JP3359450B2 - Gas meter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas meter having a gas safety shut-off function by a microcomputer.

[0002]

2. Description of the Related Art In recent years, a household gas meter has a function of detecting the flow rate of gas passing through a flow meter, and when a gas flow rate of a predetermined amount or more is detected or a gas flow rate of a predetermined period or more. In some cases, various devices having a gas safety shutoff function of driving a gas shutoff valve to close a gas flow path have been developed. In this way, leakage of gas in the pipe or unnatural gas outflow is detected to prevent accidents before they occur, thereby ensuring safety.

When the gas flow path is shut off by such a gas safety shut-off function, a gas leak inspection is performed and a recovery operation is performed. When the recovery operation is completed, the shutoff valve is returned by the return lever. Then, after the shut-off valve is restored, the gas is not used for a predetermined time (for example, 2 minutes) (for example, the flow rate is 50 liter /
h), the gas leak inspection is terminated on the assumption that there is no gas leak downstream from the gas meter. On the other hand, the use of gas is detected within 2 minutes (for example, when the flow rate is 50 l / h).
If the above is done, it is determined that there is still gas leakage due to a construction error or the like, and the gas shutoff valve is driven again to close the gas flow path.

[0004]

However, such a conventional gas meter requires a long leak inspection time (2 minutes) after the gas shut-off valve is restored, and has a small gas flow rate of 50 liter / h or less. Is difficult to detect.

The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a gas meter capable of performing a gas leak inspection at a small flow rate in a short time and further improving a gas safety shut-off function. is there.

[0006]

According to a first aspect of the present invention, a gas meter detects a gas flow rate flowing through a gas flow path, and shuts off the gas flow path according to a detection result of the gas flow rate detection means. A gas flow path shutoff means that can be electrically returned together with the gas flow path; a reset flow shutoff means for driving the gas flow path cutoff means to shut off the gas flow path again after returning the gas flow path cutoff means; Gas pressure detecting means for detecting a change in gas pressure in the path, and a rate of change in pressure detectable by the gas pressure detecting means are stored in a plurality of stages according to the magnitude thereof, and these distinguished values are stored. For each of the pressure change rates, a storage means in which a plurality of inspection times of a size inversely proportional to the magnitude of the pressure change rate are stored, and in a state where the gas flow path is shut off again, the gas pressure detection means Detection result Monitoring and determining the pressure change rate, discriminating to which range the pressure change rate corresponds to the pressure change rate stored in the storage means, and further determining the pressure within the inspection time corresponding to the range. Determine whether the fluctuation value is within a predetermined reference value, the pressure fluctuation value,
When it is larger than the reference value, it is determined that there is gas leakage, and when it is less than the reference value, it is determined that there is no gas leakage. And a return means for returning again.

In this gas meter, the gas flow rate flowing through the gas flow path is detected by the gas flow rate detection means, and the gas flow path is cut off by the gas flow path cut-off means according to the detection result of the gas flow rate detection means. Then, after the restoration work is performed, when the gas flow path shutoff means is returned by the return cutoff means, the gas flow path cutoff means is driven, and the gas flow path is shut off again. In a state in which the gas flow path is shut off again, the judging means monitors the detection result of the gas pressure detecting means and obtains the pressure change rate, and the pressure change rate is calculated based on the pressure change rate stored in the storage means in advance. In the inspection time corresponding to the range, the inspection time corresponding to the range (ie, a short inspection time when the pressure change rate is large, a long inspection time when the pressure change rate is small) is determined. It is determined whether the pressure fluctuation value is within a predetermined reference value. If the pressure fluctuation value is larger than the reference value, it is determined that there is gas leakage, and if it is within the reference value, it is determined that there is no gas leakage. When it is determined by the determining means that there is no gas leak, the gas flow path shut-off means is returned again by the re-return means, thereby ending the gas leak inspection.

The gas meter according to a second aspect of the present invention is the gas meter according to the first aspect, further comprising an alarm notifying means for notifying that the gas leak is determined by the determining means.

According to a third aspect of the present invention, in the gas meter according to the first or second aspect, the reference value of the pressure change is set to be constant regardless of the magnitude of the pressure change rate. It is configured to determine the presence or absence of gas leakage using the same reference value regardless of the size.

According to a fourth aspect of the present invention, in the gas meter according to the first or second aspect, the reference value of the pressure change is set in a plurality of stages according to the magnitude of the pressure change rate. Is configured to determine the presence or absence of gas leakage by using different reference values according to the magnitude of.

