JP6141691B2 - Pressure calibration device - Google Patents

Description

  The present invention relates to a pressure calibration device, and more particularly to a portable pressure calibration device capable of calibrating various pressure gauges with high accuracy.

  A pressure transmitter, which is a type of pressure gauge, is often used in various refineries and factories such as oil, gas, paper pulp, and power generation. In calibrating such a pressure transmitter at the installation site, a pressure calibration device is used.

  As a conventional pressure calibration device, as described in Patent Document 1, a device incorporating a pressure calibration function inside the pressure measurement device, or as described in Patent Document 2, between the counter electrodes accompanying the measurement pressure Measurement with built-in pressure sensor that is optimal for the measurement range, such as detecting the displacement of the sensor as a change in capacitance and detecting the strain displacement of the diaphragm accompanying the measurement pressure as the resistance change of the strain gauge. There is an apparatus including a plurality of air pressure detection units having different ranges.

  Further, Patent Document 3 describes a pressure measuring device provided with a tilt sensor so that the zero offset value is automatically corrected even when the posture changes depending on the use state.

  By the way, the installation site of the pressure transmitter is often a poor environment such as a large working space due to the influence of temperature change and vibration, so that the pressure calibration device can withstand these environments. Performance as a field measuring instrument is required.

JP 2001-66210 A JP-A-8-68713 JP 2012-247252 A

  However, the conventional pressure calibration device is housed in a rectangular housing case with a relatively large outer shape, so it is inconvenient to carry the device, and a pressure calibration device is installed for calibration at the installation site of the pressure transmitter. There is a problem such as having to secure a working space to do.

  Since the display unit and operation panel of the pressure calibration device are provided on the front surface of the housing case, when the pressure calibration device is in use, the bottom surface of the pressure calibration device is arranged so that it is almost horizontal. However, depending on the place of use, it may be difficult to align the front part with the operator, which may interfere with operation of the operation panel or reading of the display unit. is there.

  In addition, although the pressure sensor unit is configured to be shared regardless of whether the pressure medium is gas or liquid, if the pressure medium is liquid, residue may adhere to the pressure sensor unit. is there. As a countermeasure, for example, it is conceivable to attach a filter for filtration. However, if the filter is attached, the number of parts increases and the configuration becomes complicated, and it is necessary to manage the replacement time of the filter.

  In the case of a type using a resistance change of a strain gauge as a pressure sensor, for example, the stability against temperature change and change with time is relatively poor, the resolution is relatively low, the measurement range is relatively narrow, and high-precision measurement is possible. Have difficulty.

  The present invention solves these problems, and its purpose is excellent in portability and operability as an on-site measuring instrument, and can be used for both gas and liquid pressure media. An object of the present invention is to provide a pressure calibration device that has a relatively high stability and can perform high-precision pressure measurement with a high resolution and a relatively wide measurement range.

In order to achieve such a problem, the invention according to claim 1 of the present invention is:
In a pressure calibration device having a pressure measurement unit and configured to calibrate a pressure gauge,
An inclination sensor for detecting the attitude of the device;
A reference calibration means for measuring a zero reference calibration value;
Attitude error correction means for correcting an attitude error included in a measurement value of the pressure measurement unit based on a reference calibration value by the reference calibration means and attitude information output from the tilt sensor;
A correction enable / disable determining means for determining whether or not posture error correction within a predetermined error range based on the posture information output from the tilt sensor;
The reference calibration value is measured by the reference calibration means when the correction possibility judgment means judges that the correction is impossible.

The invention according to claim 2 is the pressure calibration device according to claim 1,
The pressure measurement unit uses a silicon resonant sensor configured to detect a measurement pressure based on a change in a resonance frequency of a silicon vibrator formed on a diaphragm.

The invention according to claim 3 is the pressure calibration device according to claim 1 or 2,
A cleaning unit for cleaning the pressure measuring unit is provided.

The invention according to claim 4 is the pressure calibration device according to claim 3,
The cleaning gas is air.

