JP3169731B2 - Flowmeter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flow meter for measuring a flow rate of a fluid such as a city gas or an LPG gas, and more particularly to a flow meter having a safety function for shutting off when an abnormality is found in a use state of a fluid. Things.

[0002]

2. Description of the Related Art Conventionally, this type of flow meter is disclosed in
As disclosed in Japanese Patent Application Laid-Open No. 08921, a fluid sensor for detecting a flow velocity is provided in a fluidic element, and in a small flow rate range, measurement is performed using the output from the flow sensor.
In a large flow rate region, a method of measuring the oscillation frequency of a fluidic element by a piezoelectric sensor has been proposed, and has a configuration as shown in FIG. 5, for example.

That is, in the conventional flow meter of FIG. 5, 1 is a flow meter main body, 2 is a gas pipe, 3 is a fluidic element,
Fluid oscillation is generated using the kinetic energy of the fluid. A piezoelectric sensor 4 detects the frequency of fluid oscillation. Reference numeral 5 denotes a flow sensor that detects a flow velocity of a fluid at a nozzle (not shown) of the fluidic element and generates an analog signal proportional to the flow velocity. Reference numeral 6 denotes a shut-off valve which is closed when an abnormal use state is detected, and shuts off gas supply. Reference numeral 7 denotes a return device which can open the shut-off valve 6 by manual operation to restart the use of gas. A control device 8 controls the drive of the shut-off valve 6.

In the flow meter having the above-described structure, the flow rate is measured by the detection signal of the piezoelectric sensor 4 in the large to middle flow rate range and the detection signal of the flow sensor 5 in the small flow rate range. The characteristics of the fluid vibration generated by the fluidic element 3 depend on its shape.
In the case of a home-use No. 3 gas meter, it is necessary to measure the flow rate in the range of 3 to 3000 L / H, but it is difficult to measure the flow rate in this range with a single element, so it is difficult to generate fluid vibration. Is measured by the flow sensor 5. The change in the flow rate measured in this manner over time is monitored by the control device 8, and if an abnormality is recognized, the shutoff valve 6 is closed to shut off the gas supply. When the gas is shut off, the user can release the abnormal state (for example, disconnection of the gas hose) and confirm safety, and then operate the return device 7 and open the shut-off valve 6 to use the gas again. Becomes

[0005]

However, in the flowmeter having the above-described structure, if the sensor fails, the flow rate cannot be measured correctly, and the abnormal usage state of the gas cannot be recognized, and a gas accident such as an explosion occurs. There is a risk of overlooking.

An object of the present invention is to solve the above-mentioned problem and to prevent an accident due to a sensor failure from occurring beforehand and to improve safety.

[0007]

In order to solve the above-mentioned problems, a flow meter according to the present invention comprises one or more flow detecting means, a flow measuring means for obtaining a flow rate from an output of the flow detecting means,
Interrupting means provided upstream of the flow detecting means for shutting off fluid; and failure determining means for determining a failure state of the flow detecting means based on an output of the flow detecting means and outputting a shut-off signal to the interrupting means when a failure occurs. And the above flow rate detection
The output means is a first flow rate detection mainly detecting a flow rate in a large flow rate range.
Means and a second flow rate detection for mainly detecting a flow rate in a small flow rate range
And the first and second flow rate detecting means
The first flow rate detecting means having a flow rate range that can be detected simultaneously;
The output of the stage falls below a first set value and the second flow rate
When the output of the output means exceeds the second set value,
And a failure judging means for outputting .

[0008]

[0009]

With the above arrangement, in the flow meter according to the present invention, when a failure occurs in the flow rate detecting means, a shut-off signal is output from the fault determining means, and as a result, the shut-off means operates to shut off the gas.

Further, despite the output of the first flow rate measuring means falls below a first set value and the output of the second flow rate detecting means second
In other words, when the output of the first flow rate detecting means for detecting a large flow rate indicates a small flow rate, the output of the large 2 flow rate detecting means for detecting a small flow rate is far greater than the set value. If the flow rate is large, it is determined that one of the flow rate detection means is out of order, and a failure signal is output from the failure determination means. You.

Therefore, the gas cannot be used if the flow rate detecting means has failed, and a gas accident caused by the failure of the flow rate detecting means is prevented.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS.

