RU2568943C1 - Meter of fluid medium quantity and method to determine quantity of fluid medium - Google Patents

Abstract

FIELD: measurement equipment.

SUBSTANCE: meter comprises a controller, a tachometric converter connected to a controller, which records and counts pulses of the tachometric converter and also determines quantity of fluid medium that leaked through the meter. At the same time it also comprises a clock pulse oscillator connected to the controller, at the same time the controller is made as capable of determining the number of pulses of the clock pulse generator N_t between serial pulses of the tachometric converter, determination of the weight coefficient W(N_t), corresponding to current value of quantity of pulses of the clock pulse oscillator N_t, and correction of the number of pulses of the tachometric converter by a weight coefficient W(N_t). The proposed method to determine quantity of the fluid medium is carried out by means of the meter.

EFFECT: increased accuracy of measurement of leaked quantity of fluid medium, reduced number of counting operations from the moment of readings taking to the moment of measurement results display, which reduced the rated error at each stage and decreases rated errors in general.

13 cl

Description

The invention relates to the field of measuring technology, namely to measuring the amount of fluid, as well as to a method for determining the amount of fluid. The invention can be used to reduce the error of tachometric transducers when measuring the number of fluids passing through them.

The tachometric method for determining the flow rate of a fluid that passes through the meter is generally based on the principle of measuring the rotation speed of a movable element that rotates under the influence of a fluid. The use of a movable element as a sensitive one can significantly simplify the design of the meter, reduce maintenance costs, and also simplify the requirements for installing such meters in fluid supply systems. However, with all of the above advantages, there are a number of significant drawbacks, such as: the sensitivity of the moving element to the quality and viscosity of the flowing medium, the change in the sensitivity of the moving element in the flow with a low flow rate, as well as a relatively high level of error for such measurements.

For example, in accordance with regulatory documents, in the upper flow range the permissible measurement error is 2% for cold water meters and 3% for hot water meters. In the lower flow range, the permissible measurement error is 5%. In the flow range from the sensitivity threshold to the minimum flow, the permissible error is not standardized.

The above described features of tachometric methods for determining the volume of fluids necessitated the development of new, more accurate devices and methods for determining the amount of fluids.

A known method of determining the flow rate and amount of fluid, which is implemented by tachometric measuring instruments [P.P. Kremlevsky. Flow meters and quantity counters. Directory. 4th edition, revised. and add. -L.: Engineering. Leningra. Department, 1989. - 701 p.]. The method is based on a tachometric principle in which a flowing fluid affects the rotation speed of a movable element such as a turbine or impeller. The speed of the moving element is proportional to the volumetric flow rate of the fluid.

In this case, the measuring instruments are equipped with a tachometric transducer that generates a measuring signal (pulse), the frequency of which is proportional to the speed of movement of the moving element. Thus, by counting the number of pulses, the amount of fluid passed through the meter is determined.

A feature of such measuring instruments is that at low flow rates of the fluid, the price of one pulse of a tachometric transducer is greater than in some steady state, when the price of one pulse is no longer dependent on the flow of fluid.

Under the price should be understood the flowing amount of fluid corresponding to one pulse of the tachometric transducer. The change in price depending on the flow rate of the fluid is non-linear. The price gradually decreases from a certain value at a flow rate corresponding to the sensitivity threshold (when the moving element starts to rotate stably) to a transitional flow rate (when the price of one revolution no longer depends on the flow rate of the fluid).

However, the use of this method implies that when calculating the volume of fluid flowing through a tachometric means, only the pulse price corresponding to the interval from the transition to the maximum flow rate will be taken into account. This leads to a significant measurement error at low flow rates.

The closest analogue, selected as a prototype, is the solution described in the patent of the Russian Federation No. 2458196, in which the claimed device is a turbine flow meter, and a method for determining the amount of liquid. The method is aimed at determining the amount of fluid passing through a turbine meter containing a rotor with blades and a controller for continuously recording a pulse at time T _i generated for each full revolution of the rotor. The method includes the stages in which:

(a) measuring time intervals ΔT _i = (T _i -T _i-1 ) passing between successive pulses;

(b) determine the flow rate FR _i corresponding to each of the indicated intervals ΔT _i = (T _i -T _i-1 ), based on the experimental calibration non-linear analytical function, which corrects the change in the flow rate of a pre-selected fluid with a change in the time interval between successive pulses turbine meter;

(c) calculating a discrete amount of fluid V _i = T _i · FR _i that flows during each of the indicated time intervals ΔT _i = (T _i -T _i-1 ) between successive pulses;

(d) calculate the total amount of fluid V _t = Σ _i V _i flowing through the meter.

