JPH08189872A - Pressure measuring device for gas meter and correcting method for it - Google Patents

Abstract

PURPOSE: To simplify adjustment of a pressure sensor at the time of shipment from factory and enhance the sensing accuracy of the pressure value calculated on the basis of the output signal of the pressure sensor when gas meter is in use practically. CONSTITUTION: On the basis of the output signal of a pressure sensor 15, a pressure calculation part 32 calculates the pressure value using the relation of the output signal with the pressure value. If a pressure correction instructing switch 22 is pushed when a gas meter is installed, the relationship between the output signal of pressure sensor 15 used in the pressure calculation part 32 and the pressure value is corrected by a pressure correction processing part 33 so that the output signal of the pressure sensor 15 in a state that the gas supply pressure is zero, corresponds to the pressure value being zero computed by the pressure calculation part 32.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas meter pressure measuring device for detecting a gas supply pressure and a correction method thereof.

[0002]

2. Description of the Related Art A gas meter is provided with a pressure sensor for detecting the supply pressure of gas. Then, the gas meter automatically determines that the gas is shut off when the pressure value calculated based on the output signal of the pressure sensor falls below a predetermined value and determines that there is an abnormality.

By the way, conditions such as maximum allowable pressure, measurement range, span, accuracy, temperature drift, operating temperature range, etc. are imposed on the design specifications of the pressure sensor. Adjustment is made for each pressure sensor. Of these conditions,
Accuracy means the limit of the maximum error allowed in the formal specification of equipment under standard operating conditions, and includes linearity, hysteresis, and repeatability errors. Linearity refers to the degree of proximity indicated by the difference between the calibration curve and the straight line approximated by it. Hysteresis is the dependence of an output value on the history of change and the direction of change with respect to a given change in input. Repeatability error refers to the maximum value of the output difference obtained when the measurement is repeated by approaching the same input value from the same direction while changing the input over the entire range in a relatively short time under the same operating conditions. .

[0004]

As described above, conventionally,
There is a problem that many adjustments are required for each pressure sensor at the time of factory shipment and a complicated process is required to some extent. Also, even if you adjust the pressure sensor at the time of factory shipment,
There is a possibility that an error may occur during actual use of the gas meter due to differences in the environment where the gas meter is installed.

The present invention has been made in view of the above problems, and an object thereof is to simplify the adjustment of the pressure sensor at the time of factory shipment, and to calculate based on the output signal of the pressure sensor when the gas meter is actually used. It is an object of the present invention to provide a pressure measuring device for a gas meter and a method for correcting the pressure measuring device, which are capable of improving the detection accuracy of the pressure value.

[0006]

A pressure measuring device for a gas meter according to claim 1 is provided in a gas meter, and a pressure sensor for detecting a gas supply pressure, and an output signal and a pressure value of the pressure sensor. The pressure calculation means for calculating the pressure value based on the output signal of the pressure sensor, and the output signal of the pressure sensor and the pressure calculation means when the gas supply pressure is zero when the gas meter is attached Pressure correction processing means for correcting the correspondence between the output signal of the pressure sensor used in the pressure calculation means and the pressure value is provided so that the pressure value corresponds to zero.

In this pressure measuring device for gas meter, the output signal of the pressure sensor when the gas supply pressure is zero when the gas meter is attached and the zero pressure value calculated by the pressure calculating means correspond to each other by the pressure correction processing means. As described above, the correspondence between the output signal of the pressure sensor used in the pressure calculation means and the pressure value is corrected. The pressure calculation means calculates the pressure value based on the output signal of the pressure sensor by using the correspondence relationship between the output signal of the pressure sensor and the pressure value.

According to a second aspect of the gas meter pressure measuring device of the present invention, in the gas meter pressure measuring device of the first aspect, the pressure calculating means has a table showing the correspondence between the output signal of the pressure sensor and the pressure value. The pressure value is calculated based on the output signal of the pressure sensor with reference to this table.

According to a third aspect of the pressure measuring apparatus for gas meter of the present invention, in the pressure measuring apparatus for gas meter according to the first aspect, the pressure calculating means approximates the correspondence between the output signal of the pressure sensor and the pressure value by a straight line. The pressure value is calculated based on the output signal of the pressure sensor using the function to be expressed.

