JP4609025B2 - Pressure detector and clogging diagnosis method for pressure detector - Google Patents

Description

  The present invention relates to a pressure detector for detecting pressure in a pressure guiding tube and a clogging diagnosis method for the pressure detector, and more particularly to a vibration type pressure sensor that transmits differential pressure and static pressure and clogging diagnosis for the pressure detector. Regarding the method.

Some conventional pressure detectors and clogging diagnosis methods for pressure detectors diagnose clogging of a pressure guiding tube based on dispersion of pressure fluctuations (see, for example, Patent Document 2).
For example, in a differential pressure / pressure transmitter, which is a pressure detector, statistical calculation of fluctuation of a differential pressure signal or a static pressure signal is performed to diagnose clogging of a pressure guiding tube.

  Hereinafter, the present invention will be described in detail with reference to FIG. FIG. 6 is a block diagram showing a conventional pressure detector.

  An orifice 2 is installed in the middle of the conduit 1 through which the fluid flows. The pressure on the high pressure side and the pressure on the low pressure side of the orifice 2 are transmitted to the pressure transmitter 50 through the pressure guiding tube 3.

  The pressure transmitter 50 includes a sensor 41 and a calculation means 52. The sensor 41 detects the pressure of the pressure guiding tube 3, and the calculation means 52 generates a differential pressure signal and a static pressure signal from the output of the sensor 41. Further, the sensor 41 is formed by a vibration type sensor, for example.

  Further, the calculation means 52 includes a frequency counter 63, a swing calculation unit 61, a dispersion calculation unit 62, and a determination unit 72. Then, the swing calculation unit 61 outputs the above-described differential pressure signal and static pressure signal based on the integration time defined by the counter 63 and periodically samples them, and swings F0p ( n) is calculated. Further, the variance calculation unit 62 calculates the variance V0d of the swing F0p (n). Further, the determination unit 72 diagnoses clogging of the pressure guiding tube 3 based on the value of the dispersion V0d.

Japanese Patent No. 3129121 JP 2004-132817 A

  However, the conventional pressure detector and the method for diagnosing clogging of the pressure detector may be affected by the flow rate flowing through the orifice, and there is a problem that the accuracy of diagnosis is low.

  An object of the present invention is to solve the problems described above, and to provide a pressure detector with high diagnostic accuracy and a clogging diagnosis method for the pressure detector.

The present invention which achieves such an object is as follows.
(1) In a pressure detector that detects a differential pressure or static pressure of two pressure guiding tubes with a sensor and diagnoses clogging of the pressure guiding tube based on dispersion of fluctuations in the differential pressure or static pressure,
A fluctuation calculation unit for sampling a short integration time output of the sensor to calculate a differential pressure or a static pressure signal, and calculating a fluctuation of the differential pressure or the static pressure signal;
A first sampling means for calculating a first variance of the oscillation, comprising a variance computing unit for computing the variance of the differential pressure or the static pressure oscillation;
A fluctuation calculating unit for calculating a differential pressure or a static pressure signal by sampling an output of a long integration time of the sensor and calculating a fluctuation of the differential pressure or the static pressure signal, and dispersion of the differential pressure or the static pressure fluctuation Second sampling means for calculating the second variance of the oscillation,
Storage means for storing a ratio of the first dispersion and the second dispersion in a normal state,
The first dispersion at diagnosis and the second dispersion ratio based on said first dispersion and said second dispersion ratio in a normal state, the pressure, characterized in that to diagnose blockage of the impulse line Detector.
(2) In a clogging diagnosis method for a pressure detector that detects a differential pressure or static pressure between two pressure guiding tubes with a sensor and diagnoses clogging of the pressure guiding tube based on dispersion of fluctuations in the differential pressure or static pressure. ,
Sampling the output of the short integration time of the sensor to calculate the first variance of the fluctuation of the differential pressure or static pressure, sampling the output of the long integration time of the sensor and fluctuation of the differential pressure or static pressure Calculating a second variance of
Calculating a ratio of the first variance and the second variance;
Diagnosing clogging of the pressure guiding tube based on a ratio between the first dispersion and the second dispersion in a normal state and a ratio between the first dispersion and the second dispersion obtained at the time of diagnosis;
A method for diagnosing clogging of a pressure detector, comprising:

As is apparent from the above description, the present invention has the following effects.
According to the present invention, it is possible to provide a clogging diagnosis method that is not affected by the flow rate.

