SU894527A1 - Device for measuring parameters of gas media - Google Patents

Description

one

The invention relates to a measuring technique and can be used in determining the humidity and temperature of gases.

A device for measuring the humidity of gases is known, consisting of two high-frequency generators f and fg, an electronic modulator, a passive mixer on resistors, a buffer stage, made according to the emitter-coupling amplifier circuit, the input transistor being connected according to a common-collector circuit, the output transistor is according to the common base scheme cz, and the measuring circuit in the collector, consisting of inductance, trimmer capacitance, measuring capacitor and humidity sensor, detector, low-frequency amplifier and indicator 1.

A disadvantage of this device is the low measurement accuracy.

The closest to the present invention is a device for measuring parameters of gaseous media in which third-degree polynomials, approximating dependences Pj (KVA I / PH (RC and their product), are calculated by analog methods.

where Рц is the partial pressure of water vapor;

P (is the pressure of the above water vapor;

R. - resistance of a wet thermometer;

RJ, is the resistance of a dry thermometer,

and also implementation

10 dependencies (Re)., (Ерd) (where t is the temperature of water vapor; tr is the temperature of saturated water vapor) based on a piecewise linear approximation of the correction function (the difference between the function and its linear approximation).

The system consists of several hundred converters,

20 devices, a block of clock intervals, a moisture meter containing intervals Int. 1, Int. 2 and Int. 3, the outputs of which are connected to comparators that emit signals to the automatic unit of the moisture meter, which connects to the integrators of sources of disputed voltages , as well as a thermometer, generator of exemplary frequency, reversible pulse counter (RSI),

a switch allowing signals from the functional converters to control the RSI depending on the measurement mode and three memory registers with digital reading devices 2,

The disadvantages of the known device are low accuracy of measuring the humidity of gaseous media due to the use for approximating the dependencies P (Cdd), 1 / P (R,) and other analog elements, as well as due to approximation by these elements not real, but approximated by a polynomial of the third degree dependencies, the large hardware complexity of the system, which includes hundreds of diode converters, is necessary for the analog method of generating functions, the impossibility of measuring the parameters of the gaseous media of objects located over a considerable distance (since the transfer of analog signals over long distances is extremely difficult), as well as a narrow temperature range limited by the 3rd degree of the approximating polynomial. Note that increasing the temperature range by increasing the polynomial degree would result in a significant increase in the number of diode converters.

The purpose of the invention is to increase the fineness of measurement of parameters of gas media, reduce hardware complexity and enable measurement of the parameters of gas environments of distant objects.

This goal is achieved in that an analog-to-digital converter (. ADC), the address generator of the storage device representing the calculator, is inserted into a device for measuring parameters of gas media containing a distribution switch, a digital indicator and a sensor whose outputs are connected to the inputs of a KOiviMyTaTOpa distribution board. constants and offset graph to the left on the x-axis, counter and register of analog-to-digital converter, storage device (memory), processor switch, converter from binary to binary-decimal code and a processor containing registers P and Pg, registers equipped with right and left shift circuits by one bit of P3 and P, an adder, commutator commutator and a reverse code circuit, the output of the distribution switch is connected via An analog-to-digital converter and a memory address shaper to the information inputs of meter triggers (high ADC bits) and a register (low-bit ADC bits) of an analog-to-digital converter, and the ADC counter outputs are connected to the memory address inputs, signals whose output buses arrive at the processor switch inputs in the first switching direction, in the second switching direction of which (for the lower bits) signals from the output buses of the ADC register arrive, and in the third direction of switching signals from the output buses of the processor register Fg, in addition, output signals the processor switch is connected to the inputs of the register P of the processor, the output of which is fed to the inputs of the FO1 circuit of the return code and the switch of the adder in the first direction of the switch the second direction of which receives signals from the output buses of the reverse code formation circuit, and the switch outputs of the adder are connected to the inputs of one of the adder's components, to the inputs of the second term of which are connected the outputs of the P register of the processor, which are also connected to the information inputs of the relay register The outputs of which through the converter from binary to binary code are connected to the inputs of the digital indicators P of the processor, and the outputs of the adder are connected to the information inputs of the register the country of the processor, and, in addition, the output of the higher bit of the register Rd of the processor is connected to the input of the lower bit of the register Rd of the processor in the direction of the left shift, the output of which is connected to the input of the control unit, and the corresponding outputs of the control unit are connected to the control and clock inputs of all units included in the device.

The drawing shows a block diagram of the device.

The device contains a resistance sensor 1, distribution switch 2, analog-digital converter 3, ADC counter 4, register 5 ADC, memory 6, processor switch 7, processor registers 8 and 9 respectively, reverse code generation circuit 10, adder switch 11, adder 12 , the shift registers 13 and 14 of the processor Pd and P, respectively, the control unit 15, the converter 16 from binary to binary-decimal-crd, digital indicator 17 and the memory address generator 18.

