CN114440998B - Fluid mass flow measuring circuit and fluid mass flow meter - Google Patents
Fluid mass flow measuring circuit and fluid mass flow meter Download PDFInfo
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- CN114440998B CN114440998B CN202111565885.6A CN202111565885A CN114440998B CN 114440998 B CN114440998 B CN 114440998B CN 202111565885 A CN202111565885 A CN 202111565885A CN 114440998 B CN114440998 B CN 114440998B
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- 239000012530 fluid Substances 0.000 title claims abstract description 86
- 238000005259 measurement Methods 0.000 claims abstract description 56
- 238000001514 detection method Methods 0.000 claims description 19
- 238000009529 body temperature measurement Methods 0.000 claims description 13
- 230000003321 amplification Effects 0.000 claims description 12
- 238000003199 nucleic acid amplification method Methods 0.000 claims description 12
- 238000010438 heat treatment Methods 0.000 claims description 7
- 239000003990 capacitor Substances 0.000 description 48
- 238000000605 extraction Methods 0.000 description 38
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 18
- 238000010586 diagram Methods 0.000 description 16
- 229910052697 platinum Inorganic materials 0.000 description 9
- 238000000034 method Methods 0.000 description 8
- 238000001914 filtration Methods 0.000 description 7
- 230000004044 response Effects 0.000 description 5
- 238000004861 thermometry Methods 0.000 description 4
- 230000008878 coupling Effects 0.000 description 3
- 238000010168 coupling process Methods 0.000 description 3
- 238000005859 coupling reaction Methods 0.000 description 3
- 239000000523 sample Substances 0.000 description 3
- 238000000827 velocimetry Methods 0.000 description 3
- 238000004891 communication Methods 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000004590 computer program Methods 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005485 electric heating Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 1
- 239000010931 gold Substances 0.000 description 1
- 229910052737 gold Inorganic materials 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
- G01F1/76—Devices for measuring mass flow of a fluid or a fluent solid material
- G01F1/86—Indirect mass flowmeters, e.g. measuring volume flow and density, temperature or pressure
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Abstract
The invention relates to the technical field of fluid measurement, and discloses a fluid mass flow measurement circuit and a fluid mass flow meter.
Description
Technical Field
The present disclosure relates to fluid measuring technology, and more particularly, to a fluid mass flow measuring circuit and a fluid mass flow meter.
Background
The thermal gas mass flowmeter originates from the 60 s, has been accumulated over 20 years, has been produced in the early 90 s, is a meter for measuring gas flow, and is based on the gold law of resistance measurement by using double platinum by utilizing the relationship between flowing gas and heat source in the gas or heat source outside the measuring tube. The device has the characteristics of high reliability, strong stability, small pressure loss, convenient installation, high measuring range ratio and the like.
At present, the thermal type gas mass flowmeter adopts a microprocessor to measure mass flow, and the microprocessor is required to receive and calculate data, so that the response speed for acquiring a measurement result is slower.
Disclosure of Invention
The following presents a simplified summary in order to provide a basic understanding of some aspects of the disclosed embodiments. This summary is not an extensive overview, and is intended to neither identify key/critical elements nor delineate the scope of such embodiments, but is intended as a prelude to the more detailed description that follows.
In view of the above-mentioned drawbacks of the prior art, the present invention provides a fluid mass flow measuring circuit and a fluid mass flow meter, so as to improve the response speed of obtaining the measurement result.
The invention discloses a fluid mass flow measuring circuit, which comprises: the speed measuring module is connected with the working power supply and is used for measuring the flow velocity of the fluid to be measured in the pipe wall; the temperature measuring module is connected with the constant current source and used for measuring the temperature of the fluid to be measured; the voltage control module is respectively connected with the speed measuring module and the temperature measuring module, and is used for converting the temperature of the temperature measuring module and the flow rate of the speed measuring module into corresponding voltages, determining the temperature difference between the speed measuring module and the temperature measuring module according to the voltage difference between the speed measuring module and the temperature measuring module, and controlling the temperature difference to be kept within a preset threshold range to realize constant temperature difference; and the mass flow determining module is connected with the speed measuring module and is used for determining the mass flow of the fluid to be measured according to the heating power of the speed measuring module and the temperature difference between the speed measuring module and the temperature measuring module.
Optionally, the fluid mass flow measurement circuit further comprises an overcurrent protection module, and the speed measurement module is connected to the working power supply through the overcurrent protection module.
Optionally, the overcurrent protection module comprises a protection MOS tube, a protection triode, a load resistor, a pull-down resistor, a protection resistor and a filtering unit, wherein the working power supply is respectively connected with one end of the load resistor and an emitter of the protection triode, and the other end of the load resistor is respectively connected with a base electrode of the protection triode and a source electrode of the protection MOS tube; the collector electrode of the protection triode is respectively connected with one end of the pull-down resistor and the grid electrode of the protection MOS tube; the other end of the pull-down resistor is grounded; a protection resistor is connected between the source electrode and the drain electrode of the protection MOS tube; the drain electrode of the protection MOS tube is connected with a filter unit output current in parallel; when the protection MOS is in a conducting state, outputting a filtered current signal; when the emitter and the base of the protection triode are conducted, the pull-down resistor is connected with a working power supply, the grid voltage of the protection MOS tube is increased, the protection MOS tube is in a cut-off state, and the working power supply is caused to carry out overcurrent protection through the current output by the protection resistor.
Optionally, the fluid mass flow measurement circuit further includes a current detection module, and the current detection module is connected with the speed measurement module and is used for measuring the current of the speed measurement module.
