RU1791794C - Air-operated regulator with limitation of output signal - Google Patents

Abstract

The invention relates to instrumentation, in particular to pneumatic process control devices. The aim of the invention is to increase dynamic accuracy and simplify the design of the controller. The goal is achieved by the fact that the proposed regulator additionally has two constant chokes, a divider and a throttle adder for constant chokes, and a single-membrane repeater without a shift, the control chamber of which is connected to the output of the divider, one input of which is connected to the atmosphere, another - with an output channel and one input of a throttle sum; a mat, the other input of which is connected directly to the output of the lower level regulator and through the first constant choke to the flow chamber of the first repeater with a shift, the control chamber of which is connected to the output of the throttle adder. The control chamber of the second repeater with a shift is connected to the atmosphere, its flow chamber is connected to the output of the repeater without a shift, and the nozzle of the second repeater with a shift through a second constant choke is connected to the capacitance (/) of the integrating unit. 1 ill. f

Description

The invention relates to instrumentation, in particular to pneumatic controllers with an integral component in the control law, with limitations of the output signal and protection against saturation.

Pneumatic controllers are known with output signal limitation and with saturation protection, containing proportional and integral links, two comparison elements and two adjusters of upper and lower limit levels.

A disadvantage of the known regulators is their low dynamic accuracy. In particular, the output signal is limited in the oscillatory mode, the parameters of which (amplitude in frequency) may be worse than the permissible values.

Closest to the proposed is a controller containing related

between each other and the output channel, the proportional and integrating units, the capacitance of which is connected to the nozzle of the first repeater with a shift, a pressure regulator and input channels connected to the proportional and integrating units.

The disadvantage of this controller is the complexity of its design, a saturation protection node and limiting the output signal / - ..-; - - -. The purpose of the invention is to increase dynamic accuracy and simplify the design of the controller.

The goal is achieved in that in the proposed regulator comprising a proportional unit and an integrating unit interconnected with each other and the output channel, the capacity of which is connected to the nozzle of the first single-membrane repeater with a shift,

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ABOUT

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a low-level output pressure limiting controller and input channels connected to the proportional and integrating units, two constant throttle, a divider and a throttle adder for constant throttle and a single-membrane repeater without shift, the control chamber of which is connected to the output of the divider, is additionally installed the input of which is connected to the atmosphere, the other via the output channel, and one BXQ is the throttle adder, the other input of which is connected to the output of the lower level master directly and through the first constant throttle is to the flow chamber of the first repeater with a shift, the control chamber of which is connected to the output of the throttle adder, the control chamber of the second repeater is shifted to the atmosphere, erd the flow chamber is with: the output of the repeater without shift, and the nozzle the second repeater with a shift through the second constant choke is connected to the capacity of the integrating unit.

The drawing shows a schematic diagram of the proposed regulator.

The controller contains a proportional unit 1V, an integrating unit 2, based on the adder 3, a throttle 4 height 5, a single-membrane repeater

8 without shift, divider 7 and throttle adder 8 for constant throttle, master

9 lower it at the throat ogee at all without exiting pressure Rvykh, the first and second single-membrane repeaters 10 and 11 with positive shifts Ai and Yes, the first constant choke 12 (pO, 18 mm or .00.32 mm) and the second constant choke 13 (p 0.18 mm), the input channels Pn and P3 and the output channel Pvy. .

The nozzle of the first repeater 10 with a shift is connected to the capacitance 5 of the integrating unit 2 and, through the second constant throttle 13, with the nozzle of the second repeater 11 with a shift, the control chamber of which is connected to the atmosphere and its flow-through chamber is connected to the output of the single-membrane repeater 6 without a shift, the control chamber of which is connected to the EXIT of the divider 7 for constant throttles, one input of which is connected to the atmosphere, its other input is connected to the output channel Rvykh and one input. throttle adder 8, the output channel Rvyvy p dklyuchen to the divider 7 and the adder 8 with a throttle ct 0 royy those inputs where permanent set drossblirO, 18 mm; from the other remaining inputs of the elements 7, 8, constant chokes about 0.32 mm are installed, i.e. with a big pass

section. Such another input of the throttle adder 8 is connected to the output of the setter 9 directly and through the first constant choke 12 to the flow chamber of the first repeater 10, the control chamber of which is connected to the output of the throttle adder 8.

The controller operates as follows. Pre-setter output

9 set the pressure, the value of which should be maximum (100 kPa), which increases the area of normal operation of the regulator. On the first and second single-membrane repeaters 10, 11, positive AN and L Offsets are set, respectively, of such a magnitude that the nozzles of these repeaters with a shift open when the pressure of Pout exceeded the required lower and upper

restriction levels Rn and Rv.