At the same time, at step (b), a calibration array is created, formed from equidistant time periods Δp _i and the corresponding flow rates v _i calculated by entering the indicated equidistant time periods into the experimental calibration nonlinear analytical function. After that, each time interval ΔT _i measured between successive pulses T _{i is} compared with equally spaced time periods Δp _{i of the} calibration array to determine between which periods the measured time interval is located. The next step is linear interpolation between the flow rates v _i corresponding to equally spaced time periods Δp _{i of the} calibration data array, between which equally spaced time periods ΔT _{i are located} , taking into account the determination of the actual flow rate FR _i corresponding to the measured time interval ΔT _i .

The disadvantages of the described method include the need for calculations at each time interval, which significantly increases the processed array of the processed data and, accordingly, the load on the controller. At the same time, the use of time intervals for determining the amount of leaking fluid medium, the value of which can be significantly small, leads to the need for mathematical accounting of a number of small quantities, which, when a certain decimal point is reached, cease to be taken into account to reduce the load on the computing processor / controller, which leads to accumulation systematic error and, accordingly, calculation errors.

The device described in the patent, the flow meter, is a turbine flow meter containing a rotor with blades and a controller for continuously recording the pulse signals generated at times T _i for each complete revolution of the rotor and determining the amount of current medium flowing through the meter. Moreover, the controller is configured to measure time intervals ΔT _i = (T _i -T _i-1 ) passing between successive pulses to determine the flow rate FR _i corresponding to each of the indicated intervals ΔT _i = (T _i -T _i-1 ) based on an experimental gauge non-linear analytic function. The function corrects a change in the flow rate of a pre-selected fluid with a change in the time interval between successive pulses of the meter. Also, the controller is configured to calculate a discrete amount of fluid V _i = T _i · FR _i , which flows during each of the indicated time intervals ΔT _i = (T _i -T _i-1 ) between successive pulses.

The disadvantages of the described solution include the use of time intervals for determining the amount of fluid that has flowed, the value of which can be significantly small, which leads to the need for mathematical accounting of a number of small values that, when a certain decimal place is reached, are no longer taken into account to reduce the load on the computing processor. Since a number of values are no longer taken into account, a systematic error is accumulated in the calculation of the flow rate / quantity of the fluid. Also, in such calculations, there is a high load on the controller, which can lead to an increase in data processing time. It should be noted that the presence of a timer also complicates the design of the controller and increases the cost of production of such a controller.

The basis of the invention is the task of developing a meter of the amount of leaking fluid, the design of which will provide improved measurement accuracy, as well as improving the accuracy of measuring the amount of fluid during transients, such as the beginning of the passage of the fluid and the completion of the passage. Improving the accuracy of the meter will be achieved by taking into account the correction values that will be determined for each type of fluid. In this case, the design of the meter will not contain a timer, which allows to exclude the measurement of small segments of time and subsequent calculation based on small values, which in turn will increase the speed of calculations and, accordingly, the speed of the meter.

The invention is also based on the task of developing a method for determining the amount of fluid using a meter, which will improve the accuracy of measuring the amount of leaked fluid by ensuring the use of correction factors determined for each type of fluid. Also, the accuracy of the measurement by the method will be ensured by excluding from the calculation time intervals, the value of which may be small. At the same time, the developed method will also allow to reduce the number of settlement operations from the moment of taking readings to the moment of displaying the measurement results, which allows to reduce the calculated error at each stage, thereby reducing the calculated errors in general.

