JPH06346901A - Electropneumatic transducer - Google Patents

Abstract

PURPOSE:To diagnose failure of an electropneumatic transducer in its driving state by generating such a diagnosis signal as providing a certain amplitude change to a pneumatic signal, detecting a return signal at a prescribed application time, and comparing whether its peak value is normal or not. CONSTITUTION:An electropneumatic transducer 16 is composed of an electropneumatic transducing part 17 and a diagnostic part 18, and a diagnosis signal VC besides an input signal Vi and a return signal Vf is added in an arithmetic amplifier 19 of the electropneumatic transducer 17. The diagnosis signal VC is output from a diagnosis signal generator 20 in the diagnostic part 18 and the diagnostic signal VC is controlled by an application time which is prescribed by a diagnosis time signal Vf generated from a time setting device 21. The diagnosis time signal Vf and the return signal Vf are applied in a peak value detector 22 and a peak value of the diagnosis signal VC which is contained in the return signal Vf at the application time is detected so as to be output as the peak signal Vk. The peak signal Vk is input in a comparative arithmetic device 23, it is judged whether this is within the prescribed value or not, and if not, an alarm signal AL is output. Thus a pressure detector and the like are diagnosed in driving state.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electropneumatic converter for outputting a pneumatic signal so that a feedback signal corresponding to an output pneumatic signal and an input signal corresponding to an input current signal are matched, and more particularly, to an electropneumatic converter. The present invention relates to an electropneumatic converter improved so that it is possible to determine whether or not an air pressure signal is within a predetermined value range while performing failure diagnosis in an operating state.

[0002]

2. Description of the Related Art FIG. 4 is a configuration diagram showing a configuration of a conventional electropneumatic converter. The electro-pneumatic converter 10 includes an input device 11, an operational amplifier 12, an electric / air converter 13, a pressure detector 14,
It is composed of a calculator 15 and the like.

[0003] The input device 11 is unified current signal I _i such of, for example, controllers via the two transmission lines 4~20mA is supplied, using a 4mA a base current of the current signal I _i Circuit power supply is produced and an input signal V _i corresponding to a current of 0 to 16 mA is output.

The operational amplifier 12 receives the input signal V
The deviation between _i and the feedback signal V _f is calculated to calculate the electric / air converter 1
The deviation voltage V _D is output to 3. A supply pressure P _S is applied to the electric / air converter 13, and the electric / air converter 13
Converts the supply pressure P _S into an air pressure signal P _O proportional to the deviation voltage V _D.

The pressure detector 14 is composed of, for example, a semiconductor pressure sensor or the like, and uses this semiconductor pressure sensor to convert it into an electric signal V _P proportional to the air pressure signal P _O. The electric signal V _P is calculated by the calculator 15 such that the zero point or the span is adjusted and fed back to the operational amplifier 12 as the feedback signal V _f .

In the above structure, the electropneumatic converter 10 is
While receiving the supply of the supply air pressure P _S , the current signal I _i is input to cover the circuit power supply and is converted into the air pressure signal P _O corresponding to the current signal I _i .

[0007]

However, in order to diagnose whether or not the electropneumatic converter 10 as described above is operating normally, the current signal I _i is applied and the air pressure output to this is applied. This is done by measuring the signal P _O.

Therefore, in order to diagnose whether or not the electropneumatic converter 10 is normal, the entire control process must be stopped for diagnosis, or the electropneumatic converter 10 must be removed from the loop of the control process for diagnosis. However, there is a problem that diagnosis cannot be performed in the operating state.

Further, in the electropneumatic converter shown in FIG. 4, it is not possible to diagnose whether or not it is normal in the operating state, and in addition, the pneumatic signal is accurately output at the point of 0% or 100% in the operating state. It is not possible to check whether or not

[0010]

The present invention has, as a main configuration for solving the above problems, (A) First, it corresponds to a feedback signal corresponding to an output air pressure signal and an input current signal. A first diagnostic signal generating means for generating a first diagnostic signal that gives a constant amplitude change to the preceding air pressure signal in the electro-pneumatic converter that outputs the preceding pneumatic pressure signal so that the input signal to 1 time setting means for setting the application time for applying the diagnostic signal, peak value detection means for detecting the previous feedback signal at the previous application time to detect its peak value, and whether the peak value is normal or not And a comparison calculation means for performing a comparison calculation.

(B) Second, under the above-mentioned premise, the above-mentioned current signal is inputted, and the amplitude value is set while keeping the average value constant so that the air pressure signal becomes a predetermined value based on this current signal. Second diagnostic signal generating means for generating the second diagnostic signal, time setting means for setting an application time for applying the second diagnostic signal, and a peak value of the previous feedback signal detected at the previous application time. A peak value detecting means for detecting
And a comparison calculation means for performing a comparison calculation on whether or not this peak value is within the value corresponding to the above predetermined value.