Optionally, the voltage control module includes a temperature difference setting unit, a voltage operation unit, an amplifier unit, and an adjusting tube, and the fluid mass flow measurement circuit further includes: the temperature difference setting unit is used for outputting a set voltage according to the preset temperature difference threshold value; the input end of the voltage operation unit is respectively connected with the speed measurement module, the temperature measurement module and the current detection module, and the voltage operation unit is used for outputting operation voltage according to the voltage of the speed measurement module, the voltage of the temperature measurement module and the voltage of the current detection module; the input end of the amplifier unit is respectively connected with the output end of the voltage operation unit and the output end of the temperature difference setting unit, the output end of the amplifier unit is connected with the base electrode of the adjusting tube, the working power supply is connected with the speed measuring module after passing through the collector electrode and the emitter electrode of the adjusting tube in sequence, and the amplifier unit is used for determining the output current of the adjusting tube according to the temperature difference between the speed measuring module and the temperature measuring module after comparing with the set voltage serving as a reference, so as to reversely control the operation voltage to be kept in the set voltage.
Optionally, the voltage operation unit includes a first amplifying subunit, a second amplifying subunit, a third amplifying subunit, a dividing subunit, and a subtracting subunit, and the fluid mass flow measurement circuit further includes: the input end of the first amplifying subunit is connected with the speed measuring module, the second amplifying subunit is connected with the current detecting module, and the input end of the third amplifying subunit is connected with the temperature measuring module; the input end of the dividing subunit is respectively connected with the output end of the first amplifying subunit and the output end of the second amplifying subunit; the input end of the subtracting subunit is respectively connected with the output end of the third amplifying subunit and the output end of the dividing subunit, and the output end of the subtracting subunit is connected with the second input end of the amplifying unit.
Optionally, the voltage operation unit further includes a voltage follower subunit, an output end of the division subunit is connected to an input end of the subtraction subunit through the voltage follower subunit, and the voltage follower subunit is used for isolating signal interference between the division subunit and the subtraction subunit.
Optionally, the set voltage is determined by: Wherein V 7 is the set voltage, K is an operation coefficient, T s is the preset temperature difference threshold, K 1 is the gain of the first amplifying subunit, K 2 is the gain of the second amplifying subunit, K 3 is the gain of the dividing subunit, K 5 is the gain of the third amplifying subunit, a 1 is the temperature coefficient between the tachometer resistor and the temperature of the tachometer module, a 2 is the temperature coefficient between the temperature measuring resistor and the temperature of the temperature measuring module, R 1 is the resistor of the current detecting module, and I PT2 is the current of the constant current source.
Optionally, the mass flow of the fluid to be measured is determined by: Wherein, Q m is the mass flow of the fluid to be measured, S is the cross-sectional area of the fluid to be measured, V is the flow velocity of the fluid to be measured, P PT1 is the speed measurement power of the speed measurement module, Δt is the temperature difference between the speed measurement module and the temperature measurement module, and n 1、n2、n3 is a preset calibration parameter.
The invention discloses a fluid mass flow meter which is characterized by comprising the fluid mass flow measuring circuit.
The invention has the beneficial effects that: connecting a speed measuring module for measuring the flow velocity of fluid to be measured in a pipe wall with a working power supply, connecting a temperature measuring module for measuring the temperature of the fluid to be measured with a constant current source, respectively connecting the speed measuring module and the temperature measuring module through a voltage control module, converting the temperature of the temperature measuring module and the flow velocity of the speed measuring module into corresponding voltages, determining the temperature difference between the temperature measuring module and the temperature measuring module according to the voltage difference between the speed measuring module and the temperature measuring module, further controlling the temperature difference to be kept within a preset threshold range to realize constant temperature difference, and connecting a mass flow determining module with the speed measuring module to determine the mass flow of the fluid to be measured according to the heating power of the speed measuring module and the temperature difference between the speed measuring module and the temperature measuring module.
Drawings
FIG. 1 is a schematic diagram of a representative model of Goldahl's law in an embodiment of the invention;
FIG. 2 is a schematic diagram of a fluid mass flow measurement circuit according to an embodiment of the present invention;
FIG. 3 is a schematic diagram of an embodiment of an over-current protection module;
FIG. 4 is a schematic diagram of another fluid mass flow measurement circuit according to an embodiment of the present invention;
FIG. 5 is a schematic diagram of a signal power extraction unit according to an embodiment of the present invention;
FIG. 6 is a schematic diagram of a constant current source circuit in accordance with an embodiment of the present invention;
FIG. 7 is a schematic diagram of a pre-amplifying subunit according to an embodiment of the present invention;
FIG. 8 is a schematic diagram of a division subunit according to an embodiment of the present invention;
FIG. 9 is a schematic diagram of a temperature difference setting unit according to an embodiment of the present invention;
Fig. 10 is a schematic diagram of an amplifier unit in an embodiment of the invention.
Detailed Description
Other advantages and effects of the present invention will become apparent to those skilled in the art from the following disclosure, which describes the embodiments of the present invention with reference to specific examples. The invention may be practiced or carried out in other embodiments that depart from the specific details, and the details of the present description may be modified or varied from the spirit and scope of the present invention. It should be noted that, without conflict, the following embodiments and sub-samples in the embodiments may be combined with each other.
It should be noted that the illustrations provided in the following embodiments merely illustrate the basic concept of the present invention by way of illustration, and only the components related to the present invention are shown in the drawings and are not drawn according to the number, shape and size of the components in actual implementation, and the form, number and proportion of the components in actual implementation may be arbitrarily changed, and the layout of the components may be more complicated.