  Hereinafter, the present invention will be described in detail with reference to FIG. FIG. 1 is a block diagram showing an embodiment of the present invention. Elements equivalent to those in the conventional example of FIG. 6 are denoted by the same reference numerals, and description thereof is omitted.

  A feature of the embodiment of FIG. 1 is that a first sampling means 10 and a second sampling means 20 are provided.

  The first sampling unit 10 includes a counter 13 that measures a short time frequency, a swing calculation unit 11, and a dispersion calculation unit 12. Further, the swing calculation unit 11 calculates a differential pressure signal by sampling the frequency at regular intervals, and calculates a differential pressure swing F1dp (n) of the differential pressure signal. Further, the dispersion calculating unit 12 calculates a differential pressure dispersion V1dp of the differential pressure fluctuation F1dp (n).

For example, the differential pressure fluctuation F1dp (n) is defined by the following equation (1). It is assumed that the differential pressure signal D1dp (n) to be sampled nth is the differential pressure signal D1dp (n-1) to be sampled (n-1) th.
F1dp (n) = D1dp (n) −D1dp (n−1) (1)

Further, for example, the differential pressure dispersion V1dp is defined by the following equation (2). N is the total number of samples.
V1dp = Σ {F1dp (n) · F1dp (n)} / N (2)

  The second sampling unit 20 includes a counter 23 that measures a long time frequency, a swing calculation unit 21, and a dispersion calculation unit 22. Further, the swing calculation unit 21 calculates the differential pressure signal by sampling the frequency at regular intervals, and calculates the differential pressure swing F2dp (n) of the differential pressure signal. Further, the dispersion calculating unit 22 calculates a differential pressure dispersion V2dp of the differential pressure fluctuation F2dp (n).

For example, the differential pressure fluctuation F2dp (n) is defined by the following equation (3). It is assumed that the differential pressure signal D2dp (n) to be sampled nth is the differential pressure signal D2dp (n-1) to be sampled (n-1) th.
F2dp (n) = D2dp (n) -D2dp (n-1) (3)

Further, for example, the differential pressure dispersion V2dp is defined by the following equation (2). N is the total number of samples.
V2dp = Σ {F2dp (n) · F2dp (n)} / N (4)

  Further, the ratio calculation unit 31 calculates a ratio (V1dp / V2dp) between the differential pressure dispersion V1dp and the differential pressure dispersion V2dp.

  Further, the storage means 33 stores a predetermined threshold value K. Further, the determination unit 32 compares the ratio (V1dp / V2dp) with the threshold value K. When the ratio (V1dp / V2dp) is larger than the threshold value K, it is determined that the state is normal, and when the ratio (V1dp / V2dp) is smaller than the threshold value K, it is determined that the pressure guiding tube is clogged.

Here, the operation of the first sampling means 10 and the second sampling means 20 will be described in detail with reference to FIG. FIG. 2 is a diagram showing the fluctuation of the differential pressure in the embodiment of FIG. The horizontal axis indicates time.

In the figure, a waveform p shows a change in the differential pressure of the pressure guiding tube, a waveform g1 shows a change in the differential pressure signal D1dp (n) sampled by the first sampling means 10, and a waveform g2 is sampled by the second sampling means 20. A change in the differential pressure signal D2dp (n) is shown.