The problem is solved in that a fluid quantity meter is developed, comprising a controller, a tachometric transducer connected to a controller that records and counts the pulses of the tachometric transducer, as well as determining the amount of fluid flowing through the meter, while it contains a clock generator connected to the controller, where the controller is configured to determine the number of pulses of the clock generator N _t between successive tachometric pulses the transducer, determining the weight coefficient W (N _t ) corresponding to the current value of the number of pulses of the clock generator N _t , and adjusting the number of pulses of the tachometric converter by the weight coefficient W (N _t ). Thanks to this embodiment of the invention, the following technical result is achieved: improving the accuracy of measuring the amount of fluid by taking into account the correction value - the weight coefficient W (N _t ), and the exclusion of the timer from the design of the meter eliminates the need for counting small quantities, which improves the speed and accuracy of the meter .

Correction of the number of pulses of the tachometric transducer by the weight coefficient W (N _t ) consists in summing the weight coefficient W (N _t ) to the number of pulses of the tachometric transducer. Moreover, the value of the weight coefficient W (N _t ) is an integer with a positive value, that is, the value of the weight coefficient cannot be negative.

The clock generator generates pulses of a given frequency. The frequency of the clock generator is chosen so that it is greater than the pulse frequency of the tachometric Converter at the maximum flow rate of the fluid, which requires adjustment, for example, transitional flow rate.

The controller is configured to compare the number of pulses of the clock generator N _t with a given maximum value N _t ^max . Thus, the controller provides a logical cycle aimed at monitoring the moment of stopping the fluid flow. With each occurrence of a clock pulse, the controller compares when the value of N _t <N _t ^max increases the number of pulses of the clock generator N _t by 1, when the value N _t ^max ≤ N _{t, the} controller can turn off the clock and turn it on when the next tachometer pulse occurs transducer. The controller can also set a value corresponding to the number of pulses of the clock generator N _t equal to a predetermined initial value. Advantageously, the predetermined initial value is zero, and the value of N _t ^{max is} chosen so that it is not less than the number of pulses of a clock generator between consecutive pulses of a tachometric transducer with a minimum flow rate of the fluid at which correction is required, for example, a sensitivity threshold.

Obviously, the controller contains a computing module and a memory module. The computing module includes a processor that performs all the calculation operations.

The tachometric transducer is a magnetic field change sensor. A permanent magnet is fixed on one axis with a movable element rotating under the action of a fluid. A magnetic field change sensor is located near the magnet rotation region, which transmits a signal (impulse) to the controller every time when the change in the magnetic field acting on the sensor exceeds a threshold value, including the change in the direction of the magnetic field.

It is advisable to design a meter that contains conclusions for connection to a calibration device. Thanks to the ability to connect to the calibration device, it is possible to adjust the meter for each type of fluid, as well as depending on the necessary operating conditions. This allows you to significantly expand the scope of the inventive meter of the amount of fluid.

The weight coefficient W (N _t ) is determined depending on the number of pulses of the clock generator at a given time based on the calibration data of the device for each particular case.

The problem is also solved by the fact that a method for determining the amount of fluid using the meter described above is developed, which includes recording the pulse of the tachometric transducer, counting the pulses of the tachometric transducer and determining the amount of fluid that passed through the meter of the amount of fluid, before determining the amount fluid, determine the number of pulses of a clock generator N _t between successive pulses of a tachometric pre the browser and determine the weight coefficient W (N _t ) of the pulse of the tachometric transducer corresponding to the current value of the number of pulses of the clock generator N _t , then the number of pulses of the tachometric transducer is adjusted by the weight coefficient W (N _t ). Thanks to this sequence of actions, the following technical result is achieved: improving the accuracy of measuring the flowing amount of fluid by taking into account the correction value - the weight coefficient W (N _t ), also reduces the number of calculation operations from the moment of taking readings to the moment of outputting the measurement results, which reduces the calculated error by each stage and reduces the calculated errors in general.

The weight coefficient W (N _t ) is determined depending on the number of pulses of the clock generator at a given time based on the calibration data of the device for each particular case.

Correction of the number of pulses of the tachometric transducer by the weight coefficient W (N _t ) consists in summing the weight coefficient W (N _t ) to the number of pulses of the tachometric transducer. Moreover, the value of the weight coefficient W (N _t ) is an integer with a positive value, that is, the value of the weight coefficient cannot be negative.

