Empty pipe detection method and electromagnetic flowmeter

Abstract

The invention relates to the technical field of flow meters, and discloses an empty pipe detection method and an electromagnetic flow meter, and the method comprises the steps: obtaining a current forward voltage and a current backward voltage after the stabilization time under the condition that the empty pipe detection begins; determining a first air traffic control detection state according to the current forward voltage and the current backward voltage, wherein the first air traffic control detection state comprises an intermediate state; if the first air traffic control detection state is the intermediate state and the current forward voltage and the current backward voltage are not detected for the first time, determining a second air traffic control detection state according to a historical forward voltage, a historical backward voltage, the current forward voltage and the current backward voltage, and taking the second blank pipe detection state as a blank pipe detection result. According to the current forward voltage, the current backward voltage, the historical forward voltage and the historical backward voltage, multiple times of air traffic control detection are carried out in different modes, and the accuracy of air traffic control detection is improved.

Description

Technical Field

[0001] The present application relates to the technical field of flowmeters, and in particular to an empty pipe detection method and an electromagnetic flowmeter. Background Art

[0002] In recent years, electromagnetic metering technology has received more and more attention in the field of flow measurement and detection due to its metering characteristics such as high reliability, high stability, high range ratio and low pressure loss. However, at present, due to the electromagnetic water meter and electromagnetic flowmeter under different temperatures and complex water flow environment in the pipe section, the two ends of the electrode will be unstable, and the collected voltage fluctuation will cause the empty pipe state to jump, resulting in flow fluctuations, which will cause the electromagnetic flowmeter to be unable to measure accurately. However, empty pipe detection is a very important link in the electromagnetic metering process, which always affects the measurement accuracy.

[0003] In summary, it is necessary to provide an empty pipe detection method and an electromagnetic flowmeter that can improve the accuracy of empty pipe detection. Summary of the invention

[0004] To solve the above problems, the present application proposes an empty pipe detection method and an electromagnetic flowmeter.

[0005] In a first aspect, the present application proposes an empty traffic control detection method, comprising:

[0006] When the empty pipe detection starts, after the stabilization time, the current forward voltage and the current reverse voltage are obtained;

[0007] Determine a first empty pipe detection state according to the current forward voltage and the current reverse voltage, the first empty pipe detection state comprising: an intermediate state;

[0008] If the first empty pipe detection state is the intermediate state, and the current forward voltage and the current reverse voltage are not detected for the first time, the second empty pipe detection state is determined according to the historical forward voltage, the historical reverse voltage, the current forward voltage and the current reverse voltage, and the second empty pipe detection state is used as the empty pipe detection result.

[0009] Preferably, determining the first empty pipe detection state according to the current forward voltage and the current reverse voltage includes:

[0010] If the current forward voltage is less than the current reverse voltage, the first empty pipe detection state is an empty pipe state;

[0011] If the current forward voltage is greater than or equal to the current reverse voltage, determining the first empty pipe detection state according to the current forward voltage, the current reverse voltage and a preset empty pipe threshold;

[0012] If the first empty pipe detection state is the intermediate state, determining the current empty pipe detection state according to the current forward voltage, the current reverse voltage, a first preset forward empty pipe detection voltage, and a first preset reverse empty pipe detection voltage;

[0013] If the current empty pipe detection state is the intermediate state, the first empty pipe detection state is determined according to the current forward voltage, the current reverse voltage, a second preset forward empty pipe detection voltage, and a second preset reverse empty pipe detection voltage.

[0014] Preferably, determining the first empty pipe detection state according to the current forward voltage, the current reverse voltage and a preset empty pipe threshold comprises:

[0015] Determine a voltage difference according to the current forward voltage and the current reverse voltage;

[0016] If the voltage difference is greater than the preset empty pipe threshold, the first empty pipe detection state is the empty pipe state;

[0017] If the voltage difference is less than or equal to the preset empty pipe threshold, the first empty pipe detection state is the intermediate state.