The invention according to claim 5 is the pressure calibration device according to claim 3,
The cleaning gas is an inert gas.

  As a result, a pressure calibration device with excellent portability, high accuracy, wide range, and low power consumption can be realized. In addition, a cleaning unit that can be used with either liquid or gas that can be attached and removed externally provides a clean sensor surface. A highly reliable pressure calibration device can be realized.

It is a block diagram which shows the specific example of the pressure calibration system using the pressure calibration apparatus based on this invention. It is a block diagram which shows one Example of this invention. It is a principal part schematic sectional drawing of the differential pressure measurement apparatus used as the pressure measurement part 301 by this invention. It is a block diagram which shows the specific example of the washing | cleaning unit SU used by this invention. It is explanatory drawing of the usage example of washing | cleaning unit SU. It is a circulation route explanatory view of cleaning gas in cleaning unit SU. FIG. 11 is a display screen example diagram of the display unit 307. 5 is a specific example diagram of an operation panel of the pressure calibration device 3 including a key operation unit 308. FIG. FIG. 4 is a diagram illustrating an example of data stored in an internal memory 310. It is a flowchart explaining operation | movement of the pressure calibration apparatus 3 based on this invention. It is a display example figure of the alarm information displayed on the display unit 307. It is a display example figure of the measured value displayed on the display part 307, and a calibration value.

  Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram showing a specific example of a pressure calibration system using a pressure calibration apparatus according to the present invention. In FIG. 1, a pressure generator 1 supplies and outputs a predetermined pressure for pressure calibration in parallel to, for example, a pressure transmitter 2 and a pressure calibration device 3 which are calibration target devices. For example, a hand pump is used as the pressure generator 1.

  The pressure transmitter 2 and the pressure calibration device 3 are connected via a two-wire loop power supply line 4. The pressure calibration device 3 outputs a drive signal of 4-20 mA / 1-5 V to the pressure transmitter 2, and the pressure transmitter 2 converts the measured value of the predetermined pressure input from the pressure generator 1 to a direct current of 4-20 mA. It is superimposed on the current and sent back to the pressure calibration device 3.

  A control PC (personal computer) 5 is connected to the pressure calibration device 3 as necessary.

  FIG. 2 is a block diagram showing a specific example of the pressure calibration device 3. In FIG. 2, as the pressure measurement unit 301, for example, a silicon resonant sensor configured to detect a measurement pressure based on a change in the resonance frequency of a silicon vibrator formed on a diaphragm is used. According to the silicon resonant sensor, pressure measurement can be performed with high sensitivity and high accuracy, and the influence of pressure change and temperature change is extremely small, and long-term stability can be obtained.

  FIG. 3 is a schematic cross-sectional view of a main part of a differential pressure measuring device used as the pressure measuring unit 301. In FIG. 3, 301a is a detection unit made of a known silicon resonant sensor, 301b is a protection unit, and a pressure guiding space (not shown) of the detection unit 301a and the protection unit 301b are connected via pressure guiding paths 301c and 301d. Yes. The detection unit 301a converts the differential pressure to be measured into an electrical signal and outputs it, and the protection unit 301b protects the detection unit 301a against the introduction pressure.

  The protection part 301b is mainly composed of bodies 301e and 301f, a center diaphragm 301g, and wetted diaphragms 301h and 301i, and the bodies 301e and 301f are provided on the left and right sides so as to sandwich the center diaphragm 301g. Are hermetically joined to each other.

  The surface of the body 301e facing the center diaphragm 301g is formed as a curved surface having a predetermined curvature, and a space 301j is formed between the center diaphragm 301g, and the surface facing the body 301f and the center diaphragm 301g is also formed with the body 301e. A space 301k having substantially the same shape as the space 301j is formed between the center diaphragm 301g and a curved surface having the same curvature.