In the following description, numerous details are set forth in order to provide a more thorough explanation of embodiments of the present invention, it will be apparent, however, to one skilled in the art that embodiments of the present invention may be practiced without these specific details, in other embodiments, well-known structures and devices are shown in block diagram form, rather than in detail, in order to avoid obscuring the embodiments of the present invention.
The terms first, second and the like in the description and in the claims of the embodiments of the disclosure and in the above-described figures are used for distinguishing between similar objects and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used may be interchanged where appropriate in order to describe embodiments of the present disclosure. Furthermore, the terms "comprise" and "have," as well as any variations thereof, are intended to cover a non-exclusive inclusion.
The term "plurality" means two or more, unless otherwise indicated.
In the embodiment of the present disclosure, the character "/" indicates that the front and rear objects are an or relationship. For example, A/B represents: a or B.
The term "and/or" is an associative relationship that describes an object, meaning that there may be three relationships. For example, a and/or B, represent: a or B, or, A and B.
Referring to fig. 1, the golden's law typical model includes a velocimetry module 101 and a thermometry module 102, q To be measured is the flow direction of a fluid to be measured, and the flow rate of the fluid to be measured is determined by:
Wherein, I PT1 is the driving current of the speed measuring module, R PT1 is the resistance of the speed measuring module, n 1、n2、n3 is a preset calibration parameter, V is the flow velocity of the fluid to be measured, T PT1 is the temperature of the speed measuring module, and T PT2 is the temperature of the temperature measuring module.
Optionally, n 1、n2 is determined by at least one of the parameters of the size of the metal probe, the fluid property of the fluid to be measured, the environmental flow conditions, etc., wherein the metal probe is used for measuring the temperature of the velocimetry module or the thermometry module.
Optionally, the speed measuring module or the temperature measuring module comprises an electric heating element, and a platinum resistor can be specifically adopted.
Alternatively, the resistance value of the platinum resistance is determined by:
R＝β+A·T，
Wherein R is the resistance value of the platinum resistor, beta is the reference resistance of the platinum resistor, A is the temperature coefficient of the platinum resistor, and T is the surface temperature of the platinum resistor.
In some embodiments, the tachometer module and the thermometry module are both PT100 platinum resistors, wherein the temperature coefficient of PT100 platinum resistor is 0.39 Ω/°c.
As shown in conjunction with fig. 2, an embodiment of the present disclosure provides a fluid mass flow measurement circuit including a velocimetry module 201, a thermometry module 202, a voltage control module 203, and a mass flow determination module 204. The speed measuring module 201 is connected with the working power supply A and is used for measuring the flow velocity of the fluid to be measured in the pipe wall. The temperature measurement module 202 is connected to the constant current source B for measuring the temperature of the fluid to be measured. The voltage control module 203 is respectively connected with the speed measuring module and the temperature measuring module, and is used for converting the temperature of the temperature measuring module and the flow rate of the speed measuring module into corresponding voltages, determining the temperature difference between the temperature measuring module and the temperature measuring module according to the voltage difference between the speed measuring module and the temperature measuring module, and controlling the temperature difference to be kept within a preset threshold range to realize constant temperature difference. The mass flow rate determining module 204 is connected with the speed measuring module and is used for determining the mass flow rate of the fluid to be measured according to the heating power of the speed measuring module and the temperature difference between the speed measuring module and the temperature measuring module.
By adopting the fluid mass flow measuring circuit provided by the embodiment of the disclosure, the speed measuring module for measuring the flow velocity of the fluid to be measured in the pipe wall is connected with the working power supply, the temperature measuring module for measuring the temperature of the fluid to be measured is connected with the constant current source, the speed measuring module and the temperature measuring module are respectively connected through the voltage control module so as to convert the temperature of the temperature measuring module and the flow velocity of the speed measuring module into corresponding voltages, the temperature difference between the temperature measuring module and the temperature measuring module is determined according to the voltage difference between the speed measuring module and the temperature measuring module, the temperature difference is further controlled to be kept within a preset threshold range to realize constant temperature difference, the mass flow determining module is connected with the speed measuring module so as to determine the mass flow of the fluid to be measured according to the heating power of the speed measuring module and the temperature difference between the speed measuring module and the temperature measuring module, and compared with the mass flow of the fluid to be measured obtained by adopting a microprocessor, the mass flow of the fluid to be measured is measured in a pure hardware mode, and the response speed of obtaining a measurement result is improved.
Optionally, the fluid mass flow measurement circuit further comprises an overcurrent protection module, and the speed measurement module is connected to the working power supply through the overcurrent protection module. Thus, the overcurrent protection module prevents the overcurrent from passing through the circuit, thereby preventing the circuit from being damaged and improving the safety and reliability of the circuit.
Referring to fig. 3, an embodiment of the present disclosure provides an overcurrent protection module, which includes a protection MOS transistor 301, a protection triode 302, a load resistor 303, a pull-down resistor 304, a protection resistor 305, and a filtering unit 306. The working power supply A is respectively connected with one end of the load resistor 303 and the emitter of the protection triode 302, and the other end of the load resistor is respectively connected with the base electrode of the protection triode and the source electrode of the protection MOS tube 301; the collector of the protection triode is respectively connected with one end of the pull-down resistor 304 and the grid electrode of the protection MOS tube; the other end of the pull-down resistor is grounded; a protection resistor 305 is connected between the source electrode and the drain electrode of the protection MOS tube; the drain electrode of the protection MOS tube is connected with a filtering unit 306 in parallel to output current, wherein when the protection MOS is in a conducting state, a filtered current signal is output; when the emitter and the base of the protection triode are conducted, the pull-down resistor is connected with the working power supply, the grid voltage of the protection MOS tube is increased, the protection MOS tube is in a cut-off state, and the working power supply is enabled to carry out overcurrent protection through the current output by the protection resistor.