[0018] Preferably, determining the current empty pipe detection state according to the current forward voltage, the current reverse voltage, a first preset forward empty pipe detection voltage and a first preset reverse empty pipe detection voltage includes:

[0019] If the current forward voltage is greater than or equal to the first preset forward empty pipe detection voltage, and the current reverse voltage is greater than or equal to the first preset reverse empty pipe detection voltage, then the current empty pipe detection state is the empty pipe state, and the empty pipe state is used as the first empty pipe detection state, wherein the first preset forward empty pipe detection voltage is the upper limit of the forward empty pipe detection voltage, and the first preset reverse empty pipe detection voltage is the upper limit of the reverse empty pipe detection voltage;

[0020] If the current forward voltage is less than the first preset forward empty pipe detection voltage and / or the current reverse voltage is less than the first preset reverse empty pipe detection voltage, the current empty pipe detection state is the intermediate state, and the intermediate state is used as the first empty pipe detection state.

[0021] Preferably, determining the first empty pipe detection state according to the current forward voltage, the current reverse voltage, a second preset forward empty pipe detection voltage, and a second preset reverse empty pipe detection voltage includes:

[0022] If the current forward voltage is less than or equal to the second preset forward empty pipe detection voltage, and the current reverse voltage is less than or equal to the second preset reverse empty pipe detection voltage, then the first empty pipe detection state is the empty pipe state, wherein the second preset forward empty pipe detection voltage is the lower limit of the forward empty pipe detection voltage, and the second preset reverse empty pipe detection voltage is the lower limit of the reverse empty pipe detection voltage;

[0023] If the current forward voltage is greater than the second preset forward empty pipe detection voltage and / or the current reverse voltage is greater than the second preset reverse empty pipe detection voltage, the first empty pipe detection state is the intermediate state.

[0024] Preferably, if the first empty pipe detection state is the intermediate state, and the current forward voltage and the current reverse voltage are not detected for the first time, determining the second empty pipe detection state according to the historical forward voltage, the historical reverse voltage, the current forward voltage and the current reverse voltage includes:

[0025] If the first empty pipe detection state is the intermediate state, and the current forward voltage and the current reverse voltage are not detected for the first time, a first absolute value is determined according to a difference between the historical forward voltage and the current forward voltage, and a second absolute value is determined according to a difference between the historical reverse voltage and the current reverse voltage;

[0026] determining a third absolute value according to a difference between the first absolute value and the second absolute value;

[0027] If the third absolute value is greater than a preset difference threshold, the second empty pipe detection state is an empty pipe state;

[0028] If the third absolute value is less than or equal to the preset difference threshold, the second empty pipe detection state is a non-empty pipe state.

[0029] Preferably, after determining the first empty pipe detection state according to the current forward voltage and the current reverse voltage, the method further includes:

[0030] If the first empty pipe detection state is an intermediate state, and the current forward voltage and the current reverse voltage are detected for the first time, then the first empty pipe detection state is the non-empty pipe state;

[0031] The first empty pipe detection state is used as an empty pipe detection result.

[0032] Preferably, obtaining the current forward voltage and the current reverse voltage after the stabilization time includes:

[0033] After the stabilization time has passed, obtaining the current forward voltage;

[0034] After the current forward voltage is obtained, the current reverse voltage is obtained again after the stabilization time has passed.

[0035] Preferably, after determining the first empty pipe detection state according to the current forward voltage and the current reverse voltage, the method further includes:

[0036] When the first empty pipe detection state is an empty pipe state, the first empty pipe detection state is used as an empty pipe detection result.

[0037] In a second aspect, the present application proposes an electromagnetic flowmeter for executing the empty pipe detection method described in any one of the first aspects.

