on TDR technology disclosed in the utility model, and the utility model includes: an outer tube, which is a hollow cylinder, and a water receiver 2 and a measuring pool 8 are arranged inside the outer tube, the water receiver 2 is located above the measuring pool 8, and the bottom of the water receiver 2 is connected to the top of the measuring pool 8 through a clamping valve 4, the water receiver 2 is used to collect rainwater, and the rainwater is put into the measuring pool 8 through the clamping valve 4; a water receiving port is arranged on the top of the water receiver 2, and the water receiving port is parallel to the top of the outer tube; the measuring pool 8 is connected to a TDR liquid level sensor, and the TDR liquid level sensor includes a sensor body 9 and a probe 7.

[0040] The utility model utilizes the internal measuring pool 8 of the rain gauge to collect the precipitation in nature, forms the change of liquid level in the measuring pool 8, establishes the relationship between the collected dielectric constant change and the liquid level change through the TDR liquid level sensor and outputs it as an electrical signal to calculate the precipitation.

[0041] During normal measurement, the pinch valve 4 is in an open state, precipitation enters the measuring tank 8 through the upper water injection pipe 3, and the drain valve 6 is in a closed state.

[0042] When the water level in the measuring tank 8 is too high (250 mm), the controller controls the closing of the pinch valve 4, records the current water level value, opens the drain valve 6, and closes the drain valve 6 and opens the pinch valve 4 until the water level drops to 0 water level.

[0043] The water receiving device 2 and the water receiving port are in accordance with the relevant standards, that is, the inner diameter of the water receiving port is 200mm, the inner wall depth is 150mm, and the cutting edge angle is 42.5°.

[0044] Optionally, a water injection pipe 3 is connected to the bottom of the pinch valve 4 , and the pinch valve 4 is used to control the flow of the water injection pipe 3 . The outlet of the water injection pipe 3 is at the bottom of the measuring tank 8 .

[0045] Specifically, the valve body is mainly composed of a clamp valve 4 and a drain valve 6. Both the clamp valve 4 and the drain valve 6 are electromagnetic valves. The clamp valve 4 is located on the upper part of the measuring pool 8. It is mainly used to temporarily close the measuring pool 8 when draining water. The normal state is normally open. The water injection pipe 3 adopts a high-performance latex tube, which is easy to replace. A drain valve 6 is installed below. The drain valve 6 is mainly opened for overflow drainage when the water in the measuring pool 8 is too high. The water injection pipe 3 is used to connect the water receiver 2 and the measuring pool 8. The PC material allows the rainfall collected by the water receiver 2 to be indirectly injected below the water surface to avoid adhesion to the side wall and affect the measurement accuracy. The coordinated use of the clamp valve 4 and the drain valve 6, as well as the design of the water injection pipe 3, can ensure that the water level in the measuring pool 8 remains stable during the measurement process, thereby improving the measurement accuracy. The overflow drainage function of the drain valve 6 can ensure that the measuring pool 8 will not overflow due to excessively high water levels, thereby protecting the safety of the equipment and the surrounding environment. The high-performance latex tube and the water injection pipe 3 made of PC material have a long service life and low maintenance cost, which reduces the maintenance difficulty and cost of the entire system. This design improves the stability and reliability of the system, allowing users to obtain rainfall data more accurately, thus providing users with a better user experience.

[0046] Optionally, the sensor body 9 is arranged at the top of the outside of the measuring pool 8. The measuring pool 8 is a hollow cylinder, the probe 7 is arranged at the axial position of the measuring pool 8, the probe 7 is perpendicular to the bottom surface of the measuring pool 8, the root of the probe 7 is parallel to the top of the measuring pool 8, the root of the probe 7 is connected to the sensor body 9 through a coaxial cable, a drain pipe 5 is arranged at the bottom of the measuring pool 8, a drain valve 6 is arranged on the drain pipe 5, and the drain pipe 5 is used to discharge the liquid in the measuring pool 8.

[0047] Specifically, since the sensor body 9 is arranged at the top of the outside of the measuring tank 8, it will not directly contact the water, thereby reducing the interference caused by water to the sensor. This design also avoids the corrosion or damage that may occur to the sensor components due to long-term immersion in water, ensures the long-term stability and reliability of the sensor, and thus improves the accuracy of the measurement. The probe 7 is arranged inside the measuring tank 8 and is perpendicular to the bottom surface of the measuring tank 8. This layout ensures that the probe 7 can accurately reflect the change of the water level in the measuring tank 8. When the water level rises, the contact part of the probe 7 with the water will change, thereby triggering the sensor body 9 to generate a corresponding electrical signal and accurately record the change of rainfall. The sensor body 9 is located outside the measuring tank 8, making maintenance and cleaning easier. When the sensor needs to be repaired or replaced, it is not necessary to enter the measuring tank 8, reducing the difficulty and cost of maintenance. At the same time, since the sensor is not in direct contact with water, the damage to the sensor caused by improper cleaning is also reduced. A drain pipe 5 is arranged at the bottom of the measuring tank 8, and a drain valve 6 is arranged on the drain pipe 5. This design allows the water to be drained by opening the drain valve 6 when the water level in the measuring tank 8 is too high, thereby avoiding overflow caused by the excessively high water level. This not only protects the device itself, but also prevents inconvenience or damage to the surrounding environment caused by overflow.

