JPH0915019A - Device for correcting flow rate of flowmeter - Google Patents

Abstract

PURPOSE: To obtain an accurate instantaneous flow rate without needing complicated mechanical correction processing. CONSTITUTION: A circuit plate 51 rotates interlocking with a mechanical moving part in which cyclic operation is performed at a speed in accordance with flow rate. A position discrimination part 62 detects positions during one cycle of operation of the mechanical moving part on the basis of each output of magnetic resistance elements 54, 55 for detecting the rotation position of the circular plate 51, a correction coefficient calculation part 64 calculates a correction coefficient in response to the positions by referring to a correction table 63, and a flow operation part 65 computes corrected flow rate on the basis of a pulse cycle and the correction coefficient measured by a pulse measuring part 61. A correction table correction part 68 corrects the correction coefficient stored in the correction table 63 on the basis of information from an automatic gage examination center 71.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flow rate correction device for a flow meter that corrects instrumental differences that differ depending on the flow rate.

[0002]

2. Description of the Related Art Generally, in a flow meter used for a gas meter or the like, if the flow rate (flow velocity) passing therethrough is different, the instrumental difference is different. Here, the instrumental error refers to the difference between the indicated flow rate of the reference instrument and the indicated flow rate of each flow meter, expressed as a percentage of the indicated flow rate of each flow meter. Further, in the flowmeter, a measurement error due to the mechanism also occurs depending on the fluid passage amount during the test. Therefore, for gas meters, conduct a test with the flow rate (verification flow rate) and passage rate according to the maximum usable flow rate or number indicated on the gas meter, and correct the gas meter so that the instrumental error is within the verification tolerance. It is defined by the Measurement Law.

FIG. 9 is a characteristic diagram showing a test tolerance. As shown by the diagonal lines in this figure, the test tolerance is 2.5% for the flow rate of 1/20 or more and less than 1/5 of the maximum flow rate, and 1. for the flow rate of 1/5 or more and less than 4/5 of the maximum flow rate. 5
%, And 2.5% for a flow rate of 4/5 or more of the maximum flow rate.

Therefore, conventionally, the instrumental difference is measured at two points of the maximum flow rate and the verification flow rate (about 30% of the maximum flow rate), and the number of teeth and the rotation timing of the gear in the mechanical movable part that moves according to the flow rate are measured. The gas meter was manufactured by making mechanical corrections such as changing.

[0005]

However, the above-described correction method requires a step of performing a complicated mechanical correction process such as gear replacement for correcting the instrumental error on the manufacturing line, and thus the gas meter. In addition to the increase in cost, there is a risk that defective products may be generated due to incorrect operation.

Further, as a method for measuring the flow rate in a gas meter having a mechanically movable portion such as a membrane gas meter, one cycle of the operation of the mechanically movable portion is disclosed, for example, as disclosed in JP-A-5-107096. A disk that makes one rotation in conjunction with the disk is provided, and a plurality of magnets provided on the disk and a magnetoresistive element provided in the vicinity of the disk are used during one cycle of the operation of the mechanical movable part. To output multiple pulses,
There is a method of calculating the flow rate from the frequency and period of this pulse.

However, in a membrane gas meter or the like, even when the flow rate is constant, the speed of the disc that is interlocked with the mechanically movable portion changes depending on the rotational position during one rotation, for mechanical reasons. There is a case. In such a case, there is a problem that the pulse period changes even if the flow rate is constant, and an error occurs in the measured instantaneous flow rate. Therefore,
The applicant of the present invention detects which position among a plurality of predetermined positions the mechanically movable part is in one cycle of its operation, and corrects the flow rate based on the correction information according to the detected position. Proposing technology.

However, even if the flow rate is the same, the pulse cycle may change due to aging deterioration of the mechanically movable part, and in such a case, the correction information initially set becomes inadequate. There was a problem that there were cases.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a flowmeter capable of obtaining a highly accurate instantaneous flow rate while eliminating the need for complicated mechanical correction processing. It is to provide a flow rate correction device.