[0038] The advantage of the present application is that multiple empty pipe detections are performed in different ways according to the current forward voltage, the current reverse voltage, the historical forward voltage and the historical reverse voltage, thereby improving the accuracy of the empty pipe detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] By reading the detailed description of the preferred embodiment below, various other advantages and benefits will become clear to those of ordinary skill in the art. The accompanying drawings are only used for the purpose of illustrating the preferred embodiment and are not to be considered as limiting the present application. Moreover, the same reference symbols are used throughout the accompanying drawings to represent the same components. In the accompanying drawings:

[0040] Figure 1 is a schematic diagram of an existing sensor for empty pipe detection;

[0041] Figure 2 It is a schematic diagram of an existing empty pipe detection result;

[0042] Figure 3 It is a schematic diagram of the steps of an empty pipe detection method provided by the present application;

[0043] Figure 4 It is a schematic diagram of collecting the current forward voltage and the current reverse voltage of an empty pipe detection method provided by the present application;

[0044] Figure 5 is a schematic diagram of an empty pipe detection result of an empty pipe detection method provided by the present application;

[0045] Figure 6 It is a schematic diagram of empty pipe detection results of another empty pipe detection method provided in this application. DETAILED DESCRIPTION

[0046] The exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided in order to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0047] like Figure 1 As shown, the single-chip microcomputer can be used to time the empty pipe detection periodically. There are two signals for empty pipe detection, which are controlled by analog switches. The single-chip microcomputer needs to collect the voltages at the A and B electrodes in the sensor respectively during empty pipe detection as the original voltage signal data of the empty pipe. When starting the empty pipe detection, the single-chip microcomputer controls the IO port, applies a PWM wave with a fixed frequency and a duty cycle of 50% at both ends of the A and B electrodes of the sensor, turns on the corresponding analog switch circuit, and the external signal is amplified and processed by the sensor signal conditioning circuit, and then collected by the high-precision analog-to-digital conversion (AD) chip and returned to the single-chip microcomputer; by collecting the voltage at the highest and lowest points of the signal for comparison, the empty pipe state in the pipe section at this time is determined.

[0048] However, the empty pipe detection results are not only prone to fluctuations in high and low temperature environments, resulting in false alarms of non-empty pipes in empty pipe states, and false alarms of empty pipes in non-empty pipe states, but also in experiments, it was found that when the pipe section is actually empty, and a small amount of water is attached to the surface of the A and B electrodes, or a small amount of water remains on the inner wall of the pipe and flows under the influence of gravity, passing through the electrode surface, it will affect the empty pipe state at the meter end. Figure 2 As shown in the figure, in the captured data, line 1 is the forward voltage, line 2 is the reverse voltage, and line 3 is the empty pipe detection state (empty pipe detection result). When the value of line 3 is 1250, it indicates that the current state is an empty pipe, and when it is 0, it indicates that the current state is a non-empty pipe. Due to a small amount of water attached to the pipe section, the value of line 3 has a false alarm of a non-empty pipe state in a stable empty pipe state.

[0049] To solve the above problems, in the first aspect, according to the implementation methods of the present application, a method for detecting an empty pipe is proposed, such as Figure 3 As shown, including:

[0050] S101, when the empty pipe detection starts, after the stabilization time, obtain the current forward voltage and the current reverse voltage;

[0051] S102, determining a first empty pipe detection state according to a current forward voltage and a current reverse voltage, the first empty pipe detection state including: an intermediate state, an empty pipe state, and a non-empty pipe state;

[0052] S103, if the first empty pipe detection state is an intermediate state, and the current forward voltage and the current reverse voltage are not detected for the first time, the second empty pipe detection state is determined according to the historical forward voltage, the historical reverse voltage, the current forward voltage and the current reverse voltage, and the second empty pipe detection state is used as the empty pipe detection result.

[0053] The intermediate state is a state that is neither an empty pipe state nor a non-empty pipe state, and it needs to be processed further to obtain the empty pipe state or the non-empty pipe state.

[0054] In the case where the empty pipe detection starts, after the stabilization time and before obtaining the current forward voltage and the current reverse voltage, it also includes: in the case where there is no stabilization time, determining the stabilization time according to the detection voltage data.

