JP2002014000A - Self-recording pressure gauge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the pressure measuring accuracy in the pressure condition for use when calibrating the self-recording pressure gauge in a governor chamber in a location field. SOLUTION: The gas pressure sampled per each 0.5 seconds by a pressure sensor 51 is converted to a digital value by an A/D converting unit 52, and displayed as a pressure value in a liquid crystal display unit 55 by a CPU 53, and recorded in an IC memory card 54. A switch 56 is pushed for 20 seconds or more so as to change the mode to the calibration mode. The display flashes. A plus correcting switch 56 or a minus correcting switch 57 is pushed so that a value of the display unit 55 coincides with a command value of a water column manometer (not expressed in a figure). A numerical value obtained by adding the correction value is displayed in the display unit 55. Both the switches 56 and 57 are pushed at the same time so as to return the mode to a measurement mode. The correction value is stored in a memory 59. Thereafter, the CPU 53 computes the pressure correction by adding the correction value to the measurement value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improved self-recording pressure gauge for recording gas pressure in a gas supply governor chamber.

[0002]

2. Description of the Related Art In a gas supply business, a governor for reducing and maintaining a constant gas pressure is provided at a base of a high / medium pressure conduit which is a main line for supplying gas, and a governor chamber is provided with a primary side of the governor. A self-recording pressure gauge that records the pressure on the secondary side is provided.

[0003] Japanese Patent Application Laid-Open No.
Japanese Patent No. 108788 discloses a digital self-recording pressure gauge (hereinafter referred to as a first conventional technique).

[0004] This digital type self-recording pressure gauge has a CPU for collecting data, a PC card mounting section, a connector section for connecting cables of two pressure sensors, and a connector section for connecting a battery cable. And a battery box with a built-in dry cell and a current limiting resistor and connected to a cable with a connector, two pressure sensors connected to a cable with a connector, and a PC card. One of the two pressure sensors is primary. Connect to the side fluid conduit to detect the fluid pressure, connect the other to the secondary fluid conduit to detect the fluid pressure, and separate the cable with connector of both pressure sensors to the connector part of the recording device Cable, connect the cable with connector of the battery box to the connector of the acquisition device in a separable manner, and mount the PC card on the PC card mounting section. And drives the two sensors and acquisition device by the battery, the data from the two pressure sensors C
The necessary data recorded in the PU is recorded in a PC card in which necessary data recorded in the CPU is collected. The recorded card is collected, and data processing is performed by a personal computer using the PC card.

FIG. 2 shows a state in which the digital self-recording pressure gauge is connected to a gas pipe of a governor chamber.

In FIG. 2, a primary gas conduit 1 on the high pressure side and a secondary gas conduit 2 on the low pressure side are connected via a governor 3, and the governor 3 connects the gas conduit 2 in the secondary gas. Is kept constant.

[0007] A pressure extraction pipe 4 is connected to the primary gas conduit 1, and a connector 5 is provided at the end thereof. Further, a pressure extraction pipe 6 is connected to the gas pipe 2 on the secondary side,
The connector 7 is provided at the tip.

A connector 9 provided on a primary pressure sensor 8 as an inlet pressure sensor is connected to the primary connector 5, and a secondary connector as an output pressure sensor is connected to the secondary connector 7. A connector 11 provided on the pressure sensor 10 is connected.

The two pressure sensors 8 and 10 sense the gas pressure in the gas conduits 1 and 2 connected to the pressure sensors 8 and 10, respectively. To be sent. Further, a primary connector 15 is attached to the other end of the primary cable 12, and the primary connector 15 is detachably connected to a primary connector 16 provided in the recording device 14. Further, a secondary connector 17 is attached to the other end of the secondary cable 13 so as to be detachably connected to a secondary connector 18 provided in the recording device 14.

A battery box 19 is attached to the recording device 14 so as to be separable.
Is connected to one end of a cable 20, and a connector 21 attached to the other end of the cable 20 is separably connected to a connector section 22 provided on the recording device 14.

The case 14a of the recording device 14 has an insertion hole 24 forming a mounting portion for a PC card 23 as a recording medium.
The opening is formed at the lower end of the opening, and the opening / closing lid provided at the lower end of the opening is opened downward in the drawing, so that the PC card 23 can be detachably mounted in the insertion hole 24 from the lower surface of the case 14a. ing.