[0010]

According to a first aspect of the present invention, there is provided a flow rate correction device for a flow meter, which corrects a measured flow rate in a flow meter having a mechanically movable portion that periodically operates at a speed according to the flow rate. A flow rate correction device for a flow meter, which detects which position of a plurality of predetermined positions the mechanical movable part is in one cycle of its operation, and generates a pulse corresponding to each position. Position detection means for outputting, pulse cycle measuring means for measuring the cycle of pulses output from the position detecting means, and correction table storing correction information determined in accordance with a plurality of positions detected by the position detecting means. And by referring to this correction table to obtain correction information according to the position detected by the position detection means, and based on this correction information and the pulse cycle measured by the pulse cycle measurement means. , Those having a correction flow rate calculation means for calculating a corrected flow rate, and a correction table correction means for correcting the correction information stored in the correction table.

In the flow rate correction device of this flow meter, the position detecting means detects which of a plurality of predetermined positions the mechanical movable portion is in during one cycle of its operation, and at the same time each position is detected. The pulse corresponding to
The period of this pulse is measured by the pulse period measuring means. Then, the correction flow rate calculation means refers to the correction table, and the corrected flow rate is calculated based on the correction information corresponding to the position detected by the position detection means and the pulse cycle measured by the pulse cycle measurement means. It Further, the correction table correction means corrects the correction information stored in the correction table.

A flow rate correction device for a flowmeter according to claim 2 is
In the flow rate correction device for a flow meter according to claim 1, the correction table correction means is configured to correct the correction information based on the correction information input from outside the flow meter.

A flow rate correction device for a flowmeter according to claim 3 is
In the flow rate correction device for a flow meter according to claim 1, the correction table correction means is configured to correct the correction information based on the flow rate calculated by the corrected flow rate calculation means.

A flow rate correction device for a flowmeter according to claim 4 is
The flow rate correction device for a flow meter according to any one of claims 1 to 3, further comprising a correction flow rate abnormality detection means for detecting an abnormality in the flow rate calculated by the correction flow rate calculation means.

A flow rate correction device for a flow meter according to a fifth aspect,
5. The flow rate correction device for a flow meter according to claim 4, wherein the corrected flow rate abnormality detecting means has an abnormal flow rate when the flow rate calculated by the corrected flow rate calculating means has a periodic fluctuation or does not change for a predetermined period or longer. It is configured to determine that

[0016]

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

1 to 6 relate to a first embodiment of the present invention. FIG. 1 is a sectional view showing a schematic configuration of a membrane gas meter as a flow meter including the flow rate correction device according to the present embodiment. As shown in the figure, the gas meter has a case body 10, and a gas inlet portion 11 and a gas outlet portion 12 are provided on the upper portion of the case body 10. Also,
A front measuring chamber 20 and a rear measuring chamber 30 are provided inside the case body 10.

A film 21 is provided in the front measuring chamber 20 at the center in the front-rear direction (the left side of the drawing is the front), and a film plate 22 is attached to the film 21. Here, the space in front of the membrane 21 in the front measuring chamber 20 is defined as a chamber, and the space in the rear is defined as a chamber. A gas inlet / outlet portion 23 that communicates with the chamber and a gas inlet / outlet portion 24 that communicates with the chamber are provided at the upper portion of the front measuring chamber 20. A blade shaft 26 is connected to the membrane plate 22 via a blade 25. The blade shaft 26 is adapted to rotate as the membrane 21 moves in the front-rear direction. Further, the blade shaft 26 is used for the front measuring chamber 2
It penetrates 0 and projects to the upper part.

Similarly, in the rear measuring chamber 30, a film 31 is provided at the center in the front-rear direction, and a film plate 32 is provided on the film 31.
Is attached. Here, the space in front of the membrane 31 in the rear measurement chamber 30 is defined as a chamber, and the space in the rear is defined as a chamber. A gas inlet / outlet portion 33 that communicates with the chamber and a gas inlet / outlet portion 34 that communicates with the chamber are provided on the upper portion of the rear measuring chamber 30. A blade shaft 36 is connected to the film plate 32 via a blade. The blade shaft 36 is adapted to rotate as the film 31 moves in the front-rear direction. Further, the blade shaft 36 penetrates the rear measuring chamber 30 and projects upward.

Further, between the gas inlet / outlet portions 23 and 24,
An opening of the gas outlet pipe 13 is arranged between the gas inlet / outlet portions 33 and 34. This gas outlet pipe 13
Is connected to the gas outlet 12. A valve 14 is provided above the gas inlet / outlet portions 23 and 24. The valve 14 has a state in which both the gas inlet / outlet portions 23 and 24 are closed, and the gas inlet / outlet portion 23 and the gas outlet pipe 13 are
It is possible to select a state in which the gas outlet port 24 and the gas outlet pipe 13 are in communication with each other. Similarly, the valve 15 is provided above the gas inlet / outlet portions 33, 34. The valve 15 has a state in which the gas inlet / outlet portions 33 and 34 are both closed, a state in which the gas inlet / outlet portion 33 and the gas outlet pipe 13 are in communication, and a state in which the gas inlet / outlet portion 34 and the gas outlet pipe 13 are in communication. You can choose.

