JP3494688B2 - Flow rate change determination device - 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 rate change discriminating apparatus for discriminating what kind of event causes a change in gas flow rate, and in particular whether the flow rate change is caused by ignition or extinction of a gas appliance. Or, it relates to a flow rate change determination device for determining whether or not the flow rate variation (proportional control) is caused by the same gas appliance being used.

[0002]

2. Description of the Related Art Recently, as a gas meter for home use, a meter equipped with a microcomputer and a safety function in addition to the function of measuring the flow rate of passing gas has been put into practical use. When the gas flow rate is detected or when the predetermined gas flow rate is detected for a predetermined time or longer, the gas cutoff valve is driven to cut off the gas flow path. These functions detect leaks in pipes and outflows of unnatural gas to prevent accidents and guarantee safety.

In this type of gas meter, the gas cutoff time is set on the basis of the maximum flow rate (maximum individual flow rate) of the individual flow rates of individual gas appliances (flow rates of individual gas appliances). If there is ignition or extinguishing of the gas appliance, the gas appliance and its individual flow rate are estimated and registered, and if this registration changes the maximum individual flow rate of the gas appliances currently in use, the gas cutoff time is reset. I have decided. Therefore, unless the gas appliances that have ignited or extinguished the fire and the individual flow rates are registered correctly, it is difficult to distinguish the dangerous gas usage state from the normal gas usage state, and the above-mentioned safety function operates effectively. do not do.

Conventionally, the ignition or extinction of a gas appliance has been detected as follows. That is, if the absolute value of the difference (changed flow rate) between the current flow rate and the flow rate at the immediately preceding flow rate unit time point is equal to or greater than the threshold value, there is always one independent change, that is, a new gas appliance is ignited and is not used. It is judged that the gas appliance that has started or is being used has been extinguished due to fire extinguishing, and the magnitude of the changed flow rate is compared with the magnitude of the individual flow rate value of each gas appliance, and the gas appliance with the flow rate change is determined. I'm estimating.

[0005]

As described above, in the conventional gas meter, the magnitude of the changed flow rate and the magnitude of the individual flow rate value of each gas appliance are compared to estimate the gas appliance having the flow rate change. Therefore, there were the following problems. That is, when, for example, a fan heater and a water heater are used as gas appliances and a flow rate change (decrease) equal to the flow rate used by the gas fan heater occurs due to proportional control of the water heater, the flow rate reduction by the water heater is reduced. May be erroneously determined to be due to being erased. If the gas appliance causing the change in the flow rate is erroneously estimated in this manner, there is a problem that the above-mentioned safety function does not operate accurately.

The present invention has been made in view of the above problems, and an object thereof is, when there is a change in the flow rate, whether the change in the flow rate is caused by ignition or extinction of a gas appliance,
Another object of the present invention is to provide a flow rate change discriminating apparatus which can more accurately discriminate whether or not it is due to a flow rate fluctuation due to the same gas appliance being used, and can improve safety.

[0007]

According to a first aspect of the present invention, there is provided a flow rate change discriminating apparatus which comprises a flow rate measuring means for measuring an instantaneous flow rate of a fluid, and an instantaneous flow rate measured by the flow rate measuring means.
Pulsations that occur during a series of flow rate changes and cause errors
An average value computing means for outputting a flow rate average value by averaging a predetermined set so as to smooth out abrupt flow change time in a storage means for storing the flow rate average value output from the average value calculating means Inputting each output signal of the average value calculating means and the storage means, outputting the current flow average value output from the average value calculating means and one time before the output of the current flow average value The change flow rate calculation means for calculating the change flow rate using the flow rate average value stored in the storage means, the flow rate change duration measuring means for measuring the flow rate change duration, and the change flow rate calculation means If the changed flow rate is greater than or equal to the specified change flow value, then
It is determined that the change in the flow rate of the
The time that the change in the flow rate of the
If the flow rate is shorter than
Caused by ignition or extinguishment of gas appliances
Change flow determined by the change flow rate calculation means
If the amount is less than the specified change flow rate value or the flow rate changes
Threshold that is set to be longer than the specified time
If it is longer than the value, the change of the flow rate is one gas
It was determined that this was due to flow rate fluctuations during continuous use of the ingredient.
And a determining means for determining.

