JP3147275B2 - Differential pressure detector diagnostic device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a diagnostic apparatus for a differential pressure detector, and more particularly to a diagnosis of a pressure guiding line in a differential pressure detector.

[0002]

2. Description of the Related Art FIG. 5 is a conceptual view of the use of a differential pressure detector.
In the figure, reference numeral 1 denotes a conduit through which a fluid to be measured flows. An orifice 2 is provided in a part of the pipe 1, and pressure guiding pipes 3 and 4 are provided so as to sandwich the orifice 2. The pressure guiding lines 3 and 4 are connected to a differential pressure detector 7 via on-off valves 5 and 6, respectively. In addition, the pressure guiding pipelines 3 and 4
Is connected via an on-off valve 8 on the differential pressure detector 7 side.

In such a configuration, the zero point check of the differential pressure detector 7 is performed with the on-off valves 5 and 6 closed and the on-off valve 8 opened. The normal measurement is performed with the on-off valves 5 and 6 opened and the on-off valve 8 closed. By the way, as a failure form of such a measurement system, it is conceivable that the pressure guiding pipelines 3 and 4 are clogged or the abnormality of the differential pressure detector 7 is abnormal.

[0004]

However, according to such a conventional structure, the blockage of the pressure guiding lines 3 and 4 and the abnormality of the main body of the differential pressure detector 7 are determined only by the change in the measurement result of the differential pressure detector 7. In order to identify a failure, it is necessary to remove the differential pressure detector 7 from the impulse lines 3 and 4 and check the operating state with the differential pressure detector 7 alone. There was a problem that it took.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and an object of the present invention is to identify a blockage of a pressure guiding line and a failure of a main body of a differential pressure detector without removing the differential pressure detector. It is another object of the present invention to realize a differential pressure detector diagnostic device that can be used.

[0006]

According to the present invention, there is provided a differential pressure detector diagnostic apparatus comprising: a differential pressure detector connected to a pipe through which a fluid to be measured flows through a pressure guiding pipe; And a valve whose opening / closing amount is controlled in accordance with an opening / closing operation signal output from a valve operating section, and a switching signal for averaging zero as a diagnostic signal is selectively superimposed on the valve opening / closing operation signal. A valve operation unit having a diagnostic signal generation unit,
A fault discriminator for discriminating between a blockage of the pressure guiding line and a fault in the main body of the differential pressure detector based on a response characteristic of the differential pressure detector when the diagnostic signal is superimposed.

[0007]

The change of the response characteristic of the differential pressure detector when the diagnostic signal is superimposed on the presence or absence of the blockage of the pressure guiding line can be obtained in advance by an experiment. Therefore, based on the response characteristics of the differential pressure detector when the diagnostic signal is superimposed, it is possible to accurately identify the blockage of the pressure guiding line and the failure of the differential pressure detector main body.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing one embodiment of the present invention.
Parts common to those in FIG. 5 are denoted by the same reference numerals. In the figure, reference numeral 10 denotes a differential pressure measuring system, the configuration of which is the same as that of FIG. Reference numeral 20 denotes a valve system, which includes a valve 21 connected to the pipeline 1 through which the fluid to be measured flows, and a valve operation unit 22 such as a positioner for applying an opening / closing operation signal to the valve 21. Reference numeral 30 denotes a controller which controls the valve system 20 based on the output signal of the differential pressure measurement system
1 is output. Controller 3
In 0, data on change in response characteristics such as the response time of a differential pressure detector when a diagnostic signal is superimposed due to the presence or absence of a blockage in the pressure guiding pipe determined in advance by experiment is also stored. It also functions as a failure identification unit that identifies a blockage of the pressure guiding line and a failure of the differential pressure detector main body based on the response waveform of the detector.

FIG. 2 is a block diagram showing a specific example of the valve operating section 22. As shown in FIG. In the figure, reference numeral 23 denotes an input signal detection unit, to which a valve opening degree setting signal is added from a controller 30 and an opening / closing control signal whose average value is zero is selectively added as a diagnosis signal from a diagnosis signal generation unit 24. 2
Reference numeral 5 denotes a diagnostic activation unit, which selectively activates the diagnostic signal generation unit 24. Reference numeral 26 denotes a calculation unit which controls the electropneumatic converter 28 to control the opening / closing degree of the valve 21 to a desired value based on the output signal of the input signal detection unit 23 and the output signal of the valve opening detection unit 27. Is output. The valve opening detection section 27 returns a signal corresponding to the opening / closing degree of the valve 21 to the calculation section 26. The electropneumatic converter 28 generates and outputs an air signal for opening and closing the valve 21 according to the control signal applied from the calculator 26.