An elbow 27 is connected to the upper end of the blade shaft 26, and an elbow 37 is connected to the upper end of the blade shaft 36. These elbows 27, 37 are connected to the adjusting plate 42 by pins 41. A crank arm 44 and valve arms 45 and 46 are connected to the adjusting plate 42 via a crank pin 43. The crank arm 44 is connected to a crank shaft 47 and is configured to rotate the crank shaft 47. Also, the valve arms 45, 4
6 is connected to valves 14 and 15, respectively, and these valves 14 and 15 are moved. A disc 51 described below is attached to the crankshaft 47 via a worm and a worm wheel (not shown).

An outline of the operation of the gas meter shown in FIG. 1 will be described with reference to FIG. Weighing room 20,
The introduction of gas into 30 and the discharge of gas from the measuring chambers 20 and 30 are performed by the interlocking action of the valves 14 and 15 and the membranes 21 and 31. The driving force of the movement of the membranes 21 and 31 is the pressure difference between the gas at the gas inlet 11 and the gas at the gas outlet 12. In the state shown in FIG. 2A, the valve 14 closes both the gas inlet / outlet portions 23 and 24, and the valve 15 connects the gas inlet / outlet portion 33 and the gas outlet pipe 13. In this state, the gas entering the chamber through the gas inlet / outlet portion 34 pushes the membrane 31 toward the chamber due to the pressure difference, and the gas in the chamber passes through the gas inlet / outlet portion 33, the valve 15 and the outlet pipe 13 in this order, and the gas outlet portion. It is discharged from 12. The movement of the membrane 31 is transmitted in the order of the blade shaft 36, the elbow 37, the adjusting plate 42, and the valve arms 45 and 46, and as shown in FIG. 2B, the valve 14 is moved to the gas inlet / outlet portion 24 and the gas outlet pipe. 1
The valve 15 is moved to the state of communicating with the valve 3 and the valve 15 is moved to the state of closing both the gas inlet / outlet portions 33 and 34. At this time, the gas in the room is the gas inlet / outlet part 23 and the valve 1.
4, the gas passes through the outlet pipe 13 in order and is discharged from the gas outlet 12. Thereafter, similarly, the motion of returning to the state of (a) through the states of FIGS. 2 (c) and (d) is repeated. Further, the crank arm 44 and the crank shaft 47 rotate due to the above movement. Then, the rotation of the crankshaft 47 rotates a disc 51 described later through a worm and a worm wheel (not shown).

FIG. 3 is a block diagram showing the circuit configuration of a gas meter including the flow rate correction device according to this embodiment. The disk 51 connected to the crankshaft 47 is adapted to make one rotation corresponding to one cycle of the operation of the gas meter shown in FIG. This disc 51 has one magnet 52 near the outer periphery.
And a plurality of, for example, five magnets 53 are attached to the position inside the magnet 52 at equal intervals along the circumferential direction. The gas meter further includes a magnetoresistive element 54 provided at a position facing the magnet 52 and a magnetoresistive element 55 provided at a position facing the magnet 53. These magnetoresistive elements 5
Numerals 4 and 55 detect changes in the magnetic field due to the approach and separation of the magnets 52 and 53 as changes in resistivity.

The disk to which the magnet 52 is attached and the magnet 5
The discs to which 3 is attached may be separately provided so as to be connected to the crankshafts 47, respectively. Alternatively, only the magnet 53 may be provided on the disk 51, and the magnet 52 may be provided on another mechanically movable part, such as the elbow 27, that periodically operates in the gas meter at a speed according to the flow rate.

The gas meter further includes an analog amplifier 56 for amplifying the output signal of the magnetoresistive element 54, a waveform shaping circuit 57 for shaping the output signal of the analog amplifier 56 to generate a pulse, and a magnetoresistive element 55. An analog amplifier 58 for amplifying an output signal, and this analog amplifier 5
A waveform shaping circuit 59 for shaping the waveform of the output signal of No. 8 to generate a pulse.