In this flow rate change discriminating apparatus, the instantaneous flow rate of the gas is measured by the flow rate measuring means, and the instantaneous flow rate is averaged (stepwise approximation) by the average value calculating means to output the average flow rate value. The flow rate average value is stored in the storage means. Then, the change flow rate calculation means calculates the change flow rate from the past flow rate average value stored in the storage means and the current flow rate average value output from the average value calculation means. On the other hand, the flow change duration measuring means measures the duration of the flow change. In the discrimination means,
According to the change flow rate calculated by the change flow rate calculation means and the flow rate change duration measured by the flow rate change duration measuring means, what kind of event (ignition or extinguishing,
Alternatively, it is determined whether it is caused by the fluctuation of the flow rate of the same gas appliance).

According to a second aspect of the present invention, there is provided a flow rate change discriminating apparatus in which the absolute value of the change flow rate calculated by the change flow rate computing means exceeds a predetermined change flow rate value.
And the time during which the flow rate continues to change is at the specified time
If it is shorter than the threshold that is set to
If the change flow rate increases with time,
The change in flow rate is caused by the ignition of the gas appliance
When it is determined that the change flow rate decreases with time
The change in the flow rate was caused by the extinction of gas appliances.
It is configured to determine that it is a thing.

According to a third aspect of the present invention, there is provided a flow rate change determination device according to the first or second aspect of the present invention.
The body is a fuel gas, and the flow rate measuring means is
Propagation time or velocity when a wave is propagated in the fluid
Ultrasonic flowmeter that measures the instantaneous flow rate based on
Based on oscillation of fluidic device in fluid
The fluidic flow meter for measuring the instantaneous flow rate, the flow rate
The instantaneous flow rate is measured based on the amount of heat taken by the body.
Use at least one of the heat flow meters to measure
It was what I had .

[0011]

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

FIG. 1 shows an example in which a flow rate change determination device according to an embodiment of the present invention is applied to a gas meter. The gas meter 10 has a safety function using a microcomputer. Inside the gas meter 10, a gas flow path 11 having a gas inlet 16 and a gas outlet 17 is provided. Gas 20, such as city gas, flows into the gas passage 11 through a pipe (not shown),
The gas 20 is supplied to a gas appliance such as a gas stove (not shown). A gas shutoff valve 12 for shutting off the gas passage 11 and a gas flow meter 13 for measuring the flow rate of the gas passing through the gas passage 11 are sequentially arranged in the gas passage 11 from the gas inlet 16 side. It is set up.

A control unit 14 for controlling the gas cutoff valve 12 by inputting the output signal of the gas flow meter 13 is provided in the gas meter 10.

FIG. 2 is a block diagram showing the configuration of the control unit 14 and its peripherals in the gas meter 10 of this embodiment.
As shown in this figure, the control unit 14 includes a CPU (central processing unit) 30, a ROM (read only memory) 31,
A RAM (random access memory) 32, a clock 33 for measuring time, and an input / output port 34 are provided,
These are connected to each other by a bus 35. A drive circuit 36 for driving the gas cutoff valve 12 is connected to the input / output port 34 in addition to the gas flow meter 13 described above. In the control unit 14, the CPU 30 executes a program stored in the ROM 31 using the RAM 32 as a working area to determine an event (ignition or extinguishment, or flow rate fluctuation of the same gas appliance) that causes a gas flow rate change, Also, safety functions such as gas leak inspection are realized.

FIG. 3 is a functional block diagram showing the function of the flow rate change discriminating apparatus of this embodiment. As shown in this figure, the flow rate change determination device averages the flow rate measuring means 41 for measuring the instantaneous flow rate of the gas and the instantaneous flow rate measured by this flow rate measuring means 41 at every predetermined time to obtain a flow rate average value. And an average value calculating means 42 for outputting
Storage means 43 for storing the average value of the flow rate output from 2
And the respective output signals of the average value calculation means 42 and the storage means 43 are input, and the current flow rate average value output from the average value calculation means 42 and the past flow rate average value stored in the storage means 43 are used. Change flow rate calculation means 44 for calculating the change flow rate
It has and. The flow rate measuring means 41 is a gas flow meter 13,
The average value calculation means 42 is the control unit 14, and the storage means 43 is RA.
The M32 and the changed flow rate calculation means 44 are realized by the control unit 14, respectively.

The reason for calculating the average value by performing the step approximation by the average value calculating means 42 is as follows. That is,
Since the gas flow rate measured by the flow rate measuring means 41 always contains an error, it constantly fluctuates. Therefore, if this flow rate is directly used for the calculation of the change flow rate by the change flow rate calculation means 44, the accurate change flow rate cannot be calculated.
Therefore, the calculation accuracy of the change flow rate is increased by calculating the flow rate average value for each predetermined time.

