SU389536A1 - DEVICE FOR ALARM SIGNALS, - 'N - Google Patents

Description

This invention relates to the field of fire alarm.

It is known an alarm device comprising a receiving point with a power source connected to an electronic key, the input of which is connected to one trigger output, the other output of which is connected to a time element, and the trigger inputs are connected to the outputs of the delay element and selector, the output and program blocks and a sensor mounted on a guarded object and connected via a communication line with a measuring element included in it, to the reception: to the first point.

The proposed alarm device differs from the known one in that it includes a differential analyzer, the input of which is connected to the input of the delay element and the trigger output, a reset bus connected to the output of the program block, and the output of the differential analyzer is connected to the input block.

This allows to increase the reliability of the device.

FIG. I shows the layout of the alarm device; in fig. 2 - a variant of the differential analyzer circuit.

The device contains n smoke detectors /, receiving station 2 and two-wire communication line 3.

The smoke detector consists of a phase-shifting chain (ionization chamber 4 with a radioactive isotope and a condenser 5), the input of which is connected to line 3, and the output is

to the control grid of the thyratron 6 of a glow discharge.

Receiver station 2 contains a power source 7, an electronic switch 8, a meter, a primary element 9, a pulse selector

JO, trigger //, delay element 12, differential analyzer 13, output block 14, and software 15.

The differential analyzer (Fig. 2) consists of a trigger 16, a pulse generator 17 and a reversible counter 18.

At the receiving station 2, polling pulses are generated and the "KOTCipbie." Is sent along the communication line 3 to one or several sensors /. The response pulse of the sensor in the absence of fire shifts in time relative to the leading edge of the interrogation pulse by means of a phase-shifting chain 4, 5. When smoke enters chamber 4, this time shift increases in proportion to the increase in the resistance of the chamber. At the receiving station 2, the time intervals between the leading edges of the interrogation pulses and the response pulses of the sensor are sent to a differential analyzer, in which they are digitized, measured, and comparisons of subsequent comparison results are made. After a predetermined time, the comparison results are reset. If the comparison result does not exceed the permissible value, there is no fire signal.

The generation of the interrogation pulses Un at the receiving station is carried out periodically by the power source 7, the electronic key 8 and the trigger 11.

When a signal appears at the output of the trigger I connected to the input of the electronic key 8, the latter is turned on and sends a pulse t / n through the communication line 5 to the input of the phase-shifting chain. In this case, the capacitor 5 starts charging through the chamber 4. When the voltage on the capacitor 5 reaches the ignition voltage of the thyratron 6 on the control grid, the capacitor 5 is discharged, the thyratron 6 turns on —n abruptly increases the current in line 3. The current surge in the form the voltage drop across resistor 9 is fixed by the selector 10 at the receiving station as the arrival of a sensor response pulse. The selector 10 overturns the trigger 11, at its output connected to the input of the key 8, the signal disappears, the key is turned off, the sending of voltage is stopped, the thyratron 6 goes out and a pause occurs. At the same time, a signal appears at the output of flip-flop tl associated with the input of delay delay element 12, which determines the duration of the pause. When a signal appears at the output of the delay element 12 associated with the trigger input 11, the latter overturns, the pause stops, and the next polling pulse starts.

The time interval between the leading edges of the polling pulse and the response pulse of the sensor behind (depends on the time constant of chain 4, 5. When smoke develops, the resistance of chamber 4 increases, the charging time of capacitor 5 increases to the ignition voltage of thyratron 6, and accordingly the time interval between the leading edges of the polling pulses and the response pulse of the sensor.

An increase in this time interval can also occur in the absence of smoke due to an increase in the capacitance of the capacitor 5, an increase in the ignition voltage of the thyratron 6, a decrease in T01ka of the chamber 4 at a low temperature or high humidity of the environment, etc.

Due to the fact that the value of the specified time interval is proportional to the value of the smoke detector parameter R (resistance of the ionization chamber), to determine the rate of change of R d it is sufficient to determine the speed of the time interval between the leading edges of the interrogation pulse and the response pulse of the sensor.

