A system and method for calibration of tipping-bucket rain gauges

Abstract

The application discloses a system and a calibration method suitable for tipping-bucket rain gauge measurement and calibration, comprising a water supply unit, a standard volume unit, a pump injection unit, a pipeline switching unit, a data acquisition control unit, a measured tipping-bucket rain gauge and a backwater unit. Compared with the prior art, the application has the following advantages: 1. full-range accurate verification, significant improvement in comprehensive evaluation; 2. multi-channel parallel operation, significant improvement in calibration efficiency; 3. multi-aperture universal adaptation, strong equipment compatibility; 4. closed-loop water circulation design, reduced resource consumption; 5. pipeline switching without disassembly, convenient and efficient operation; 6. automatic and digital operation, stable and reliable results.

Description

Technical Field

[0001] This invention relates to the field of meteorological and hydrological instrument measurement and calibration technology, specifically to a system and calibration method applicable to the measurement and calibration of tipping bucket rain gauges. Background Technology

[0002] Tipping bucket rain gauges are among the most widely used rainfall measurement devices in meteorology and hydrology. Their measurement accuracy directly affects the reliability of rainfall data, therefore, regular calibration and adjustment are necessary. Current calibration devices and methods for tipping bucket rain gauges have several shortcomings:

[0003] 1. Incomplete range verification: There is a lack of standardized multi-range verification procedures. Most devices only test for a single or a small number of rainfall ranges, which cannot cover all rainfall scenarios such as light rain, moderate rain, heavy rain, and rainstorm. It is easy to miss systematic errors under specific ranges, and the assessment of rain gauge accuracy is not comprehensive enough.

[0004] 2. Poor accuracy of manual calibration: Existing calibration methods mostly involve manually pouring water from a measuring cup. The water flow rate is difficult to control stably, and the accuracy of the manually injected water fluctuates greatly, which directly leads to high calibration error and fails to meet the requirements of high-precision measurement.

[0005] 3. Weak equipment versatility: Traditional calibration devices can only calibrate rain gauges of a single tipping bucket size and a single caliber. When dealing with tipping bucket rain gauges of different calibers and measurement ranges, special tooling needs to be changed, which results in high adaptation costs and cumbersome operation.

[0006] 4. Serious waste of water resources: In the traditional calibration process, calibration water is directly discharged and cannot be recycled. Long-term operation results in a large amount of water consumption and is highly dependent on the water supply conditions at the calibration site.

[0007] 5. Low level of automation and digitalization: Traditional devices rely heavily on manual operation and manual reading and recording. Random errors introduced by manual operation are difficult to control, resulting in low calibration efficiency, high labor costs, and poor data traceability.

[0008] 6. Low pipeline switching efficiency: In calibration devices using peristaltic pumps, switching between the inlet and outlet water functions requires manual plugging and unplugging of the inlet and outlet water pipelines, which is time-consuming, reduces the efficiency of batch calibration, and increases time costs. Summary of the Invention

[0009] To address the aforementioned shortcomings of existing technologies, the present invention aims to provide a system and calibration method suitable for measuring and calibrating tipping bucket rain gauges.

[0010] To solve the above-mentioned technical problems, the technical solution provided by the present invention is: a system and calibration method suitable for measuring and calibrating tipping bucket rain gauges, including a water supply unit, a standard volume unit, a pumping unit, a pipeline switching unit, a data acquisition and control unit, the tipping bucket rain gauge under test, and a return water unit;

[0011] The standard volume unit comprises four constant-capacity glass containers certified by a legal metrology institution, with each container's volume corresponding to the calibration requirements for different rainfall intensities.

[0012] The pumping unit includes four independently controlled high-precision peristaltic pumps, each connected to one of the glass containers. The peristaltic pumps support bidirectional operation in both forward and reverse directions. In forward rotation, the peristaltic pump pumps water from the water supply unit into the corresponding glass container to the rated volume, completing the preparation of standard water volume. In reverse rotation, the peristaltic pump pumps the standard water volume in the glass container into the tipping bucket rain gauge being measured at a constant speed.

[0013] The pipeline switching unit adopts Luer multi-way valves. Each peristaltic pump pipeline is equipped with a set of valves, with two pre-set water inlet and outlet channels. The flow direction of the peristaltic pump can be switched by changing the valve position, without the need to disassemble or replace the pipeline.

