A method for calibrating water temperature of ultrasonic water meter

Abstract

The present invention discloses a method for calibrating the water temperature of an ultrasonic water meter. Under different water temperature states and different flow rates, the upstream and downstream ultrasonic transmission times are collected; the total upstream and downstream transducer ultrasonic transmission times at different temperatures are obtained; according to the corresponding relationship between the time sum and the water temperature, the turning points of the change of the time sum and the water temperature are found, and a linear relationship is formed between the turning points; through the slope S ab , establish C a and C b between them, and a formula for calculating the temperature according to the time sum at any temperature point; Step S6: According to formula (6), calibrate the difference between the time sum of each meter and the model, and perform time sum compensation. The beneficial effect of the present invention is that without adding a temperature sensor, by using the characteristic that the propagation speed of ultrasonic waves in water is affected by temperature, data modeling and temperature calibration are carried out, and the real-time temperature can be deduced through the sound speed for temperature compensation in ultrasonic flow calculation.

Description

Technical Field

[0001] The invention relates to the field of metering devices, and in particular to a method for calibrating water temperature of an ultrasonic water meter. Background Art

[0002] The propagation speed of ultrasound in water changes with temperature, so ultrasonic water meters need to make temperature compensation when calculating flow. In ultrasonic water meter products, the current way to measure water temperature is to add a temperature sensor to the water meter pipe section and collect the real-time temperature of the water through the temperature sensor. This solution requires adding a hole for the temperature sensor to the pipe section, which increases the risk of water leakage and the cost of the temperature sensor.

[0003] The ultrasonic water meter uses two transducers to send ultrasonic signals in opposite directions through reflective lenses. Under the influence of flow velocity, the time required for the ultrasonic sound path from upstream to downstream is different from that from downstream to upstream. However, regardless of still water or flow rate, the total time of the oppositely transmitted ultrasonic waves is relatively stable, and the total time changes regularly with changes in temperature. Based on this characteristic, the purpose of calculating the water temperature based on the total time can be achieved through experimental data collection and modeling operations. Summary of the invention

[0004] The purpose of the present invention is to overcome the above technical defects and propose a method for calibrating water temperature of an ultrasonic water meter to realize temperature calculation of ultrasonic water meters and batch calibration of temperature.

[0005] The technical solution adopted by the present invention to achieve its technical purpose is: a method for calibrating water temperature of an ultrasonic water meter, comprising the following steps:

[0006] Step S1: First, at the same temperature and different flow rates, collect the ultrasonic transmission time of the upstream and downstream transducers, as shown in formula (1):

[0007]

[0008] In the formula, t 1 is the time from upstream to downstream, t 2 is the time from downstream to upstream, L is the sound path length of ultrasonic transmission,

[0009] Vs is the ultrasonic sound velocity, Vw is the water flow velocity;

[0010] Step S2: Obtain the sum of the ultrasonic transmission time of the upstream and downstream transducers through formula (2):

[0011]

[0012] Step S3: Under different water temperature conditions and different flow rates, collect the upstream and downstream ultrasonic transmission time, as shown in formula (1):

[0013] Step S4: Obtain the sum of ultrasonic transmission time of the upstream and downstream transducers at different temperatures through formula (2);

[0014] Step S5: finding the turning points of the time and water temperature changes according to the corresponding relationship between the time and the water temperature, and forming a linear relationship between the turning points;

[0015] Establish the X-axis as water temperature, the Y-axis as ultrasonic time, a as the starting point of water temperature, b as the first temperature inflection point, c as the second temperature inflection point, d as the third temperature inflection point, and e as the end point of water temperature;

[0016] Build C a is the temperature at point a, C b is the temperature at point b, C c is the temperature of point c, C d is the temperature at point d, C e is the temperature of point e;

[0017] Build T a is the time of point a and T b is the time of point b and T c is the time of point c and T d is the time of point d and T e The time and time of point e;

[0018] According to formula (3), the slope between each temperature inflection point is determined by the temperature data and time data of five points a, b, c, d, and e;