[0011]

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

FIG. 1 shows a schematic configuration of a gas meter according to an embodiment of the present invention. This gas meter 10
A gas pipe 12 for supplying gas a to a gas appliance (not shown) is provided inside the housing 11. The gas pipe 12 has a gas shut-off valve 13 for shutting off a gas flow path when an abnormality occurs, a gas flow meter 14 for detecting a flow rate of gas passing through the gas flow path, Pressure sensors 15 for detecting pressure are arranged in this order. Further, a control unit 16 is provided in the housing 11 for receiving the output signals of the gas flow meter 14 and the pressure sensor 15 to determine the presence / absence of gas leakage and to control the gas cutoff valve 13.

The gas shut-off valve 13 is constituted by a valve (two-way valve) capable of performing both shut-off and return electrically. 2 and 3 show the gas shut-off valve (bidirectional valve) 1
3 shows a specific configuration. Here, FIG. 2 shows an open state (return state), and FIG. 3 shows a closed state (cut-off state). In the following description, the positional relationship between the opening 12a and the gas shutoff valve 13 in the gas flow path in the gas pipe 12 is described with the opening 12a side being the upper side and the gas shutoff valve 13 side being the lower side. .

The gas shutoff valve 13 has a housing 41 formed of a magnetic material. This housing 41
The upper part is formed in a cylindrical shape with a small diameter on the upper side, and the cylindrical part with a large diameter on the lower side. The upper end is open and the lower end is closed. A flange portion 42 is provided outside a central portion of the housing 41 in the vertical direction.
Has been fixed. This flange portion 42 is fixed to the main body (housing 11) of the gas meter 10 in FIG. A cylindrical permanent magnet 4 is provided on the upper side in the housing 41.
3 is provided, and a coil 44 serving as an electromagnet is provided below the housing 41. A plunger 45 is inserted in a hollow portion formed by the permanent magnet 43 and the coil 44 so as to be movable in the axial direction. The plunger 45 includes an upper magnetic portion 45 made of a magnetic material.
a and a lower nonmagnetic portion 45b formed of a nonmagnetic material. The upper end of the plunger 45 projects from the upper end of the housing 41, and the upper end of the plunger 45 is provided with a rubber valve body 4 capable of closing the opening 12a in FIG.
6 is attached. A spring 47 is provided between the rubber valve body 46 and the flange portion 42 to urge the rubber valve body 46 upward.

No electric current normally flows through the coil 44 of the gas shutoff valve 13. Further, as shown in FIG. 2, the magnetic force of the permanent magnet 43 acts as shown by the arrow 48, the plunger 45 is retracted, and the opening 12a is opened. As a result, the gas passes through the opening 12a as indicated by the arrow 49. In order to bring the gas shutoff valve 13 into the shutoff state, a current is applied to the coil 44 to generate a magnetic field for canceling the magnetic field generated by the permanent magnet 43 as shown in FIG. The magnetic force generated by the coil 44 is indicated by a broken arrow 50. Then, the plunger 45 projects by the force of the spring 47, and the opening 12 a is closed by the rubber valve body 46. On the other hand, in order to return the gas shut-off valve 13, a current in a direction opposite to the direction in which the gas shut-off valve 13 is turned off is supplied to the coil 44 to generate a magnetic field that strengthens the magnetic field generated by the permanent magnet 43. As a result, the plunger 45 is retracted by overcoming the force of the spring 47, and as a result, the opening 12a is opened.

FIG. 4 shows a control unit 1 constituting the gas meter 10.
FIG. 6 is a block diagram showing a configuration 6 and its periphery. As shown in this figure, the control unit 16 includes a CPU (central processing unit) 2
0, ROM (read only memory) 21, RAM
(Random access memory) 22, a clock 23, and an input / output port 24, which are connected to each other by a bus 25.
Connected by The input / output port 24 is connected to a gas flow meter 14, a pressure sensor 15, and a drive circuit 26 for driving the gas cutoff valve 13. In the control unit 16, the CPU 20 realizes a function as a gas meter by executing a program stored in the ROM 21 using the RAM 22 as a working area.