Next, the collecting device 14 and the battery box 19
Will be described with reference to FIG.

The recording device 14 includes the two pressure sensors 8, 1
A voltage generated at 0 is input through both the connector sections 16 and 18, A / D converted by the A / D converter 26 and stored in the memory of the CPU 27, and a necessary part of the data stored in the CPU 27 is provided. A liquid crystal display 28 for displaying data on a screen, a display switch 29 for displaying and operating the liquid crystal display 28, and a P to which data stored by the CPU 27 are attached.
It has a PC card interface 30 for recording on the C card 23, a communication interface 31, and a communication connector 31a.

When the display switch 29 is turned on, the screen of the liquid crystal display 28 displays the highest pressure and the lowest pressure in the recording period of the primary pressure and the secondary pressure, and the date and time of occurrence and the current pressure. The current time can be displayed.

In the battery box 19, a dry battery 32,
A current limiting resistor 33 connected in series with this is built in, and the dry cell 32 drives the recording device 14 and both pressure sensors 8 and 10 through the cable 20. Recording device 1
The so-called intrinsically safe explosion-proof circuit is configured such that even if some kind of accident (short circuit, etc.) occurs on the 4 side, the current is limited, the ignition energy to the gas is suppressed, and the gas does not ignite. Further, since the battery box 19 and the collecting device 14 can be separated from each other, and the cable 20 thereof can be separated from the collecting device 14 by the connectors 21 and 22, the battery box 19 can be separated from the gas conduit portion of the governor chamber. To carry out battery replacement.

A mounting piece (not shown) is provided on the case 14a of the recording device 14, and the collecting device 14 and the battery box 19 are mounted on the wall surface of the governor room by the mounting piece.

The pressure sensors 8 and 10 are time-divisionally driven by a program of the CPU 27 in the recording device 14. The drive cycle (measurement cycle) is, for example, every 0.5 seconds. The driving time is set to about 7 ms.

By driving the two pressure sensors 8 and 10,
The gas pressure in the primary gas conduit 1 on the high pressure side and the gas pressure in the secondary gas conduit 2 on the low pressure side are detected, and the voltage generated at both pressure sensors 8 and 10 during the above-mentioned time is represented by A. A / D conversion is performed by the / D converter 26 and the result is stored in the memory of the CPU 27. The recording cycle is 3 minutes, and the maximum pressure value and the minimum pressure value on the high pressure side and the maximum pressure value and the minimum pressure value on the low pressure side are stored every 3 minutes. The date and time when the value occurred is stored.

The stored data is stored in the recording device 1
4 is written and recorded on the PC card 23 inserted therein.
This recording is performed every 12 minutes. That is, the data is written to the PC card 23 when the data for every three minutes is taken four times. With such writing, for example, when a 4 MB PC card is used, the recordable data amount is about six months.

At regular intervals, the patrol inspector removes and collects the PC card 23 on which the data has been recorded from the recording device 14, reads the data recorded on the PC card 23 into a personal computer, and reads the file on the personal computer side. Create, modify and process that data. That is, based on the read data, it is possible to confirm whether there is a pressure abnormality on the graph display screen or to transfer the data to a hard disk or an external MO.
It performs data processing and data management such as batch registration on a disk or the like and reading of data registered in the past.

As described above, by performing data processing on a personal computer, data verification and search can be performed quickly, and details of data in a desired period such as one hour, one day, and one week can be easily seen. We can respond quickly. Further, the operation time on the side of the recording device is shortened and the current consumption is reduced, and the intermittent driving of the pressure sensor, together with the intermittent driving of the pressure sensor, prolongs the life of the dry cell, and the four dry cells can last for 6 months or more.

Although the liquid crystal display 28 is normally off,
The patrol inspector turns on the display switch 29 of the recording apparatus 14 at the site to turn on the light, and confirms the maximum pressure, the minimum pressure, the occurrence date and time, the current pressure, and the current time during the recording period. I have.

