SU1594381A1 - Apparatus for measuring dust concentration - Google Patents

Abstract

The invention relates to a measurement technique, is intended to control the dustiness of air and can be used in the electronic and other industries. The purpose of the invention is to improve the measurement accuracy by taking into account the temperature and humidity according to a given algorithm. The device contains a gas-ionizing device with an air duct and an ionizer electrode, a high-voltage converter and a fan with an electric motor, three sensitive elements in the form of piezoelectric sensors, three measuring channels, each of which consists of a series-connected measuring generator, element I, counter and adder, three coding elements , two adders, five memory registers, a decoder, a control unit with a time interval shaping circuit and a display unit. 1 il.

Description

The invention relates to the field of measurement technology, is intended to control the dustiness of air and can be used in electronic and other industrial fields.

The aim of the invention is to improve the measurement accuracy by taking into account the temperature and humidity according to a given algorithm.

The drawing shows a functional diagram of the device.

The device contains a gas-sensing device 1 with an air duct 2 and an ionizer electrode 3, the first 4, the second 5 and the third 6 sensitive elements made in the form of piezoelectric elements, a fan with an electric motor 7, a high-voltage converter 8, the first 9, the second 10 and

third 11 measuring generators, control unit 12 with a time interval shaping scheme, first t3, second 14 and third 15 elements AND first 16, second 17 and third 18 counters, first 19, second 20 coding elements, first 21, second 22 and third 23 adders, the nc channel meter, the first adder 24, the third coding element 25, the first 26, the second 27, the third 28, the fourth 29 and the fifth 30 memory registers, the second adder 31, the decoder 32 and the display unit 33.

Sensitive elements together with measuring generators, elements And, counters and adders form three measuring channels.

SP

00 00

3 159 The device works as follows,.

After the supply voltage to the device, the sensitive elements 4-6, including in the frequency-up circuits of the measuring generators 9-11, respectively, determine the frequencies generated by the signal generators. After a certain fad time (not less than the average measurement time 6), a signal appears at the third output of the control unit 12 that permits the passage of pulses from the generators 9-11 through the elements 13 and 15 to counters 16-18, and the information recording signal on counters 16-18, arriving from the fourth output of the block, 12 controls. The sensing element 6 is exposed only to temperature, the number of pulses in the counter 18 after the expiration of the time

/ -I

to.

f.,

t 0; f t where f is the natural frequency of the senses

tel element S - coefficient of conversion

frequency variation; JT is the change in ambient temperature.

Code K from the output of the counter 18 is fed to one of the inputs of the adder 23 of the third channel. The constant Q is supplied to its other input. Jc If K is chosen so that K, + 1, the third channel adder 23 performs the summation in the additional code and at its output there appears a code that is equivalent to the temperature:

yk TO,. + K,

The moisture sensing element 5 is made in the form of a piezoelectric plate coated with a sorbent, and has direct contact with the environment, thereby being exposed to temperature on the resonator frequency. After the expiration of the averaging time on the counter code 17, the code appears

TO,

(f "

h 5

v

de lft - ,, g here

Sg - sensitivity coefficient

on humidity;

/ 1B - change in ambient humidity;

one

S .. - integral coefficient

sensitivity.

The second term of this expression is a function of temperature and can be calculated using coding element 20, performed, for example, in the form of a permanent reprogrammable memory. The input code for element 20 is temperature, as well. the output word of item 20 is

(f.

+ S -.;. 4T)

) D

+ 1.

The codes with the output of the counter 17 and the element 20 are fed to the adder 22 of the second channel, at its output there is a code that is equivalent to the humidity at a given temperature:

-DSg / JB + -; („+) + f

(f

ZV.

06 + 5t,) + 1 fS

The sensing element 4 performs oscillation with a frequency

fn 0-, p + v, p

50

The frequency of the dust sensor is a function of the precipitated mass of dust, temperature and humidity due to the effect on the sensor frequency of all these parameters.

After: expiry: averaging time in counter 16 will be the code

(fo ll + PP-4 Lp - 5 where /) f С „-ЛМ; г, п, 6. (1, С .. - coefficient of sensitivity

(L. -

by weight;

IM - change in the mass of dust;

S is the averaged coefficient of sensitivity over temperature;

0

45

S - average coefficient

 moisture sensitivity.