  Moreover, the average value of the pressure p of the pressure guiding tube in the integration time Ave1 (n) defined by the short-time counter 13 is the differential pressure signal D1dp (n). Specifically, the average value of the pressure pipe pressure p in the integration time Ave1 (1) is the differential pressure signal D1dp (1), and the average value of the pressure pipe pressure p in the integration time Ave1 (2) is the differential pressure signal D1dp. (2),..., The average value of the pressure p in the pressure guiding tube in the integration time Ave1 (6) is the differential pressure signal D1dp (6).

  Similarly, the average value of the pressure p in the pressure guiding tube during the integration time Ave2 (n) defined by the long-time counter 23 is the differential pressure signal D2dp (n). Specifically, the average value of the pressure pipe pressure p in the integration time Ave2 (1) is the differential pressure signal D2dp (1), and the average value of the pressure pipe pressure p in the integration time Ave2 (2) is the differential pressure signal D2dp. (2), and the average value of the pressure guide pipe pressure p in the integration time Ave2 (3) is the differential pressure signal D2dp (3).

The operation of the first sampling means 10 and the second sampling means 20 will be described in detail with reference to FIG. FIG. 3 is a Bode diagram at the output of the embodiment of FIG. The horizontal axis indicates the frequency . The vertical axis represents the fluctuation gain (Fluctuation Gain) which is the ratio of the fluctuation of the static pressure measured in the embodiment of FIG. 1 to the fluctuation of the static pressure at the connection point between the orifice and the pressure guiding tube.

  In the figure, a characteristic fs is a characteristic in a normal state, and a characteristic fA is a characteristic in a state where a pressure guiding tube is clogged. Point 1S and point 1A correspond to the characteristics sampled by the first sampling means 10, and point 2S and point 2A correspond to the characteristics sampled by the second sampling means 20.

  Specifically, since the characteristics of the first sampling means 10 have a short integration time, the sensitivity is high with respect to the high-frequency component of the pressure fluctuation, and the characteristics of the second sampling means 20 have a long integration time. High sensitivity to low frequency components of motion.

  When the pressure guiding tube is clogged from the normal state, the characteristic fs changes to the characteristic fA, the characteristic of the first sampling means 10 changes from the point 1S to the point 1A, and the characteristic of the second sampling means 20 changes to the point. It changes from 2S to point 2A.

  Furthermore, the change from point 1S to point 1A is larger than the change from point 2S to point 2A.

  Therefore, if the change from the point 1S to the point 1A and the change from the point 2S to the point 2A are monitored, the clogging of the pressure guiding tube can be diagnosed.

  Such a diagnosis can be easily realized by calculating the ratio (V1dp / V2dp) between the differential pressure variance V1dp and the differential pressure variance V2dp and comparing it with the threshold value K. That is, it can be simply formed by providing the ratio calculation unit 31 and the storage means 33.

  In the above-described embodiment, only the case where the calculation related to the sampling of the differential pressure signal is performed has been described. However, the same calculation can be performed regarding the sampling of the static pressure signal.

At this time, for example, the static pressure fluctuation F1p (n) in the first sampling means 10 is defined by the following equation (5), similarly to the differential pressure fluctuation F1dp (n). However, it is set as the static pressure signal D1p (n) sampled nth, and the static pressure signal D1p (n-1) sampled (n-1) th.
F1p (n) = D1p (n) −D1p (n−1) (5)

Further, for example, the static pressure dispersion V1p is defined by the following equation (6), similarly to the differential pressure dispersion V1dp.
V1p = Σ {F1p (n) · F1p (n)} / N (6)

Further, for example, the static pressure fluctuation F2p (n) in the second sampling means 20 is defined by the following equation (7), similarly to the differential pressure fluctuation F2dp (n). However, the differential pressure signal D2p (n) to be sampled n-th and the static pressure signal D2p (n-1) to be sampled (n-1) -th.
F2p (n) = D2p (n) -D2p (n-1) (7)

Further, for example, the static pressure dispersion V2p is defined by the following equation (8), similarly to the differential pressure dispersion V2dp.
V2p = Σ {F2p (n) · F2p (n)} / N (8)

  Further, the ratio calculation unit 31 calculates a ratio (V1p / V2p) between the static pressure dispersion V1p and the static pressure dispersion V2p.

