JPH04204327A - Flow meter - Google Patents

Abstract

PURPOSE:To perform reset safety confirmation to confirm the presence of leakage in good response and in a short time for judgement by detecting whether measured fluid leaks or not at the downstream side in accordance with the rotational frequency of a rotor which rotates corresponding to the flow rate of the measured fluid. CONSTITUTION:When an earthquake greater than a preset magnitude occurs, a signal from a sensor 25 is input to a control circuit 22 via a safety gear 23, a solenoid 6c is electrified to close a shutoff valve 6, a main flow passage 3 is shut off, and a gas cock in each family is closed. When the earthquake is stopped and a signal from a reset safety confirmation switch 24 is input to the circuit 22, the valve 6 is opened and gas flowing from valve seats 4, 5 in the main flow passage 3 through a flow instrumentation section 11 to an outflow port 3d is filled into a downstream side pipe, but after a certain time for filling gas to the end passed a change valve 7 is opened to change gas jetting from a nozzle 19 into gas supply from the passage 3b when the rotational frequency of a turbine rotor 12 is higher than a reference frequency. When the frequency is still not reduced or when the frequency is reduced into an approximately constant condition in a certain time after the valve 6 is opened, judgement is made that gas leaks at the downstream side to close the valve 6.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a flow meter, and more particularly to a flow meter configured to detect gas leaks on the downstream side with good responsiveness.

Conventional technology Traditionally, flexible membranes were used as flowmeters to measure the amount of gas used by each household in the pipes that delivered city gas (hereinafter simply referred to as gas) to each household. A so-called belly-type meter is provided that is configured to be displaced according to the volume and measure the flow rate for that volume. Furthermore, in conventional gas piping, the presence or absence of gas leakage has been detected using this abdominal meter.

Problems to be Solved by the Invention For example, after an earthquake or the like occurs, the flow meter must detect the occurrence of gas leaks in the piping downstream of the flow meter. Performance will depend on the performance of the flowmeter itself. Therefore, when the above-mentioned model meter is used, the presence or absence of gas leakage is detected before using gas appliances in the home. However, with the above model meter, for example, the flow rate is 27 in 2 minutes.
I! /h, so if the gas leakage flow rate is relatively large, gas leakage can be detected with high sensitivity. However, if the gas leakage flow rate is small, the gas intake time will be longer. There was a problem in that the leak detection flow rate was limited by the gas leak detection time.

Further, in the gas supply line, a turbine-type flowmeter that measures the flow rate by rotation of a turbine rotor having a plurality of blades is being considered as a flowmeter other than the above-mentioned model meter.

By the way, in the event of an emergency such as an earthquake, the shutoff valve upstream of the flow meter is temporarily closed to prevent accidents such as fires caused by the gas appliances in use, and then the shutoff valve is closed again to use the gas appliances. When opening a shutoff valve, it is necessary to confirm the safety of return to ensure that piping, etc. is not damaged.

However, if the above-mentioned turbine-type flowmeter is installed in the middle of the piping, the gas will pass through the turbine rotor and rapidly fill the downstream piping when the shutoff valve is opened during the safety return check. Therefore, the turbine rotor rotates at high speed.

Therefore, when a turbine flow meter is used in place of the above-mentioned model meter, the turbine rotor continues to rotate due to its inertia after the shutoff valve is opened, so it takes time until the turbine rotor can detect leaks. Issues such as this arise.

Therefore, an object of the present invention is to provide a flowmeter that solves the above problems.

Means and Effects for Solving the Problems The present invention provides a main channel provided in a flow meter main body through which a fluid to be measured flows, and a rotating body rotatably provided in the main channel and rotates in accordance with the flow rate of the fluid to be measured. a rotation detection unit that detects the rotation of the rotating body; and a switching valve that is provided in the main flow path on the upstream side of the rotating body and opens due to a pressure difference between the upstream side and the downstream side due to a pressure drop on the downstream side. , one end opens into the main flow channel upstream of the valve seat of the switching valve, and the other end opens so as to face the outer periphery of the rotating body so as to rotate the rotating body, and supplies the fluid to be measured to the rotating body. a detection means installed downstream of the valve body to detect a pressure drop that would cause the valve body to leave its seat; and a valve drive unit that drives the valve body of the switching valve to the open position based on a signal from the detection means. and a cutoff valve that is installed upstream of the rotating body and closes the main flow path only in an emergency. The system is equipped with a means for detecting rotation by a signal from a rotation detection section and determining whether or not there is a leakage of the measured fluid on the downstream side based on a change in the rotational wave number of the rotating body, and when the cutoff valve is opened, the downstream The return safety confirmation, which confirms whether there is a leak on the side, can be determined in a short time with good responsiveness.

Embodiment FIG. 1 shows a first embodiment of a flowmeter according to the present invention. 1st
In the figure, a flow meter 1 is disposed in the middle of a pipe (not shown) that supplies gas such as city gas, for example. A main flow path 3 is formed inside a flowmeter main body 2 of the flowmeter 1 .