The gas meter further includes a pulse period measuring unit 61 for measuring the period of the pulse output from the waveform shaping circuit 59, a pulse output from the waveform shaping circuit 57 and a pulse output from the waveform shaping circuit 59. Based on this, the position determination unit 62 that determines the position of each of the five locations in one cycle of rotation of the disk 51, and the flow rate and the position determination unit 62 that correspond to the pulse period measured by the pulse period measurement unit 61 are determined. Correction table 63 that stores a correction coefficient that is determined according to the position that is determined, and a correction coefficient that refers to this correction table 63 and that calculates a correction coefficient that depends on the flow rate and the position determined by the position determination unit 62. Based on the calculation unit 64, the correction coefficient calculated by the correction coefficient calculation unit 64, and the pulse period measured by the pulse period measurement unit 61. A flow rate calculation unit 65 that calculates a corrected flow rate for each pulse and integrates the flow rates to calculate an integrated flow rate, and a display unit 66 that displays the integrated flow rate calculated by the flow rate calculation unit 65. I have it. The correction table 63 is configured by a RAM (random access memory), and the correction coefficient can be rewritten.

The gas meter further includes a corrected flow rate calculated by the flow rate calculation unit 65 (hereinafter, referred to as a corrected flow rate) based on the flow rate between each pulse calculated by the flow rate calculation unit 65 (hereinafter referred to as inter-pulse flow rate). A correction flow rate abnormality detection unit 67 for detecting an abnormality of the flow rate), a correction table correction unit 68 for correcting the correction coefficient stored in the correction table 63, a flow rate calculation unit 65, a correction flow rate abnormality detection unit 67, and A communication control unit 69 connected to the correction table correction unit 68 is provided. The communication control unit 69 communicates with the automatic meter reading center 71 via a communication line 70 such as a telephone line, and notifies the automatic meter reading center 71 of the corrected flow rate and the integrated flow rate calculated by the flow rate calculation unit 65.
When the correction flow rate abnormality detecting section 67 detects an abnormality in the correction flow rate, the fact is notified to the automatic meter reading center 71,
Further, the correction information for correcting the correction coefficient sent from the automatic meter reading center 71 is received and sent to the correction table correction unit 68. Correction table correction unit 68
Is adapted to correct the correction coefficient based on the correction information sent from the automatic meter reading center 71. Instead of the communication line 70, the communication between the communication control unit 69 and the automatic meter-reading center 71 may be performed wirelessly.

The pulse period measuring section 61, the position determining section 62,
Correction table 63, correction coefficient calculation unit 64, flow rate calculation unit 6
5, the correction flow rate abnormality detection unit 67 and the correction table correction unit 68 are realized by the microcomputer 60, for example.

FIG. 4 shows an example of the contents of the correction table 63. (A) has an average flow rate of 500 l / h
Table contents when less than, (b) average flow rate is 50
The contents of the table are shown when the value is 0 liter / h or more and less than 1000 liter / h. Although not shown,
Similar tables are prepared for the average flow rate of 1000 liters / h or more according to the appropriately divided flow rate range. As shown in FIG. 4, the correction table 63 stores the correction coefficient determined according to the average flow rate and the position determined by the position determination unit 62.

The flow rate calculation unit 65 calculates the corrected flow rate Q based on the correction coefficient calculated by the correction coefficient calculation unit 64 and the pulse period measured by the pulse period measurement unit 61, for example, by the following equation. Calculate However, T is a pulse period and k is a correction coefficient.

[0031]

## EQU1 ## Q = k / T

The flow rate calculator 65 calculates the average flow rate for each predetermined time from the calculated flow rate, and switches the contents of the correction table 63 according to the average flow rate. For example, when the average flow rate is less than 500 liters / hour, FIG.
When the average flow rate changes from 500 liters / h or more to less than 1000 liters / h, the table having the content shown in FIG. 4B is switched to be used. .

The contents of the correction table 63 are set in advance.
Based on the flow rate indicated by the gas meter before correction and the flow rate indicated by the reference device, the corrected flow rate is set to match the reference flow amount indicated by the reference device.