  The left side surface of the body 301e is formed as a curved surface having a predetermined curvature, and a plurality of grooves (not shown) are formed concentrically on the curved surface so that the cross-sectional shape is corrugated. The peripheral edge of the liquid contact diaphragm 301h in which a plurality of grooves (not shown) are formed concentrically so as to have substantially the same waveform as the curved surface is joined in an airtight manner so as to form a predetermined space 301m.

  The right side surface of the body 301f is also formed as a curved surface having substantially the same curvature as the left side surface of the body 301e, and a plurality of groove portions (not shown) are formed concentrically on the curved surface so that the cross-sectional shape is corrugated. The surface of the wetted diaphragm 301i in which a plurality of grooves (not shown) are formed concentrically so that the cross-sectional shape has substantially the same waveform as that of the curved surface is formed on the surface to form a space 301n having substantially the same shape as the space 301m. And are airtightly joined.

  The pressure guiding path 301c is formed so as to communicate the space portions 301j and 301n formed on both surfaces of the body 301e and a pressure guiding space (not shown) of the detecting unit 301a, and the pressure guiding path 301d is formed on both surfaces of the body 301f. The space portions 301k and 301p and the pressure guiding space (not shown) of the detecting portion 301a are communicated with each other, and the pressure guiding passages 301c and 301d and the space portions 301j, 301k, 301m, and 301n are respectively provided with pressure transmitting fluids. Is filled with silicon oil (filled liquid).

  When the pressures to be measured are received by the respective liquid contact diaphragms 301h and 301i, the respective introduction pressures are transmitted to the detection unit 301a via the pressure guiding paths 301c and 301d. In the detection unit 301a, a differential pressure based on each introduction pressure is converted into an electric signal by a known detection unit and output.

  Such a pressure measuring unit 301 is configured to be able to measure both pressures of gas and liquid. When measuring the pressure of a gas after measuring the pressure of the liquid, or measuring the pressure of different types of liquids. When doing so, a pressure input unit (not shown) of the pressure measurement unit 301 is cleaned using, for example, a cleaning unit SU as shown in FIG.

  4A is a perspective view, and FIG. 4B is an enlarged cross-sectional view of FIG. One end C of the main body 10 is formed as a cylindrical body 101 having an open end, and the other end D is formed as a base 102 having a hexagonal cross-sectional shape that supports the other end of the cylindrical body 101.

  A plurality of holes 103 communicating with the outside are provided in the side wall near the opening end of the cylindrical body 101, and the bottom surface 104 of the base 102 orthogonal to the longitudinal direction of the cylindrical body 101 is for a port communicating with the cylindrical body 101. A hole 107 for a port communicating with the cylindrical body 101 is provided on the side surface 106 of the base 102 parallel to the longitudinal direction of the cylindrical body 101.

  Inside the cylindrical body 101 and the base 102 of the main body 10, a pipe 11 having both ends opened is attached.

  The outer diameter of the pipe 11 is such that a gap G communicating with a port hole 107 provided on a side surface of the base 102 is formed between the outer peripheral surface of the pipe 11 and the cylindrical body 101 of the main body 10 and the inner wall of the base 102. Further, it is formed slightly smaller than the inner diameter of the cylindrical body 101. One end 111 of the pipe 11 is fixed to a port hole 106 provided on the bottom surface of the base 102, and the other end 112 is fixed to an inner wall near the opening end of the cylindrical body 101.

  FIG. 5 is an explanatory view of an example of use of the cleaning unit SU configured as described above, in which (A) is a perspective view and (B) is an enlarged sectional view of (A). In FIG. 5, a projection 21 is formed on the plane E of the pressure vessel 20, and a unique port hole 22 communicating with the inside of the pressure vessel 20 is provided in the projection 21. A thread groove is provided on the inner periphery of the opening end of the port hole 22.

  As shown in FIG. 5B, the end of the cylindrical body 101 of the main body 10 of the cleaning unit SU is the interior of the pressure vessel 20 in which a plurality of holes 103 provided in the side wall in the vicinity of the opening end are to be cleaned. Is inserted into the pressure vessel 20 until it communicates with the pressure vessel 20.