As shown in connection with fig. 3, the load resistor 303 includes a first load sub-resistor 3031, a second load sub-resistor 3032, and a third load sub-resistor 3033; the filtering unit 306 includes a first filtering capacitance 3061, a second filtering capacitance 3062, and a third filtering capacitance 3063.
Optionally, the fluid mass flow measurement circuit further comprises a flow detection module, and the flow detection module is connected with the speed measurement module and is used for measuring the current of the speed measurement module.
Optionally, the current detection module comprises a current detection resistor, wherein the resistance value of the current detection resistor comprises 1 Ω to 10 Ω.
Optionally, the voltage control module includes a temperature difference setting unit, a voltage operation unit, an amplifier unit, an adjusting tube, and the fluid mass flow measuring circuit further includes: the temperature difference setting unit is used for outputting a set voltage according to a preset temperature difference threshold value; the input end of the voltage operation unit is respectively connected with the speed measuring module, the temperature measuring module and the current detecting module, and the voltage operation unit is used for outputting operation voltage according to the voltage of the speed measuring module, the voltage of the temperature measuring module and the voltage of the current detecting module; the input end of the amplifier unit is respectively connected with the output end of the voltage operation unit and the output end of the temperature difference setting unit, the output end of the amplifier unit is connected with the base electrode of the adjusting tube, the working power supply is connected with the speed measuring module after passing through the collector electrode and the emitter electrode of the adjusting tube in sequence, and the amplifier unit is used for determining the output current of the adjusting tube after comparing with the temperature difference between the speed measuring module and the temperature measuring module according to the set voltage as a reference, so as to reversely control the operation voltage to be kept in the set voltage.
Optionally, the voltage operation unit includes a first amplifying subunit, a second amplifying subunit, a third amplifying subunit, a dividing subunit, a subtracting subunit, and the fluid mass flow measuring circuit further includes: the input end of the first amplifying subunit is connected with the speed measuring module, the second amplifying subunit is connected with the flow detecting module, and the input end of the third amplifying subunit is connected with the temperature measuring module; the input end of the division subunit is respectively connected with the output end of the first amplifying subunit and the output end of the second amplifying subunit; the input end of the subtracting subunit is respectively connected with the output end of the third amplifying subunit and the output end of the dividing subunit, and the output end of the subtracting subunit is connected with the second input end of the amplifying unit.
Optionally, the voltage operation unit further comprises a voltage follower subunit, wherein an output end of the division subunit is connected with an input end of the subtraction subunit through the voltage follower subunit, and the voltage follower subunit is used for isolating signal interference between the division subunit and the subtraction subunit.
As shown in conjunction with fig. 4, an embodiment of the present disclosure provides a fluid mass flow measurement circuit, including a speed measurement module 201, a temperature measurement module 202, a voltage control module 203, a mass flow determination module 204, an over-current protection module 205, and a current detection module 206. The speed measuring module 201 is connected with a working power supply. The temperature measurement module 202 is connected to a constant current source. The flow detection module 206 is connected with the speed measurement module. The voltage control module 203 includes a temperature difference setting unit 2031, a voltage operation unit 2032, an amplifier unit 2033, and an adjustment tube 2034. The voltage operation unit 2032 includes a first amplification subunit 20321, a second amplification subunit 20322, a third amplification subunit 20323, a division subunit 20324, a subtraction subunit 20325, and a voltage follower subunit 20326. The input end of the first amplifying subunit 20321 is connected with a speed measurement module. The second amplifying subunit 20322 is connected to the current detection module. The input end of the third amplifying subunit 20323 is connected with a temperature measurement module. The input of the divide subunit 20324 is connected to the output of the first amplifying subunit and the output of the second amplifying subunit, respectively, and the output of the divide subunit is connected to the input of the subtract subunit through the voltage follower subunit 20326. The input of the subtraction subunit 20325 is connected to the output of the third amplification subunit, and the output of the subtraction subunit is connected to the second input of the amplifier unit 2033. A first input end of the amplifier unit 2033 is connected to an output end of the temperature difference setting unit 2031, and an output end of the amplifier unit is connected to a base electrode of the adjustment tube 2034. The working power supply is connected with the speed measuring module after passing through the overcurrent protection module 205 and the collector and the emitter of the adjusting tube 2034 in sequence,
By adopting the fluid mass flow measuring circuit provided by the embodiment of the disclosure, the speed measuring module for measuring the flow velocity of the fluid to be measured in the pipe wall is connected with the working power supply, the temperature measuring module for measuring the temperature of the fluid to be measured is connected with the constant current source, the speed measuring module and the temperature measuring module are respectively connected through the voltage control module so as to convert the temperature of the temperature measuring module and the flow velocity of the speed measuring module into corresponding voltages, the temperature difference between the temperature measuring module and the temperature measuring module is determined according to the voltage difference between the speed measuring module and the temperature measuring module, the temperature difference is further controlled to be kept within a preset threshold range to realize constant temperature difference, the mass flow determining module is connected with the speed measuring module so as to determine the mass flow of the fluid to be measured according to the heating power of the speed measuring module and the temperature difference between the speed measuring module and the temperature measuring module, and compared with the mass flow of the fluid to be measured obtained by adopting a microprocessor, the mass flow of the fluid to be measured is measured in a pure hardware mode, and the response speed of obtaining a measurement result is improved.
