RU227155U1 - Pressure generator - Google Patents

Abstract

The utility model relates to the field of metrology. The technical result is to increase the accuracy of maintaining a given pressure. The technical result is achieved due to the fact that the pressure generator contains thermostated absolute pressure sensors and stable pressure is maintained using receivers sequentially installed in the pneumatic path. 3 ill.

Description

The utility model relates to the field of metrology, can be used as part of test equipment for checking aviation air signal systems and is intended for the precise task of absolute pressure, converting the specified pressure into a digital signal and issuing a digital signal to automate procedures for calibration and verification of instruments.

Pressure calibrators are reference instruments that, depending on the accuracy of the required parameters, are used for checking and calibrating various pressure measuring instruments. At the same time, when creating an automated calibration and verification system, specialized calibrators-controllers are used - devices that can set the pressure automatically.

A pressure calibrator is known (Great Britain patent No. 2295249 dated November 2, 1994, IPC G05D 16/2, adopted as a prototype). This pressure calibrator has an inlet, a vent and an outlet and includes: means for allowing a user to select a pressure to be maintained at the outlet; supply and release valves, each of which has an input, an output and a control input for receiving pulse-width modulated control signals, wherein the supply valve input is configured to connect to a source of compressed gas, the supply valve output is connected to an exhaust port, the exhaust valve input connected to the outlet port, and the outlet of the outlet valve is configured to be connected to the vent hole; a pressure sensor coupled to the outlet and configured to generate a digital signal representing the pressure; processing means connected to the pressure sensor and selector means, configured to generate control signals for turning the valves on and off; valve characterization means for calibrating the controller by independently determining for each valve at least two set pressures within the range of the controller; and means for storing calibration values for use by said processor means in generating control signals during operation of the controller.

The disadvantages of this pressure calibrator are the need to use temperature compensation of absolute pressure sensors, as well as an external source of vacuum and pressure.

The technical result of the utility model is to increase the accuracy of maintaining a given pressure.

The specified technical result is achieved due to the fact that the pressure generator contains a measurement and control unit connected to the pneumatic control unit via a digital interface, as well as a pressure sensor unit connected via a frequency line to the measurement and control unit, and by a pneumatic path to the pneumatic control unit, and the pressure sensor block contains thermostated pressure sensors, the pressure generator contains an internal source of vacuum and pressure connected to the pneumatic control unit via a pneumatic path, and receivers are connected in series to the pneumatic paths connected to the pneumatic control block.

In fig. Figure 1 shows the appearance of the pressure generator, where:

1 - pressure generator

2 - output fittings of the front panel

3 - front panel

4 - control unit

5 - IEEE-488 interface connector

6 - rear panel output fittings

7 - inlet fittings

8 - rear panel

The pressure generator 1 is made in the form of a monoblock, on the front panel 3 of which there are output fittings 2 and a control unit 4, and on the rear panel 8 there are input fittings 7 and output duplicate fittings 6, as well as an IEEE-448 connector 5 for remote control of the pressure generator.

In fig. Figure 2 shows a block diagram of the proposed pressure generator, where:

1 - pressure generator

2 - output fittings of the front panel

4 - control unit

5 - IEEE-488 interface connector

6 - rear panel output fittings

7 - inlet fittings

9 - measurement and control unit

10 - pneumatic control unit

11 - built-in source of vacuum and pressure

12 - pressure sensor block

13 - power supply

14 - ventilation and heating unit

15 - PVM (personal computer)

16 - power connection connector

17 - external source of vacuum and pressure

18 - device under test

19 - receiver.

Pressure generator 1 consists of a measurement and control unit 9, connected via a digital SPI interface to a pneumatic control unit 10, pneumatically connected through receivers 19 with a built-in source of vacuum and pressure 11, consisting of an oil-free membrane vacuum pump and compressor, and inlet fittings 7, as well as with a block of pressure sensors 12 and output fittings 2 and 6. The block of pressure sensors 12 consists of two thermostated pressure sensors and has a line connecting frequency signals with the measurement and control block 9.