Next, referring to the flow chart of FIG. 5, the flow rate calculation processing in the flow rate correction apparatus according to this embodiment will be described. The gas meter performs the operation shown in FIG. 2 at a speed according to the gas flow rate, and with this operation, the disk 51 shown in FIG. 3 rotates at a speed according to the gas flow rate. And the disc 51
The output of the magnetoresistive element 54 changes with the approach and separation of the magnet 52 provided in the. The output signal of the magnetoresistive element 54 is amplified by the analog amplifier 56, and the waveform shaping circuit 57.
The waveform is shaped by, and a pulse is generated for each rotation of the disk 51, that is, for each cycle of the operation of the gas meter. On the other hand, the output of the magnetoresistive element 55 changes with the approach and separation of the five magnets 53 provided on the disk 51, and the output signal of the magnetoresistive element 55 is amplified by the analog amplifier 58 and the waveform shaping circuit 59. The waveform is shaped by, and a pulse having a period according to the flow rate is generated. As shown in FIG. 5, the flow rate correction device first measures the period of the pulse output from the waveform shaping circuit 59 by the pulse period measuring unit 61 (step S101). Next, the position determining unit 62 determines the disk 51 based on the pulse output from the waveform shaping circuit 57 and the pulse output from the waveform shaping circuit 59.
Which position among the five positions in one cycle of the rotation is determined (step S102).
Next, the correction coefficient calculation unit 64 calculates a correction coefficient according to the flow rate and the position determined by the position determination unit 62 (step S103). Next, the flow rate calculation unit 65 calculates the corrected flow rate based on the pulse period measured by the pulse period measurement unit 61 and the correction coefficient calculated by the correction coefficient calculation unit 64 (step S).
104). Then, the integrated flow rate obtained by integrating the corrected flow rates is displayed on the display unit 66. Further, the flow rate calculation unit 65 switches the contents of the correction table 63 according to the average flow rate.

Next, the correction flow rate abnormality detecting process in the correction flow rate abnormality detecting section 67 will be described with reference to the flow chart of FIG. The corrected flow rate abnormality detection unit 67 first obtains the flow rate calculation unit 65 every time the inter-pulse flow rate is calculated,
A predetermined plurality of rotations of the disk 51 are stored (step S11).
1). Next, it is determined whether the corrected flow rate calculated by the flow rate calculation unit 65 is abnormal based on the stored pulse-to-pulse flow rates (step S112). Specifically, for example, the correction flow rate is determined to be abnormal when there is a periodic change in the inter-pulse flow rate or when there is no change over a predetermined period. The periodic variation in the inter-pulse flow rate means that the inter-pulse flow rate calculated at a specific position is larger or smaller than the average value of the inter-pulse flow rate calculated at other positions by a predetermined value or more. It can be detected by continuing a predetermined number of times or more. If there is a periodic fluctuation in the pulse-to-pulse flow rate, the operating speed of the mechanical moving part changes partially due to aging deterioration or sudden changes of the mechanical moving part, and the correction coefficient at a specific position becomes inadequate. It is believed to be accurate. When the pulse-to-pulse flow rate does not change for a predetermined period of time, it may always show the maximum flow rate, always show zero flow rate, or always show an arbitrary constant flow rate. Abnormalities etc. are considered. The correction flow rate abnormality detection unit 67 detects that the correction flow rate is abnormal (step S11).
2; Y), to that effect is notified to the automatic meter reading center 71 via the communication control unit 69 and the communication line 70 (step S).
113), if there is no abnormality in the corrected flow rate (step S11)
2; N) is not notified.

In the automatic meter-reading center 71, the cause of the correction flow rate abnormality is determined in response to the notification from the correction flow rate abnormality detecting section 67, and the correction coefficient at a specific position of the correction table 63 is inaccurate. If determined, correction information for correcting the correction coefficient, that is, information on the newly set correction coefficient is sent to the communication control unit 69 via the communication line 70. This correction information is sent from the communication control unit 69 to the correction table correction unit 68. The correction table correction unit 68 corrects the correction coefficient stored in the correction table 63 based on the correction information. In addition, when it is determined that the correction coefficient at a specific position is incorrect, for example, the inter-pulse flow rate calculated at the specific position is the average value of the inter-pulse flow rates calculated at other positions. The correction coefficient corresponding to a specific position is changed so that they match.

As described above, according to the present embodiment, it is detected which of a plurality of predetermined positions the mechanically movable part of the gas meter is in one cycle of its operation, and the correction table 63 is detected. The correction flow rate is calculated based on the average flow rate and the position and the correction flow rate is calculated based on this correction coefficient and the pulse period. Therefore, in order to correct the instrumental error on the manufacturing line. The process of performing complicated mechanical correction processing such as gear replacement is unnecessary, the cost of the gas meter can be reduced, and defective products due to erroneous operation can be prevented, so process management is simplified. .