[0055] After the empty pipe detection circuit is powered on, the voltage at the electrode is continuously collected through an external analog-to-digital converter (ADC), the voltage data is put into a cache queue, and the standard deviation is calculated for 5 consecutive data. The standard deviation is calculated by the following formula:

[0056]

[0057] When the standard deviation S is less than the preset comparison value, it is considered that the electrode voltage is stable at this time, and the time range corresponding to the five consecutive data is the stable time, which is recorded as t0. i represents the i-th data, represents the mean of the data, and n represents the number of data.

[0058] Empty pipe detection is a periodic detection. If there is a stable time, the empty pipe detection is started directly according to the preset detection period, that is, according to the preset detection period, the steps of obtaining the current forward voltage and the current reverse voltage are executed after the stable time when the empty pipe detection starts. If the empty pipe detection has not started, wait until the preset detection period arrives, and execute the steps of obtaining the current forward voltage and the current reverse voltage after the stable time when the empty pipe detection starts.

[0059] After the stabilization time, the current forward voltage and the current reverse voltage are obtained, including: after the stabilization time has passed, the current forward voltage is obtained; after the current forward voltage is obtained, the current reverse voltage is obtained after the stabilization time has passed again.

[0060] Determining a first empty pipe detection state according to a current forward voltage and a current reverse voltage includes: if the current forward voltage is less than the current reverse voltage, the first empty pipe detection state is an empty pipe state; if the current forward voltage is greater than or equal to the current reverse voltage, determining the first empty pipe detection state according to the current forward voltage, the current reverse voltage and a preset empty pipe threshold; if the first empty pipe detection state is an intermediate state, determining the current empty pipe detection state according to the current forward voltage, the current reverse voltage, the first preset forward empty pipe detection voltage and the first preset reverse empty pipe detection voltage; if the current empty pipe detection state is an intermediate state, determining the first empty pipe detection state according to the current forward voltage, the current reverse voltage, the second preset forward empty pipe detection voltage and the second preset reverse empty pipe detection voltage.

[0061] The first empty pipe detection state is determined according to the current forward voltage, the current reverse voltage and the preset empty pipe threshold, including: determining the voltage difference according to the current forward voltage and the current reverse voltage; if the voltage difference is greater than the preset empty pipe threshold, the first empty pipe detection state is the empty pipe state; if the voltage difference is less than or equal to the preset empty pipe threshold, the first empty pipe detection state is the intermediate state.

[0062] If the first empty pipe detection state is an intermediate state, the current empty pipe detection state is determined according to the current forward voltage, the current reverse voltage, the first preset forward empty pipe detection voltage and the first preset reverse empty pipe detection voltage, including: if the current forward voltage is greater than or equal to the first preset forward empty pipe detection voltage, and the current reverse voltage is greater than or equal to the first preset reverse empty pipe detection voltage, then the current empty pipe detection state is an empty pipe state, and the empty pipe state is used as the first empty pipe detection state, wherein the first preset forward empty pipe detection voltage is the upper limit of the forward empty pipe detection voltage, and the first preset reverse empty pipe detection voltage is the upper limit of the reverse empty pipe detection voltage; if the current forward voltage is less than the first preset forward empty pipe detection voltage and / or the current reverse voltage is less than the first preset reverse empty pipe detection voltage, then the current empty pipe detection state is an intermediate state, and the intermediate state is used as the first empty pipe detection state.

[0063] If the current empty pipe detection state is an intermediate state, the first empty pipe detection state is determined according to the current forward voltage, the current reverse voltage, the second preset forward empty pipe detection voltage and the second preset reverse empty pipe detection voltage, including: if the current forward voltage is less than or equal to the second preset forward empty pipe detection voltage, and the current reverse voltage is less than or equal to the second preset reverse empty pipe detection voltage, then the first empty pipe detection state is an empty pipe state, wherein the second preset forward empty pipe detection voltage is the lower limit of the forward empty pipe detection voltage, and the second preset reverse empty pipe detection voltage is the lower limit of the reverse empty pipe detection voltage; if the current forward voltage is greater than the second preset forward empty pipe detection voltage and / or the current reverse voltage is greater than the second preset reverse empty pipe detection voltage, then the first empty pipe detection state is an intermediate state.