[0014] The data acquisition and control unit is electrically connected to the pumping unit and the pipeline switching unit. It is used to control the running direction, flow rate and duration of each peristaltic pump, control the passage status of the pipeline switching unit, and at the same time collect the output data of the tipping bucket rain gauge under test and calculate the measurement error.

[0015] The water return unit is located at the drain end of the tipping bucket rain gauge being tested. It is used to collect the calibration water and return it to the water supply unit, thereby realizing the recycling of water resources.

[0016] Furthermore, the flow accuracy of each of the high-precision peristaltic pumps is no less than ±0.3%, and the flow rate adjustment range is 0.1 mL / min to 389 mL / min.

[0017] Furthermore, the four constant-capacity glass containers have volumes of 200 mL, 314.16 mL, 600 mL, and 942.48 mL, respectively.

[0018] Furthermore, the data acquisition and control unit has a built-in microcontroller control program and is equipped with a 10-inch industrial touch screen as a human-machine interface, supporting two working modes: single-channel independent calibration and multi-channel combined calibration.

[0019] Furthermore, the data acquisition and control unit supports manual and automatic modes; in automatic mode, two standard rain gauge diameter options are preset: 159.60mm and 200mm, and it also supports custom input of rain gauge diameter parameters.

[0020] Furthermore, the water return unit includes a water collection structure and a water tank. The calibration water discharged by the tipping bucket rain gauge being tested flows into the water tank through the water collection structure and is then sent to the water supply unit for reuse through the return pipeline.

[0021] A calibration method for a tipping bucket rain gauge includes the following steps:

[0022] S1 parameter settings: Select the calibration mode and the diameter of the rain gauge being measured, select the enabled calibration channel and set the water injection flow rate;

[0023] S2 Prefilling: Control the Luer multi-way valve to switch to the water inlet passage, start the peristaltic pump to rotate forward, pump the water from the water supply unit into the corresponding glass container to the rated volume, and complete the preparation of standard water volume;

[0024] S3 Calibration Test: Control the Luer multi-way valve to switch to the water outlet passage, start the peristaltic pump to reverse, and inject the standard amount of water in the glass container into the tipping bucket rain gauge under test at a set flow rate.

[0025] S4 Error Calculation: Real-time acquisition of the output data of the rain gauge under test, combined with the standard volume of the glass container, to calculate the measurement error of the rain gauge under this range;

[0026] S5 Full-range verification: Switch to calibration channels with different volumes and repeat steps S2-S4 to complete the accuracy verification under multiple ranges;

[0027] During the calibration process, the water discharged from the rain gauge being measured flows back to the water supply unit via the return water unit for reuse.

[0028] The advantages of this invention compared with the prior art are: 1. Full-range accurate verification and significantly improved comprehensiveness of evaluation: By using four standard glass containers of different volumes, it can cover multiple levels of rainfall scenarios such as light rain, moderate rain, heavy rain, and rainstorm. Full-range accuracy verification is completed according to the metrological procedures, and the measurement performance of the rain gauge is comprehensively evaluated, avoiding the limitations of single-range calibration and reducing the risk of error omission.

[0029] 2. Multi-channel parallel operation significantly improves calibration efficiency: The four-channel independent peristaltic pump design can complete multiple calibrations or multiple rain gauge calibrations simultaneously. Compared with the single-channel calibration method, the operation time is reduced by 75%, which greatly saves labor and time costs and is suitable for batch calibration needs.

[0030] 3. Multi-caliber universal adaptation and strong equipment compatibility: The system presets mainstream standard rain gauge caliber parameters and supports custom caliber input. It can adapt to different specifications of tipping bucket rain gauges without changing special tooling, which is highly versatile and reduces equipment adaptation costs.

[0031] 4. Closed-loop water circulation design to reduce resource consumption: The calibration drainage is collected and reused through the return water unit, realizing a closed-loop circulation of calibration water, which greatly reduces water waste and reduces the dependence of calibration operations on on-site water supply conditions.

[0032] 5. Seamless pipe switching with ease and efficiency: The Luer multi-way valve enables switching between inlet and outlet water functions. The pre-installed complete pipeline allows for function conversion simply by switching gears, eliminating the need for manual pipe insertion and removal. This simplifies the operation process and avoids errors and leakage risks associated with pipe disassembly and assembly.