In this embodiment, since the flow rate is corrected by referring to the correction table 63, the flow rate can be easily corrected regardless of the relationship between the flow rate before correction and the correct flow rate. A more accurate correction is possible as compared with a mechanical correction.

Further, in this embodiment, since the correction is performed according to the position and the average flow rate of the mechanically movable portion of the gas meter during one cycle, the speed of the mechanically movable portion of the operation is at the position during one cycle. It is possible to obtain a highly accurate instantaneous flow rate even when it changes according to

Further, in this embodiment, when it is considered that the correction coefficient is inaccurate when the correction flow rate calculated by the flow rate calculation unit 65 is abnormal, the correction coefficient can be corrected. Therefore, even if the correction coefficient becomes inaccurate due to deterioration of the mechanically movable part due to age, etc., it is possible to obtain a highly accurate instantaneous flow rate by correcting the correction coefficient. Further, since the correction coefficient in the correction table 63 can be corrected from the outside by remote operation, it is possible to save the trouble of going to the gas meter installation place for the correction coefficient correction.

Further, in this embodiment, the correction flow rate abnormality detecting section 67 automatically detects the correction flow rate abnormality and notifies it to the automatic meter reading center 71, so that when the correction flow rate abnormality occurs. You can quickly recognize this.

FIG. 7 is a block diagram showing the circuit configuration of a gas meter including a flow rate correction device according to the second embodiment of the present invention. In this embodiment, the correction flow rate abnormality detection unit 67 is not provided on the gas meter side, and the correction flow rate abnormality is detected on the automatic meter reading center 71 side based on the inter-pulse flow rate calculated by the flow rate calculation unit 65. It was done. In this embodiment,
The flow rate calculating unit 65 notifies the calculated inter-pulse flow rate to the automatic meter reading center 71 via the communication control unit 69 and the communication line 70. The automatic meter reading center 71 determines whether or not there is an abnormality in the corrected flow rate on a regular basis or at an arbitrary time based on the notified inter-pulse flow rate. Other configurations and operations of this embodiment are similar to those of the first embodiment. Also,
In this embodiment, unlike the first embodiment, it is not possible to automatically detect an abnormality in the corrected flow rate, but other effects are the same as in the first embodiment.

FIG. 8 is a block diagram showing the circuit configuration of a gas meter including a flow rate correction device according to the third embodiment of the present invention. In this embodiment, a correction table correction unit 78 is provided instead of the correction table correction unit 68 in the first embodiment. This correction table correction unit 78 has the function of the correction table correction unit 68 in the first embodiment,
The correction flow rate abnormality detecting section 67 has a function of automatically correcting the correction coefficient of the correction table 63 when the correction flow rate abnormality is detected. The correction coefficient is corrected as follows, for example. That is, when the inter-pulse flow rate calculated at a specific position is larger or smaller than the average value of the inter-pulse flow rate calculated at other positions by a predetermined value or more, the inter-pulse flow rate calculated at the specific position is The correction coefficient corresponding to the specific position is changed so as to match the average value of the inter-pulse flow rate calculated at the position.

According to this embodiment, since the correction coefficient can be automatically corrected on the gas meter side, it is possible to further save the labor of human. Other configurations, operations and effects of this embodiment are similar to those of the first embodiment.

The present invention is not limited to the above embodiments, and the correction table 63 may store a correction coefficient corresponding to the pulse period and the position determined by the position determination unit 62, for example. In this case, the correction coefficient calculation unit 64 uses the pulse cycle measured by the pulse cycle measurement unit 61 and the position determined by the position determination unit 62 to obtain the correction coefficient from the correction table 63.

Further, the correction table 63 is used by the position determination unit 6
The correction coefficient corresponding to only the position determined by 2 may be stored. In this case, the correction coefficient calculation unit 6
In step 4, the position determined by the position determination unit 62 is used to obtain the correction coefficient from the correction table 63.

As the position detecting means, the magnet 52,
Instead of 53 and the magnetic resistance elements 54 and 55, an optical rotary encoder or the like may be used. Further, the position detecting means may detect the position of the mechanically movable portion that periodically reciprocates in the gas meter at a speed according to the flow rate.

The flow rate correction device for the flow meter of the present invention is
The present invention can be applied not only to the membrane gas meter but also to other types of gas meters having mechanically movable parts.