In FIG. 1, the same components and elements as those in FIG. 5 are denoted by the same reference numerals. FIG. 1 is a block diagram of a flow meter according to the present invention. In FIG. 1, reference numeral 3 denotes a fluidic element, which is provided in the middle of the gas pipe 2 and uses the kinetic energy of the fluid to generate fluid oscillation. Reference numeral 9 denotes first flow rate detection means for mainly detecting a large flow rate, a piezoelectric sensor 4 for detecting the oscillation frequency of the fluid as a change in output voltage, and a pulse signal conversion unit for converting a pulse signal having a frequency equivalent to the voltage fluctuation. And 10. Reference numeral 11 denotes a second flow rate detecting means for mainly detecting a small flow rate. The flow rate sensor 5 generates a voltage proportional to the flow rate, and the A / D generates a pulse number proportional to the output of the flow sensor 5 at regular intervals. It is composed of a conversion unit 12. FIG. 2 shows the flow rate Q and the first flow rate detecting means 9.
FIG. 3 schematically shows the relationship between the flow rate Q and the number of pulses P (pulses) output from the second flow rate detecting means 11. The range of the flow rate Q that can be measured by the first flow rate detecting means 9 is a range from QA to QB. At a flow rate below that, F = 0 or unstable, and the output F becomes saturated in a range above that. To a constant value FB. The range of the flow rate that can be measured by the second flow rate detecting means 11 is equal to or less than QC.
Saturates to a constant value PC. Therefore, the flow rate is measured by the second flow rate detecting means 11 in the area where the flow rate is equal to or less than QA, and is measured by one of the flow rate detecting means in the area where the flow rate is equal to or more than QC. Measurement. Outputs corresponding to the flow rates at that time are always output from both the flow rate detection means and output to the flow rate measurement means 13. Reference numeral 14 denotes a measurement switching unit which determines which of the output of the first flow detection unit 9 and the output of the second flow detection unit 11 to obtain the flow rate and outputs the result. The measurement switching means 14 makes a determination so that the flow rate is measured by the output of the first flow rate detecting means 9 when F exceeds FD, and by the output of the second flow rate detecting means 11 when F falls below FD. Numeral 15 denotes a calculating means for performing a calculating process of converting the output of one of the flow detecting means into a flow rate per unit time based on the judgment result of the measurement switching means 14. Numeral 16 denotes an integrating means for adding the flow rate obtained by the calculating means 15 to obtain an integrated value of the flow rate. Reference numeral 6 denotes blocking means, which is located upstream of the fluidic element 3, ie, the first
It is provided on the upstream side of the flow rate detecting means 9 and the second flow rate detecting means 11 and has a function of blocking a gas flow path. Reference numeral 7 denotes a return means, which, after the gas is cut off by the cutoff means 6, manually opens the gas flow path to enable the gas to be used again. Reference numeral 8 denotes a control unit that controls driving of the blocking unit 6.

Next, the configuration of the control means 8 will be described.
Reference numeral 17 denotes an abnormality judging means which monitors the use state of the gas based on the flow rate obtained by the arithmetic means 15 and, when it is judged that the gas is abnormal, outputs a shutoff signal to the shutoff means 6 to shut off the gas. Reference numeral 18 denotes a failure determination means, and the first flow rate detection means 9
Based on the output of the second flow detecting means 11 and the output of the second flow detecting means 11, it is determined whether the two flow detecting means are normal or faulty.

Next, the operation of the above configuration will be described. When the gas flow is generated, the flow rate is obtained by the calculating means 15 based on the output signal from the first flow rate detecting means 9 or the second flow rate detecting means 11. The abnormality judging means 17 monitors the gas use state based on the flow rate obtained by the arithmetic means 15, and outputs a shutoff signal to the shutoff means 6 if an abnormal use state is detected. The abnormal usage state includes, for example, a case where the total gas usage is abnormally large, a case where the gas usage abnormally increases in a short time, and a case where the gas is used for an abnormally long time. The abnormality determining means 17 stores the total flow rate and the increase pattern of the flow rate assuming the abnormal use state as described above, and based on information such as the generated flow rate per unit time and the flow rate change amount,
When this pattern is matched, a cutoff signal is output.