[0033] 6. Automated and digital operation, stable and reliable results: The built-in intelligent control system can automatically complete the entire process of water preparation, uniform injection, data acquisition and error calculation, reducing the random errors introduced by manual operation and improving the consistency and traceability of calibration results; the operating parameters are displayed in real time through the industrial control screen, and the status is intuitive and clear. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of a system and calibration method suitable for measuring and calibrating tipping bucket rain gauges.

[0035] As shown in the figure: 1. Water supply unit; 2. Standard volume unit; 3. Pumping unit; 4. Pipeline switching unit; 5. Data acquisition and control unit; 6. Test tipping bucket rain gauge; 7. Return water unit. Detailed Implementation

[0036] The present invention will now be described in further detail with reference to the accompanying drawings.

[0037] Combined with appendix Figure 1 A system and calibration method for measuring and calibrating tipping bucket rain gauges are disclosed. The system is integrated into a single cabinet, with the main body made of carbon steel and the operating table made of steel and wood. It features equipment integration, operational load-bearing capacity, and protection functions. The system consists of six parts: a water supply unit 1, a standard volume unit 2, a pumping unit 3, a pipeline switching unit 4, a data acquisition and control unit 5, and a return water unit 7.

[0038] Details of each unit structure:

[0039] Water supply unit 1:

[0040] The system adopts a closed water storage structure and is installed at the bottom of the cabinet to provide a stable calibration water source for the system. The return pipeline of the water supply unit 1 and the return water unit 7 are connected to receive the circulating return water and form a closed-loop water supply system.

[0041] Standard volumetric unit 2:

[0042] It includes four standard glass containers calibrated and certified by a legal metrology institute, fixedly installed in the cabinet's operating area. The container volumes are 200mL, 314.16mL, 600mL, and 942.48mL, respectively, and their volume specifications meet the requirements of JJG(Meteorology) 005-2015 "Verification Procedure for Tipping Bucket Rain Gauge Sensors of Automatic Weather Stations". Each container has precise graduation lines on its side wall as a visual reference for the rated volume. The four containers correspond to standard water volumes for different rainfall intensities, covering the full range of calibration needs from light rain to heavy rain.

[0043] Pumping unit 3:

[0044] It consists of four high-precision peristaltic pumps, which are fixedly installed in two groups inside the cabinet. Channel 1 and Channel 2 form the first group, and Channel 3 and Channel 4 form the second group. Each peristaltic pump is independently controlled and supports bidirectional operation in both forward and reverse directions.

[0045] The flow accuracy of a single peristaltic pump can reach ±0.3%, and the flow rate adjustment range covers 0.1mL / min to 389mL / min. The injection flow rate can be precisely adjusted according to calibration requirements to simulate natural precipitation processes under different rainfall intensities.

[0046] When the peristaltic pump rotates forward, it draws water from the water supply unit 1 and injects it into the standard glass container in the corresponding channel until the water level reaches the rated scale, thus completing the precise preparation of the standard water volume. When the peristaltic pump rotates in reverse, it injects a fixed amount of water from the standard glass container into the rain inlet of the tipping bucket rain gauge 6 under test at a set flow rate to perform the calibration test.

[0047] Pipeline switching unit 4:

[0048] Each calibration channel is equipped with a set of Luer multi-way valves. The valve body is made of 304 stainless steel with a thickness of 3mm, which is corrosion resistant and has a long service life.

[0049] The valve has two independent inlet and outlet channels: the inlet channel is connected to “water supply unit 1 - peristaltic pump - standard glass container”, corresponding to the standard water preparation condition; the outlet channel is connected to “standard glass container - peristaltic pump - rain gauge”, corresponding to the calibrated water injection condition.

[0050] By switching the valve position, the direction of pipeline connection can be changed. In conjunction with the forward and reverse rotation of the peristaltic pump, the function can be switched. The entire process does not require manual plugging or unplugging or changing of pipelines, making the operation convenient and avoiding connection errors and leakage risks caused by pipeline disassembly and assembly.

[0051] Data acquisition and control unit 5:

[0052] Using a self-developed microcontroller as the control core, and paired with a 10-inch industrial touchscreen as the human-machine interface, the control system is installed in the front operating area of ​​the cabinet. The control system has the following core functions:

[0053] Pump group parameter control: The running direction, flow rate, and running time of each peristaltic pump can be set individually to achieve precise water preparation and injection control;

[0054] Channel operating modes: Supports independent calibration of a single channel to meet the needs of precise debugging of a single range; also supports combined calibration mode with multiple channels starting simultaneously to achieve rapid verification across the entire range.