Moreover, the main flow path 3 includes an inflow path 3a, a branch chamber 3b, a measurement chamber 3c,
It consists of an outflow path 3d. A first valve seat 4 is provided between the inflow path 3a and the diversion chamber 3b, and a second valve seat 5 is provided between the diversion chamber 3b and the measurement chamber 3C.

Reference numeral 6 designates a shutoff valve, which includes a valve body 6a that seats on the valve seat 4 from the upstream side, a coil spring 6b that biases the valve body 6a in the seating direction, and a valve opening signal that drives the valve body 6a in the unseated direction. It has an electromagnetic solenoid 6C.

Reference numeral 7 designates a switching valve, which includes a valve body 7a that seats on the valve seat 5 from the downstream side, a coil spring 7b that biases the valve body 7a in the seating direction, and a valve opening signal that drives the valve body 7a in the unseating direction. It has an electromagnetic solenoid 7C.

The valve body 7a is formed by fixing a disk-shaped valve plate 7a2 to the lower end of a rod 7a that fits into the electromagnetic solenoid 7c by screwing or the like. Also, valve plate 7a! A ring-shaped rubber gasket 7aa is attached to the lower step.

In addition, the electromagnetic solenoid 6c of the cutoff valve 6 and the switching valve 7
, 7c are openings 3e above the valve seats 4 and 5.

It is mounted and fixed on a mounting base 8 on a flat plate that closes the area 3f. Also, the distance between the openings 3e and 3f and the mounting base 8 is 0.
Sealed by rings 9.10.

Here, the electromagnetic solenoids 6c and 7c will be explained in detail.
These electromagnetic solenoids 6c and 7c have a self-holding function, and once the solenoid is energized and the core is attracted, they continue to attract the core even after the solenoid current is released. . To explain in conjunction with the embodiment, when the electromagnetic solenoids 6c and 7c are excited, the rods 6az 7a+ are pulled upward in the figure. Then, the rods 6a+7a are attracted to permanent magnets (not shown) provided in the electromagnetic solenoids 6c and 7c. In this state, the electromagnetic solenoid 6c,
Even if 7c is demagnetized, rods 6a+7a will maintain their positions, that is, their upwardly displaced positions.

Also, in order to lower the rods 6a+, 7a held above, by applying a current in the opposite direction to the above (to cancel the magnetic field of the permanent magnet), the rods 6a+, 7a are released from the electromagnetic solenoids 6c, 7c. , descend. After this, electromagnetic solenoid 6c.

Even if 7c is demagnetized, the coil springs 6b and 7b keep the valve body 6a
, 7a are energized by the valve seats 4 and 5 to close the valves.

In this way, the electromagnetic solenoids 6c, 7c of this type are used because if current is supplied only at the beginning of operation, the state can be maintained without supplying current thereafter, resulting in power savings.

During normal flow rate measurement, the electromagnetic solenoid 6c is initially energized, so the rod 6a moves upward and is held upward, so that the valve body 6a of the cutoff valve 6 is unseated. Therefore, the cutoff valve 6 is designed such that the valve element 6a is closed by the coil spring 6b only in an emergency if current is supplied only momentarily so that the magnetic field of the electromagnetic solenoid 6C is canceled out.

Reference numeral 11 denotes a flow rate measuring section as a detection means (this detection means detects a pressure drop on the downstream side such that the valve body 7a is separated from its seat, and the details will be described later), which is installed on the downstream side of the switching valve 7. It is attached and fixed to part 3g.

The flow rate measurement unit 11 has a flow path 11b within a cylindrical main body 11a, and within the flow path 11b, an upstream cone 11c and a downstream cone lid are supported by support columns lie.

Reference numeral 12 denotes a turbine rotor (rotating body), which has a plurality of blades 12a on the outer periphery of the hub, and is provided between the upstream cone lie and the downstream cone lid. Moreover, the turbine rotor 12
is rotatably supported by bearings 13a and 13b so as to rotate according to the flow rate flowing through the flow path 11b. Further, a magnet 14 is embedded in the hub of the turbine rotor 12.

Reference numeral 15 denotes a rotation detection pickup consisting of a magnetic sensor or the like, which is embedded in the downstream cone tic so as to face the magnet 14 of the turbine rotor 12. This pickup 15 detects the rotation of the turbine rotor 12 and outputs pulses corresponding to the rotation to the control circuit 22.

Note that the control circuit 22 is an electromagnetic solenoid 6c.

7c, detects pulses from the pickup 15, integrates the flow rate, and opens or closes the switching valve 7 according to the pulse interval.

An O-ring 16.
17 is provided, and the inner wall of the mounting portion 3g and the main body 11a
This O-ring 16.17 seals between the two. Further, the inner wall of the mounting portion 3g has a first stepped portion 3g and a second stepped portion 3g.
It has a step portion 3gt. Therefore, the main body 11a
The nozzle chamber 18 is formed between the second step 3gx and the second step 3gx.

19 is a small-diameter nozzle hole that opens at one end into the flow path 11b;
The other end is bored in the main body 11a so as to open into the nozzle chamber 18. Further, one end of the nozzle hole 19 is opened so as to face the outer periphery of the blade 12a of the turbine rotor 12.