This flow meter measures by two flow rate detecting means. However, as described above, both flow rate detecting means always output, and a fault can be detected by comparing the outputs. Becomes If the two flow rate detecting means are normal, the flow rates corresponding to both outputs should be equal. However, when the flow rate values corresponding to the outputs of the two flow rate detecting means are largely apart from each other, it can be determined that one of them has failed.

For example, as shown in FIGS. 2 and 3, the output of the first flow detecting means 9 is F1, and the output of the second flow detecting means 1 is F1.
Assume that the output of 1 is P2. F1 corresponds to the flow rate Q1,
P2 corresponds to the flow rate Q2, and has a relationship of Q1 << Q2. Therefore, since the flow rate detected by the first flow rate detecting means 9 for detecting a large flow rate is much smaller than the flow rate detected by the second flow rate detecting means 11 for detecting a small flow rate, one of the flow rate detecting means fails. Output a cutoff signal.

As described above, when the output of the second flow detecting means 11 is large even though the output of the first flow detecting means 9 is small, on the contrary, the first flow detecting means 9 shows a large output. However, when the output of the second flow rate detecting means 11 is small, a cutoff signal is output.

When the output of the flow rate detecting means exceeds the range which can be normally considered, a failure can be determined only by the output of one flow rate detecting means. For example, when the output of the first flow rate detecting means 9 exceeds the value FB at which F saturates,
The output of the second flow rate detecting means 11 is a value P at which the output P is saturated.
The case exceeding C corresponds to this.

As described above, when the failure determination means 18 determines that a failure has occurred in one of the two flow rate detection means, it outputs a failure signal.

If the flow rate detecting means breaks down, it is difficult to judge the subsequent gas use situation, and in the worst case, a gas accident may occur. In order to prevent the occurrence of an accident, the failure determination means 18
A shutoff signal is output to the shutoff means 6 to shut off the gas.

As described above, in the flow meter according to the present invention, both the flow rate detecting means are broken down based on the output of the first flow rate detecting means 9 and the output of the second flow rate detecting means 11 for detecting a large flow rate. It is determined whether or not there is a failure. In the event of a failure, a shutoff signal is output to the shutoff means 6, and as a result, gas is shut off. Therefore, the occurrence of a gas accident due to the failure of the flow rate detecting means is prevented beforehand and safety is improved.

In the above embodiment, the gas meter for measuring the flow rate by the two flow rate detecting means has been described. However, even if the number of the flow rate detecting means is different or the type of the fluid is a liquid (water meter), the same applies. The effect of is obtained.

Next, another embodiment of the present invention will be described with reference to FIGS. 2, 3 and 4. FIG. In FIG. 4, FIG.
The same reference numerals are given to the same components and elements as described above, and the detailed description is omitted. Reference numeral 18 denotes a failure determination unit that outputs a shutoff signal to the shutoff unit 6 based on outputs of the first flow rate detection unit 9 and the second flow rate detection unit 11. The failure judgment means 18
The output F of the flow rate detecting means 9 is compared with a first set value F1. If F is less than F1, a first comparing means 19 for outputting a first determination signal, and an output P of the second flow rate detecting means 11 are output. The second
The second comparison means 20 outputs a second determination signal if P exceeds P2, and the cutoff determination means 21 outputs a cutoff signal when the first and second determination signals are input. It is composed of

Next, the operation of the above configuration will be described. It is assumed that the first flow rate detecting means 9 for detecting a large flow rate has failed and the output is zero despite the occurrence of a flow rate. If the gas appliance continues to be used in such a state, it is not possible to recognize the situation where a large amount of gas is flowing out, such as when the rubber tube for gas supply comes off. There is a risk of overlooking. Therefore,
The failure determination means 18 assumes a failure state in which a detection signal from the first flow rate detection means for detecting a large flow rate of the two flow rate detection means cannot be obtained, and in that case, shuts off the gas. Act like so.