FIG. 5 shows a functional configuration of the gas meter 10 of the present embodiment. That is, the gas meter 10
A gas flow rate detecting means 30 for detecting a gas flow rate flowing through the gas flow path; and a gas flow path shutoff means 31 for shutting off the gas flow path and electrically recoverable according to the detection result of the gas flow rate detecting means 30. After the gas flow path shutoff means 31 is returned, the return flow shutoff means 32 for shutting off the gas flow path again
A gas pressure detecting means 33 for detecting a change in gas pressure in the gas flow path; and a rate of change in pressure (a pressure change amount for each predetermined time) detectable by the gas pressure detecting means 33 according to the magnitude thereof. In addition to being stored separately in a plurality of stages, corresponding to each of these distinguished pressure change rates,
A storage means 34 in which a plurality of inspection times of a magnitude inversely proportional to the magnitude of the pressure change rate are stored, and a detection result of the gas pressure detection means 33 is monitored while the gas flow path is shut off again, and the pressure is monitored. The rate of change is determined, the range of the rate of pressure change stored in the storage means 34 is discriminated, and the value of the pressure change within the inspection time corresponding to the range is determined in advance. A judgment means 35 judges whether the pressure fluctuation value is within the reference value or not, and judges that there is gas leakage when the pressure fluctuation value is larger than the reference value, and judges that there is no gas leakage when the pressure fluctuation value is within the reference value. When the means 35 determines that there is no gas leakage, a re-return means 36 is provided for returning the gas flow path shut-off means 31 again.

The gas flow detecting means 30 includes a gas flow meter 14,
The gas flow path shutoff means 31 is realized by the gas shutoff valve (bidirectional valve) 13 and the drive circuit 26, the gas pressure detection means 33 is realized by the pressure sensor 15, and the storage means 34 is realized by the RAM 22. Further, the return blocking unit 32, the determination unit 35, and the re-return unit 36 are each realized by the control unit 16.

FIG. 6 shows a gas flow path shutoff means (two-way valve) 31.
Represents the relationship between the elapsed time after being shut off again by the return shut-off means 32 and the pressure in the gas flow path, where A is a normal state with no gas leakage, and B and C are abnormal with slight gas leakage. The state at the time is shown. As is clear from this figure, the pressure (P0) hardly changes in the normal state (A), whereas the pressure decreases with the lapse of time in the abnormal state (B, C) with minute gas leakage. .
Here, the pressure may change abruptly as shown by B (that is, when the pressure change rate (the amount of pressure fluctuation at every predetermined time) is large), or may gradually change as shown by C. It may change (ie, the rate of pressure change is small).

In the gas meter 10 of the present embodiment, such a pressure change rate is stored in the RAM 22 in accordance with the magnitude thereof, for example, in two stages, large and small, and the pressure change rate is classified into these two steps. Corresponding to each of the two types of inspection time (a short inspection time (small time T) when the pressure change rate is large)
1) When the pressure change rate is small, a long inspection time (large time T2) is stored. That is, the magnitude of the detected pressure change rate is distinguished, and a pressure fluctuation value within the inspection time having a length corresponding to the pressure change rate is obtained. This pressure fluctuation value is a predetermined value (reference value) (FIG. 6). Where P0 -P1)
It is determined whether or not the pressure is within the reference value. If the pressure fluctuation value is larger than the reference value, it is determined that there is gas leakage, and if the pressure fluctuation value is within the reference value, it is determined that there is no gas leakage.

Next, the operation of the gas meter 10 of this embodiment will be described with reference to the flowchart shown in FIG.

In accordance with the detection result of the gas flow detecting means 30, the gas flow path is shut off by the gas flow path shut-off means (two-way valve) 31, and after the restoration work is performed, the gas flow path is shut off by the return shut-off means 32. The means 31 is returned (Step S7)
00) is the same as in the prior art. In the present embodiment, thereafter, the gas flow path cutoff means 31 is driven by the return cutoff means 32, and the gas flow path is cut off again (step S70).
1). In this state, the pressure fluctuation in the gas flow path is detected by the gas pressure detecting means 33. Then, the judgment means 35
The detection result of the gas pressure detecting means 33 is monitored (step S702), and the pressure change rate is calculated.
The magnitude of the pressure change rate is distinguished (step S703), and if the pressure change rate is large (Y), it is determined whether or not the pressure fluctuation value is within a reference value (step S704). When the pressure fluctuation value is within the reference value (Y) and a predetermined inspection time (small time T1) has elapsed (step S705; Y)
The gas flow path shut-off means 31 is returned again by the re-return means 36 assuming that there is no gas leakage (step S70).
6). This ends the gas leak inspection. If the predetermined inspection time (small time T1) has not elapsed (step S7)
05; N), the process returns to step S704. When the pressure fluctuation value is larger than the reference value (step S704; N)
In this case, it is determined that there is a gas leak, and the gas flow path is shut off.