[0019] S ab : Temperature point C a With temperature point C b The slope between

[0020] S bc : Temperature point C b With temperature point C c The slope between

[0021] S cd : Temperature point C c With temperature point C d The slope between

[0022] S de : Temperature point C d With temperature point C e The slope between Step S6: By using the slope S ab , build C a With C bFrom any temperature point, according to time and, the temperature is calculated using the formula (4):

[0023] C x =C a +S ab *(T a -T x )(4);

[0024] By slope S bc , build C b With C c From any temperature point, according to time and, calculate the temperature using the formula (5): C x =C b +S bc *(T b -T x )(5);

[0025] By analogy, the water temperature at different temperatures can be calculated using a linear formula based on the table's own time and the linear relationship with each temperature point;

[0026] Step S7: According to formula (6), calibrate the time of each meter and the difference with the model, and perform time compensation;

[0027] By C x =C b +S bc *(T b -T x )

[0028] C x =20℃, C b , S bc Determined value when modeling temperature, T b is the compensation value of the meter to be calibrated, through T b and S ab , calculate T a , and so on to calculate T c , T d , T e , the T value is calibrated;

[0029] Preferably, the collection range of different water temperature states selected by the present invention is 0-55°C.

[0030] Preferably, the flow velocity Vs of the ultrasonic wave in the water is greater than 1450 m / s, and the flow velocity Vw of the water in the water meter is less than 10 m / s. Therefore, through the above formula and formula (7), it can be concluded that the sum of the time of the oppositely transmitted ultrasonic wave is relatively stable.

[0031]

[0032] Preferably, the water temperature starting point at point a is 0°C.

[0033] Preferably, in step S5: C a , C b , C c , C d , C e The temperature point is determined in the modeling stage and is a constant for subsequent use;

[0034] T a , T b , T c , T d , T e This is the time and data of the test meter when modeling. After the model is established, the subsequent production meters will calibrate this value.

[0035] The beneficial effects of the present invention are as follows: the present invention does not need to add a temperature sensor. By using the characteristics that the propagation speed of ultrasound in water is affected by temperature, data modeling, and temperature calibration, the real-time temperature can be derived from the speed of sound for temperature compensation of ultrasonic flow calculation. The solution does not need to open a hole for the temperature sensor, reduces the risk of water meter leakage, saves costs, and can be applied to production in batches to offset errors introduced by installation, assembly, and device differences. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is the schematic diagram of ultrasonic transmission time acquisition;

[0037] Figure 2 It is a line graph of the sum of ultrasonic transmission time of upstream and downstream transducers and water temperature change.

[0038] The markings in the figure are: 1. water flow direction; 2. upstream ultrasonic transducer; 3. water meter pipe section; 4. downstream ultrasonic transducer; 5. water meter pipe section; 6. water flow direction; 7. downstream reflective lens;

[0039] 8. Ultrasonic wave conduction direction from upstream to downstream; 9. Water meter pipe section; 10. Ultrasonic wave conduction direction from downstream to upstream;

[0040] 11. Upstream reflector. DETAILED DESCRIPTION

[0041] The present invention will be further described below in conjunction with the accompanying drawings.

[0042] Embodiment 1

[0043] like Figure 1 , Figure 2 As shown:

[0044] The ultrasonic water meter uses two transducers to send ultrasonic signals in opposite directions through reflective lenses. Under the influence of flow velocity, the time required for the ultrasonic sound path from upstream to downstream is different from that from downstream to upstream. However, regardless of still water or flow rate, the total time of the oppositely transmitted ultrasonic waves is relatively stable, and the total time changes regularly with changes in temperature. Based on this characteristic, the purpose of calculating the water temperature based on the total time can be achieved through experimental data collection and modeling operations. The ultrasonic water meter temperature calculation method and batch calibration temperature method are as follows:

[0045] A method for calibrating water temperature of an ultrasonic water meter comprises the following steps:

[0046] Step S1: First, at the same temperature and different flow rates, collect the ultrasonic transmission time of the upstream and downstream transducers, as shown in formula (1):

[0047]

[0048] In the formula, t 1 is the time from upstream to downstream, t 2 is the time from downstream to upstream, L is the sound path length of ultrasonic transmission,

[0049] Vs is the ultrasonic sound velocity, Vw is the water flow velocity;

[0050] Step S2: Obtain the sum of the ultrasonic transmission time of the upstream and downstream transducers through formula (2):

[0051]

[0052] Step S3: Under different water temperature conditions, the present invention selects a collection range of different water temperature conditions of 0 to 55°C, and collects upstream and downstream ultrasonic transmission times under different flow rates, as shown in formula (1):

[0053] Step S4: Obtain the sum of ultrasonic transmission time of the upstream and downstream transducers at different temperatures through formula (2);

[0054] Step S5: finding the turning points of the time and water temperature changes according to the corresponding relationship between the time and the water temperature, and forming a linear relationship between the turning points;

[0055] The X-axis is water temperature, the Y-axis is ultrasonic time, a is the starting point of water temperature, and the starting point of water temperature at point a is 0°C, b is the first temperature inflection point, c is the second temperature inflection point, d is the third temperature inflection point, and e is the end point of water temperature; Figure 2 Shown

[0056] Build C a is the temperature at point a, C b is the temperature at point b, C cis the temperature of point c, C d is the temperature at point d, C e is the temperature of point e;

[0057] Build T a is the time of point a and T b is the time of point b and T c is the time of point c and T d is the time of point d and T e The time and time of point e;

[0058] According to formula (3), the slope between each temperature inflection point is determined by the temperature data and time data of five points a, b, c, d, and e.

[0059] S ab : Temperature point C a With temperature point C b The slope between

[0060] S bc : Temperature point C b With temperature point C c The slope between

[0061] S cd : Temperature point C c With temperature point C d The slope between

[0062] S de : Temperature point C d With temperature point C e The slope between

[0063] Step S6: By using the slope S ab , build C a With C b From any temperature point, according to time and, the temperature is calculated using the formula (4):

[0064] C x =C a +S ab *(T a -T x )(4);

[0065] By slope S bc , build C b With C c From any temperature point, according to time and, calculate the temperature using the formula (5): C x =C b +S bc *(Tb -T x )(5);

[0066] By analogy, the water temperature at different temperatures can be calculated using a linear formula based on the table's own time and the linear relationship with each temperature point;

[0067] Step S7: According to formula (6), calibrate the time of each meter and the difference with the model, and perform time compensation;

[0068] For example, when the water temperature is 20℃, the 20℃ temperature point is between the temperature turning points b and c. The time when the meter is to be calibrated at 20℃ is T x ,

[0069] By C x =C b +S bc *(T b -T x )

[0070] C x =20℃, C b , S bc Determined value when modeling temperature, T b is the compensation value of the meter to be calibrated,

[0071] By T b and S ab , calculate T a , and so on to calculate T c , T d , T e , the T value is calibrated;

[0072] The flow velocity Vs of ultrasonic waves in water is greater than 1450 m / s, and the flow velocity Vw of water in the water meter is less than 10 m / s. Therefore, through the above formula and formula (7), it can be concluded that the sum of the time of the oppositely transmitted ultrasonic waves is relatively stable.

[0073]

[0074] In step S5: C a , C b , C c , C d , C e The temperature point is determined in the modeling stage and is a constant for subsequent use;

[0075] T a , T b , T c , T d , T eThis is the time and data of the test meter when modeling. After the model is established, the subsequent production meters will calibrate this value.

[0076] Due to assembly and batch reasons, the same type of ultrasonic water meters have different times. Therefore, during the production process, it is necessary to use a calibration station to calibrate the time of each meter and the difference with the model to make time compensation.