[0049]

As described above, according to the flow rate correction device for the flowmeter according to the first aspect, the position detecting means causes the mechanically movable portion to be selected from among a plurality of predetermined positions in one cycle of its operation. While detecting which position it is,
The pulse cycle measuring means measures the cycle of the pulse output from the position detecting means, and the correction flow rate calculating means
The correction table is obtained by referring to the correction table, and the corrected flow rate is calculated based on the correction information and the pulse period. In addition to the effect that the dynamic correction process is unnecessary and the highly accurate instantaneous flow rate can be obtained, the correction table correction means for correcting the correction information stored in the correction table is further provided. Even if the correction coefficient becomes inaccurate due to aging deterioration of the mechanically movable portion, it is possible to obtain a highly accurate instantaneous flow rate by correcting the correction coefficient.

According to the flow rate correction device of the flow meter of the second aspect, in addition to the above-mentioned first effect, the correction table correction means is used to remotely control the flow meter based on the correction information inputted from the outside of the flow meter. The effect is that the correction information can be corrected.

According to the flow rate correction device of the flow meter of the third aspect, in addition to the first effect, the correction information is corrected by the correction table correction means based on the flow rate calculated by the correction flow rate calculation means. The effect is that it can be corrected automatically.

According to the flow rate correction device of the flow meter of the fourth or fifth aspect, in addition to the above effects, the correction flow rate abnormality detecting means automatically causes the abnormality of the flow rate calculated by the correction flow rate calculating means. The effect is that it can be detected.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a schematic configuration of a gas meter including a flow rate correction device according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram showing an outline of the operation of the gas meter shown in FIG.

FIG. 3 is a block diagram showing a circuit configuration of a gas meter including a flow rate correction device according to a first example of the present invention.

FIG. 4 is an explanatory diagram showing an example of contents of a correction table in FIG.

FIG. 5 is a flowchart showing a flow rate calculation process in the flow rate correction device according to the first embodiment of the present invention.

FIG. 6 is a flowchart showing a correction flow rate abnormality detection process in the flow rate correction apparatus according to the first embodiment of the present invention.

FIG. 7 is a block diagram showing a circuit configuration of a gas meter including a flow rate correction device according to a second embodiment of the present invention.

FIG. 8 is a block diagram showing a circuit configuration of a gas meter including a flow rate correction device according to a third embodiment of the present invention.

FIG. 9 is a characteristic diagram showing a test tolerance.

[Explanation of symbols]

 51 disk 52, 53 magnet 54, 55 magnetoresistive element 57, 58 waveform shaping circuit 61 pulse period measurement unit 62 position determination unit 63 correction table 64 correction coefficient calculation unit 65 flow rate calculation unit 67 correction flow rate abnormality detection unit 68 correction table correction Department 69 Communication control unit

Claims (5)

[Claims] 1. A flowmeter having a mechanically movable part that periodically operates at a speed according to the flowrate, which is a flowmeter compensator for a flowmeter that corrects the measured flowrate, wherein the mechanically movable part is Position detecting means for detecting which position among a plurality of predetermined positions in one cycle of the operation, and outputting a pulse corresponding to each position, and a pulse output from this position detecting means A pulse cycle measuring means for measuring the cycle of, a correction table storing correction information determined according to a plurality of positions detected by the position detecting means, and referring to this correction table, the position detecting means A correction flow for obtaining the correction information according to the detected position and calculating the corrected flow rate based on the correction information and the pulse period measured by the pulse period measuring means. Calculating means and the for modifying the correction information stored in the correction table correction table correction means and flow meter flow rate correction device characterized by comprising a. 2. The flow rate correction device for a flow meter according to claim 1, wherein the correction table correction means corrects the correction information based on correction information input from the outside of the flow meter. 3. The flow rate correction device for a flow meter according to claim 1, wherein the correction table correction means corrects the correction information based on the flow rate calculated by the correction flow rate calculation means. 4. The flow rate of the flowmeter according to claim 1, further comprising a correction flow rate abnormality detecting means for detecting an abnormality in the flow rate calculated by the correction flow rate calculating means. Correction device. 5. The correction flow rate abnormality detecting means determines that the flow rate is abnormal when the flow rate calculated by the correction flow rate calculating means has a periodic fluctuation or does not change for a predetermined period or longer. The flow rate correction device for a flow meter according to claim 4, wherein