Japanese Patent Application Laid-Open No. 10-62287 discloses an electronic self-recording pressure gauge shown in FIG. 4 (hereinafter referred to as a second conventional technique). 41 is a gas conduit, 42 is a governor inserted and installed in the gas conduit 41, 43 is a primary side pressure sensor and is a governor 4
The primary pressure is measured every 0.5 seconds and converted into an analog electric signal. A secondary pressure sensor 44 measures the secondary pressure of the governor 42 every 0.5 seconds and converts it into an analog electric signal.

Reference numeral 45 denotes an electronic self-recording pressure gauge,
A C memory card 46, a battery 47 for power supply, a liquid crystal display 48 and the like are provided.

The liquid crystal display 48 displays the present pressure value, the past minimum and maximum pressure values, the date and time of each occurrence, and the current time.

The pressure value displayed on the liquid crystal display 48 is displayed by converting the output signals of the pressure sensors 43 and 44 into digital values by an A / D converter.

The pressure values of the governor primary side and secondary side obtained by converting the analog signals of the pressure sensors 43 and 44 into digital signals by the A / D converter are recorded on the IC memory card 46 with time.

These operations are performed by a microcomputer built in the electronic self-recording pressure gauge.

The IC memory card 46 has a capacity for recording governor primary pressure and secondary pressure data measured at 0.5 second intervals together with time data for up to one year.

[0030]

SUMMARY OF THE INVENTION A recording device of this kind and an electronic self-recording pressure gauge (hereinafter referred to simply as a self-recording pressure gauge).
In such a case, the accuracy is defined by the error rate of the maximum scale, as in a general measuring instrument. Therefore, when used below the measurement range, the relative error increases.

For example, the maximum scale (full scale) is 5k
In the case where the allowable error is 1.0% FS in Pa, an error of 0.05 kPa is allowed in the entire range of 0 to 5 kPa. However, if this is always used at around 2 kPa, the relative error becomes (0.05).
(kPa / 2 kPa) × 100 = 2.5%, which is a large error.

Like the gas pressure in the gas supply business,
When the gas pressure is almost constant and is lower than the maximum scale (full scale), it is important to increase the accuracy at the actual working pressure, but a conventional self-recording pressure gauge is provided. Accuracy adjustment on site (governor room) (calibration work)
Could not.

For this reason, the self-recording pressure gauge was removed from the governor room during the periodic inspection, brought back to the factory, and adjusted by the calibration device, so that there was a problem that the periodic inspection cost was increased.

Accordingly, the present invention is to provide a self-recording pressure gauge that can periodically calibrate pressure in a local governor room where a self-recording pressure gauge is installed, and can increase the accuracy near the pressure in use. Aim.

[0035]

According to one aspect of the present invention, there is provided a pressure sensor for measuring a gas pressure in a gas conduit of a governor chamber at regular time intervals and converting the gas pressure into an analog electric signal. An A / D converter for converting an electric signal of the pressure sensor into a digital signal, a CPU for arithmetic control, an IC memory card for recording the digital signal with time, and a display unit for displaying gas pressure. A mode switching unit that switches between a measurement mode in which the gas pressure measured by the pressure sensor is displayed on the display unit and a calibration mode in which a correction value for calibrating the gas pressure measured by the pressure sensor is input in the self-recording pressure gauge; Correction value input means for inputting a value, a memory for storing the correction value input by the correction value input means,
A self-recording pressure gauge, comprising: a calculation unit for performing a pressure correction calculation based on the stored correction value.

According to a second aspect of the present invention, in the pressure gauge of the first aspect, a pressure correction operation is performed by adding the stored correction value ΔP to the measured gas pressure P ′ over the entire measurement range. Is what you do.

The present invention carries out a pressure correction operation for shifting the measured value in parallel over the entire measuring range and shifting it, and is effective when the relationship between the true value of the gas pressure and the measured value has zero drift. .

According to a third aspect of the present invention, in the self-recording pressure gauge according to the first or second aspect, the gas pressure at the time of calibration is P ₁ , the correction value at the time of calibration is ΔP, and the maximum measurement pressure is the maximum scale of the self-recording pressure gauge. was a Pmax, 'has the following cases the gas pressure P ₁ at the time of calibration, the correction value (P' measured gas pressure P performs pressure compensation operation by adding the / P ₁₎ · [Delta] P gas pressure P 'of the measurement of the , 'it is a time when pressure P ₁ or more gas during calibration, the correction value {(Pmax-P' measured gas pressure _{P) / (Pmax-P 1} )} · ΔP
Is added to the measured gas pressure P 'to perform a pressure correction operation.