[0077] For example, the water temperature is 20℃, the 20℃ temperature point is between the temperature turning points b and c, and the time when the meter to be calibrated is 20℃ is T x , according to formula C x =C b +S bc *(T b -T x ) C x =20℃, C b , S bc The T of the meter to be calibrated can be obtained by determining the value of temperature modeling. b Value, through T b and S ab T can be calculated a , and so on, we can get T c , T d , T e After calibrating the T value, the ultrasonic water meter can accurately calculate the water temperature at different temperatures through a linear formula based on the meter's own time and the linear relationship with each temperature point.

Claims

1. A method for calibrating water temperature of an ultrasonic water meter, characterized in that: The following steps are involved: Step S1: First, at the same temperature and different flow rates, collect the ultrasonic transmission time of the upstream and downstream transducers, as shown in formula (1): In the formula, t1 is the time from upstream to downstream, t2 is the time from downstream to upstream, L is the sound path length of ultrasonic transmission, Vs is the ultrasonic sound velocity, Vw is the water flow velocity; Step S2: Obtain the sum of the ultrasonic transmission time of the upstream and downstream transducers through formula (2): Step S3: Under different water temperature conditions and different flow rates, collect the upstream and downstream ultrasonic transmission time, as shown in formula (1): Step S4: Obtain the sum of ultrasonic transmission time of the upstream and downstream transducers at different temperatures through formula (2); Step S5: finding the turning points of the time and water temperature changes according to the corresponding relationship between the time and the water temperature, and forming a linear relationship between the turning points; Establish the X-axis as water temperature, the Y-axis as ultrasonic time, a as the starting point of water temperature, b as the first temperature inflection point, c as the second temperature inflection point, d as the third temperature inflection point, and e as the end point of water temperature; Build C a is the temperature at point a, C b is the temperature at point b, C c is the temperature of point c, C d is the temperature at point d, C e is the temperature of point e; Build T a is the time of point a and T b is the time of point b and T c is the time of point c and T d is the time of point d and T e The time and time of point e; According to formula (3), the slope between each temperature inflection point is determined by the temperature data and time data of five points a, b, c, d, and e; S ab : Temperature point C a With temperature point C b The slope between S bc : Temperature point C b With temperature point C c The slope between S cd : Temperature point C c With temperature point C d The slope between S de : Temperature point C d With temperature point C e The slope between Step S6: By using the slope S ab , build C a With C b From any temperature point, according to time and, the temperature is calculated using the formula (4): C x =C a +S ab *(T a -T x ) (4); By slope S bc , build C b With C c From any temperature point, according to time and, calculate the temperature using the formula (5): C x =C b +S bc *(T b -T x ) (5); By analogy, the water temperature at different temperatures can be calculated using a linear formula based on the table's own time and the linear relationship with each temperature point; Step S7: According to formula (6), calibrate the time of each meter and the difference with the model, and perform time compensation; By C x =C b +S bc *(T b -T x ) C x =20℃, C b , S bc Determined value when modeling temperature, T b is the compensation value of the meter to be calibrated, through T b and S ab , calculate T a , and so on to calculate T c 、T d 、T e , the T value calibration is completed.

2. The method for calibrating water temperature of an ultrasonic water meter according to claim 1, characterized in that: The collection range of different water temperature conditions is 0~55℃.

3. The method for calibrating water temperature of an ultrasonic water meter according to claim 1, characterized in that: The flow velocity Vs of ultrasonic waves in water is greater than 1450 m / s, and the flow velocity Vw of water in the water meter is less than 10 m / s. Through the above formula and formula (7), it can be concluded that the time sum of the oppositely transmitted ultrasonic waves is relatively stable; 4. The method for calibrating water temperature of an ultrasonic water meter according to claim 1, characterized in that: The starting point of water temperature at point a is 0℃.

5. The method for calibrating water temperature of an ultrasonic water meter according to claim 1, characterized in that: In step S5: C a , C b , C c , C d , C e The temperature point is determined in the modeling stage and is a constant for subsequent use; T a 、T b 、T c 、T d 、T e This is the time and data of the test meter when modeling. After the model is established, the subsequent production meters will calibrate this value.

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