[0055] Operation mode selection: There are manual and automatic modes. In manual mode, each step of the operation can be controlled step by step, which is suitable for special debugging and non-standard calibration scenarios; in automatic mode, the entire calibration process can be completed with one click, which is suitable for routine batch calibration.

[0056] Rain gauge diameter compatibility: Built-in parameters for two mainstream standard rain gauge diameters, 159.60mm and 200mm, which can be selected with one click; it also provides a custom diameter input function to adapt to non-standard tipping bucket rain gauges.

[0057] Data acquisition and calculation: The tipping pulse signal of the tipping bucket rain gauge 6 under test is acquired in real time through the signal acquisition module and converted into parameters such as real-time rainfall, cumulative rainfall, and minute rainfall intensity; after the liquid is injected, the measurement error of the rain gauge under this range is automatically calculated in combination with the rated volume of the standard container.

[0058] Operational status monitoring: The touch interface displays parameters such as measurement mode, minute rainfall intensity, real-time rainfall, and cumulative time for each channel in real time, making the equipment's operational status intuitive and clear.

[0059] Return water unit 7:

[0060] It includes a water collection structure and a water tank, and is located below the drain outlet of the tipping bucket rain gauge 6 being tested. During the calibration process, the calibration water discharged from the rain gauge being tested flows into the water tank through the water collection structure, and is then sent to the water supply unit 1 for reuse through the return pipeline, realizing a closed-loop cycle of water resources and reducing water waste.

[0061] 2. Calibration Workflow

[0062] Taking full-range calibration in automatic mode as an example, the workflow of this system is as follows:

[0063] Step 1: Parameter Settings. Select the automatic calibration mode on the touch screen, select the corresponding diameter according to the actual specifications of the tipping bucket rain gauge 6 being tested (or customize the input diameter value), select all calibration channels to be enabled, and set the water injection flow rate for each channel.

[0064] Step 2: Pre-filling stage. The control system sends a command to the corresponding channel to switch the Luer multi-way valve to the water inlet position, and at the same time starts the peristaltic pump to rotate forward; the peristaltic pump draws water from water supply unit 1 and injects it into the standard glass container of the corresponding specification. When the water volume in the container reaches the rated volume, the peristaltic pump automatically stops running, completing the preparation of the standard water volume.

[0065] Step 3: Calibration Test Phase. After pre-filling, the control system automatically switches the Luer multi-way valve to the outlet position, starts the peristaltic pump in reverse, and injects the standard amount of water in the glass container into the rain inlet of the tipping bucket rain gauge 6 under test at a set uniform speed, simulating a natural rainfall process of corresponding intensity.

[0066] Step 4: Error Calculation Stage. The data acquisition module collects the tipping pulse signal of the rain gauge in real time, calculates and displays the rainfall data in real time; when all the water in the standard container is filled, the control system automatically calculates the measurement error of the rain gauge under this range based on the rated volume of the standard container and stores the result.

[0067] Step 5: Full-range verification. Start the calibration channels of different volumes sequentially, repeat the pre-filling-calibration test-error calculation process described above, and complete the calibration tests under four different volumes and rainfall intensities to achieve comprehensive verification of the rain gauge's full-range measurement accuracy.

[0068] Step 6: Water Recycling and Reuse. Throughout the calibration process, the water discharged from the rain gauge being measured is continuously collected by the return water unit 7 and returned to the water supply unit 1, where it can directly participate in subsequent calibration processes, thus realizing the recycling of water resources.

[0069] In summary, this system, through the organic combination of multi-channel peristaltic pumps, multi-specification standard containers, valve switching without disassembly, and intelligent control system, solves the problems of incomplete range coverage, low accuracy, poor efficiency, weak versatility, and resource waste in existing calibration devices, and has outstanding technological progress and practical value.

[0070] The above description is only a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention; any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included within the scope of protection of the present invention.

[0071] The present invention and its embodiments have been described above. This description is not restrictive, and the accompanying drawings are only one embodiment of the present invention; the actual structure is not limited thereto. In conclusion, if those skilled in the art are inspired by this description and design similar structures and embodiments without departing from the spirit of the invention, such designs should fall within the protection scope of the present invention.