The outputs of the resistance sensor 1 are connected to the inputs of the distribution switch 2, and its output is connected via the ADC 3 and the driver 18 to the information inputs of the ADC counter 4 triggers (high ADC bits) and the ADC 5 register (lower ADC bits), and the outputs of the ADC counter are connected To the address inputs of the storage unit 6, the output buses of which are connected to the inputs of the processor switch 7 in the first direction of switching, in the second direction of switching, the output buses of the register 8 processes P, in addition to the output, are connected Processor cohmutator 7s are connected to inputs of processor register 9, whose outputs are connected to the inputs of the circuit 10 formed and the return code and the commutator switch 11 in the first switching direction, in the second commutation direction of which the output buses of the circuit 10 generating the connection are connected, and the outputs the switch 11 of the adder is connected to the inputs of one of the components of the adder 12, to the inputs of the second component of which are connected the outputs of the register 13 of the processor Rd, which, moreover, are connected to the information The inputs of the RZ processor register 14, the outputs of which through the converter 16 from binary to binary to decimal code are connected to the inputs of the digital indicator 17, and its low-order bit is also connected to the input of the control unit and register 8 of the processor P and the outputs The adder 12 is connected to the information inputs of the register P4 13 of the processor, and, in addition, the output of the higher bit of the register 13 is connected to the input of the shift to the left of the register 14. The device operates in the modes of measuring the relative humidity of gas (Cf), gas temperature (t), temperature the dew point of the gas (G). The measurement of the relative humidity of a gas is carried out by calculating the formula I p °. i c-RSYp. with e with s; where ROS is the pressure of the saturated feud vapor, corresponding to the resistance g, -Rgc odCE.Ia) f-- interpolation step. -integer; - corresponds to the resistance. For all I, similar ratios are fulfilled for P ° and P with respect to RU. t and C is carried out according to the measurement formula LF ;, g - g ° where t (C) and t ° (t °) correspond to the resistances moaceji) c-, V / / R, (e.) L B R --f - V with Ve g In the moisture meter mode, the control unit generates a sequence of control pulses for which: the following operations are performed. After arriving from the distribution switch through the ADC and the address memory generator, the value corresponding to the resistance E, the control unit 15 generates a signal on which information is received to the ADC register and the ADC counter. Further, according to the information recorded in the ADC counter, the water vapor pressure code corresponding to the resistance Rc-Rcwiod {t, f2) E is read from the memory and written along the first switching direction of the processor switch to the processor's P register. In the same clock cycle, the processor register register (13) is zeroed. Then through the switch 11 of the adder and the adder 12 (folding from 0) the code from the register P of the processor is copied to the register P 2 of the processor. In the next work cycle, the unit is subtracted from the ADC counter, and thus the resistance code is generated, which corresponds to which is read from memory P and written to the register P (9) of the processor in the first switching direction. After that, the contents of register 9 are subtracted from the contents of register 13, i.e. a PC-PC difference is generated, which is written to register 13. Next, the information from register 13 is copied from register 13 to the register 14 in the ADC register in the second direction of the processor switch. Then, according to a standard program written in the control block, multiplying the codes recorded in registers 9 and 14 (with the help of the register 13), the product Rc-Rc od (e./2) e 1 is formed (with This control unit it analyzes the first register register 14 in each operating cycle).

The work is generated in register 13,

In the next clock cycle, according to the counter code, the ADC reads the PC code from the charger into the processor's Py register. Next, the contents of register 13 and 9 are added, and in register 13 the value is generated

V c- odjWO

Pc y

which is rewritten into register 8. Then the resistance value is processed by a similar program.

R

In with

Calculated value

P + t ftc-R8ctw d (& il2), ni -o

Lg TGG LS nt

The sun

"G

formed in register 13.

In the next cycle, information from register 8 is rewritten in the third direction to register 9, and according to the standard program, the contents of register 13 are divided by the code recorded in register 9 (the low order of register 14 is analyzed in each working cycle). The value of the quotient is formed in register 14 (on the left-shift circuit, the information is copied from the high register register 13 to the low register register 14) and recorded through the converter 16 by a digital indicator.

If the external toggle switch 18 one-time counting in the control unit sets the one-time counting mode, then the calculations are interrupted; if the toggle switch is not in the indicated state, then the same calculations are repeated again.

The operation of the device in the calculation modes t (Rc) H C (Rec) is completely analogous to the calculation of the magnitude

about Rc-RcmodCgil2) fpi roch

RS

3 of the moisture meter mode (the difference between the functioning of the device in these modes and the moisture meter mode is only that other ROM cells are used to calculate t and Γ)

The result is generated in register 13 and rewritten into register 14.

The complexity of the device is determined by the size of the registers, switches, adder and charger included in the device, as well as the number of memory cells.

All of these values depend on the required accuracy of the calculation of f, t and IT. The error in determining the humidity is determined by the formula

Drs

Pfec p

HS

U.PQ and dP Qf are the errors in determining the pressure of water and saturated water vapor, respectively.

iM „.

where l Pgc and l P are the errors of the method for determining pressure P

and P

the sun

6pfc and dere

calculation errors by pressure device and PC by the specified method. . t

.

lrs)

p G (PB

Blue since Pgc P &

Dependencies Rcs () with

t (RC), tr (RBC) are distinguished by the fact that their piecewise linear interpolation, even with a significant interpolation step, makes it possible to obtain a very accurate approximation to the true curves.

Thus, in comparison with the known, the proposed device has significant advantages in terms of both hardware cost savings and the accuracy in determining the gas parameters of the test.

In addition, since the determinations of f, t and T are carried out digitally, the device can measure the parameters of the gaseous media of objects (almost without loss of accuracy) located at a considerable distance if the sensor, switchboard switch and ADC are near the object, and the rest of the system is connected with them via telemetry.

40

Claims (2)

1. Author's certificate of the USSR 616567, cl. G 01 N 27/22, 1977. 2. Tsjdelko V.L. et al. Measuring system for monitoring vapor gas media. - Measuring equipment, 1978, 4 (prototype).