According to a fourth aspect of the present invention, there is provided a correction method for a pressure measuring device for a gas meter, the pressure sensor being provided in the gas meter for detecting a gas supply pressure, and a correspondence relationship between an output signal of the pressure sensor and a pressure value. In a gas meter pressure measuring device having a pressure calculating means for calculating a pressure value based on an output signal of a pressure sensor, a method for correcting the pressure value calculated by the pressure calculating means, comprising: Correspondence between the output signal of the pressure sensor used in the pressure calculating means and the pressure value so that the output signal of the pressure sensor when the gas supply pressure is zero at the time of mounting and the zero pressure value calculated by the pressure calculating means correspond to each other. It corrects the relationship.

[0011]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 2 is a sectional view showing the structure of a gas meter including a pressure measuring device for a gas meter according to an embodiment of the present invention. The gas meter shown in this figure has a main body 10, and a pipe 13 that forms a gas flow path from an inlet portion 11 to an outlet portion 12 is inserted into the main body 10. This piping 1
A flow rate measuring unit 14 is provided in the middle of 3. Piping 1
A pressure sensor 15 for detecting the supply pressure of the gas is provided on the outer side of 3, and the pressure sensor 15 communicates with the inside of the pipe 13 through a pressure introduction hole 16 provided in the pipe 13. A partition 17 that separates the upstream side and the downstream side is provided in the pipe 13 on the upstream side of the flow rate measuring unit 14 and the pressure introducing hole 16, and the partition 17 is provided with an opening 18. A cutoff valve 20 is further provided in the main body 10. The shutoff valve 20 has a rubber valve body 21 capable of closing the opening 18, and the rubber valve body 21 allows the opening 1 to be closed.
A state in which 8 is opened and a state in which the opening 18 is closed can be selected. On the outside of the main body 10, the pressure sensor 1
A pressure correction instruction switch 22 for instructing a correction process for correcting the pressure value calculated based on the output signal of No. 5 is provided. Inside the main body 10, there is a seismic detector 2 for detecting an earthquake.
3 is provided. The gas meter further includes a control unit 25 connected to the flow rate measuring unit 14, the pressure sensor 15, the shutoff valve 20, the pressure correction instruction switch 22, and the vibration sensor 23.

FIG. 1 is a block diagram showing the circuit configuration of a gas meter including the gas meter pressure measuring device according to this embodiment. The control unit 25 includes a flow rate calculation unit 31 that calculates a flow rate and an integrated flow rate based on the output signal of the flow rate measurement unit 14,
When the correction processing is instructed by the pressure calculation unit 32 which calculates the pressure value based on the output signal of the pressure sensor 15 using the correspondence relationship between the output signal of the pressure sensor 15 and the pressure value, and the pressure correction instruction switch 22. In addition, the pressure sensor 15 when the gas supply pressure is zero when the gas meter is attached
Pressure correction processing unit 33 that corrects the correspondence relationship between the output signal of the pressure sensor 15 used in the pressure calculation unit 32 and the pressure value so that the output signal of the pressure calculation unit 32 corresponds to zero of the pressure value calculated by the pressure calculation unit 32. And the flow rate calculation unit 31 and the pressure calculation unit 3
2 and a shutoff valve control unit 34 that controls the shutoff valve 20 based on each output of the seismic sensor 23. Pressure sensor 1
5, the pressure calculation unit 32, the pressure correction instruction switch 22, and the pressure correction processing unit 33 constitute the gas meter pressure measuring device in the present embodiment. The control unit 25 is realized by, for example, a microcomputer.

The pressure calculation unit 32 is, for example, the pressure sensor 1.
It is also possible to have a table showing the correspondence between the output signal of No. 5 and the pressure value, and refer to this table to calculate the pressure value based on the output signal of the pressure sensor 15,
The pressure value may be calculated based on the output signal of the pressure sensor 15 by using a function that approximates the correspondence between the output signal of the pressure sensor 15 and the pressure value by a straight line.