Before determining the weight coefficient W (N _t ) of the pulse of the tachometric converter corresponding to the current value of the number of pulses of the clock generator N _t , the tabular values of the weight coefficient W (n) are approximated. Table values of the weight coefficient W (n) are determined during calibration.

Calibration includes the steps of at least one measurement of the volume V of the leaked fluid, measuring the number of pulses of the clock generator and the tachometer transducer for a given amount of fluid, and then determining the average number of pulses of the clock generator n between the pulses of the tachometer transducer, as well as the average volume v of the fluid corresponding to one pulse of the tachometric transducer, then the dependence v (n) is approximated and the dependence W (n) is determined. The dependence v (n) is nonlinear; its form depends on the design of the device used to measure it, as well as on its characteristics, on the design of the movable element, which records the readings and on the type of tachometric transducer. During calibration, if several measurements are made, the approximation may be linear. It should be noted that the value of W (n) is calculated for each measurement during calibration. Thanks to the calibration, it is possible to use the inventive method for any fluid, while the inventive method is effective for any operating conditions.

When calibrating after determining the values of W (n), if the values of W (n) are not integer, then an additional correction factor k is introduced by which the values of W (n) are multiplied in order to exclude fractional values. Thus, the accuracy of calculating the amount of fluid is improved by eliminating the summation of small quantities. This eliminates the need to consider decimal places, which reduces the load on the controller.

Obviously, to determine the amount of leaking fluid, the number of pulses of the tachometer transducer is divided by the coefficient k determined during calibration.

When determining the number N _t of the clock pulse generator is compared number N _t clock pulses with a predetermined maximum value N _t ^max. When the value of N _t <N _t ^max , then increase the number of pulses of the clock by 1, otherwise turn off the clock. Thus, the operation of the logical cycle aimed at tracking the moment of stopping the fluid flow is ensured, which allows to reduce the error in determining the amount of fluid during transients, such as, for example, the completion of the fluid supply.

The following is a method of implementing the claimed invention.

Previously, before starting the meter, it is calibrated, for which the meter is connected to a calibration device. Then, at least one measurement of the volume V of fluid passing through the meter, the number of pulses of the clock generator n between the pulses of the tachometer transducer, and the number of pulses of the tachometric transducer m are carried out. For each measurement, the average value v of the fluid corresponding to one pulse of the tachometric transducer is calculated and the dependence v (n) is determined. The v (n) dependence is approximated and the W (n) dependence is determined. Based on the values of W (n), a correction factor k is determined by which the values of W (n) are multiplied to obtain integers. All defined data is stored in the controller memory. Also, data on N_t ^max _. N value_t ^max chosen so that it was not less than the number of pulses of a clock generator between consecutive pulses of a tachometric transducer with a minimum flow rate of the fluid at which correction is required, for example, a sensitivity threshold. After calibration, the meter is ready for operation.

During operation of the meter, at each occurrence of a clock pulse, the number of pulses of the clock generator N _{t is} compared with N _t ^max . If N _t <N _t ^max , then increase the number of pulses of the clock generator by 1. When a pulse of the tachometer converter appears, the controller adjusts the number of pulses of the tachometer converter by the weight coefficient W (N _t ) corresponding to the current value of the number of pulses of the clock generator. After that, the controller sets the number of pulses of the clock generator N _t equal to the specified initial value. The cycle is repeated until N _t ^max ≤ N _t , after which the controller turns off the clock and turns it on when the next pulse of the tachometer converter occurs.

Below is an example calculation.

During calibration, the following measurement results were determined:

No. The volume of leaked water, l The number of pulses of the tachometric Converter, m The number of pulses of a clock generator, n one 2,910 123 0 2 2,982 127 127 3 3,044 127 254

Then, the average number of pulses of the clock generator between the pulses of the tachometric transducer is calculated and the average transmitted water volume is calculated:

No. n v one 0 0,02366 2 one 0,02348 3 2 0,02397

After that, the dependence v (n) is approximated and a correction factor is selected. Based on the above values of the function v (n), it can be seen that the preferred value of the correction coefficient is k = 100000. The weight values of the function are given below:

n W 0 2366 one 2348 2 2397

The data obtained in the table is written to the controller memory.