FIG. 3 is a flowchart for explaining the flow of the operation of the present invention, and FIG. 4 is a waveform diagram of each section for explaining the operation of the present invention. When the start of the diagnosis operation is instructed by the diagnosis starting unit 25, a diagnosis signal as shown in FIG. 4A is applied from the diagnosis signal generation unit 24 to the input signal detection unit 23 (step). Here, as the diagnostic signal, an opening / closing control signal in which the opening / closing degree of the valve 21 at which the average value is zero is about ± 10% and the time for two cycles is about 30 seconds is output. The input signal detection unit 23 selectively superimposes the diagnostic signal on the signal applied from the controller 30 and outputs the signal to the arithmetic unit 26. The arithmetic unit 26 outputs the opening / closing operation signal on which the diagnostic signal is superimposed to the electropneumatic conversion unit 28. Output. As a result, the valve opening of the valve 21 changes in synchronization with the diagnostic signal as shown in FIG. 4B, and this change in the valve opening is detected by the valve opening detector 27 and fed back to the calculator 26. (Step).

On the other hand, in the differential pressure measuring system 10, the differential pressure detector 7 detects a pressure change of the fluid to be measured due to the opening / closing operation of the valve 21 (step), and the measurement result is stored in the controller 3.
Output to 0. FIG. 4C shows a differential pressure measurement output waveform in a normal state where there is no clogging in the pressure guiding lines 3 and 4.
(D) shows a differential pressure measurement output waveform in an abnormal state in which clogging occurs in the pressure guiding pipelines 3 and 4. Where t _s
The response time in a normal state without clogging the guide pressure line 3,4, t ₁ is the response time in an abnormal state to the conductive pressure line 3 and 4, that has occurred. Therefore, the failure identification unit calculates, for example, (t ₁ −t _s ), compares the calculation result with a predetermined determination constant a, and when (t ₁ −t _s ) <a, the impulse line It is determined that there is no clogging in 3 and 4 (step), and when (t ₁ −t _s )> a, it is necessary to judge that the pressure guiding pipelines 3 and 4 are in an abnormal state where clogging has occurred. An alarm is output according to (step).

With this configuration, it is possible to identify the presence or absence of the blockage of the pressure guiding conduits 3 and 4 by a simple operation of only instructing the start of diagnosis without removing the differential pressure detector 7 as in the related art. In the above embodiment, the presence or absence of the blockage of the pressure guiding conduits 3 and 4 is identified by focusing on the response time as a diagnostic item. However, for example, the sensitivity is focused on the difference between the output voltages V _S and V ₁ in FIG. May be a diagnostic item, or the response waveform pattern itself may be a diagnostic item.

Also, the function of the failure identification unit is changed to the valve operation unit 2.
Or the function of a controller including a failure identification unit may be provided in the differential pressure measurement system 10 or the valve system 20.

[0014]

As described above, according to the present invention,
It is possible to realize a differential pressure detector diagnostic device capable of distinguishing between a blockage of the pressure guiding conduit and a failure of the differential pressure detector main body without removing the differential pressure detector.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention.

FIG. 2 is a block diagram showing a specific example of a main part of FIG. 1;

FIG. 3 is a flowchart showing the flow of the operation of the present invention.

FIG. 4 is a waveform chart of each part for explaining the operation of the present invention.

FIG. 5 is a conceptual diagram of use of a differential pressure detector.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Pipeline 2 Orifice 3, 4 Pressure guiding pipeline 5, 6, 8 On-off valve 7 Differential pressure detector 10 Differential pressure measuring system 20 Valve system 21 Valve 22 Valve operation part 30 Controller

Claims (1)

(57) [Claims] 1. A differential pressure detector connected to a pipe through which a fluid to be measured flows through a pressure guiding pipe, and an open / close operation signal output from a valve operating section connected to a pipe through which the fluid to be measured flows and output from a valve operating section. A valve whose opening / closing amount is controlled in accordance with a valve operating unit having a diagnostic signal generating unit for selectively superimposing an opening / closing control signal having an average value of zero as a diagnostic signal on a valve opening / closing operation signal; And a failure identification unit that identifies a blockage of the pressure guiding conduit and a failure of the differential pressure detector main body based on a response characteristic of the differential pressure detector.