FIG. 5 shows the ignition and extinguishing waveforms of the gas table during use of the bath, which are measured by the flow rate measuring means 41, and FIG. 6 shows a state in which these waveforms are averaged by the average value calculating means 42 (step approximation). Is shown.

The flow rate change discriminating apparatus of this embodiment further includes a flow rate change duration measuring means 45 for measuring the flow rate change duration, and a change flow rate calculated by the change flow rate computing means 44 and a flow rate change duration measuring means. Based on the flow rate change duration measured by 45, a determination unit 46 for determining what event caused the flow rate change. The flow rate change duration measuring means 45 uses the clock 3
3. The discriminating means 46 is realized by the control unit 14, respectively.

Specifically, the discriminating means 44 is adapted to make the following determination.

First, when the absolute value of the change flow rate calculated by the change flow rate calculating means 44 is larger than a predetermined range and the flow rate change duration measured by the flow rate change duration measuring means 45 is shorter than the predetermined time, , The change in flow rate shall be caused by either the ignition of a new gas appliance or the extinction of a gas appliance in use. Here, it is assumed that a new gas appliance is ignited when the flow rate increases and a gas appliance in use is extinguished when the flow rate decreases. On the other hand, if the absolute value of the changed flow rate calculated by the changed flow rate calculation means 44 is less than or equal to a predetermined range, or if the flow rate change duration measured by the flow rate change duration measurement means 45 is greater than or equal to a predetermined time, then the flow rate change Is due to flow rate fluctuation (proportional control) by the same gas appliance in use. That is, when the flow rate changes due to proportional control of a gas appliance such as a water heater, it gradually changes over a plurality of flow rate units, while when the gas appliance is ignited or extinguished, the rise of the flow rate change is steep. The flow rate changes between a small number of flow rate units, and such characteristics are used for the determination.

Next, the discriminating operation of the flow rate change discriminating apparatus of this embodiment will be concretely described with reference to the flow chart shown in FIG.

In this embodiment, the flow rate measuring means 41 measures the instantaneous flow rate of the gas 20, and the average value calculating means 42 averages the instantaneous flow rate every predetermined time (step approximation) and outputs the average flow rate value. The flow rate average value is stored in the storage means 43. Then, the changed flow rate calculation means 44
Then, the past flow average value stored in the storage means 43,
The change flow rate ΔQt is calculated from the current average flow rate value output from the average value calculation means 42. On the other hand, the flow rate change duration time measuring means 45 measures the flow rate change duration time ΔT (step S100).

Next, the judging means 46 judges whether or not the absolute value of the changing flow rate ΔQt calculated by the changing flow rate calculating means 44 is larger than a predetermined value α (step S10).
1). Here, when the absolute value of ΔQt is equal to or less than α (N), the change in the flow rate is small, and therefore it is determined that the flow rate is changed by the proportional control of the same gas appliance (for example, the water heater) (step S104). On the other hand, the absolute value of ΔQt is α
If it is larger (step S101; Y), the determination means 46 next determines whether or not the flow rate change duration time ΔT is shorter than the predetermined time β (step S102). And
When ΔT is equal to or larger than β (N), the flow rate change is gradual, and therefore it is determined that the flow rate variation is caused by proportional control of the same gas appliance (for example, a water heater). On the other hand, Δ
When T is β or less (step S102; Y),
Further, it is determined whether the changed flow rate ΔQt is increasing (step S103). When the change flow rate ΔQt is caused by the increase (Y), it is determined that a new gas appliance is ignited (step S105). If the change flow rate ΔQt is caused by the decrease (N), it is determined that the gas appliance in use has been extinguished (step S106).

When a gas flow rate of a predetermined amount or more is detected, or when a predetermined gas flow rate is detected for a predetermined time or more,
The actuation of the gas shutoff valve 12 to shut off the gas flow path 11 is the same as in the prior art, and therefore its description is omitted.

Thus, in this embodiment, the flow rate measuring means 4
1, the instantaneous flow rate of the gas is measured, and the average value calculation means 42 averages the instantaneous flow rate at every predetermined time (step approximation) to output the average flow rate value. The average flow rate value is stored in the storage means 43. To be done. Then, in the changed flow rate calculation means 44, the changed flow rate ΔQt is calculated from the past flow rate average value stored in the storage means 43 and the current flow rate average value output from the average value calculation means 42. On the other hand, the flow rate change duration measuring means 45 measures the flow rate change duration ΔT. Then, the discriminating means 46 discriminates what kind of event (ignition or fire extinguishment or flow rate fluctuation of the same gas appliance) caused the flow rate change based on the change flow rate ΔQt and the flow rate change duration ΔT. Therefore, the accuracy of estimating the gas appliance and the individual flow rate is increased, and the safety function of the gas meter 10 is improved.