That is, if the first flow rate detecting means 9 is out of order despite the occurrence of a flow rate and the output is such that the flow rate is almost zero, FIG.
When a flow rate exceeding the flow rate QC (the upper limit flow rate detected by the second flow rate detecting means 11) shown in FIG.
P = PC. In this state, even if a larger flow rate is actually generated, only the upper limit flow rate QC of the second flow rate detecting means 11 can be recognized. Therefore, the failure determination means 18 sets two determination levels so that an accident does not occur due to such a failure of the flow rate detection means. First, the output F of the first flow rate detecting means 9 is compared with a first set value F1 which is 0 or slightly larger than 0, and if F is smaller than F1, the first judgment means 19 makes a first judgment. A signal is output. Further, the output P of the second flow rate detecting means 11 is compared with a set value P2 which is equal to or slightly smaller than the upper limit output PC, and P becomes P
If it exceeds 2, a second determination signal is output from the second determination means 20. When the determination signal is input from both the first determination unit 19 and the second determination unit 20, the cutoff determination unit 21 determines that there is a risk of being overlooked despite the large flow rate occurring. , And outputs a cutoff signal to the cutoff means 6.

As described above, in the flow meter of the present invention, the output of the first flow rate detecting means 9 for detecting a large flow rate is lower than the first set value and the second flow rate detecting means for detecting a small flow rate. 11
If the output exceeds the second set value, it is determined that a large flow rate may not be detected due to the failure of the first flow rate detection means 9 and the risk of an accident such as an explosion is determined. In order to avoid this, a shutoff signal is output from the failure determination means 18, and as a result, the gas is shut off. Therefore, the occurrence of an accident due to the failure of the flow rate detecting means for detecting a large flow rate is prevented beforehand, and safety is improved.

In the above embodiment, the gas meter has been described, but the same effect can be obtained even if the type of fluid is a liquid (water meter).

[0029]

As described above, in the flow meter according to the present invention, when the flow rate detecting means fails, the failure determining means outputs a shutoff signal to shut off the gas. Therefore, since the gas is not used in a state where the flow rate detecting means has failed, there is an effect that an accident is prevented from occurring and safety is enhanced. Moreover, the failure judgment of the flow rate detection means
The output of the first flow rate detecting means falls below the first set value and
The output of the second flow rate detecting means exceeds a second set value.
At other times, either the first or second
Even if the detection means is out of order, the other detection means
Operate the flow meter while preventing the worst case due to gas outflow
Gas can be used as a condition, improving convenience
There is also an advantage.

Further, particularly when there is a possibility that a large flow rate cannot be detected due to a failure of the flow rate detection means for detecting a large flow rate, the failure determination means outputs a shutoff signal to shut off the gas. Therefore, there is an effect that the occurrence of an accident due to overlooking the large flow rate is prevented beforehand, and the safety is enhanced.

[Brief description of the drawings]

FIG. 1 is a block diagram of a flow meter according to an embodiment of the present invention.

FIG. 2 is a characteristic diagram showing a relationship between an output of a first flow detecting means and a flow in the flow meter.

FIG. 3 is a characteristic diagram showing a relationship between an output of a second flow detecting means and a flow in the flow meter.

FIG. 4 is a block diagram of a flow meter according to another embodiment of the present invention.

FIG. 5 is a block diagram of a conventional flow meter.

[Explanation of symbols]

 6 Shut-off means 9 First flow detecting means 11 Second flow detecting means 18 Failure determining means

Continuing on the front page (72) Inventor Koichi Takemura 1006 Kadoma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Inventor Koichi Ueki 1006 Odaka Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd. (56 References JP-A-4-250319 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01F 3/22 G01F 1/00 G01F 1/20 G01F 7/00

Claims (1)

(57) [Claims] At least one flow rate detecting means, a flow rate measuring means for obtaining a flow rate based on an output of the flow rate detecting means, a shutoff means provided upstream of the flow rate detecting means to shut off a fluid, and the flow rate detecting means Failure determination means for determining a failure state of the flow rate detection means based on an output of the means and outputting a shutdown signal to the shutdown means when a failure occurs ,
The stage is first flow rate detecting means for mainly detecting a flow rate in a large flow rate range.
And second flow rate detecting means for mainly detecting a flow rate in a small flow rate range
And the first and second flow rate detecting means are
A flow rate range that can be detected by the first flow rate detection means.
The output is below a first set value and the second flow rate detection
Output cut-off signal when the output of the stage exceeds the second set value
A flow meter having a failure determination unit that performs the determination .