The present invention performs a pressure correction operation by proportional calculation, and is effective when there is a sensitivity drift in the relationship between the true value of the gas pressure and the measured value.

According to a fourth aspect of the present invention, in the self-recording pressure gauge of the first, second or third aspect, the correction value input means is two push-button switches, and each time one of the two push-button switches is pressed. Is input with the correction value of the positive unit amount,
Each time the other switch is pressed, a negative unit amount correction value is input.

The invention of claim 5 is based on claim 1,
In the pressure gauge of 2, 3, or 4, the pressure display is blinked in the calibration mode, and the pressure display is turned on in the measurement mode.

[0042]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a preferred embodiment of the present invention will be described with reference to FIGS. 1 (a) and 1 (b).

The self-recording pressure gauge 50 is installed in a governor chamber (not shown), and measures a gas pressure of a gas conduit at regular time intervals, for example, every 0.5 seconds, and converts the pressure into an analog electric signal. An A / D converter 52 for converting an electric signal of the pressure sensor 51 into a digital signal;
U53 and an IC for recording the digital signal with time
The memory card 54, the current gas pressure value, the maximum pressure value,
A liquid crystal display 55 for displaying the minimum pressure value, time, etc., a display changeover switch 56 for switching the display of the current pressure value, the maximum pressure value, and the minimum pressure value, and a setting switch 57 for setting a pressure measurement range and a device number. An IC card interface 58 for recording pressure data and time on the IC memory card 54, and a memory 59 for storing correction values and the like described later.
And a dry battery 60 for power supply.

Incidentally, the memory 59 is actually a CPU 53
Built into the chip.

The display changeover switch 56 is disposed on the front surface of the case 60 so that it can be operated from the surface of the case 61 in FIG. Since it is not normally used for measurement and recording on an IC memory card, the structure is such that the operation can be performed by opening the lower cover of the case 61 so that the operation is not performed carelessly. 62 indicates the pressure sensor 51 as A
This is a cable connected to the / D converter 52.

The pressure sensor 51 is attached to a gas conduit in the governor chamber, samples the gas pressure in the gas conduit every 0.5 seconds, and outputs an analog voltage proportional to the gas pressure. This voltage is converted into a digital signal by the A / D converter 52, and the CPU 53, the IC card interface 58
Is recorded on the IC memory card 54 together with the time via the. The maximum pressure value and the minimum pressure value are also recorded on the IC memory card.

The pressure calibration is performed in the following procedure.

A reference pressure gauge such as a water column manometer is connected to the gas conduit to which the pressure sensor 51 is attached, and the gas supply pressure at that time is simultaneously measured by the self-recording pressure gauge 50 and the reference pressure gauge. Display P ₁ of self-recording pressure gauge 50 at this time, for example 2.003KPa, the reference indication pressure gauge P ₀ = 2.00
It is assumed that the pressure is 1 kPa.

In this state, the pressure gauge 50 is switched from the (pressure) measurement mode to the (pressure) calibration mode.
In this embodiment, if the display changeover switch 56 is kept pressed for a certain period of time (about 20 seconds), the mode switches to the calibration mode,
The display of the current pressure value flashes to indicate that the mode is the calibration mode. That is, the display changeover switch 56
Also functions as mode switching means for switching from the measurement mode to the configuration mode.

Next, the displayed pressure value P ₁ is adjusted to the indication P ₀ of the reference pressure gauge and calibrated. This is performed by using the display changeover switch 56 and the setting switch 57 as correction value input means. When increasing the pressure value P ₁ that is displayed, if the unit quantity + 0.001 kPa plus every press of the display changeover switch 56 is input summing reduces the pressure value P ₁ shown are Each time the setting switch 57 is pressed, a minus unit amount of -0.001 kP
The program of the CPU 53 is configured so that a is input and added. Thus, the display changeover switch 56 and the pushbutton switch of the setting switch 57 are configured to function as plus and minus correction value input means in the calibration mode, respectively.