[0048] Compensation algorithm: Since the TDR liquid level probe 7 and the water injection pipe 3 also have a certain volume, compensation should be performed in actual applications. The compensation algorithm is: the outer radius of the water injection pipe 3 is r1, the inner radius is r2, and the water injection pipe wall is equal to r1-r2; the radius of the TDR liquid level probe 7 is r3, and the deviation of volume compensation V=πr3 2 L1+π(r1-r2) 2 L2, L1=Lw, L2=Lw-Lk2, where L1 is the height of the probe 7 in the water, Lw is the height of the rainwater level, L2 is the height of the water injection pipe 3 in the water, and Lk2 is the height from the main water pipe to the bottom of the measuring tank 8.

[0049] The sensor range size change and the design of the measurement pool 8 size. The inner diameter of the measurement pool 8 is 30mm, the full range of the sensor is 300mm, the normal use range is 0-250mm, the drainage speed is 10mm / second, and according to the hydrological and meteorological data, the 24-hour rainfall is more than 200mm, which is a heavy rainstorm, about 0.0023148mm rainfall per second, converted to a volume of 0.07268mL, and converted to a height of 1.02828mm. According to the hydrological and meteorological data, a heavy rainstorm has been satisfied and no overflow is required. Avoid overflow and water replenishment process to affect the rainfall measurement. At the same time, the overall height of the instrument is about 640mm, which also meets the requirements of the precipitation observation specification (≤700mm).

[0050] Reference Figure 3In an optional embodiment, the TDR liquid level sensor measures the TDR trace. In the picture, the horizontal axis is the time axis, the vertical axis is the amplitude, m1 and m2 are marked points, (36.53, 0.26) is the coordinate value of m1, and (40.32, 0.07) is the coordinate value of m2. 36.53 is the first time point, and 40.32 is the second time point.

[0051] According to an optional embodiment of the present scheme, the design size of the measuring pool is 30mm in diameter, the probe diameter is 2mm, the water inlet pipe wall thickness is 0.5mm, the measuring pool height is 300mm, and the water inlet pipe is 10mm from the bottom of the measuring pool. The following is a TDR technology rainwater measurement data table.

[0052]

[0053] The working principle and beneficial effects of the utility model are:

[0054] (1) Use TDR technology to measure liquid level changes and establish a stable and reliable relationship between dielectric constant and liquid level changes; currently, most liquid level rain gauges on the market use magnetostriction and floats, but the float in the measured water body will inevitably interfere with the measured water body. Its accuracy and stability are affected not only by the accuracy of the sensor itself, but also by the viscosity between water and float, the buoyancy of float, etc. TDR liquid level rain gauges do not need to use floats, have little interference with the measured water body, and have high sensitivity.

[0055] (2) TDR technology is used to measure the water surface and convert the liquid level change. The dielectric constant of water is 81, which has a large attenuation on electromagnetic waves. The reflection of the water surface is obtained by measuring the air segment. The dielectric constant of air is 1, and the attenuation of electromagnetic waves in air is small. This method can also avoid the measurement error caused by the influence of water temperature on the dielectric constant of water.

[0056] (3) Algorithm filtering mechanism: Since the measuring pool 8 is a closed container and the well is in a high humidity environment for a long time, it is inevitable that water will adhere to the surface of the probe 7, which will affect the accuracy of the sensor to a certain extent. The surface treatment process can be used to avoid continuous water droplets on the probe 7, which will affect the measurement accuracy. At the same time, in view of the influence of the dielectric constant of the high temperature environment, high-frequency filtering is used to distinguish and identify the water-gas interface (that is, although there is some liquid water on the part of the probe 7 that is not in the water, it can be identified because it is not completely and discontinuously covered).

[0057] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the utility model, rather than to limit it. Although the utility model has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the utility model.

Claims

1. A rainwater measurement device based on TDR technology, characterized in that: include: An outer cylinder, the outer cylinder being a hollow cylinder, a water receiver (2) and a measuring pool (8) being arranged inside the outer cylinder, the water receiver (2) being located above the measuring pool (8), the bottom of the water receiver (2) being connected to the top of the measuring pool (8) via a pinch valve (4), the water receiver (2) being used to collect rainwater, and the rainwater being placed into the measuring pool (8) via the pinch valve (4); The top of the water receiver (2) is provided with a water receiving opening, and the water receiving opening is parallel to the top of the outer cylinder; The measuring cell (8) is connected to a TDR liquid level sensor, and the TDR liquid level sensor comprises a sensor body (9) and a probe (7).

2. The rainwater measuring device based on TDR technology according to claim 1 is characterized in that: include: The bottom of the pinch valve (4) is connected to a water injection pipe (3), and the pinch valve (4) is used to control the flow of the water injection pipe (3). The outlet of the water injection pipe (3) is at the bottom of the measuring pool (8).

3. The rainwater measuring device based on TDR technology according to claim 1 is characterized in that: include: The sensor body (9) is arranged on the top of the outside of the measuring cell (8).

4. The rainwater measuring device based on TDR technology according to claim 1 is characterized in that: include: The measuring pool (8) is a hollow cylinder, the probe (7) is arranged at the axial center position of the measuring pool (8), and the probe (7) is perpendicular to the bottom surface of the measuring pool (8).

5. The rainwater measuring device based on TDR technology according to claim 4 is characterized in that: include: The root of the probe (7) is parallel to the top of the measuring cell (8), and the root of the probe (7) is connected to the sensor body (9) via a coaxial cable.

6. The rainwater measuring device based on TDR technology according to claim 1 is characterized in that: include: A drain pipe (5) is provided at the bottom of the measuring pool (8), a drain valve (6) is provided on the drain pipe (5), and the drain pipe (5) is used to drain the liquid in the measuring pool (8).

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