Claims

1. A system for measuring and calibrating tipping bucket rain gauges, characterized in that: It includes a water supply unit (1), a standard volume unit (2), a pumping unit (3), a pipeline switching unit (4), a data acquisition and control unit (5), a tipping bucket rain gauge under test (6), and a return water unit (7). The standard volume unit (2) contains four constant-capacity glass containers certified by a legal metrology institution, and the volume of each container corresponds to the calibration requirements of different rainfall intensities. The pumping unit (3) includes four independently controlled high-precision peristaltic pumps, each of which is connected to one of the glass containers. The peristaltic pumps support bidirectional operation in both forward and reverse directions. In the forward rotation state, the peristaltic pump pumps the water from the water supply unit (1) into the corresponding glass container to the rated volume, thus completing the preparation of the standard water volume. In the reverse rotation state, the peristaltic pump pumps the standard water volume in the glass container into the tipping bucket rain gauge (6) under test at a constant speed. The pipeline switching unit (4) adopts Luer multi-way valve. Each peristaltic pump pipeline is equipped with a set of valves. Two water inlet and outlet channels are pre-set. The flow direction of peristaltic pump water inlet and outlet can be switched by switching the valve position. There is no need to disassemble and replace the pipeline. The data acquisition control unit (5) is electrically connected to the pumping unit (3) and the pipeline switching unit (4) to control the running direction, flow rate and duration of each peristaltic pump, control the passage status of the pipeline switching unit (4), and simultaneously collect the output data of the tipping bucket rain gauge (6) under test and calculate the measurement error. The water return unit (7) is located at the drain end of the tipping bucket rain gauge (6) being measured. It is used to collect the calibration water and return it to the water supply unit (1) to realize the recycling of water resources.

2. The system for measuring and calibrating tipping bucket rain gauges according to claim 1, characterized in that: Each of the aforementioned high-precision peristaltic pumps has a flow accuracy of no less than ±0.3% and a flow rate adjustment range of 0.1 mL / min to 389 mL / min.

3. The system for measuring and calibrating tipping bucket rain gauges according to claim 1, characterized in that: The four constant-capacity glass containers have volumes of 200 mL, 314.16 mL, 600 mL, and 942.48 mL, respectively.

4. A system for measuring and calibrating tipping bucket rain gauges according to claim 1, characterized in that: The data acquisition and control unit (5) has a built-in microcontroller control program and is equipped with a 10-inch industrial touch screen as a human-machine interface. It supports two working modes: single-channel independent calibration and multi-channel combined calibration.

5. A system for measuring and calibrating tipping bucket rain gauges according to claim 4, characterized in that: The data acquisition and control unit (5) supports manual mode and automatic mode; in automatic mode, two standard rain gauge diameter options of 159.60mm and 200mm are preset, and it also supports custom input of rain gauge diameter parameters.

6. A system for measuring and calibrating tipping bucket rain gauges according to claim 1, characterized in that: The water return unit (7) includes a water collection structure and a water holding tank. The calibration water discharged by the tipping bucket rain gauge (6) is collected into the water holding tank through the water collection structure and then sent to the water supply unit (1) for reuse through the return pipeline.

7. A calibration method for a tipping bucket rain gauge based on the system described in any one of claims 1-6, characterized in that: Includes the following steps: S1 parameter settings: Select the calibration mode and the diameter of the rain gauge being measured, select the enabled calibration channel and set the water injection flow rate; S2 pre-filling: Control the Luer multi-way valve to switch to the water inlet passage, start the peristaltic pump to rotate forward, pump the water from the water supply unit (1) into the corresponding glass container to the rated volume, and complete the preparation of standard water volume; S3 calibration test: Control the Luer multi-channel valve to switch to the water outlet passage, start the peristaltic pump to reverse, and inject the standard water volume in the glass container into the test tipping bucket rain gauge at a set flow rate (6). S4 Error Calculation: Real-time acquisition of the output data of the rain gauge under test, combined with the standard volume of the glass container, to calculate the measurement error of the rain gauge under this range; S5 Full-range verification: Switch to calibration channels with different volumes and repeat steps S2-S4 to complete the accuracy verification under multiple ranges; During the calibration process, the water discharged from the rain gauge is returned to the water supply unit (1) via the return water unit (7) for recycling.

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