SU962840A1 - Multipoint relay-pulsed system for automatic control of production process variables - Google Patents

Description

The invention relates to the automatic regulation of technological processes, in particular, to multipoint relay-relay systems controlling parameters (temperature, humidity, fluid flow, etc.) of the technological process, and can be used to control the temperature of the distillate at the outlet of refrigerators of distilleries and oil-feed raw materials. .

A known system for controlling the temperature of the distillate at the outlet of the refrigerators of distillers and cohobators, comprising temperature sensors, a multi-point balanced bridge, a relay unit, software relay blocks and control valves with actuators 1,

The disadvantage of the system is low accuracy.

The closest is a multi-point relay-pulse system for automatic control of process parameters, containing n actuators, n sensors of an adjustable parameter, connected via the first

a switch with an input of the setpoint of the reference, a relay amplifier whose outputs are connected respectively to the inputs of the second and third switches, the control inputs of the switches are connected to the first output of the block

.instructions of the task, the second output of which is connected to the input of the relay amplifier, the outputs of the second and third

ten

I switches are connected to the inputs of two relay devices, the outputs of which are connected to the corresponding inputs of the n actuators, two time relays, inputs and outputs

15 of which are connected to the inputs and outputs of the corresponding relay devices 2J,

The disadvantage of the lime system is the low control accuracy, caused by a large delay due to the low speed of the switch, due to the fact that the system does not provide connection to the next (1 + 1) -th polling object,

25 until the interrogation and supply of the control pulse to the actuating mechanism of the previous 1st object is completed.

In addition, the system in each cycle

30 a sweep sends control pulses to the control object, the sum of which exceeds the value necessary to compensate for the error, which causes an oscillatory transient process in the control system and increases the dynamic error.

The purpose of the invention is noBbEuei | fie system control accuracy.

The goal is provided by the fact that in a known system containing two gZelny devices, outputs connected to actuators, n sensors of an adjustable parameter, the outputs of which are connected through the serially connected first switch, setpoint unit, and relay amplifier to the inputs of the second and third switchboards , a frequency master is entered, and in each control channel a control pulse driver, the first input of which is connected to the output of the corresponding switch, the second input is connected to the corresponding The main output of the frequency adjuster, the third input with the second output of the driver of another channel, the first output with the input of the corresponding relay device, the second output with the third input of the driver of the first channel.

The control impulse driver contains a frequency divider, two triggers and series-connected elements AND, an OR element and a delay element, an output connected to the first input of the first trigger and a frequency divider, the second input of which is connected to the first output of the driver, and the second the input connected to the third input of the imager and through the first trigger with the first input of the element I, the second input of which is connected to the output of the second trigger, the third input of the frequency divider connected to the second input dy shaper, the shaper second output connected to the first input of.

With this solution, the first control pulse is supplied to the object, the polarity of which depends on the sign of the error signal, and the rest of the control impulses:: (The pulses are applied at a multiplicity of time of the run-in cycle. Quick control of objects, storing the error signal at each run-around cycle and feeding on the object of control of the control pulse with an interval of time corresponding to the multiplicity of the run-around cycle, eliminates the pulsating mode of operation of the actuator and, accordingly, the oscillatory transition process cc in control systems. This allows to significantly improve the control accuracy of the system and expand its functionality.

The drawing shows a block diagram of a relay-pulse system for automatic control of process parameters.

The system contains setpoint block 1, switch 2, p sensors 3 of adjustable parameter, relay amplifier 4, switches 5 and b, RS flip-flop 7, trigger 8, element AND 9, element OR 10, frequency divider 11, delay element 12, drivers 13 -tn control pulse, frequency adjuster 14, triggers 15 and 16, element 17, element OR 18, frequency divider 19, delay element 20, drivers, control pulse, relay devices 22 and 23, n actuators 24. I

The system works as follows.