[0064] After determining the first empty pipe detection state according to the current forward voltage and the current reverse voltage, the method further includes: when the first empty pipe detection state is the empty pipe state, taking the first empty pipe detection state as the empty pipe detection result.

[0065] If the first empty pipe detection state is an intermediate state, and the current forward voltage and the current reverse voltage are not detected for the first time, the second empty pipe detection state is determined according to the historical forward voltage, the historical reverse voltage, the current forward voltage and the current reverse voltage, including: if the first empty pipe detection state is an intermediate state, and the current forward voltage and the current reverse voltage are not detected for the first time, a first absolute value is determined according to the difference between the historical forward voltage and the current forward voltage, and a second absolute value is determined according to the difference between the historical reverse voltage and the current reverse voltage; a third absolute value is determined according to the difference between the first absolute value and the second absolute value; if the third absolute value is greater than a preset difference threshold, the second empty pipe detection state is an empty pipe state; if the third absolute value is less than or equal to the preset difference threshold, the second empty pipe detection state is a non-empty pipe state.

[0066] After determining the first empty pipe detection state according to the current forward voltage and the current reverse voltage, the method further includes: if the first empty pipe detection state is an intermediate state, and the current forward voltage and the current reverse voltage are detected for the first time, then the first empty pipe detection state is a non-empty pipe state; and the first empty pipe detection state is used as the empty pipe detection result.

[0067] After determining the first empty pipe detection state according to the current forward voltage and the current reverse voltage, the method further includes: updating the historical forward voltage and the historical reverse voltage according to the current forward voltage and the current reverse voltage. The current forward voltage is used as the historical forward voltage, and the current reverse voltage is used as the historical reverse voltage.

[0068] Below, as Figure 4 As shown, the embodiments of the present application are further described.

[0069] A single complete empty pipe collection and detection process first requires that when the empty pipe detection is turned on, the analog switch and the forward empty pipe signal output in the empty pipe detection circuit are turned on, the internal timer of the microcontroller counts the delay t0, and the external AD collects the current forward voltage Ua1 and the current reverse voltage Ub1.

[0070] like Figure 4 As shown, when the preset detection cycle T starts, the empty pipe detection starts. The current forward voltage Ua1 is obtained after the delay t0. After the current forward voltage Ua1 is acquired, the reverse empty pipe signal output is turned on, and the delay t0 is again performed. After the electrode voltage is stable, the current reverse voltage Ub1 is acquired through the external AD, where the voltage unit is unified as mV.

[0071] Secondly, after the current reverse voltage Ub1 is collected, the empty pipe signal and the empty pipe signal output are turned off, and the empty pipe voltages collected twice are processed as follows:

[0072] First, if the current forward voltage Ua1 is less than the current reverse voltage Ub1, the first empty pipe detection state is the empty pipe state, and the first empty pipe detection state is used as the empty pipe detection result; if the current forward voltage Ua1 is greater than or equal to the current reverse voltage Ub1, the first empty pipe detection state is the intermediate state, and the next step of processing is continued;

[0073] Second, the voltage difference ΔU between the current forward voltage Ua1 and the current reverse voltage Ub1 is calculated, ΔU=Ua1-Ub1; then, the voltage difference ΔU is compared with the preset empty pipe threshold, where the preset empty pipe threshold can be configured according to demand and actual conditions; if the voltage difference ΔU is greater than the empty pipe threshold, the first empty pipe detection state is the empty pipe state, and the first empty pipe detection state is used as the empty pipe detection result; if the voltage difference ΔU is less than or equal to the empty pipe threshold, the first empty pipe detection state is the intermediate state, and the next step of processing is continued;