In this embodiment, the displayed pressure value P
₁= 2.003 kPa is the indicated value P of the reference pressure gauge.₀= 2.
Input a negative correction value to match 001 kPa
Press the setting switch 57 twice as the₁To
Add −0,001 kPa twice. Thus, the autograph pressure
The blinking display of the force gauge 50 indicates the indicated value P of the reference pressure gauge. ₀
Confirm that it has changed to 2.001 kPa, the same as
The display changeover switch 56 and the setting switch 57 are simultaneously pressed.
By the simultaneous operation of both switches, P₀−P₁-0.002
kPa is stored in the memory 59 as the correction value ΔP.
Pressure at this time₁Or P₀Is stored in the memory 59.
And the current pressure display changes from flashing to lit (pressure)
Program of CPU53 configured to return to measurement mode
Have been. Thus, the mode is changed from the calibration mode to the measurement mode.
When returning after switching the mode, both switches 56 and 57
By pressing simultaneously, mode switching is executed. Follow
In this case, both switches 56 and 57 are provided as mode switching means.
Act as

Thereafter, the measured pressure value P ′ is subjected to ΔP correction calculation, the calibrated pressure value P ′ + ΔP is displayed on the liquid crystal display 55, and the calibrated pressure value is also displayed on the IC memory card 54. The program of the CPU 53 is configured to record the values.

In the above-described embodiment, the correction is performed by adding the correction value ΔP to the measured gas pressure P ′ in the entire measurement range to perform the pressure correction calculation, thereby effectively shifting the gas pressure P ′ when there is zero drift. However, based on the correction value ΔP at the gas pressure P ₁ at the time of calibration, the correction value for the subsequent gas pressure P ′ other than P _{1 is} calculated as follows and proportionally calculated. It can also be determined.

The measured gas pressure P ′ is the gas pressure P ₁ at the time of calibration.
For the following, namely, the 0 ≦ P 'of ≦ P ₁ conditions, the value of compensation value is obtained by the following equation (1).

Correction value = (P ′ / P ₁ ) · ΔP (1) Then, when the measured gas pressure P ′ is equal to or higher than the gas pressure P ₁ at the time of calibration, that is, P ₁ ≦ P ′ ≦ Pmax Under the condition (1), the correction value is a value obtained by the following equation (2).

Correction value = {(Pmax−P ′) / (Pmax−P ₁ } · ΔP (2) where Pmax is the maximum value of the measurement range, that is, the maximum measurement pressure.

The values of P ₁ and Pmax are stored in the memory 59 together with ΔP at the time of calibration, and are used. The maximum measured pressure Pmax is stored in the CPU 53 in advance when the self-recording pressure gauge is manufactured. Can also.

[0058] In this correction, during calibration of the correction value is the maximum value ΔP becomes a gas pressure P _1, 'the, proportional to the maximum value ΔP constant P' the pressure P other than the gas pressure P ₁ at the time of calibration Toka / P ₁ (P
max-P ') / the correction value multiplied by (Pmax-P ₁₎ Gas pressure P' performing pressure compensation operation by adding the. By doing so, the correction value becomes the maximum ΔP at the pressure P ₁ at the time of calibration, and decreases proportionally as the gas pressure P ′ moves away from P ₁ , and the correction value becomes 0 when the gas pressure is 0 or Pmax. In other words, the gas pressure P 'scale of the horizontal axis of the rectangular coordinate and the vertical axis Memoru the correction value, the gas pressure P' relationship between the correction value and the correction value ΔP gas pressure P ₁ during calibration It is expressed as a triangle relationship with the determined coordinate points as vertices.

As described above, since the optimum correction is performed by the gas pressure at the time of calibration, the measurement accuracy at the gas pressure P _{1 which} is always used can be particularly improved.

In any case, it is sufficient to select a correction calculation method suitable for the characteristics of the self-recording pressure gauge, and satisfy the standard required for accuracy in the entire measurement range, and use the gas pressure which is frequently used in practice. And a correction method for improving the accuracy of.

Although the number of pressure sensors is one in the above embodiment, a plurality of pressure sensors may be provided. In this case, each pressure sensor is calibrated, and the correction value ΔP and the correction value ΔP are calibrated. The pressure at that time is stored in the memory 59, and the pressure correction calculation is performed.