The setpoint setting unit 1 (provides a separate setpoint for each object of different setpoint values), controlled by switch 2, compares the signals of sensors 3 alternately with the set value set in it. When the error is between the settings (within the dead zone) at the outputs of relay amplifier 4 and switch 5 (6), there are no signals and, accordingly, at the output of the driver 13 (21) of the control pulse. In the initial state, the frequency divider 11 (19) is preliminarily set with the help of the program setting unit 14 a numerical value F of the pulse frequency, which corresponds to the frequency of the circling cycle, and the RS flip-flop 8 (16) and RS flip-flop 7 (15) the inverse output has a logical unit and a logical zero, respectively. When the error exceeds: the dead amplifier of the relay amplifier expands, a logical one appears at one of the inputs of the latter, depending on the sign of the suiby

 the signal H, which with the help of switches 5 (6), controlled by the 6.rtOKOM setpoint settings synchronously with switch 2, is fed to the input of splitter 11 (19) frequencies and to the input. Setting zero to RS flip-flop 7 (15) with inverse output, at the output of which a logical unit appears. Them . pulses from the element AND 9 (17) through the elements OR 10 (18) are simultaneously received at the inputs of the relay device 22 (23) and the element 12 (20) of the delay. From the relay device 22 (23), the signal is fed to the input of the corresponding actuator 24, which changes the controlled parameter.

Regardless of the switching time of the switch, the effect of the regulating pulse on the actuator 24 is prolonged by means of the delay element 12 (20). After the set delay time t has elapsed, the delay element 12 (20) brings the RS-flip-flop 8 (16) to the zero state (a logical zero appears at its output) and the frequency divider 11 (19), and the signal to the actuator is turned off. the mechanism of the relay device 22 (23).

The duration of the control pulse on the executive mechanism is determined by the formula

and

7TT (s).

K „5-100%

where L is the time for a complete revolution of the output shaft of the actuator mechanism, s;

Kpg - object gain, dimension of parameter 1 meter

% H.P.O.

and - the value of the control pulse upon a single impact on the object, the dimension of the parameter.

The magnitude of the control pulse U depends on the time interval between successive effects on one of the control objects, the parameters of the static and dynamic characteristics of the object, the deadband of the relay amplifier and the required control quality indicator.

When the next pulse arrives through switch 5 (6) at the output of the frequency changing unit and the control pulse duration at the output of the last signal, the signal does not appear until the number of pulses arriving at the frequency divider 11 (19) becomes equal to the number corresponding to the frequency set on the frequency divider 11 (19). Thus, a control pulse is supplied to the actuator 24 at a multiplicity of the time of the run-around cycle. However, the appearance of the signal at the output of the switch 6 (5) is fed to the inputs of the Setting unit for RS flip-flop 8 (16) and RS trigger 7 (15) with inverse output and reset them. The other channels of the control system work in the same way.

Using new elements AND, OR, RS-flip-flop, RS-flip-flop with inverse output, frequency divider of the time delay block, program frequency adjuster block for each control channel, providing memory and control feed with a time interval multiple of the object run round, allows to increase the control accuracy and the quality of transients.

The proposed multipoint relay-impulse system dp control parameters of the process provides stability

0. the process of regulating objects with different inertia and the ratio of the delay time to a constant time, due to the formation of different intervals of switching-on time of actuators in the control cycle, as well as different time intervals of the control cycles themselves, which significantly increases the accuracy of the regulation .. and extends the field of application of the device.

Claims (2)

Invention Formula 25 A multipoint relay-pulse system for automatic control of process parameters, containing two relay 0 devices, outputs connected to actuators, n sensors of an adjustable parameter, the outputs of which through the first switch connected in series, block 5 setpoints and a relay amplifier are connected to the inputs of the second and third switches, characterized in that, in order to improve the control accuracy of the system, a frequency adjuster is inserted into it and a control pulse driver, the first input of which is connected to the output of the corresponding switch, into each control channel , the second input 5 with the corresponding output of the frequency adjuster, the third input with the second output of the driver of another channel, the first output with the input of the corresponding relay device, the second output - with the third input of the first channel Foomivertor. 2. The system of claim 1, wherein the control pulse shaper comprises a frequency divider, two flip-flops and series-connected AND elements, an OR element and a delay element, output connected to the first input of the first trigger and a frequency divider, the second input of which is connected to the first output of the imaging device, as well as to the first input of the second trigger, the second input connected to the third input of the imaging device and through the first trigger with the input of the And element, the second input of which is connected to the output of the second trigger, the third input of the frequency divider is connected to the second input of the driver, and the second output of the driver is connected to the first input of the driver. Sources of information taken into account in the examination  1. Chkoni K.P. and others. Automation of the process of cooling the distillate. Oil-fat industry, 1978, 3, p. thirty. 2. USSR author's certificate 607183, cl. G 05 B 11/32, 1977 (prototype). 2i 3 and 1 $ 23