[0074] Third, compare the current forward voltage Ua1 and the current reverse voltage Ub1 with the first preset forward empty pipe detection voltage (the upper limit of the forward empty pipe detection voltage) and the first preset reverse empty pipe detection voltage (the upper limit of the reverse empty pipe detection voltage) respectively. If the current forward voltage is greater than or equal to the first preset forward empty pipe detection voltage, and the current reverse voltage is greater than or equal to the first preset reverse empty pipe detection voltage, then the current empty pipe detection state is the empty pipe state, and the empty pipe state is used as the first empty pipe detection state, and the first empty pipe detection state is used as the empty pipe detection result; if the current forward voltage is less than the first preset forward empty pipe detection voltage and the current reverse voltage is less than the first preset reverse empty pipe detection voltage, or the current forward voltage is less than the first preset forward empty pipe detection voltage or the current reverse voltage is less than the first preset reverse empty pipe detection voltage, then the current empty pipe detection state is the intermediate state, and the intermediate state is used as the first empty pipe detection state, and the next step of processing is continued;

[0075] Fourth, compare the current forward voltage Ua1 and the current reverse voltage Ub1 with the second preset forward empty pipe detection voltage (the lower limit of the forward empty pipe detection voltage) and the second preset reverse empty pipe detection voltage (the lower limit of the reverse empty pipe detection voltage) respectively; if the current forward voltage is less than or equal to the second preset forward empty pipe detection voltage, and the current reverse voltage is less than or equal to the second preset reverse empty pipe detection voltage, then the first empty pipe detection state is the empty pipe state, and the first empty pipe detection state is used as the empty pipe detection result; if the current forward voltage is greater than the second preset forward empty pipe detection voltage and the current reverse voltage is greater than the second preset reverse empty pipe detection voltage, or the current forward voltage is greater than the second preset forward empty pipe detection voltage or the current reverse voltage is greater than the second preset reverse empty pipe detection voltage, then the first empty pipe detection state is the intermediate state, and the next step of processing is continued;

[0076] Fifth, if the first empty pipe detection state is an intermediate state, and the current forward voltage and the current reverse voltage are detected for the first time, the first empty pipe detection state is a non-empty pipe state, the current forward voltage is used as the historical forward voltage, the current reverse voltage is used as the historical reverse voltage, and the first empty pipe detection state is used as the empty pipe detection result; if the first empty pipe detection state is an intermediate state, and the current forward voltage and the current reverse voltage are not detected for the first time, the first empty pipe detection state is an intermediate state, and the next step of processing is continued;

[0077] Sixth, calculate the first absolute value ΔUa of the difference between the current forward voltage Ua1 and the historical forward voltage Ua0 collected last time, ΔUa=|Ua1-Ua0|, and calculate the second absolute value ΔUb of the difference between the current reverse voltage Ub1 and the historical reverse voltage Ub0 collected last time, ΔUb=|Ub1-Ub0|;

[0078] Seventh, a third absolute value ΔUdiff is determined according to the difference between the first absolute value and the second absolute value, ΔUdiff=|ΔUa-ΔUab|; if the third absolute value is greater than a preset difference threshold, the second empty pipe detection state is an empty pipe state; if the third absolute value is less than or equal to the preset difference threshold, the second empty pipe detection state is a non-empty pipe state;

[0079] Eighth, use the current forward voltage value to update the historical forward voltage value, that is, Ua0=Ua1, and use the current reverse voltage value to update the historical reverse voltage value, that is, Ub0=Ub1, in preparation for the next empty pipe detection, and set the non-first empty pipe detection flag; and use the second empty pipe detection status as the empty pipe detection result, waiting for the start of the next preset detection cycle.

[0080] like Figure 5As shown in the figure, according to the above method, the data is captured again in the same scenario, and the test results are obtained, with line 1 as the forward voltage, line 2 as the reverse voltage, and line 3 as the empty pipe detection state (empty pipe detection result). Figure 5 As shown in the figure, the complex fluctuations in the empty pipe state cause the positive and reverse voltage acquisition to still jump greatly. However, after processing the collected data, the empty pipe state corresponding to the empty pipe detection result still remains stable at 1250, that is, the empty pipe state, and does not jump.