When the pressure change rate is small (step S70)
3; N), it is determined whether the pressure fluctuation value is within the reference value (step S708). When the pressure fluctuation value is within the reference value (Y) and a predetermined inspection time (large time T2) has elapsed (step S709; Y), the gas recirculation means 31 is determined by the re-return means 36 as having no gas leakage. Is returned again (step S706). This ends the gas leak inspection. If the predetermined time (large time T2) has not elapsed (step S709; N), step S70
Return to 4. If the pressure fluctuation value is larger than the reference value (step S708; N), it is determined that there is a gas leak, and the gas flow path is shut off.

As described above, in the gas meter 10 of this embodiment, after the gas flow path shutoff means (two-way valve) 31 is returned by the return cutoff means 32, the gas flow path cutoff means 31 is driven, and the gas flow path And the pressure change rate in this state is measured in real time, and whether the pressure change value within the inspection time of the size corresponding to the magnitude of the pressure change rate is larger than a predetermined reference value is determined. Determine the presence or absence of gas leakage. That is, since the size of the inspection time is changed according to the magnitude of the pressure change rate, the gas leakage inspection with a small flow rate can be performed in a short time and with high accuracy.
Thereby, the safety function of the gas meter 10 is further improved.

Next, a second embodiment of the present invention will be described.

In the first embodiment, the reference value of the pressure fluctuation is the same irrespective of the magnitude of the pressure change rate. In the present embodiment, however, the pressure fluctuation together with the inspection time depends on the magnitude of the pressure change rate. The size of the reference value is also changed. That is, as shown in the characteristic diagram of FIG. 8, when the pressure change rate is large, the reference value of the pressure fluctuation is increased (hereinafter referred to as a first reference value) as shown by P0-P1 in FIG. On the other hand, when the pressure change rate is small, as shown by P0 -P2 in the figure, the reference value of the pressure fluctuation is set small (hereinafter, referred to as a second reference value), so that the inspection time can be further increased. And to improve the detection accuracy at the same time.

Next, the operation of the gas meter according to the second embodiment will be described with reference to the flowchart of FIG.

The gas flow path is cut off by the gas flow path cut-off means (bidirectional valve) 31 according to the detection result of the gas flow rate detection means 30, and after the restoration work is performed, the gas flow path is cut off by the return flow cut-off means 32. The means 31 is returned (Step S9)
00) is the same as in the prior art. In the present embodiment, thereafter, the gas flow path cutoff means 31 is driven by the return cutoff means 32, and the gas flow path is cut off again (step S90).
1). In this state, the pressure fluctuation in the gas flow path is detected by the gas pressure detecting means 33. Then, the judgment means 35
The detection result of the gas pressure detection means 33 is monitored by
The pressure change rate is calculated, and the magnitude of the pressure change rate is distinguished (step S903). If the pressure change rate is large (Y), it is determined whether the pressure change value is within the first reference value. (Step S904). The pressure fluctuation value is within the first reference value (Y) and a predetermined inspection time (small time T
1) When the time has elapsed (Step S905; Y), the gas flow path shut-off means 31 is returned again by the re-return means 36 without any gas leakage (Step S906). This ends the gas leak inspection. If the predetermined inspection time (small time T1) has not elapsed (step S905; N), the process returns to step S904. If the pressure fluctuation value is larger than the first reference value (step S904; N),
It is determined that there is gas leakage, and the gas flow path is kept shut off.

On the other hand, when the pressure change rate is small (Step S903; N) (Step S902), it is determined whether the pressure fluctuation value is within the second reference value (Step S9).
08). The pressure fluctuation value is within the second reference value (Y),
If the predetermined inspection time (large time T2) has elapsed (step S909; Y), the gas flow path shut-off means 31 is returned again by the re-return means 36 without any gas leakage (step S906). This ends the gas leak inspection. If the predetermined time (large time T2) has not elapsed (step S909; N), the process returns to step S908. When the pressure fluctuation value is larger than the second reference value (step S908; N), it is determined that there is gas leakage, and the gas flow path is shut off.

According to the present embodiment, since the magnitude of the reference value of the pressure change is changed according to the magnitude of the pressure change rate, for example, as shown by the broken line in FIG. Even if the inspection time T2 is set to T2 ', gas leakage can be detected, and the inspection time can be further reduced.