For this, the input of the differential analyzer 5 is connected to the output of the trigger I or to the output of the pulse selector, and the "reset analyzer" is connected to the output of the software device 15. In the differential analyzer 13 the time intervals are converted into a digital sample, the increments of the subsequent results are calculated measurements over previous ones.

In the differential analyzer, the generator 17 pulses the input of the reversible counter 18. The switching of the operating modes of the counter 18 "addition or subtraction is performed by the trigger 16. The software device 15 clears the counter 18 readings after periods of time that depend on the required sensitivity of the sensors to smoke and interference level.

FIG. 3 shows voltage graphs as a function of time, where denoted:

Un is the voltage of the polling pulses; 4 (O- response pulses of sensors on

measuring element 9; Uoin is the amplitude value of the response pulse of the sensor, chosen above the line noise level; tl is the predetermined time interval by which the response pulse of the sensor shifts relative to the polling pulse in the absence of smoke. Pa figs. 2 a, b shows the graphs of the polling pulses / 7II and the corresponding response pulses of the sensors. During the first two polling pulses, the sensor was not affected by smoke and interference, since its response kmnulses are shifted by a predetermined time interval t. The response of the sensor emulsion to the third impulse of the interrogation arrived later than a predetermined time interval through ti + t, to the fourth interrogation pulse - through the interval t. + Ati + At,

The increments ti and 4/2 are determined by a differential analyzer. If the magnitude of each increment or their sum exceeds the level or the number corresponding to it on the counter (see Fig. 4 c; 46, b) over the period of time AT TI - TQ T - Ti 73 - 2, then an alarm will occur. If the temporal shift of the response pulse of the sensor continuously increases, for example, due to an increase in the ignition voltage of the thyratron 14, but the increments caused by this do not exceed the level t (average speed or derivative change) over time intervals t, then a false fire signal does not occur , despite the fact that the time shift (see FIG. 3, c, d). With the appearance of smoke and a rapid increase in the time shift of 2/4/3, a fire signal appears, i.e. the system functions normally in this case.

If the temporal shift of the response pulse of the sensor is reduced, as shown in FIG. 4, a; Rfla f, (Oe, t), then the sensitivity of the system that responds only to the rate of change of Rn. Is not out of; 1en.