After substitution receive the code at the output of the counter 16 and the first input of the adder 21

k „-e + with Sg -f c (f, +).

The output t) (f (, + S) is a function of temperature and can be set in a tabular way on a reprogrammed read-only memory implemented in element 19 of the encoding. They contain the function

p7f + S-./IT) + 1, and it is also T | P “

vut at the second input of the adder zl

the first channel, the code at its output is proportional to

 . Lv

8p

In encoding element 25, the function DSj, 3B + 1 from argument 4 B is implemented in a tabular way. The input words of the first adder 24 on both of its inputs, respectively; , n4b + 1.

Then the output word of this adder +

3S,

PLV n-1

 RS., GZI.

 -M-- v, n 8.0 - m

At the sixth output of the control unit 12, a strobe pulse is written to write the output words of the adders 23-24 into the memory registers 30, 29 and 27, respectively.

Then the control unit 12 generates at its first output a signal on} of the motor 7 with a fan and at the second output a turn-on signal of the high-voltage converter 8.

Under the action of the fan motor 7, the compressed air passes through the duct 2, the dust particles are charged in the ionizing chamber by the electrode 3, are deposited on the surface of the sensing element 4 and their oscillation frequency is changed {due to a change in the resonant frequency due to the changed resonator mass) .

Frequency measurement is the same as in the measurement before sedimentation of dust, only the output code of the adder 24 is proportional to, Self, the change in the mass of dust in the operating mode) and is recorded in the memory register 28 by the signal generated at the seventh output of the control unit 12. Next, the output of the adder 31

code is generated

1) C „lM - (M,).

Thereafter, at the fifth output of the control unit 12, a pulse is written to write the code C (10, - d M) memory register 26.

The information codes about the extent, humidity and temperature through the decoder 32 are infected on the display of the display unit 33.

Claims (1)

DETAILED DESCRIPTION OF THE INVENTION A device for measuring dust concentration containing gas ionisation. ten 15 20 25 the diving device, in the chamber of which the ionizer electrode is installed, the first sensitive element made in the form of a piezoelectric sensor and connected to the input of the first measuring generator, a high-voltage converter of the constant voltage, the output of which is connected, to the ionizer electrode, the second sensitive element connected to the second measuring generator, motor: spruce with a fan for pumping the pie-gas flow, the control unit, the first and second outputs of which are connected to the control units in the motor and the high-voltage DC / DC converter respectively, and an indication unit, characterized in that, in order to improve the measurement accuracy by taking into account the temperature and humidity according to a given algorithm, the device further comprises a third sensitive element connected to the third measuring generator with protection against moisture, three measuring channels, each of which consists of 30 consecutively connected sensitive elements, measuring gene And, the counter and the adder element, the second inputs of the And element and the counter in each channel are connected to the third and fourth outputs of the control unit, the first and the second adders, the first, second and third coding elements, first, second, third, fourth and fourth The fifth memory registers and the decoder, in this case, the first input of the first adder is connected to the output of the third coding element, the input of which is connected to the output of the adder of the second i-j measuring channel and the input of the fourth memory register, output The third measuring channel is connected to the inputs of the fifth memory register, as well as the first and second coding elements, the outputs of which are connected respectively to the second inputs of the summators of the first and second measuring channels, and the second input of the third measuring channel is made with the possibility of connecting an external code; the first adder is connected to the inputs of the second and third memory registers, the outputs of which are connected to the outputs of the second 0 five pogo cjnsfMaTopa, the output of the second totalizer is connected to the input of the first memory register, the output of which is connected to the first input of the decoder, the second and third inputs of the decoder. connected to the outputs of the fourth and fifth memory registers, respectively; the common output of the decoder is connected to the display unit, the control input a- and 1594381 8 The first memory register is connected to the fifth output of the control unit, the sixth and seventh outputs of which are connected to the corresponding control inputs of the second, third, fourth and fifth memory registers, while the second and the third sensitive elements are in the form of piezoelectric sensors. ten