Alternatively, the set voltage is determined by:
Wherein V 7 is a set voltage, K is an operation coefficient, T s is a preset temperature difference threshold, K 1 is a gain of the first amplifying subunit, K 2 is a gain of the second amplifying subunit, K 3 is a gain of the dividing subunit, K 5 is a gain of the third amplifying subunit, a 1 is a temperature coefficient between a tachometer resistor and a tachometer module temperature, a 2 is a temperature coefficient between the thermometer resistor and the thermometer module temperature, R 1 is a resistor of the current detection module, and I PT2 is a current of the constant current source (so that values of left and right sides of K are equal, independent of units).
Referring to fig. 4, in some embodiments, the resistance value of the speed measurement module is R PT1, the current value of the speed measurement module is I PT1, the resistance value of the temperature measurement module is R PT2, the resistance value of the current detection module is 1Ω, the current of the constant current source is 1mA, the gain of the first amplifying subunit is 0.25, the gain of the second amplifying subunit is 5, the gain of the third amplifying subunit is 50, the gain of the dividing subunit is 1, the voltage at the output end of the first amplifying subunitThe voltage V 2＝5·IPT1 at the output end of the second amplifying subunit, the voltage V 3＝0.05·RPT2 at the output end of the third amplifying subunit, the voltage V 4＝0.05·RPT1 at the output end of the dividing subunit (V4 is equal to V1 divided by V2), the voltage V 5＝0.05·(RPT1-RPT2)＝0.05×A×(TPT1-TPT2 at the output end of the subtracting subunit), if A is 0.39Ω/°c, the temperature difference between the speed measuring module and the temperature measuring module is 30 ℃, and the voltage at the output end of the temperature difference setting unit is 0.585V.
Optionally, the mass flow rate determining module includes a signal power extracting unit and a mass flow rate voltage computing unit, where the mass flow rate voltage computing unit is configured to calculate the power obtained by the signal power extracting unit to determine the mass flow rate.
As shown in fig. 5, the embodiment of the disclosure provides a signal power extraction unit, which includes a first power signal extraction chip U51, a second power signal extraction chip U52, a power extraction unit amplifier U53, a first power extraction unit capacitor C51, a second power extraction unit capacitor C52, a third power extraction unit capacitor C53, a fourth power extraction unit capacitor C54, a fifth power extraction unit capacitor C55, a first power extraction unit resistor R51, a second power extraction unit resistor R52, a third power extraction unit resistor R53, a fourth power extraction unit resistor R54, and a fifth power extraction unit resistor R55, wherein the first power signal extraction chip is respectively connected to the first power extraction unit capacitor C51, the second power extraction unit capacitor C52, the third power extraction unit capacitor C53, and the first power extraction unit resistor R51, the input end of the power extraction unit amplifier U53 is respectively connected with the first power extraction unit resistor R51 and the second power extraction unit resistor R52, the reverse input end of the power extraction unit amplifier U53 is respectively connected with the second power extraction unit resistor R52 and the third power extraction unit resistor R53, the homodromous input end of the power extraction unit amplifier U53 is respectively connected with the fourth power extraction unit capacitor C54 and the fourth power extraction unit resistor R54, the second power signal extraction chip U52 is respectively connected with the fourth power extraction unit resistor R54, the fifth power extraction unit resistor R55 and the fifth power extraction unit capacitor C55, wherein the first power extraction unit port P51 is respectively connected with the output end of the first amplification subunit and the first power signal extraction chip, the second power extraction unit port P52 is respectively connected with the homodromous input end of the power extraction unit amplifier U53 and the output end of the second amplification subunit, and the port of the third power extraction unit is connected with the mass flow voltage operation unit.
Referring to fig. 6, the embodiment of the disclosure provides a constant current source circuit, which includes a first constant current source amplifier U61, a second constant current source amplifier U62, a first constant current source capacitor C61, a second constant current source capacitor C62, a first constant current source resistor R61, a second constant current source resistor R62, a third constant current source resistor R63, a fourth constant current source resistor R64, a fifth constant current source resistor R65, a constant current source MOS transistor Q61, a constant current source diode D61, and a constant current source inductance L61, wherein the same-direction input end of the first constant current source amplifier U61 is respectively connected with 10V voltage and the first constant current source capacitor C61, the reverse input end of the first constant current source capacitor C61 is sequentially connected with the first constant current source resistor R61 and the second constant current source resistor R62, the power input end of the first constant current source capacitor C61 is respectively connected with 12V voltage and the second constant current source capacitor C62, the output end of the first constant current source capacitor C61 is connected with the third constant current source resistor R63, the reverse input end of the second constant current source amplifier U62 is respectively connected with the third constant current source resistor R63 and the gate of the MOS transistor Q61, the second constant current source amplifier U62 is sequentially connected with the second constant current source input end of the first constant current source resistor R62, the constant current source amplifier U62 is sequentially connected with the fourth constant current source resistor R61, the constant current source resistor R64 and the constant current source resistor Q61 is sequentially connected with the fourth constant current source resistor.
Optionally, at least one of the first amplifying subunit or the second amplifying subunit is a preset amplifying subunit.