  FIG. 6 is an enlarged view of a circular portion F indicated by a broken line in FIG. 5B, and is an explanatory diagram of a circulation path of the cleaning gas in the cleaning unit SU. When the cleaning gas is introduced from the port 107 in a state where the plurality of holes 103 provided in the side wall near the opening end of the cylindrical body 101 communicate with the inside of the pressure vessel 20 to be cleaned, the cleaning gas is The inside of the pressure vessel 20 is sprayed from the plurality of holes 103 provided in the side wall in the vicinity of the opening end of the shape body 101 to wash the inside of the pressure vessel 20 while refluxing, and the inside of the pressure vessel 20 is washed while refluxing The cleaned gas is discharged from the port 105.

  Here, the pipe 11 having both ends opened is attached to the inside of the cylindrical body 101 and the base 102 of the main body 10 of the cleaning mechanism, and the holes 102 and 107 for the ports are provided in the base 102. 105 is communicated with the inside of the pipe 11, and the port hole 107 is formed as a double pipe structure communicating with the gap between the inner wall of the cylindrical body 101 and the outside of the pipe 11, so that it becomes an object to be cleaned. The protrusion 21 of the pressure vessel 20 only needs to be provided with a port hole 22 communicating with the inside thereof.

  When the pressure vessel 1 is internally cleaned, a cleaning mechanism is inserted into the only port hole 22 that communicates with the inside of the pressure vessel 1, and a pressure measuring mechanism (not shown) is inserted in place of the cleaning mechanism when measuring pressure.

  In FIG. 2 again, the inclination sensor 302 detects the amount of inclination at the time of measurement by the pressure calibration device 3. As the tilt sensor 302, for example, a general-purpose triaxial acceleration sensor that is relatively inexpensive and has low power consumption is used.

  In order to increase the accuracy of the tilt angle calculation, the offset and gain are adjusted in two directions (+1 g direction and −1 g direction) with respect to the X, Y, and Z axes. As a result, the number of operations increases, but optimal cost performance can be obtained by adjusting the sampling rate and driving in the low power consumption mode.

  The vibration sensor configured as shown in FIG. 3 used as the pressure sensor of the pressure measurement unit 301 is sealed with silicone oil. Therefore, when the posture of the pressure calibration device 3 changes, the vibration sensor is used as a pressure receiving unit (not shown) of the detection unit 301a. The pressure due to the mass of the applied liquid changes, and the influence on the pressure measurement value is large. Therefore, the validity of the posture is determined based on the measurement result of the tilt sensor 302, and the pressure measurement value correction process in the pressure measurement unit 301 is performed.

  The temperature sensor 303 measures the temperature of the pressure measurement unit 301 in the pressure calibration device 3 and performs a correction process for removing the influence of the temperature of the pressure measurement value in the pressure measurement unit 301.

  The current voltage measuring unit 304 has a function of measuring a current of 4-20 mA and a voltage of 1-5 V, and measures a current value of 4-20 mA output from the pressure transmitter 2.

  The current / voltage generator 305 has a function of generating a current of 4-20 mA and a voltage of 1-5 V, and supplies the pressure transmitter 2 as a loop power supply. The current / voltage generator 305 can be used for instrumentation loop tests, recorder / controller operations, instruction confirmation, etc. by changing the generated signal to be programmable.

  The control unit 306 calculates a calibration value based on the measurement value of the pressure measurement unit 301 and the measurement value of the current / voltage measurement unit 304, or determines whether the measurement value is valid based on the posture information of the tilt sensor 302 or performs correction processing. And processing control of each unit such as the display unit 307, the key operation unit 308, the buzzer 309, the internal memory 310, the external memory 311, and the communication unit 312.

  The display unit 307 is composed of, for example, a liquid crystal and displays measured values, calibration values, alarm states, and the like. FIG. 7 is an example of a display screen of the display unit 307 and shows an example having two measurement systems. In FIG. 7, the pressure measurement value is displayed in the first measurement system CH1, and the loop current measurement value is displayed in the second measurement system CH2.