The gas meter further includes a display unit 35, and the integrated flow rate calculated by the flow rate calculation unit 31 is displayed on the display unit 35. The shutoff valve control unit 34 determines whether the flow rate calculated by the flow rate calculation unit 31 is equal to or more than a predetermined amount, the predetermined flow amount continues for a predetermined time or more, or the pressure value calculated by the pressure calculation unit 32 is equal to or less than a predetermined value. In the event of an abnormality such as a decrease or when an earthquake is detected by the seismic sensor 23, the shutoff valve 20 is driven to close the opening 18 and shut off gas.

Next, the operation of the gas meter pressure measuring device of this embodiment, that is, the method of correcting the gas meter pressure measuring device of this embodiment will be described. Pressure sensor 15
Has been adjusted at the time of factory shipment so as to meet the conditions that meet the design specifications. However, in this embodiment,
As will be described later, since the correspondence between the output signal of the pressure sensor 15 and the pressure value calculated by the pressure calculation unit 32 is corrected when the gas meter is attached, the pressure sensor 15 when the actual pressure is zero at the time of factory shipment. The output signal of should be approximately zero.

The installer of the gas meter presses the pressure correction instruction switch 22 when the gas supply pressure is zero when the gas meter is installed. Then, the pressure correction processing unit 33
The output signal of the pressure sensor 15 used in the pressure calculation unit 32 is such that the output signal of the pressure sensor 15 when the gas supply pressure is zero when the gas meter is attached and the zero pressure value calculated by the pressure calculation unit 32 correspond to each other. Correct the correspondence between pressure and pressure value.

Here, referring to FIG. 3, the pressure calculation unit 32
Is calculated by the pressure correction processing unit 33 when the pressure value is calculated based on the output signal of the pressure sensor 15 using a function that approximates the correspondence between the output signal of the pressure sensor 15 and the pressure value with a straight line. An example of the method will be described.
In FIG. 3, reference numeral 40 is a point indicating the value of the pressure detection signal x which is the actual output signal of the pressure sensor 15 with respect to the actual pressure value y at the time of factory shipment, and reference numeral 41 is the pressure sensor at the time of factory shipment. 15 shows a straight line that approximates the relationship between the actual pressure detection signal x and the actual pressure value y. The straight line 41 is expressed by the following equation (1).

Y = ax-b (1)

Here, a is a constant unique to the pressure sensor 15 and is known in advance. Also, in general, the pressure sensor 1
Since No. 5 has excellent linearity, there is little variation in the constant a depending on the individual pressure sensor 15. On the other hand, b is slightly different depending on each pressure sensor 15, and is an unknown value before the correction process.

The pressure calculator 32 generates a corrected pressure detection signal x'from the actual pressure detection signal x of the pressure sensor 15, and when the calculated pressure value is y ', it is expressed by the following equation (2). The calculated pressure value y ′ is calculated using the relationship described above. In FIG. 3, reference numeral 42 is a straight line representing the equation (2).

Y '= ax' (2)

From equations (1) and (2), the calculated pressure value y '
In order to match the actual pressure value y with x ′, x ′ and x may be represented by the following expression (3).

X '= x-b / a (3)

From the equation (1), b / a is obtained as the value of the actual pressure detection signal x of the pressure sensor 15 when the actual pressure value y is zero. Therefore, the pressure correction processing unit 33
When the pressure correction instruction switch 22 is pressed, that is, when the actual pressure value y is zero, the actual pressure detection signal x which is the output signal of the pressure sensor 15 is obtained, and this is calculated in (3).
It is stored as b / a in the equation and the pressure calculation unit 32
Give to. When the gas meter is actually used, the pressure calculation unit 32 uses the value of b / a given by the pressure correction processing unit 33 and the expression (3) to correct the pressure detection signal x ′ from the actual pressure detection signal x. Is calculated and the calculated pressure value y ′ is calculated using the equation (2). In this way, the calculated pressure value y ′ is calculated so as to match the actual pressure value y.

The pressure calculation unit 32 has a table showing the correspondence between the output signal of the pressure sensor 15 and the pressure value, and when the pressure value is calculated based on the output signal of the pressure sensor 15 by referring to this table. Is the relationship between the corrected pressure detection signal x ′ represented by the straight line 42 in FIG. 3 and the calculated pressure value y ′, or the corrected pressure detection signal represented more accurately without being approximated by the straight line 42. x'and calculated pressure value y
The relationship with the above is stored, and as described above, the pressure correction processing unit 33 obtains b / a in the equation (3) and supplies it to the pressure calculation unit 32. When the gas meter is actually used, the pressure calculation unit 32 uses the value of b / a given by the pressure correction processing unit 33 and the expression (3) to correct the pressure detection signal x ′ from the actual pressure detection signal x. Is generated and the calculated pressure value y ′ is obtained by referring to the table.