Referring to fig. 7, the embodiment of the disclosure provides a preset amplifying subunit, which includes an amplifying chip U71, a first amplifying unit capacitor C71, a second amplifying unit capacitor C72, a third amplifying unit capacitor C73, a fourth amplifying unit capacitor C74, a fifth amplifying unit capacitor C75, a sixth amplifying unit capacitor C76, a first amplifying unit resistor R71, a second amplifying unit resistor R72, and a third amplifying unit resistor R73, where the first amplifying unit port P71 is connected to the first amplifying unit resistor R71 and the first amplifying unit capacitor C71, the amplifying chip U71 is connected to the first amplifying unit resistor R71, the second amplifying unit resistor R72, the third amplifying unit resistor R73, +12v voltage, -12v voltage, the second amplifying unit capacitor C72, the third amplifying unit capacitor C73, the fourth amplifying unit capacitor C74, the fifth amplifying unit capacitor C75, and the sixth amplifying unit capacitor C76, and the amplifying chip U71 outputs an amplified signal through the second amplifying unit port P72 and the third amplifying unit port P73.
Referring to fig. 8, an embodiment of the disclosure provides a dividing subunit, including a divider chip U81, a first dividing unit amplifier U82, a second dividing unit amplifier U83, a third dividing unit amplifier U84, a first dividing unit capacitor C81, a second dividing unit capacitor C82, a third dividing unit capacitor C83, a fourth dividing unit capacitor C84, a fifth dividing unit capacitor C85, a first dividing unit resistor R81, a second dividing unit resistor R82, a third dividing unit resistor R83, a fourth dividing unit resistor R84, a fifth dividing unit resistor R85, a sixth dividing unit resistor R86, a seventh dividing unit resistor R87, an eighth dividing unit resistor R88, a ninth dividing unit resistor R89, and a tenth dividing unit resistor R810, wherein the divider chip is respectively connected to a working power VCC, -12V power supply, the first dividing unit capacitor C81, and the fifth dividing unit resistor R85, the homodromous input end of the first division unit amplifier U82 is connected with a first division unit resistor R81, the reverse input end of the first division unit amplifier U82 is respectively connected with a second division unit resistor R82 and a third division unit resistor R83, the output end of the first division unit amplifier U82 is connected with the second division unit resistor R82, the third division unit resistor R83 is connected with a fourth division unit resistor R84, the power input end of the first division unit amplifier U82 is respectively connected with a +12V power supply and a second division unit capacitor C82, the power output end of the first division unit amplifier U82 is respectively connected with a-12V power supply and a third division unit capacitor C83, the homodromous input end of the second division unit amplifier U83 is connected with a seventh division unit resistor R87, the reverse input end of the second division unit amplifier U83 is respectively connected with a fifth division unit resistor R85 and a sixth division unit resistor R86, the output end of the second division unit amplifier U83 is connected with the first division unit resistor R81, the output end of the third division unit amplifier U84 is respectively connected with the sixth division unit resistor R86 and the eighth division unit resistor R88, the power input end of the third division unit amplifier U83 is respectively connected with the +12V power supply and the fourth division unit capacitor C84, the power output end of the third division unit amplifier U83 is respectively connected with the-12V power supply and the fifth division unit capacitor C85, the homodromous input end of the third division unit amplifier U83 is connected with the tenth division unit resistor R810, and the reverse input end of the third division unit amplifier U83 is respectively connected with the eighth division unit resistor R88 and the ninth division unit resistor R89.
As shown in fig. 9, the embodiment of the disclosure provides a temperature difference setting unit, which includes a temperature difference setting unit output end P91, a temperature difference setting unit input end P92, a first temperature difference setting unit amplifier U91, a second temperature difference setting unit amplifier U92, a first temperature difference setting unit resistor R91, a second temperature difference setting unit resistor R92, a third temperature difference setting unit resistor R93, a fourth temperature difference setting unit resistor R94, a fifth temperature difference setting unit resistor R95, a sixth temperature difference setting unit resistor R96, a seventh temperature difference setting unit resistor R97, a first temperature difference setting unit capacitor C91, a second temperature difference setting unit capacitor C92, a third temperature difference setting unit capacitor C93, a fourth temperature difference setting unit capacitor C94, wherein the output end of the first temperature difference setting unit amplifier U91 is connected with the second temperature difference setting unit capacitor C92 and the third temperature difference setting unit resistor R93 respectively, the third temperature difference setting unit resistor R93 is connected with the first temperature difference setting unit resistor R91 and the second temperature difference setting unit resistor R92 respectively, the first temperature difference setting unit resistor R91 is connected with the fourth temperature difference setting unit resistor R92 and the fourth temperature difference setting unit resistor R92, the output end of the fourth temperature difference setting unit amplifier U92 is connected with the fourth temperature difference setting unit amplifier U92, the fourth temperature difference setting unit amplifier is connected with the fourth temperature difference setting unit output end of the fourth temperature difference setting unit amplifier 96, the fourth temperature difference setting unit amplifier is connected with the fourth temperature difference setting unit resistor R94, the fourth temperature difference setting unit capacitor C94 is connected with the fifth temperature difference setting unit resistor R95, the power input end of the second temperature difference setting unit amplifier U92 is connected with +24V voltage and the third temperature difference setting unit capacitor C93, the temperature difference setting unit output end P91 is respectively connected with the first temperature difference setting unit resistor R91, the second temperature difference setting unit resistor R92 and the third temperature difference setting unit resistor R93, and the temperature difference setting unit input end P92 is connected with the fourth temperature difference setting unit resistor R94.