  Returning to FIG. 2, the key operation unit 308 sets the measurement conditions of the pressure calibration device 3.

  FIG. 8 is a specific example of the operation panel of the pressure calibration device 3 including the key operation unit 308, and the same reference numerals are given to portions common to FIG. In FIG. 8, a rectangular display unit 307 is provided almost at the center of the left area of the operation panel. A key operation unit 308 is arranged in an inverted L shape so as to be adjacent from the right side to the lower side of the display unit 307.

  The key operation unit 308 includes up / down / left / right cursor keys 308a disposed near the right side of the key operation unit 308, a hold disposed between the cursor keys 308a and the display unit 307, maximum / minimum, relative, A plurality of function selection keys 308b for individually selecting output / measurement functions, a plurality of function keys 308c arranged near the lower side of the display unit 307, and the like.

  An electric signal terminal TML is provided near the upper side of the key operation unit 308.

  A pressure input terminal PIN is provided in the vicinity of the electrical signal terminal TML on the upper side surface adjacent to the operation panel.

  Grips GP1 and GP2 are provided on the left and right sides of the operation panel, respectively.

  Returning to FIG. 2, the buzzer 309 is used when the measurement value of the pressure measurement unit 301 or the current / voltage measurement unit 304 is abnormal, or when the posture of the pressure calibration device 3 detected by the tilt sensor 302 exceeds the tilt limit. An alarm sound is generated to notify the worker.

  The internal memory 310 stores and holds pressure measurement values, calibration values, alarm histories, and the like as shown in FIG.

  As the external memory 311, a hard disk, a memory card, a USB memory, or the like is used as necessary.

  The communication interface 312 is an interface for exchanging various data such as control data, measurement data, and alarm information of the pressure calibration device 3 by communicating between the pressure calibration device 3 and an external device. As a communication protocol, communication based on HART (registered trademark) is generally performed in a transmitter in addition to USB (Universal Serial Bus), Ethernet (Ethernet, registered trademark), and the like.

  FIG. 10 is a flowchart for explaining the operation of the pressure calibration device 3 according to the present invention configured as shown in FIGS. For pressure calibration of, for example, the pressure transmitter 2 which is a calibration target device, a predetermined pressure to be calibrated is supplied and injected from the pressure generator 1 to the pressure transmitter 2 and the pressure calibration device 3 in parallel (step S1). .

  The pressure calibration device 3 measures and calculates the pressure injected from the pressure generator 1 by the pressure measurement unit 301 (step S2), and detects the posture of the pressure calibration device 3 at the time of pressure measurement based on the output signal of the tilt sensor 302. (Step S3).

  Based on the value of the tilt amount measured by the tilt sensor 302 described above, the control unit 306 determines whether or not the measured pressure value in the current posture can be corrected within the error range required by the operator. (Step S4).

  When correction within the error range required by the operator is impossible, the control unit 306 displays alarm information as shown in FIG. 11 on the display unit 307, and outputs a warning sound with the buzzer 309. The alarm history is recorded in the memory 310, and the alarm information is notified to the outside via the communication unit 312 (step S5).

  In FIG. 11, “ZERO CAL” indicating that zero calibration for reference calibration is necessary is displayed as alarm information in the second measurement system CH2. Here, as the alarm information, the value of the tilt amount measured by the tilt sensor 302, the value of the current zero point that requires reference calibration, the magnitude of the error in the current posture, and the like are displayed as necessary. May be.

  Returning to FIG. 10, the operator determines whether or not to perform reference calibration (step S6). By executing the zero calibration, the reference calibration in the posture is performed (step S7), and the subsequent accurate pressure measurement in the posture can be realized.

  If correction within the error range required by the operator is possible in step S4, the control unit 306 calculates a measurement value based on the correction (step S8).

  The pressure transmitter 2 measures the pressure injected from the pressure generator 1 (step S9), converts the measured pressure value into an electric signal of 4-20 mA, and outputs it to the current voltage measuring unit 304 of the pressure calibration device 3. (Step S10). Steps S9 and S10 are performed in parallel with the processing of steps S2 to S8 in terms of time.