  Then, the determination unit 32 determines whether the state is normal or clogged based on the ratio (V1dp / V2dp) and the ratio (V1p / V2p). 1 can accurately diagnose clogging of the pressure guiding tube.

    The clogging diagnosis method of the embodiment of FIG. 1 will be described below with reference to FIG. FIG. 4 is a flowchart in the clogging diagnosis method of the embodiment of FIG.

  First, step S11 is performed to calculate the first dispersion (V1dp, V1p) of pressure fluctuation with respect to the low frequency component and to calculate the second dispersion (V2dp, V2p) of pressure fluctuation with respect to the high frequency component. Specifically, the above equations (2), (4), (6), and (8) are respectively calculated.

  Next, step S12 is performed to calculate the ratio (V1dp, V1p) / (V2dp, V2p) between the first variance (V1dp, V1p) and the second variance (V2dp, V2p). Specifically, the ratio (V1dp / V2dp) and the ratio (V1p / V2p) are respectively calculated.

  Finally, step S13 for diagnosing clogging of the pressure guiding tube based on the ratio value is executed. Specifically, when the ratio (V1dp / V2dp) and the ratio (V1p / V2p) are larger than the threshold value K (Kdp, Kp), it is diagnosed that the pressure guiding tube is not clogged. When the ratio (V1dp / V2dp) and the ratio (V1p / V2p) are smaller than the threshold value K (Kdp, Kp), it is diagnosed that the pressure guiding tube is clogged.

  Thus, the embodiment of FIG. 1 can diagnose clogging of the pressure guiding tube simply and accurately.

  In addition to the above-described embodiment, the storage unit 33 of the embodiment of FIG. 1 stores the ratio (V1sdp / V2sdp) and the ratio (V1sp / V2sp) at the point 1S and the point 2S in the normal state, and the determination You may make it use for the determination of the part 32. FIG.

  The clogging diagnosis method of the embodiment of FIG. 1 will be described below with reference to FIG. FIG. 5 is another flowchart in the clogging diagnosis method of the embodiment of FIG. The description equivalent to the flowchart of FIG. 4 is simplified.

  The feature of the flowchart of FIG. 5 is that it includes an operation in a normal state and an operation at the time of diagnosis. The normal state is, for example, a state where the pressure guiding tube immediately after maintenance is not clogged. In the diagnosis, the pressure guiding tube is clogged or it is not clear whether the pressure guiding tube is clogged.

First, it calculates a first dispersion V1sp the first dispersion V1sdp and static pressure oscillation of the differential pressure fluctuation with respect to high-frequency components in the normal state,
Step 21 of calculating the second variance V2sdp of the differential pressure fluctuation and the second variance V2sp of the static pressure fluctuation with respect to the low frequency component is executed.

Second, to execute a step S22 of calculating a first dispersion V1sd p and the ratio of the second dispersion V2sdp, and the first dispersion V1sp the ratio V1sdp / V2sdp and V1sp / V2sp the second dispersion V2sp under normal conditions

  Third, step S23 is executed to store the two types of ratios V1sdp / V2sdp and V1sp / V2sp in the normal state in the storage means 33.

Fourth, calculates a first dispersion V 1p of the first dispersion V1dp and static pressure oscillation of the differential pressure fluctuation with respect to the high-frequency component definitive when the diagnosis, the second dispersion V2d p of the differential pressure fluctuation with respect to the low frequency component And step 24 of calculating the second variance V2p of the static pressure fluctuation

  Fifth, step S25 is performed to calculate the ratio between the first variance V1dp and the second variance V2dp and the ratio V1dp / V2dp and V1p / V2p between the first variance V1p and the second variance V2p at the time of diagnosis.