Referring to fig. 10, an embodiment of the disclosure provides an amplifier unit, which includes an input end P101 of the amplifier unit, an output end P102 of the amplifier unit, an amplifier unit triode Q101, a first amplifier unit resistor R101, a second amplifier unit resistor R102, a third amplifier unit resistor R103, and a first amplifier unit capacitor C101, wherein a base of the amplifier unit triode Q101 is connected to the input end P101 of the amplifier unit, a collector of the amplifier unit triode Q101 is connected to the output end P102 of the amplifier unit through the third amplifier unit resistor R103, an emitter of the amplifier unit triode Q101 is connected to a 24V power supply through the second amplifier unit resistor R102, the first amplifier unit resistor R101 is respectively connected to a collector and an emitter of the amplifier unit triode Q101, and the first amplifier unit capacitor C101 is connected to the emitter of the amplifier unit triode Q101.
Optionally, the mass flow of the fluid to be measured is determined by:
Wherein Q m is the mass flow of the fluid to be measured, S is the cross-sectional area of the fluid to be measured, V is the flow velocity of the fluid to be measured, P PT1 is the speed measurement power of the speed measurement module, deltaT is the temperature difference between the speed measurement module and the temperature measurement module, and n 1、n2、n3 is a preset calibration parameter.
Embodiments of the present disclosure provide a fluid mass flow meter including the fluid mass flow measurement circuit described above.
According to the fluid mass flow meter, the speed measuring module for measuring the flow velocity of the fluid to be measured in the tube wall is connected with the working power supply, the temperature measuring module for measuring the temperature of the fluid to be measured is connected with the constant current source, the voltage control module is respectively connected with the speed measuring module and the temperature measuring module so as to convert the temperature of the temperature measuring module and the flow velocity of the speed measuring module into corresponding voltages, the temperature difference between the temperature measuring module and the temperature measuring module is determined according to the voltage difference between the speed measuring module and the temperature measuring module, the temperature difference is controlled to be kept within a preset threshold range, the temperature difference is constant, the mass flow determining module is connected with the speed measuring module so as to determine the mass flow of the fluid to be measured according to the heating power of the speed measuring module and the temperature difference between the speed measuring module and the temperature measuring module, and compared with the mass flow of the fluid to be measured obtained by adopting a microprocessor, the mass flow of the fluid to be measured is measured in a pure hardware mode, and the response speed of obtaining a measurement result is improved.
The above description and the drawings illustrate embodiments of the disclosure sufficiently to enable those skilled in the art to practice them. Other embodiments may involve structural, logical, electrical, process, and other changes. The embodiments represent only possible variations. Individual components and functions are optional unless explicitly required, and the sequence of operations may vary. Portions and sub-samples of some embodiments may be included in or substituted for portions and sub-samples of other embodiments. Moreover, the terminology used in the present application is for the purpose of describing embodiments only and is not intended to limit the claims. As used in the description of the embodiments and the claims, the singular forms "a," "an," and "the" (the) are intended to include the plural forms as well, unless the context clearly indicates otherwise. Similarly, the term "and/or" as used in this disclosure is meant to encompass any and all possible combinations of one or more of the associated listed. In addition, when used in this disclosure, the terms "comprises," "comprising," and/or variations thereof mean the presence of the stated sub-sample, integer, step, operation, element, and/or component, but do not exclude the presence or addition of one or more other sub-samples, integers, steps, operations, elements, components, and/or groups of these. Without further limitation, an element defined by the phrase "comprising one …" does not exclude the presence of other like elements in a process, method or apparatus that includes the element. In this context, each embodiment may be described with emphasis on the differences from the other embodiments, and the same similar parts between the various embodiments may be referred to each other. For the methods, products, etc. disclosed in the embodiments, if they correspond to the method sections disclosed in the embodiments, the description of the method sections may be referred to for relevance.
In the embodiments disclosed herein, the disclosed methods, articles of manufacture (including but not limited to devices, apparatuses, etc.) may be practiced in other ways. For example, the apparatus embodiments described above are merely illustrative, and for example, the division of the units may be merely a logical function division, and there may be additional divisions when actually implemented, for example, multiple units or components may be combined or integrated into another system, or some sub-samples may be omitted, or not performed. In addition, the coupling or direct coupling or communication connection shown or discussed with each other may be through some interface, device or unit indirect coupling or communication connection, which may be in electrical, mechanical or other form. The units described as separate units may or may not be physically separate, and units shown as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units may be selected according to actual needs to implement the present embodiment. In addition, each functional unit in the embodiments of the present disclosure may be integrated in one processing unit, or each unit may exist alone physically, or two or more units may be integrated in one unit.
The flowcharts and block diagrams in the figures illustrate the architecture, functionality, and operation of possible implementations of systems, methods and computer program products according to embodiments of the present disclosure. In this regard, each block in the flowchart or block diagrams may represent a module, segment, or portion of code, which comprises one or more executable instructions for implementing the specified logical function(s). In some alternative implementations, the functions noted in the block may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. In the description corresponding to the flowcharts and block diagrams in the figures, operations or steps corresponding to different blocks may also occur in different orders than that disclosed in the description, and sometimes no specific order exists between different operations or steps. For example, two consecutive operations or steps may actually be performed substantially in parallel, they may sometimes be performed in reverse order, which may be dependent on the functions involved. Each block of the block diagrams and/or flowchart illustration, and combinations of blocks in the block diagrams and/or flowchart illustration, can be implemented by special purpose hardware-based systems which perform the specified functions or acts, or combinations of special purpose hardware and computer instructions.