  The current / voltage measuring unit 304 measures the current output from the pressure transmitter 2 (step S11).

  The control unit 306 compares the current value converted from the pressure measurement value measured by the pressure measurement unit 301 of the pressure calibration device 3 with the current value measured by the current voltage measurement unit 304, and calculates the difference from the reference value. A certain calibration value is calculated (step S12).

  Further, as post-processing for the calculated calibration value, the control unit 306 displays the measurement value and the calibration value on the display unit 307 in the format shown in FIG. 12, and further, these calibration values are shown in FIG. A list display format is stored in the internal memory 310 and output to the outside via the communication unit 312 (step S13).

  When the calibration of the pressure transmitter 2 is continued (step S14), the setting of the pressure calibration device 3 is changed or the injection pressure from the pressure generator 1 is changed (step S15), and steps S1 to S15 are repeated.

  When the detection unit 301a of the pressure calibration device 3 is cleaned after finishing a series of calibration processes, the cleaning unit SU is used as described above to introduce dirt or adhering to the detection unit 301a by introducing a cleaning gas from the outside. Remove residue.

  This makes it an all-in-one on-site measuring instrument that is indispensable for manufacturing sites in poor environments such as temperature changes, vibrations and narrow spaces, rather than a large-scale configuration like the conventional one. Can realize a low power consumption pressure calibration device.

  In addition, by adopting a cleaning unit that can be attached and detached externally to the pressure sensor, it can be used without distinguishing between gas and liquid as the pressure medium, and it is not necessary to replace the filter as before, and measurement is performed while keeping the sensor surface clean. Can be maintained, and maintainability can be greatly improved.

  In addition, since calibration is possible with one device, simple operability can be realized.

  Furthermore, by using a vibration sensor as a pressure sensor, it is possible to perform strong and stable measurement against temperature drift and aging that occurs at the manufacturing site, and to realize the high accuracy and wide range that are the characteristics of this sensor, A high-performance pressure transmitter can be calibrated.

  In addition, by combining the tilt sensor, it is possible to judge the validity of the measured value with respect to the posture of the device and to correct the measured value, so that high-precision measurement can be realized even in manufacturing sites that are used in various postures in a narrow space. .

  As described above, according to the present invention, it is possible to realize a pressure calibration device that has excellent portability, high accuracy, wide range, and low power consumption, and can be used with either liquid or gas that can be attached and detached externally. By providing the sensor, the sensor surface can always be kept clean, and a highly reliable pressure calibration device can be realized.

DESCRIPTION OF SYMBOLS 1 Pressure generator 2 Pressure transmitter 3 Pressure calibration apparatus 4 Loop power supply line 5 Personal computer (PC)

Claims (5)

In a pressure calibration device having a pressure measurement unit and configured to calibrate a pressure gauge,
An inclination sensor for detecting the attitude of the device;
A reference calibration means for measuring a zero reference calibration value;
Attitude error correction means for correcting an attitude error included in a measurement value of the pressure measurement unit based on a reference calibration value by the reference calibration means and attitude information output from the tilt sensor;
A correction enable / disable determining means for determining whether or not posture error correction within a predetermined error range based on the posture information output from the tilt sensor;
A pressure calibration apparatus characterized in that, when it is determined by the correction enable / disable determining means that correction is impossible, the reference calibration value is measured by the reference calibration means.   2. The pressure according to claim 1, wherein the pressure measurement unit uses a silicon resonant sensor configured to detect a measurement pressure based on a change in a resonance frequency of a silicon vibrator formed on a diaphragm. Calibration device.   The pressure calibration device according to claim 1, further comprising a cleaning unit that cleans the pressure measuring unit.   The pressure calibration apparatus according to claim 3, wherein the cleaning gas is air.   The pressure calibration apparatus according to claim 3, wherein the cleaning gas is an inert gas.