Sixth, step S26 for diagnosing clogging of the pressure guiding tube based on the ratio value is executed. Specifically, when the ratio V1dp / V2dp is equal to the ratio V1sdp / V2sdp and the ratio V1p / V2p is equal to V1sp / V2sp , it is diagnosed that the pressure guide tube is not clogged. When the ratio V1dp / V2dp is sufficiently smaller than the ratio V1sdp / V2sdp and when the ratio V1p / V2p is sufficiently smaller than the ratio V1sp / V2sp , it is diagnosed that the pressure guiding tube is clogged.

In the above example, two counters are provided. However, separately from this, the frequency output of a short integration time and the frequency output of a long integration time are calculated from the same counter from one counter. In this case, the first sampling means and the second sampling means can be formed. Therefore, even in such a case, an equivalent effect can be obtained.
As another means, the differential pressure signal calculated from the frequency output of a short integration time can be D1dp, and the differential pressure signal obtained by averaging the differential pressure signal for a certain period of time can be D2dp.

  Furthermore, although the above-mentioned example is a vibration type pressure detector, a pressure detector other than the vibration type is substantially the same in configuration and can obtain the same operation effect. it can. Specifically, it comprises a first sampling means for sampling an analog output having a short integration time and a second sampling means for sampling an analog output having a long integration time.

  Moreover, although the above-mentioned example was an embodiment provided with two sampling means, it is possible to obtain the same operation effect even if two or more sampling means are provided.

  As described above, the present invention is not limited to the above-described embodiments, and includes many changes and modifications without departing from the essence thereof.

It is a block diagram which shows one Example of this invention. It is a figure which shows the fluctuation of the pressure in the Example of FIG. It is a Bode diagram in the output of the example of FIG. It is a flowchart in the clogging diagnostic method of the Example of FIG. It is another flowchart in the clogging diagnostic method of the Example of FIG. It is a block diagram which shows the conventional pressure detector.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Pipe line 2 Orifice 3 Impulse pipe 10,20 Sampling means 13 Short time counter (frequency counter)
23 Long-time counter (frequency counter)
11, 21 Swing calculation unit 12, 22 Dispersion calculation unit 31 Ratio calculation unit 32 Judgment unit 33 Storage unit 40 Pressure detector 41 Sensor 42 Calculation unit

Claims (2)

In a pressure detector that detects a differential pressure or static pressure between two pressure guiding tubes with a sensor, and diagnoses clogging of the pressure guiding tube based on dispersion of fluctuations in the differential pressure or static pressure,
A fluctuation calculation unit for sampling a short integration time output of the sensor to calculate a differential pressure or a static pressure signal, and calculating a fluctuation of the differential pressure or the static pressure signal;
A first sampling means for calculating a first variance of the oscillation, comprising a variance computing unit for computing the variance of the differential pressure or the static pressure oscillation;
A fluctuation calculating unit for calculating a differential pressure or a static pressure signal by sampling an output of a long integration time of the sensor and calculating a fluctuation of the differential pressure or the static pressure signal, and dispersion of the differential pressure or the static pressure fluctuation Second sampling means for calculating the second variance of the oscillation,
Storage means for storing a ratio of the first dispersion and the second dispersion in a normal state,
The first dispersion at diagnosis and the second dispersion ratio based on said first dispersion and said second dispersion ratio in a normal state, the pressure, characterized in that to diagnose blockage of the impulse line Detector. In a clogging diagnosis method for a pressure detector, which detects a differential pressure or static pressure between two pressure guiding pipes with a sensor and diagnoses clogging of the pressure guiding pipe based on dispersion of fluctuations in the differential pressure or static pressure,
The first variance of the differential pressure or static pressure fluctuation is calculated by sampling the short integration time output of the sensor, and the differential pressure or static pressure fluctuation is sampled by sampling the long integration time output of the sensor. Calculating a second variance of
The step of calculating a ratio of scattered second minute and the first dispersion,
Diagnosing clogging of the pressure guiding tube based on a ratio between the first dispersion and the second dispersion in a normal state and a ratio between the first dispersion and the second dispersion obtained at the time of diagnosis;
A method for diagnosing clogging of a pressure detector, comprising:

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