We approximately determine the values of the positive shifts Ari and Ј of these repeaters 10, 11, based on the following considerations. Division and transmission ratios

divider 7 and throttle adder 8, each of which is built on constant throttles; / 0.18 and Ј 0.32 mm, are approximately equal to Kd 0.3; Ki 0.3; Ka 1 - Ki 0.07. Moreover

: p1 red, V (1)

. Ra K1RVYH +,:. where Pi is the output pressure of the divider 7; P2 - output pressure of the throttle adder 8. - ;; ::; -,; ..: -. :.;: Repeater nozzle 10 will open if the pressure in its flow chamber is greater than the total pressure Ra and the spring (Day) in its dead chamber, i.e. AN + Ra, where Pr. is determined by the formula (2) at Rp. Then the value of the shift Dn will be in accordance with (3) and (2)

AN - P2 - (KiPH -): (1 - K2) - K1 Rey Ki (- Pn) (4) At pH 20 kPa we get the maximum value of Dn 0.3 (100-20) 24 kPa, which almost corresponds to the technical characteristics repeaters with shift.

The repeater nozzle 11 opens at DI PI, where, in accordance with the expression (i) Pi KdPv. Then the shift amount Dv will be - .-:; -

Dz Kdrv. ..:

At Rv 100 kPa, we obtain the maximum value of Dv 0.3 100 - 30 kPa. If it is required to reduce the obtained shift value Yes, then a repeater with a negative shift should be used as repeater 6 to further increase the area of the regulator's mormal operation.

The repeaters 10 and 11 in the ultrasonic coupler function as pneumatic diodes, the nozzles of which are closed if the output signal Pout varies within a given range (Rn, Rv), i.e., Rn Rvv Rv. In this case, the controller operates a. linear mode and implements the standard proportional-integral regulation law,

Relay output signal Pbv, changing, becomes greater than the upper boundary level Pb, then the pressure Pi in the lower chamber of the repeater 11 will be greater than the force Dc of the spring in the upper chamber, and this repeater 11 will open. Due to this, the pressure in the vessel 5 begins to decrease under the action of pressure Pi (through the constant throttle 13) and, accordingly, the output signal Pout until the equality of Pout Pb is restored.

Similarly, when the output signal Pout is lower than the boundary level Рн, the pressure in the flow chamber of the repeater 10 (from the setpoint 8) will be greater than the total pressure P2 and spring (An) in the deep chamber, and the nozzle of this repeater will open. As a result, the pressure in the vessel 5 and the signal Pout at the outlet of the regulator will increase under the influence of the pressure of the sensor 9 BEFORE THE CONDITION OF REV Pn.

. Unlike the known regulators, the process of limiting the output signal is not accompanied by self-oscillations, since all the elements of the ultrasound node operate almost continuously. In addition, to improve the dynamics of the output signal limiting process, constant pressure chokes (18 mm and Ј0.32 mm) are installed on the higher pressure side of the repeaters 10, 11 at the co-damper nodes of the repeaters. For a typical PI part (PRZ regulator, 31 START systems), the first permanent choke 12 can be omitted, while the dynamics of the process of restricting the PBout from below (at the pH level) does not deteriorate; The USN node is implemented on simple single-membrane repeaters and constant throttles, while the known regulators use multi-membrane (3 and 5) comparison elements. :

Through the use of a divider and a throttle adder for constant throttles with different cross-sections, the area of normal operation of the controller increases; where it is possible to limit its output signal, despite the presence of a significant mismatch between the specification of P3 and the variable RP.

Claims (1)

The controller is made on commercially available blocks and elements and is prepared for industrial use. The claims Pneumatic regulator with output signal limiting, containing interconnected proportional and integrating unit and output connected to the output of the proportional unit, the output of the integrating unit connected to the nozzle of the first single-diaphragm repeater with a shift, a regulator of the lower level of output pressure limiting, as well as input channels connected to the proportional and integrating units, and an adder, characterized in that, in order to simplify the design and increase the dynamic accuracy of the controller, in an adder configured to permanent choke x, and also installed two permanent s a throttle, a divider for constant throttle, and a single-membrane repeater without a shift, the control chamber of which is connected to the channel between the constant drills of the divider, the input of the first constant throttle of which is connected to the atmosphere, the input of the second constant throttle of which connected to the output channel and the input of the first constant choke of the adder, the input of the second constant choke of which is connected to the output of the lower level master and directly through the first constant choke to the flow chamber of the first l with a shift, the control chamber of which is connected to the channel between the constant dashes of the adder, the control chamber of the second repeater with a shift is connected to the atmosphere, its flow chamber is with the output of the repeater without a shift, and the nozzle is connected to the second through a constant choke to . the output of the integrating unit.