SU711307A1 - Pneumatic square pulse shaper - Google Patents

Description

one

The invention relates to pneumatic automation devices, namely, square pulse generators.

The pneumatic generator 1 is known. The closest in technical essence to the proposed device is a generator containing a three-membrane relay, one deaf chamber of which is connected to the output of a pressure source pressure source, and the second with an output of inertial link throttle capacity installed in the feedback channel 2.

The disadvantage of the prototype is the substantial dependence of the frequency of the generator on the magnitude of the supply pressure,

A: The purpose of the invention is to reduce the frequency response from changes in feed pressure.

This is achieved by the fact that the pressure source of the backwater is made in the form of a multiplying unit with a constant coefficient, the input of which is connected to the power supply channel, and the outlet to the other deaf chamber.

The drawing shows a diagram of the device. The pneumatic generator contains a three-membrane relay 1 with a membrane block 2 and blind chambers 3 and 4, a throttle 5, a tank 6 and a pressure source of pressure — block 7 a constant multiplication factor, filled with two membranes 8 and 9 and with input 10 and output 11 channels . Channel 10 is connected to power channel 12, the relay output is connected to the output channel 13 of the generator.

The generator works as follows.

When the supply pressure is applied, at the outlet 13 of the relay 1, the pressure P appears.

  equal to the supply pressure P,

PNT

15 and in chamber 3 a pressure Pf ,, is established equal to the pressure in the output channel 11 of the unit. 7, which can be determined from the equation of forces acting on the membranes of the block 7 in the article 20 f nwT PnW- (1)

from Pf, - KPn,

  Transmission Ratio

 block 7;

Claims (1)

S. - effective area of the membrane 8; Sj - Effective pls membrane 9; Sg - nozzle area. The filling of chamber 4 of relay 1 and capacity b through throttle 5 begins. When a response pressure is reached in capacity b, the block 2 of relay 1 is shifted, output channel 13 is in communication with the atmosphere. The process of emptying the tank 6 and cam L.4 of relay 1 begins. When a release pressure is reached in capacitance, the block 2 of relay 1 is transferred, the output channel 13 communicates with the power channel 12 and the process is terminated. The oscillation frequency of the generator does not depend on the supply pressure. The frequency of the generator, neglecting the transfer time of the membrane unit, can be determined from the equation where tj and tp are the times of filling and emptying the tank. With a laminar choke, the 5 process flow and emptying of the capacitance can be described by the equations t () (3) PdL-P. (4) where P and P are the pressure in the tank at the moment of release of the Rrit relay; the supply pressure; tr ° is the time constant. Solving equations (3) and (4) with respect to tj, and tj,, we get: i, -m P -, - hep p, 1P ,. (b) Taking into account that the pressures in the tank the moment of actuation and release can hardly be expressed, respectively, in the form% -. ) О (8) where the effective areas of the large and small membranes are relay 1, by substituting the values of Ц and from equations (5) and (b) into the equation. (2), taking into account equation 1) after simple transformations, we get f, - "---- I - .. I -te (9) and, t le N- As follows from equation (9), the frequency of pulses P does not depend from the supply pressure of the Pf, y relay. Tests of the generator sample showed that with a change in the supply pressure in the range of 0.1-0.16 MPa (1.0-1.6 kgf / cm) the generator frequency (at f 0.343 Hz) changes by no more than 0.5% . The invention is a pneumatic generator of rectangular pulses containing a source of pressure backwater and a three-relay switch, one deaf chamber of which is connected to the output of the inertial element choke-capacitance installed in the feedback channel, in order to reduce the frequency error from the pressure change the power supply, the pressure source is executed in the form of a multiplying unit with a constant coefficient, the input of which is connected to the power supply channel, and the output - to another deaf chamber. Sources of information taken into account in the examination 1. USSR author's certificate And 344430, cl. G About D 3/00, 1971.. ;. Ibragimov and.A. and other elements and systems of pneumatic automation 1975, p. 234, fig. 7-4 (prototype).