Claims (6)
1. A fluid mass flow measurement circuit, comprising:
The speed measuring module is connected with the working power supply and is used for measuring the flow velocity of the fluid to be measured in the pipe wall;
The temperature measuring module is connected with the constant current source and used for measuring the temperature of the fluid to be measured;
The voltage control module is respectively connected with the speed measuring module and the temperature measuring module, and is used for converting the temperature of the temperature measuring module and the flow rate of the speed measuring module into corresponding voltages, determining the temperature difference between the speed measuring module and the temperature measuring module according to the voltage difference between the speed measuring module and the temperature measuring module, and controlling the temperature difference to be kept within a preset threshold range to realize constant temperature difference;
The mass flow determining module is connected with the speed measuring module and is used for determining the mass flow of the fluid to be measured according to the heating power of the speed measuring module and the temperature difference between the speed measuring module and the temperature measuring module;
The fluid mass flow measurement circuit further comprises a flow detection module, wherein the flow detection module is connected with the speed measurement module and is used for measuring the current of the speed measurement module;
the voltage control module comprises a temperature difference setting unit, a voltage operation unit, an amplifier unit and an adjusting tube, and the fluid mass flow measuring circuit further comprises a temperature difference setting unit which is used for outputting a set voltage according to the preset temperature difference threshold; the input end of the voltage operation unit is respectively connected with the speed measurement module, the temperature measurement module and the current detection module, and the voltage operation unit is used for outputting operation voltage according to the voltage of the speed measurement module, the voltage of the temperature measurement module and the voltage of the current detection module; the input end of the amplifier unit is respectively connected with the output end of the voltage operation unit and the output end of the temperature difference setting unit, the output end of the amplifier unit is connected with the base electrode of the adjusting tube, the working power supply is connected with the speed measuring module after passing through the collector electrode and the emitter electrode of the adjusting tube in sequence, and the amplifier unit is used for determining the output current of the adjusting tube after comparing with the temperature difference between the speed measuring module and the temperature measuring module according to the set voltage as a reference, and further reversely controlling the operation voltage to be kept in the set voltage;
The voltage operation unit comprises a first amplification subunit, a second amplification subunit, a third amplification subunit, a division subunit and a subtraction subunit, wherein the fluid mass flow measurement circuit further comprises a speed measurement module, the input end of the first amplification subunit is connected with the speed measurement module, the second amplification subunit is connected with the flow detection module, and the input end of the third amplification subunit is connected with the temperature measurement module; the input end of the dividing subunit is respectively connected with the output end of the first amplifying subunit and the output end of the second amplifying subunit; the input end of the subtracting subunit is respectively connected with the output end of the third amplifying subunit and the output end of the dividing subunit, and the output end of the subtracting subunit is connected with the second input end of the amplifying unit;
the set voltage is determined by: Wherein V 7 is the set voltage, K is an operation coefficient, T s is the preset temperature difference threshold, K 1 is the gain of the first amplifying subunit, K 2 is the gain of the second amplifying subunit, K 3 is the gain of the dividing subunit, K 5 is the gain of the third amplifying subunit, a 1 is a temperature coefficient between the tachometer resistor and the temperature of the tachometer module, a 2 is a temperature coefficient between the temperature measuring resistor and the temperature of the temperature measuring module, R 1 is the resistor of the current detecting module, and I PT2 is the current of the constant current source.
2. The fluid mass flow measurement circuit of claim 1, further comprising an over-current protection module, the speed measurement module being connected to the operating power supply through the over-current protection module.
3. The fluid mass flow measurement circuit of claim 2, wherein the over-current protection module comprises a protection MOS tube, a protection triode, a load resistor, a pull-down resistor, a protection resistor and a filter unit,
The working power supply is respectively connected with one end of the load resistor and the emitter of the protection triode, and the other end of the load resistor is respectively connected with the base electrode of the protection triode and the source electrode of the protection MOS tube; the collector electrode of the protection triode is respectively connected with one end of the pull-down resistor and the grid electrode of the protection MOS tube; the other end of the pull-down resistor is grounded; a protection resistor is connected between the source electrode and the drain electrode of the protection MOS tube; the drain electrode of the protection MOS tube is connected with a filter unit output current in parallel;
When the protection MOS is in a conducting state, outputting a filtered current signal; when the emitter and the base of the protection triode are conducted, the pull-down resistor is connected with a working power supply, the grid voltage of the protection MOS tube is increased, the protection MOS tube is in a cut-off state, and the working power supply is caused to carry out overcurrent protection through the current output by the protection resistor.
4. The fluid mass flow measurement circuit of claim 1, wherein the voltage operation unit further comprises a voltage follower subunit, the output of the division subunit being connected to the input of the subtraction subunit through the voltage follower subunit, the voltage follower subunit being configured to isolate signal interference between the division subunit and the subtraction subunit.
5. The fluid mass flow measurement circuit of any one of claims 1 to 4, wherein the mass flow of the fluid to be measured is determined by:
Wherein, Q m is the mass flow of the fluid to be measured, S is the cross-sectional area of the fluid to be measured, V is the flow velocity of the fluid to be measured, P PT1 is the speed measurement power of the speed measurement module, Δt is the temperature difference between the speed measurement module and the temperature measurement module, and n 1、n2、n3 is a preset calibration parameter.
6. A fluid mass flow meter comprising the fluid mass flow measurement circuit of any of claims 1 to 5.
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| CN115452080B (en) * | 2022-08-08 | 2024-06-11 | 重庆川仪自动化股份有限公司 | Signal linearization circuit and method for thermal gas mass flowmeter |
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