[0081] like Figure 6 As shown in the figure, it is a schematic diagram of using the same method to test whether the non-empty pipe state fluctuates. It is a long-term high and low temperature cycle shock experiment under the condition of a full pipe section, grabbing the empty pipe to collect data, and obtaining the test results. Line 1 is the forward voltage, line 2 is the reverse voltage, and line 3 is the empty pipe detection state (empty pipe detection result). Figure 6 As shown, the empty pipe state corresponding to the empty pipe detection state has been kept at 0, that is, the non-empty pipe state, and no empty pipe alarm occurs.

[0082] The implementation method of the present application effectively solves the problem of false alarms of empty pipes in electromagnetic products by progressively processing the collected voltage layer by layer, thereby being able to solve the problem of unstable electrode voltage in empty pipe detection in traditional solutions, resulting in empty pipe state jumps that affect metering; it can also be applied to electromagnetic water meters, electromagnetic flow meters and other related electromagnetic metering products, and is widely used; the relative stability of the empty pipe state reduces the problem of metering state fluctuations and improves product metering accuracy. Although the empty pipe state can be judged only based on the current forward voltage and the current reverse voltage, without combining the historical forward voltage and the historical reverse voltage, which can relatively simplify the processing flow, the accuracy of empty pipe detection will be reduced.

[0083] In a second aspect, according to an embodiment of the present application, an electromagnetic flowmeter is proposed for executing the empty pipe detection method described in any one of the first aspects.

[0084] Among them, electromagnetic flow meters include: electromagnetic water meters and other electromagnetic metering products.

[0085] In the method of the present application, multiple empty pipe detections are performed in different ways according to the current forward voltage, the current reverse voltage, the historical forward voltage, and the historical reverse voltage to improve the accuracy of empty pipe detection. The implementation method of the present application is generally applicable to empty pipe detection of electromagnetic metering products. The logic of optimizing empty pipe detection is concise and clear, and progressive, so that the problem of false alarms of empty pipes can be effectively solved and the metering accuracy can be improved. At the same time, it can also be applied to related electromagnetic metering products such as electromagnetic water meters and electromagnetic flow meters, and is widely used; the relative stability of the empty pipe state reduces the problem of fluctuations in the metering state and improves the metering accuracy of the product.

[0086] The above is only a preferred specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. An empty pipe detection method, characterized in that: include: When the empty pipe detection starts, after the stabilization time, the current forward voltage and the current reverse voltage are obtained; Determine a first empty pipe detection state according to the current forward voltage and the current reverse voltage, the first empty pipe detection state comprising: an intermediate state; If the first empty pipe detection state is the intermediate state, and the current forward voltage and the current reverse voltage are not detected for the first time, the second empty pipe detection state is determined according to the historical forward voltage, the historical reverse voltage, the current forward voltage and the current reverse voltage, and the second empty pipe detection state is used as the empty pipe detection result.

2. The empty pipe detection method according to claim 1, characterized in that: The determining the first empty pipe detection state according to the current forward voltage and the current reverse voltage includes: If the current forward voltage is less than the current reverse voltage, the first empty pipe detection state is an empty pipe state; If the current forward voltage is greater than or equal to the current reverse voltage, determining the first empty pipe detection state according to the current forward voltage, the current reverse voltage and a preset empty pipe threshold; If the first empty pipe detection state is the intermediate state, determining the current empty pipe detection state according to the current forward voltage, the current reverse voltage, a first preset forward empty pipe detection voltage, and a first preset reverse empty pipe detection voltage; If the current empty pipe detection state is the intermediate state, the first empty pipe detection state is determined according to the current forward voltage, the current reverse voltage, a second preset forward empty pipe detection voltage, and a second preset reverse empty pipe detection voltage.

3. The empty pipe detection method according to claim 2, characterized in that: The determining the first empty pipe detection state according to the current forward voltage, the current reverse voltage and a preset empty pipe threshold comprises: Determine a voltage difference according to the current forward voltage and the current reverse voltage; If the voltage difference is greater than the preset empty pipe threshold, the first empty pipe detection state is the empty pipe state; If the voltage difference is less than or equal to the preset empty pipe threshold, the first empty pipe detection state is the intermediate state.