As described above, according to the present embodiment, the pressure correction processing unit 33 determines the output signal of the pressure sensor 15 and the pressure value calculated by the pressure calculation unit 32 when the gas supply pressure is zero when the gas meter is attached. Since the correspondence relationship between the output signal of the pressure sensor 15 used in the pressure calculation unit 32 and the pressure value is corrected so that zero corresponds, the adjustment of the pressure sensor 15 at the time of factory shipment can be simplified, and As a result, the cost of the gas meter can be reduced. Further, it is possible to improve the accuracy of the pressure value calculated based on the output signal of the pressure sensor 15 when the gas meter is actually used.

The present invention is not limited to the above embodiment,
For example, without providing the pressure correction instruction switch 22, the correction processing in the pressure correction processing unit 33 may be started by using the output of the seismoscope 23 generated by the shake or tilt of the gas meter when mounting the gas meter as a trigger. good.

[0029]

As described above, according to the pressure measuring device for a gas meter according to any one of claims 1 to 3 or the correction method for the pressure measuring device for a gas meter according to claim 4, the gas is supplied when the gas meter is attached. The correspondence between the output signal of the pressure sensor used in the pressure calculating means and the pressure value is corrected so that the output signal of the pressure sensor in the state where the pressure is zero and the pressure value of zero calculated by the pressure calculating means correspond to each other. Therefore, there is an effect that the adjustment of the pressure sensor at the time of factory shipment can be simplified and the accuracy of the pressure value calculated based on the output signal of the pressure sensor when the gas meter is actually used can be improved. .

[Brief description of drawings]

FIG. 1 is a block diagram showing a circuit configuration of a gas meter including a gas meter pressure measuring device according to an embodiment of the present invention.

FIG. 2 is a sectional view showing a configuration of a gas meter including a gas meter pressure measuring device according to an embodiment of the present invention.

FIG. 3 is a characteristic diagram showing a correspondence relationship between a pressure sensor output signal and a pressure value used by the pressure calculation unit in FIG.

[Explanation of symbols]

 15 pressure sensor 22 pressure correction instruction switch 32 pressure calculation unit 33 pressure correction processing unit

Claims (4)

[Claims] 1. A pressure sensor for detecting a gas supply pressure, which is provided in a gas meter, and a correspondence relationship between an output signal of the pressure sensor and a pressure value is used to output the pressure sensor based on the output signal of the pressure sensor. The pressure calculation means for calculating the pressure value, the pressure sensor so that the output signal of the pressure sensor when the gas supply pressure is zero when the gas meter is attached, and the zero pressure value calculated by the pressure calculation means correspond to each other. A pressure measuring device for a gas meter, comprising: a pressure correction processing means for correcting a correspondence between an output signal of a pressure sensor used in the calculating means and a pressure value. 2. The pressure calculation means has a table showing the correspondence between the output signal of the pressure sensor and the pressure value, and calculates the pressure value based on the output signal of the pressure sensor with reference to this table. The pressure measuring device for a gas meter according to claim 1. 3. The pressure calculating means calculates the pressure value based on the output signal of the pressure sensor using a function that approximates the correspondence between the output signal of the pressure sensor and the pressure value by a straight line. The pressure measuring device for a gas meter according to claim 1. 4. A pressure sensor provided in a gas meter for detecting a gas supply pressure, and a pressure sensor based on an output signal of the pressure sensor using a correspondence relationship between an output signal of the pressure sensor and a pressure value. A pressure measuring device for a gas meter, comprising: a pressure calculating means for calculating a value; a method for correcting a pressure value calculated by the pressure calculating means, the pressure sensor in a state where a gas supply pressure is zero when the gas meter is attached. Of the pressure sensor used in the pressure calculating means is corrected so that the output signal of the pressure sensor and the zero of the pressure value calculated by the pressure calculating means correspond to each other. Method for measuring pressure measuring equipment.