[0026]

As described above, according to the flow rate change discriminating apparatus of the first to third aspects, the instantaneous flow rate of gas is measured, and the instantaneous flow rate is averaged at every predetermined time to output the average flow rate value. The flow rate average value is stored in the storage means, and the change flow rate is calculated from the past flow rate average value and the current flow rate average value stored in the storage means, and the duration of the flow rate change is measured and changed. Since the flow rate and the duration of the flow rate change are used to determine what event caused the flow rate change, it is easy to determine whether the gas appliance is ignited or extinguished, or the flow rate of the same gas appliance has changed. Therefore, it is possible to improve the accuracy of estimating the gas appliance and the individual flow rate, and further it is possible to improve the safety function of the gas meter or the like.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a schematic configuration of a gas meter to which a flow rate change determination device according to an embodiment of the present invention is applied.

FIG. 2 is a block diagram showing a configuration of a control unit in FIG. 1 and its peripherals.

FIG. 3 is a block diagram showing functions of the flow rate change determination device of FIG.

FIG. 4 is a flowchart for explaining a determination operation in the flow rate change determination device of FIG.

FIG. 5 is an ignition (extinguishing) waveform diagram of the gas table during use of the bath kettle, which is measured by the flow rate measuring means.

6 is a waveform diagram after averaging (staircase approximation) the waveform of FIG. 5 by an average value calculating means.

[Explanation of symbols] 10 gas meters 12 gas cutoff valve 13 Gas flow meter (flow rate measuring means) 14 Control unit (discrimination means) 30 CPU (central processing unit) 32 RAM (storage means)

Continued front page       (56) Reference JP-A-5-107096 (JP, A)                 JP-A-2-266229 (JP, A)                 JP-A-3-71713 (JP, A)                 JP 63-25513 (JP, A)

Claims (3)

(57) [Claims] 1. A flow rate measuring means for measuring an instantaneous flow rate of a fluid, and the instantaneous flow rate measured by the flow rate measuring means is pulsatingly abruptly generated during a series of flow rate changes, which causes an error. > An average value calculating means for averaging the flow rate average value and outputting the average value of the flow rate every predetermined time set so as to smooth the sharp flow rate fluctuations, and a storage means for storing the average flow rate value output from the average value calculating means. Inputting the output signals of the average value calculating means and the storage means, and outputting the current flow average value output from the average value calculating means and one time before the output of the current flow average value. The change flow rate calculating means for calculating the change flow rate using the flow rate average value stored in the storage means, the flow rate change duration measuring means for measuring the flow rate change duration, and the change flow rate calculating means Absolute change flow rate
Value exceeds the specified change flow rate value, and
Is set to continue for more than the specified time.
If the flow rate is shorter than the
If it is determined that it was caused by ignition or extinguishing,
The change flow rate calculated by the change flow rate calculation means is
If the flow rate is below the specified change rate or the flow rate continues to change
Time is longer than the set threshold value above the specified time
If there are no
Flow change determination apparatus characterized by comprising a determining means for determining that accompanied the flow rate variations during use. 2. The absolute value of the change flow rate calculated by the change flow rate calculating means is a predetermined change flow rate value.
Is exceeded, and the change in flow rate continues before
When the time is shorter than the set threshold value for more than the specified time
And the change flow rate increases with time
Is due to the ignition of the gas appliance
It is determined that the change flow rate decreases with time.
In some cases, the change in flow may be due to extinguishing the gas appliance.
2. The flow rate change determination device according to claim 1, wherein it is determined that the flow rate change has occurred . 3. The fluid is a fuel gas, and the flow rate measuring means propagates ultrasonic waves to the fluid.
The instantaneous flow rate based on Kino propagation time or Den 播速degree
Ultrasonic flowmeter for measuring, fluid in the fluid
Full-scale measurement of the instantaneous flow rate based on the oscillation of the lock element
Idick flowmeter, for the amount of heat taken by the fluid
Of the heat flow meters that measure the instantaneous flow rate based on
The flow rate change determination device according to claim 1 or 2, wherein at least one of them is used .