4. The empty pipe detection method according to claim 2, characterized in that: The method of determining a current empty pipe detection state according to the current forward voltage, the current reverse voltage, a first preset forward empty pipe detection voltage, and a first preset reverse empty pipe detection voltage includes: If the current forward voltage is greater than or equal to the first preset forward empty pipe detection voltage, and the current reverse voltage is greater than or equal to the first preset reverse empty pipe detection voltage, then the current empty pipe detection state is the empty pipe state, and the empty pipe state is used as the first empty pipe detection state, wherein the first preset forward empty pipe detection voltage is the upper limit of the forward empty pipe detection voltage, and the first preset reverse empty pipe detection voltage is the upper limit of the reverse empty pipe detection voltage; If the current forward voltage is less than the first preset forward empty pipe detection voltage and / or the current reverse voltage is less than the first preset reverse empty pipe detection voltage, the current empty pipe detection state is the intermediate state, and the intermediate state is used as the first empty pipe detection state.

5. The empty pipe detection method according to claim 2, characterized in that: The method of determining the first empty pipe detection state according to the current forward voltage, the current reverse voltage, the second preset forward empty pipe detection voltage and the second preset reverse empty pipe detection voltage includes: If the current forward voltage is less than or equal to the second preset forward empty pipe detection voltage, and the current reverse voltage is less than or equal to the second preset reverse empty pipe detection voltage, then the first empty pipe detection state is the empty pipe state, wherein the second preset forward empty pipe detection voltage is the lower limit of the forward empty pipe detection voltage, and the second preset reverse empty pipe detection voltage is the lower limit of the reverse empty pipe detection voltage; If the current forward voltage is greater than the second preset forward empty pipe detection voltage and / or the current reverse voltage is greater than the second preset reverse empty pipe detection voltage, the first empty pipe detection state is the intermediate state.

6. The empty pipe detection method according to claim 1, characterized in that: If the first empty pipe detection state is the intermediate state, and the current forward voltage and the current reverse voltage are not detected for the first time, determining the second empty pipe detection state according to the historical forward voltage, the historical reverse voltage, the current forward voltage, and the current reverse voltage, including: If the first empty pipe detection state is the intermediate state, and the current forward voltage and the current reverse voltage are not detected for the first time, a first absolute value is determined according to a difference between the historical forward voltage and the current forward voltage, and a second absolute value is determined according to a difference between the historical reverse voltage and the current reverse voltage; determining a third absolute value according to a difference between the first absolute value and the second absolute value; If the third absolute value is greater than a preset difference threshold, the second empty pipe detection state is an empty pipe state; If the third absolute value is less than or equal to the preset difference threshold, the second empty pipe detection state is a non-empty pipe state.

7. The empty pipe detection method according to claim 1, characterized in that: After determining the first empty pipe detection state according to the current forward voltage and the current reverse voltage, the method further includes: If the first empty pipe detection state is an intermediate state, and the current forward voltage and the current reverse voltage are detected for the first time, then the first empty pipe detection state is the non-empty pipe state; The first empty pipe detection state is used as an empty pipe detection result.

8. The empty pipe detection method according to claim 1, characterized in that: After the stabilization time, obtaining the current forward voltage and the current reverse voltage includes: After the stabilization time has passed, obtaining the current forward voltage; After the current forward voltage is obtained, the current reverse voltage is obtained again after the stabilization time has passed.

9. The empty pipe detection method according to claim 3, 4 or 5, characterized in that: After determining the first empty pipe detection state according to the current forward voltage and the current reverse voltage, the method further includes: When the first empty pipe detection state is an empty pipe state, the first empty pipe detection state is used as an empty pipe detection result.

10. An electromagnetic flowmeter, characterized in that: Used to execute the empty pipe detection method described in any one of claims 1-9.

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