[0012]

[Operation] (A) First, in a state in which a current signal is input and a corresponding air pressure signal is output, the first diagnostic signal generating means gives the first diagnostic signal a change in constant amplitude to the air pressure signal. Generate. The time setting means sets an application time for applying the first diagnostic signal.

Then, the peak value detecting means detects the feedback signal corresponding to the output air pressure signal at the previous application time to detect the peak value, and the comparison calculating means compares and calculates whether or not the peak value is normal. To do.

(B) Second, in the state where the current signal is input and the corresponding air pressure signal is output, the second diagnostic signal generating means receives the previous current signal and outputs a predetermined value based on this current signal. The average value is kept constant so as to become an air pressure signal, and a second diagnostic signal having an amplitude value set is generated.

The time setting means sets an application time for applying the second diagnostic signal. Then, the peak value detecting means detects the previous feedback signal in the previous application time and detects the peak value thereof. Further, the comparison calculation means performs a comparison calculation as to whether or not this peak value is in the value corresponding to the above predetermined value.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the configuration of one embodiment of the present invention. The parts having the same functions as those of the conventional electropneumatic converter shown in FIG. 4 are designated by the same reference numerals, and the description thereof will be appropriately omitted.

The electropneumatic converter 16 is composed of an electropneumatic converter 17 and a diagnostic unit 18. The electropneumatic converter 17 corresponds to the electropneumatic converter 10 shown in FIG. 4, but the operational amplifier 19 corresponding to the operational amplifier 12 has a diagnostic signal V _{C in} addition to the input signal V _i and the feedback signal V _f. The difference is that is added. The other points are almost the same.

The diagnostic unit 18 includes a diagnostic signal generator 20, a time
Setting device 21, peak value detector 22, comparison calculator 23, etc.
It consists of The diagnostic signal from the diagnostic signal generator 20
Issue V _CIs output, but this diagnostic signal V_CIs the time setting device 2
Diagnostic time signal V output from 1_TWhen applied as specified by
Controlled by T.

The peak value detector 22 has a diagnostic time signal V _T.
The feedback signal V _f is applied, and at the application time T, the peak value of the diagnostic signal V _C included in the feedback signal V _f is detected and output as the peak signal V _K. The peak signal V _K is input to the comparison calculator 23, and it is determined whether or not the peak signal V _K has a specified value. If the peak signal V _K does not have the specified value, the alarm signal A _L is output to the outside.

Next, the operation of the embodiment shown in FIG. 1 will be described with reference to the waveform chart shown in FIG. In the operational amplifier 19, a signal component of the current signal I _i transmitted from a controller (not shown) is extracted by the input device 11 and the input signal V _i (FIG. 2) is extracted.
(A)) is input.

In addition to this, the operational amplifier 19 has a diagnostic signal V _C (FIG. 2B) controlled by a diagnostic time signal V _T (FIG. 2B) having the application time T output from the time setter 21.
(C)) has been entered.

Further, the operational amplifier 19 includes an arithmetic unit 15
Although the feedback signal V _f (FIG. 2 (d)) output from is input, the operational amplifier 19 subtracts the feedback signal V _f from the sum of these input signals V _i and the diagnostic signal V _C. Then, the deviation voltage V _D is output to the electric / air converter 13.

The electric / pneumatic converter 13 outputs as an air pressure signal P _O corresponding to the deviation voltage V _D , and this air pressure signal P _O is converted into an electric signal V _P by the pressure detector 14 and passed through the calculator 15. And is fed back to the operational amplifier 19 as the feedback signal V _f .

[0024] As described above, finally, in the state where the system is stable, and is output as the air pressure signal P _O proportional to the current signal I _i. Here, the peak value detector 22 is shown in FIG.
Although the feedback signal V _f shown in (d) is input, the peak value detector 22 detects the peak value of the diagnostic signal V _C corresponding to the application time T included therein and detects the peak signal V _K (FIG. 2).
(E)) is output.

In the state shown in FIG. 2E, the peak signal V _K1 on the right side is smaller than the peak signal V _K2 on the left side, and the peak signal V _K1 is smaller than a predetermined value which is a predetermined built-in normal value. It is a value, indicating an abnormal condition.
Therefore, in this case, from the comparison calculator 23 to FIG.
The alarm signal A _L shown in is output.

The peak value detector 22 receives the input signal V _i and the feedback signal V _f , calculates the difference between them, and then
You may make it detect a peak. With such a configuration, the detection error can be reduced when the input current signal I _i fluctuates.