The connection of the pneumatic paths of the device under test 18 with the pressure generator 1 is carried out through the output fittings 2 or output fittings 6, and the pneumatic paths of the external source of vacuum and pressure 17 through the input fittings 7. The pressure generator can be controlled either from the control unit 4, connected via a digital interface RS -232 with the measurement and control unit 9, and remotely from the FDA, connected to the measurement and control unit 9 via connector 5 of the IEEE-488 interface.

To connect to the power source, the pressure generator 1 has a power connection connector 16 connected to the power supply 13, which is connected via power channels to all units of the pressure generator 1. The pressure generator 1 also contains a ventilation and heating unit 14.

In fig. Figure 3 shows a block diagram of the pneumatic control unit, where:

10 - pneumatic control unit

20 - valve control module

21 - PWM controller

22 - pneumatic manifold

23 - solenoid valve

The pneumatic control unit 10 consists of two valve control modules 20, each of which contains a PWM controller 21 and a pneumatic manifold 22.

On the pneumatic manifold 22 there are electromagnetic valves 23, the control relays of which are connected to the PWM controller 21. The pneumatic manifold 22 has pneumatic lines connecting the pneumatic control unit 10 with a built-in source of vacuum and pressure 11 and an external source of vacuum and pressure 17, as well as with a block of pressure sensors 12 and device being verified 18.

The device operates as follows:

After connecting the device under test 18 to the output fittings 2 on the front panel 3 or to the output fittings 6 of the rear panel 8 of the pressure generator 1 and supplying the supply voltage to the power supply 13 through the power connector 16, using the control unit 4 the user sets the required parameter values that are necessary check. From the control unit 4, the specified parameter values are supplied to the measurement and control unit 9. The measurement and control unit 9, receiving from the control unit 4 the required values of pressure and rate of change of pressure, calculates and transmits control signals to the pneumatic control unit 10. PWM controller 21 controls the solenoid valves 23, installed on the pneumatic manifold 22, using a PWM signal in accordance with the proportional-integral-derivative control algorithm, which is based on the task of calculating the pulse duration of the PWM signal when calculating the difference between the target and the current value of the controlled variable. The target value of the control value is taken as information received from control unit 4 via the RS-232 interface or received from the FDA via the IEEE-488 interface. The current value of the controlled variable is calculated by the measurement and control unit 9 based on information about the current pressure in the pneumatic path from the pressure sensor unit 12.

During operation of the pressure generator 1, the built-in temperature control system for pressure sensors maintains a constant, defined temperature inside the pressure sensor block 12 and eliminates the influence of external temperature on the characteristics of the pressure sensors.

To ensure the operation of the generator in a wide temperature range, the pressure generator 1 is equipped with a ventilation and heating unit 14. When the ambient temperature reaches the specified values, the ventilation and heating unit 14 automatically turns on the heating elements of the pressure generator 1.

During operation of the pressure generator 1, maintaining a stable pressure is ensured by receivers 19, which are containers sequentially installed in the pneumatic path.

Remote control of pressure generator 1 is carried out through FDA 15. Using system commands, the specified parameter values are transmitted from FDA 15 to measurement and control unit 9 through connector 5 via the IEEE-488 interface.

Thus, the use of an internal source of vacuum and pressure in the pressure generator eliminates dependence on an external source of vacuum and pressure, and the presence in the pressure generator of thermostated absolute pressure sensors and receivers in the pneumatic path increases the accuracy of maintaining the required parameters.

Claims (1)

A pressure generator containing a measurement and control unit connected to a pneumatic control unit via a digital interface, as well as a pressure sensor unit connected via a frequency line to the measurement and control unit, and a pneumatic path to the pneumatic control unit, characterized in that the pressure sensor unit contains thermostated pressure sensors, and the pressure generator contains an internal source of vacuum and pressure connected to the pneumatic control unit via a pneumatic path, and receivers are connected in series to the pneumatic paths connected to the pneumatic control block.