The present invention has been described with reference to the embodiments.
The present invention is not limited to the above embodiment, and can be variously modified. For example, in the above embodiment, the detected pressure change rate is divided into two large and small magnitudes, and the inspection time is set to two large and small magnitudes in accordance with the magnitude of the pressure change rate. In addition to dividing the rate into three or more, the inspection time may be set to be three or more in accordance with the pressure change rate, and the reference value of the pressure change may be changed in accordance with them. You may do so.

In the above embodiment, when it is determined that there is a gas leak, the gas flow path is kept shut off. However, the presence of the gas leak is also indicated by blinking of a lamp, a buzzer, or the like. The configuration may be such that an alarm is issued, or an alarm may be issued by returning the gas flow path shutoff means 31 (the gas shutoff valve 13).

[0033]

As described above, according to the gas meter of the present invention, after the gas flow path shut-off means is restored, the gas flow path cut-off means is driven to shut off the gas flow path again. Since the pressure change rate in the flow path is calculated and the presence or absence of gas leakage is determined based on whether the pressure change value within the inspection time according to the magnitude of the pressure change rate exceeds the reference value, In addition, it is possible to perform a gas leak inspection with a very small flow rate with high accuracy, and to achieve an effect that the safety function is further improved.

[Brief description of the drawings]

FIG. 1 is a sectional view illustrating a schematic configuration of a gas meter according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view for explaining the operation of a two-way valve in the gas meter of FIG.

FIG. 3 is a cross-sectional view for explaining the operation of the two-way valve in the gas meter of FIG.

FIG. 4 is a block diagram illustrating a configuration of a control unit and its periphery in the gas meter of FIG. 1;

FIG. 5 is a functional block diagram for explaining functions of the gas meter of FIG. 1;

FIG. 6 is a characteristic diagram showing a relationship between an elapsed time and a pressure after the gas flow path of the gas meter of FIG.

FIG. 7 is a flowchart for explaining the operation of the gas meter of FIG. 1;

FIG. 8 is a characteristic diagram for explaining the operation of the gas meter according to the second embodiment of the present invention.

FIG. 9 is a flowchart for explaining the operation of the gas meter according to the second embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Gas meter 11 Housing 13 Gas shutoff valve (bidirectional valve) 14 Gas flowmeter 15 Pressure sensor 16 Control unit 30 Gas flow detection means 31 Gas flow path shutoff means 32 Return shutoff means 33 Gas pressure detection means 34 Storage means 35 Judgment means 36 Returning means

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-5-240216 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01F 1/00-9/02

Claims (4)

(57) [Claims] 1. A gas flow rate detecting means for detecting a gas flow rate flowing through a gas flow path, and a gas flow path shutoff means for shutting off a gas flow path and electrically recoverable according to a detection result of the gas flow rate detecting means. Returning the gas flow path shutoff means, and then returning the gas flow path cutoff means to drive the gas flow path cutoff means to shut off the gas flow path again; and gas pressure detection for detecting a change in gas pressure in the gas flow path. Means, and the rate of change of pressure detectable by the gas pressure detecting means is stored in a plurality of stages in accordance with the magnitude thereof, and the pressure change rate is corresponding to each of the distinguished pressure change rates. Storage means for storing a plurality of inspection times of a magnitude inversely proportional to the magnitude of the pressure, and monitoring the detection results of the gas pressure detection means and obtaining the rate of change in the pressure while the gas flow path is shut off again. ,
It discriminates to which range of the pressure change rate the pressure change rate is stored in the storage means, and further, the pressure fluctuation value within the inspection time corresponding to the range is within a predetermined reference value. It is determined whether or not there is, and when the pressure fluctuation value is larger than the reference value, it is determined that there is gas leakage, and
A determination means for determining that there is no gas leakage when the gas leakage is within the reference value; and
A gas meter, comprising: a return means for returning the gas flow path blocking means again. 2. The gas meter according to claim 1, further comprising an alarm notifying means for notifying when the gas leak is judged by said judging means. 3. The reference value of the pressure fluctuation is set to be constant regardless of the magnitude of the pressure change rate, and the determining means determines whether or not there is a gas leak using the same reference value regardless of the magnitude of the pressure change rate. The gas meter according to claim 1, wherein the determination is made. 4. A reference value for pressure fluctuation is set in a plurality of steps according to the magnitude of the rate of change of pressure, and said judging means uses a different reference value according to the magnitude of the rate of change of pressure to determine whether gas leakage has occurred. The gas meter according to claim 1, wherein the determination is made as follows.