The aim of the invention is to reduce the effects of slow changes in sensor parameters on the accuracy of the device. The smoke parameter (sensing element of the sensor), for example, the resistance of the ionization chamber, is a function of the smoke concentration dp F (G ,,), where G "is the concentration of smoke and fire. In turn, G ,, is also a variable value and depends on the intensity of the fire, for example G ,, v (0). Thus, the smoke detector parameter is a function of two variables ff. Fi (G ,, t) In standby mode (in the absence of smoke) aging of the details of the sensor and the impact of environmental conditions also cause changes in the smoke detector parameter Rn. With a positive change (increase in g), the sensitivity of the sensor increases, etc., and the negative decreases. where Ce is an equivalent concentration of smoke, i.e. conditions environment and "aging of parts equivalent in its effect to the concentration of smoke. Oe slowly changes over time Oe & t (t). Thus, in standby mode, R is also a function of two variables, G (e, J. 4a shows plots of the smoke detector parameter versus time when smoke appears FI Sse, / j in the standby mode with positive changes in the detector parameter fi (G ,, t) negative changes (Ce, OB initial state (in the absence of smoke and damage) the value of d is set equal. The fire signal is given when the value is reached. The sensitivity of the sensor (the minimum value of Rum) is limited by the degree to which the sensor affects the changing environmental conditions and the aging of the sensor parts. For example, for ionization smoke detectors, parametric reserve / g. When “2, the sensor is unstable and often gives a warning signal of fire. In the standby mode (Fig. 4, a), with a slow increase in the curve of /, e f (Gs. /), A false alarm may be triggered at the moment of time .i, at which /, pe reaches the value of Ram. Gn, i) and after time t ,, reaches the value of Rum. If the functions F, (G ,,, t) and f (G ,,, t) monotonically varying curves, then at any of the points lying on these curves, one can find derivatives or their rates of change dR ,, dCs dR G) 1 5 G dG, dt If we go from discrete continuous measurements at intervals of 4 /, then the average velocities are respectively G, etc. d, desr-d DOE DOE D / Suppose that the effect of Ga for time caused changes from R to d, n, and the effect of G "caused the same change during the time tn -fg. Then the average rates of change Rj, n for rem (' -to and de for time ij, will be recorded respectively 7 / /, - To - ak like R. then Yes "Deactivating the sensor when smoke appears (sec, and false triggering no more than a few days later, therefore: G4- / o; G - o). Then HJiiJ-D - D / If in the standby mode and when the smoke appears, to make measurements at the same intervals, and t, then During this interval, C Rnn In this case, the measurement of the supply of the sensor or system. Thus, the device that reacts to the derivative of the parameter changes and the detector, depending on the concentration of smoke, is much more resistant than the device with maximum performance sensors. To calculate the derivative of the change in the parameter of the smoke detector, it is necessary to periodically measure this parameter and the results of each subsequent measurement after a certain time interval. Each comparison result can be transferred into the memory device, analyzed, then dropped. FIG. 4.5 is a graph showing a change in the sleep mode; in fig. 4, c is a graph of the average rate of change of derivative g, defined as follows. A measurement is made at point I (Fig. 4.6), then after a time interval of 47 TI-Go a measurement is made at point II, the measurement results are entered into the differential analyzer, which determines the increment of the result of the second measurement compared to the first. If this result of the RI comparison does not exceed the specified R level, then the fire signal is absent. After analyzing R, this comparison result is reset, and similar operations are performed at points I, 111, etc. As can be seen from graphs 4, b, c, despite the fact that there have been significant changes that could have been made in the max. Sensor a false fire signal at time fj, in the device, reacting to the speed (derivative) of the change in RM, these changes are periodically reset and there is no false fire signal.

FIG. 5 a, b shows graphs of g and R with the appearance of smoke. The result of the comparison between points IV and I after the time interval 4T G; -TO exceeded the preset level g) and the achievement of which the fire signal should appear at the time point "1 1" (Fig. 5, b).

In the case of a slow increase in the concentration of smoke, the result of comparing the subsequent result of the change with the previous one will not have time to exceed the specified level in the small time interval between these measurements and the fire signal does not appear. Therefore, the minimum interval is limited by a predetermined minimum rate of increase in the concentration of smoke that must be detected. However, with a high growth rate of smoke concentration and, accordingly, a large derivative value / fire signal can be obtained much earlier, if

measure and compare the results. measure at intervals At.AT, where t ti- / 0 4- 1 4- (2, etc. (Fig. 5 a, c). In this case, the fire signal can be received at the time .

In order to simultaneously detect slow rates of change in smoke concentration, the results of comparisons at intervals t (Φ | И1Г. 5, в) are summed up in a memory device and reset at intervals of 47 TI-Gо G2-TI, etc.

Measurement errors are possible (under the influence of interference), which are also summarized in the storage device during each comparison. Therefore, the time interval through which the reset is performed must not exceed the time interval during which the noise level may exceed the permissible level and cause a false signal.

the fire. Subject invention

An alarm device comprising a receiving station with a power source connected to an electronic key,

the input of which is connected to one trigger output, the other output of which is connected to the delay element, and the trigger inputs are connected to the outputs of the delay element and the selector, the output and program blocks and the sensor installed on the protected object and connected via a communication line with the included measuring element, to the receiving point, characterized in that, in order to increase the reliability of the device in

it has a differential analyzer, the input of which is connected to the input of the delay element and the trigger output, the reset bus is connected to the output of the program block, and the output of the differential analyzer is connected to the input of the output block.

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