The controller receives pulses independent from each other from the clock generator and the tachometer converter. When the pulse of the tachometer transducer arrives, the controller finds in the table the value of the weight function W corresponding to the number of pulses of the clock generator from the moment of the previous pulse of the tachometer transducer. The controller adds the found value of W to the number of pulses of the tachometric transducer.

Thus, a leaking fluid quantity meter has been developed, the design of which allows to increase the measurement accuracy, as well as to increase the accuracy of measuring the amount of fluid during transients, such as the beginning of the passage of the fluid and the completion of the passage. Improving the accuracy of the meter is achieved by taking into account the correction values that are determined for each type of fluid. Moreover, the design of the meter does not contain a timer, which eliminates the measurement of small periods of time and subsequent calculation based on small values, which in turn allows you to increase the speed of calculations and, accordingly, the speed of the meter.

A method has also been developed for determining the amount of fluid using a meter, which allows to increase the accuracy of measuring the amount of leaked fluid by ensuring the use of correction factors determined for each type of fluid. Also, the accuracy of the measurement by the method is ensured by excluding from the calculation time intervals, the value of which may be small. Also, the developed method allows to reduce the number of settlement operations from the moment of taking readings to the moment of outputting the measurement results, which allows to reduce the calculated error at each stage, thereby reducing the calculated errors in general.

Claims (13)

1. A fluid quantity meter comprising a controller, a tachometer transducer connected to a controller that records and counts the pulses of the tachometer transducer, as well as determining the amount of flowing fluid through a meter, characterized in that it contains a clock connected to the controller, the controller being made with the ability to determine the number of pulses of a clock generator N _t between successive pulses of a tachometric transducer, determining the weight coefficient W (N _t ) corresponding to the current value of the number of pulses of the clock generator N _t , and adjusting the number of pulses of the tachometric converter by the weight coefficient W (N _t ). 2. The meter according to claim 1, characterized in that the controller is configured to compare the number of pulses of the clock generator N _t with a given maximum value N _t ^max . 3. The meter according to claim 2, characterized in that the controller is configured to increase N _t by 1 at a value of N _t <N _t ^max . 4. The meter according to claim 2, characterized in that the controller is configured to turn off the clock at a value of N _t ≥ N _t ^max , and when a tachometer pulse arises, it is configured to turn on the clock. 5. The meter according to claim 1, characterized in that the tachometric transducer is a sensor for changing a magnetic field. 6. The meter according to claim 1, characterized in that it contains conclusions for connection to a calibration device. 7. The method of determining the amount of fluid using the meter according to claim 1, including registering the momentum of the tachometer transducer, counting the pulses of the tachometer transducer and determining the amount of fluid that has passed through the meter of the amount of fluid, characterized in that before determining the amount of fluid, determine number of clock pulses N _t between successive transducer tachometer pulses and determining a weighting factor W (N _t) momenta a tachometer inverter corresponding to the current value of the number N _t clock pulses, then corrected pulse number tachometric converter by a weighting factor W (N _t). 8. The method according to p. 7, characterized in that before determining the weight coefficient W (N _t ) of the pulse of the tachometer transducer corresponding to the current value of the number of pulses of the clock generator N _t , the tabular values of the weight coefficient W (n) are approximated. 9. The method according to p. 8, characterized in that the tabular values of the weight coefficient W (n) are determined during calibration. 10. The method according to p. 9, characterized in that the calibration includes the steps of at least one measurement of the volume V of the leaked fluid, the number of pulses of a clock generator and a tachometer transducer for a given amount of fluid, and then determine the average number of pulses of a clock the generator n between the pulses of the tachometric transducer, as well as the average volume v of the fluid corresponding to one pulse of the tachometric transducer, then the dependence v (n) is approximated and share the dependence W (n). 11. The method according to p. 7, characterized in that when determining the number of pulses of the clock generator N _t compare the number of pulses of the clock generator N _t with a given maximum value of N _t ^max . 12. The method according to p. 11, characterized in that when the value of N _t <N _t ^max increase the number of pulses of the clock by 1. 13. The method according to p. 11, characterized in that when the value of N _t ≥ N _t ^max turn off the clock, and when a pulse of the tachometric Converter include a clock.