[0062]

The self-recording pressure gauge of the present invention has been calibrated as described above, so that the calibration work can be performed at the installation site at the pressure actually used, so that the calibration work is facilitated and the pressure used is reduced. Can be made more accurate.

Further, since calibration can be performed by operating the switch while looking at the display while the self-recording pressure gauge is installed without removing the pressure gauge, periodic inspection costs can be reduced.

According to the second aspect of the present invention, since the characteristics are shifted, it is particularly effective when there is a zero drift characteristic.

The invention of claim 3 has an advantage that the correction value in the gas pressure at the time of calibration becomes an optimum value, and the measurement accuracy at the gas pressure used constantly can be particularly improved.

The invention of claim 4 has an advantage that the operation of the calibration work is simplified in this type of self-writing pressure gauge having a relatively small correction value of plus or minus.

According to the fifth aspect of the present invention, since the calibration mode for inputting the correction value and the normal measurement mode are clearly distinguished and displayed, the operation of the calibration operation can be performed quickly, and the operation error can be corrected. Can be prevented.

[Brief description of the drawings]

1 (a) is a schematic front view and FIG. 1 (b) is an embodiment of the present invention.
Is a block diagram.

FIG. 2 is a diagram showing an installation state of a first related art.

FIG. 3 is a block diagram showing a wiring state of a recording device section and a battery box section according to the first prior art.

FIG. 4 is a schematic front view of a second prior art in which a self-recording pressure gauge is attached to a gas conduit.

[Explanation of symbols]

 50 Self-Recording Pressure Gauge 51 Pressure Sensor 52 A / D Converter 53 CPU (Calculation Unit) 54 IC Memory Card 55 Display Unit 56 Mode Switching Means (Display Switching Switch) 56 Correction Value Input Means (Display Switching Switch) 57 Mode Switching Means ( Setting switch) 57 Correction value input means (Setting switch) 59 Memory

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Tsuyoshi Kanamaru 19-18 Sakuradacho, Atsuta-ku, Nagoya Toho Gas Co., Ltd. Aichi Clock & Electric Co., Ltd. DD14 GG07 HH06

Claims (5)

[Claims] 1. A pressure sensor for measuring a gas pressure in a gas conduit of a governor chamber at regular time intervals and converting the same into an analog electric signal, and an A / D converter for converting an electric signal of the pressure sensor into a digital signal. A self-recording pressure gauge having an arithmetic control CPU, an IC memory card for recording the digital signal with time, and a display unit for displaying gas pressure, wherein a gas pressure measured by a pressure sensor is displayed on the display unit. Mode switching means for switching between a mode and a calibration mode for inputting a correction value for calibrating a gas pressure measured by a pressure sensor; a correction value input means for inputting a correction value; and a correction input by the correction value input means. A self-writing pressure gauge, comprising: a memory for storing a value; and a calculation unit for performing a pressure correction calculation based on the stored correction value. 2. The measured gas pressure P 'over the entire measurement range.
The self-recording pressure gauge according to claim 1, wherein a pressure correction operation is performed by adding the correction value ΔP stored in the pressure gauge. 3. The gas pressure at the time of calibration is P ₁ , the correction value at the time of calibration is ΔP, and the maximum measurement pressure which is the maximum scale of the self-recording pressure gauge is Pm.
and ax, 'has the following cases the gas pressure P ₁ at the time of calibration, the correction value (P' measured gas pressure P / P ₁₎ · Gas ΔP was measured pressure P '
Adds perform pressure compensation calculation, the measured gas pressure P 'is a time when pressure P ₁ or more gas during calibration, the correction value {(Pmax-P') / (Pmax-
2. The pressure gauge according to claim 1, wherein a pressure correction operation is performed by adding P ₁ )｝ · ΔP to the measured gas pressure P ′. 4. A correction value input means comprising two push-button switches, wherein each time one of the two push-button switches is pressed, a positive unit-value correction value is input, and each time the other switch is pressed. 4. The self-recording pressure gauge according to claim 1, wherein a correction value of a negative unit amount is input to the pressure gauge. 5. The self-recording pressure gauge according to claim 1, wherein the pressure display blinks in the calibration mode, and the pressure display is turned on in the measurement mode.