FIG. 3 is a block diagram showing the configuration of the second embodiment of the present invention. The components having the same functions as those of the components shown in FIG. 1 are designated by the same reference numerals, and the description will not be repeated.

This configuration is not limited to failure diagnosis,
In the operating state, the output air pressure signal P ₀ has a predetermined value, for example, 0.
%, 100%, etc., so that it can be inspected whether or not it is normally output.

To this end, a diagnostic signal generator 24 is provided in addition to the time setter 21, the peak value detector 22, and the comparison calculator 23 to configure a diagnostic unit 25.
An electropneumatic converter 26 is configured in combination with 7.

The diagnostic signal generator 24 receives the valve opening signal V _v proportional to the current signal I _i from the input device 11, and the application output from the time setting device 21 with this valve opening signal V _v as a reference. Diagnostic signal V _CS that changes like a pulse in the range of time T
Set the amplitude value of.

This amplitude value is, for example, this operational amplifier 19
To the air pressure signal P ₀ when applied together with the input signal V _i.
Is set as a value that results in 0%. However, the average value of this diagnostic signal V _CS is selected to be zero so as not to affect the pneumatic signal P ₀ .

On the other hand, the peak value detector 22 determines the fluctuation value of the air pressure signal P ₀ according to the diagnostic signal V _CS from the time setter 21.
The peak value is detected through the pressure detector 14 within the range of the application time T output from the output, and the comparison calculator 23 determines whether or not the peak value is present. If not, the alarm is issued. Output signal A _L.

In the above description, the diagnostic signal V _C has been described as being added to the operational amplifier 19, but the present invention is not limited to this, and it may be added to the feedback signal V _f , for example. In short, the diagnostic signal V _C may be applied anywhere as long as the pressure fluctuation can be applied to the pressure detector 14, and may be applied to the pressure detector 14.

Further, in the above description, the diagnostic signal V _C
Although the amplitude value of 10%, 50%, 10% other than 0% was explained as the specified value at the point where the pneumatic signal P ₀ becomes 0%.
It can be set to 0% or the like.

[0035]

As described above in detail with reference to the embodiments, according to the present invention, according to the first claim, a diagnostic signal is applied to a part of the configuration of the electropneumatic converter, and a predetermined position is applied. Since this diagnostic signal is detected and its peak value is detected, it is possible to diagnose the pressure detector, which is an important component of the electro-pneumatic converter, while online, improving performance and stability. It can contribute to securing.

Further, according to the second aspect, it is possible to inspect whether or not an accurate output is produced at an arbitrary point such as 0%, 10%, 50%, 100% of the pneumatic signal in the operating state. Therefore, it is possible to realize a highly reliable electropneumatic converter.

[Brief description of drawings]

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

FIG. 2 is a waveform diagram for explaining the operation of the embodiment shown in FIG.

FIG. 3 is a block diagram showing the configuration of another embodiment of the present invention.

FIG. 4 is a block diagram showing a configuration of a conventional electropneumatic converter.

[Explanation of symbols]

 10, 16, 26 Electro-pneumatic converter 11 Input device 12, 19 Operational amplifier 13 Electric / pneumatic converter 14 Pressure detector 15 Operator 18, 25 Diagnostic unit 20, 24 Diagnostic signal generator 21 Time setting device 22 Peak value detection Unit 23 Comparison calculator

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Minoru Midagawa 2-9-32 Nakamachi, Musashino-shi, Tokyo Yokogawa Electric Co., Ltd.

Claims (3)

[Claims] 1. An electropneumatic converter which outputs the air pressure signal so that a feedback signal corresponding to an output air pressure signal and an input signal corresponding to an input current signal match each other. First diagnostic signal generating means for generating a first diagnostic signal that gives a change, time setting means for setting an application time for applying the first diagnostic signal, and a peak value of the feedback signal detected at the application time. An electro-pneumatic converter comprising a peak value detecting means for detecting and a comparison calculating means for comparing and calculating whether or not the peak value is normal. 2. An electropneumatic converter that outputs the air pressure signal such that a feedback signal corresponding to the output air pressure signal and an input signal corresponding to the input current signal match each other. Second diagnostic signal generating means for generating a second diagnostic signal having an amplitude value set by holding the average value constant so that the air pressure signal has a predetermined value based on the current signal, and applying the second diagnostic signal A time setting means for setting an applying time, a peak value detecting means for detecting the feedback signal and detecting a peak value thereof during the applying time, and whether the peak value is within a value corresponding to the predetermined value. An electropneumatic converter, comprising: a comparison calculation unit that compares and calculates whether or not there is a difference. 3. The peak value detecting means receives the input signal and the feedback signal, and detects the peak value at the application time based on the difference between the input signal and the feedback signal. The electropneumatic converter according to claim 2.