Reference numeral 20 denotes a branch channel, which is provided so that one end opens into the branch flow chamber 3b and the other end opens into the nozzle chamber 18. Therefore, the gas passing through this branch passage 20 reaches the nozzle chamber 18 and passes through the nozzle hole 19 to the turbine rotor 12.
is injected onto the blades 12a. By doing this, even if the flow rate used on the downstream side is minute, the nozzle hole 19 allows
As a result of direct injection of gas to the turbine rotor 12, the turbine rotor 12 rotates at high speed.

Further, the flow rate measuring section 11 is attached so as to fit into the attachment section 3g from above, and can be easily attached by removing the lid 21 that closes the attachment section 3g.

Further, a safety device 23 is connected to the side circuit 22,
The safety device 23 includes a return safety confirmation switch 24 and a seismic sensor 2.
For example, a pressure sensor 26 is connected to the pressure sensor 26 for detecting the pressure in the downstream piping.

The return safety confirmation switch 24 is installed, for example, in a home, and is operated by a family member or the like after an earthquake with a seismic intensity greater than a predetermined intensity occurs. Furthermore, the seismic sensor 25 detects the occurrence of an earthquake and outputs the signal to the safety device 23. Pressure sensor 26
detects the gas pressure inside the pipe and outputs the signal to the safety device 23.

Therefore, if there is an abnormality in the gas pressure based on a signal from the seismic sensor 25 or a signal from the pressure sensor 26, the safety device 23 outputs an emergency valve closing signal to the control circuit 22 in order to urgently close the cutoff valve 6. do.

Further, when the return safety confirmation switch 24 is closed, the signal is supplied to the control circuit 22 via the safety device 23, and the control circuit 22 confirms the return safety after opening the cutoff valve 16 as described later. Perform the action.

FIG. 2 shows a schematic configuration of the control circuit 22. As shown in FIG. In FIG. 2, a frequency measurement section 27 is supplied with pulses from the pickup 15, measures its frequency, and compares and determines the measured signal with a determination section 27.
Supply to 8. The comparison and determination section 28 determines the determination reference frequency f in advance.
1. The setting signal from the frequency setting section 29 for setting f2 is compared with the measurement signal from the frequency measuring section 27, and a comparison signal between the two is supplied to the return safety confirmation control section 30. Further, the measurement signal from the frequency measurement section 27 is also supplied to a frequency increase/decrease determination section 31, which determines whether the rotational wave number of the turbine rotor 12 tends to increase or decrease, and sends the determination signal to the frequency increase/decrease determination section 31. The information is supplied to the confirmation control section 30.

The time measuring unit 32 is provided as a timer and measures, for example, the time T I + T2 + T2 after the cutoff valve 6 opens.

Note that the time T1 is such that the switching valve 7 is opened after a sufficient time has elapsed to fill the downstream piping with gas after the shutoff valve 6 is opened.
This is the time from when the switching valve 7 is once opened to when the opened switching valve 7 is closed and the gas flow is switched from the main channel 3 to the branch channel 20. This is sufficient time to detect gas leakage in the nozzle area where the valve is closed and the gas flow is switched from the main flow path 3 to the branch flow path 20, and the time T
3 is the time sufficient to fill the downstream piping with gas after the shutoff valve 6 is opened. The comparison/determination section 33 uses the time measurement signal from the time measurement section 32 and the time T from the time setting section 34.
, , T, , T2 are compared, and when the measurement signal reaches the setting signal, a determination signal indicating that a set certain period of time has elapsed is supplied to the return safety confirmation control section 30.

The return safety confirmation control unit 30 controls the cutoff valve 6. It is connected to the electromagnetic solenoids ec and 'yc of the switching valve 7 and the display section 35.

Next, the operation of the flowmeter 1 having the above structure will be explained with reference to FIGS. 3 and 4.

As shown in FIG. 2, the control circuit 22 initially opens the cutoff valve 6. Then, as described above, the valve element 6a remains open upward and is maintained in that state even if the current to the cutoff valve 6 is cut off. This shutoff valve 6 closes only in an emergency, and even in this case, as described above, if a current is supplied to the shutoff valve 6 for a short period of time, the shutoff valve 6 closes immediately. Generally, this shutoff valve 6 is kept open, so its explanation will be omitted.

Suppose that gas appliances are now being used downstream. For example, let's say you light the starter of a gas water heater in your home. Since the amount of gas used at this time is very small, the switching valve 7 is in a closed state, and the gas is transferred from the branch chamber 3b to the branch channel 20. Nozzle chamber 18. It is injected to the blades 12a of the turbine rotor 12 through the nozzle holes 19.

FIG. 3 shows the relationship between the rotational speed of the turbine rotor 12 and the gas flow rate. As shown in the middle diagram I in FIG. 3, when the starter of the gas water heater is ignited, the gas is forcefully blown from the nozzle hole 19 onto the blades 12a of the turbine rotor 12, although the flow rate is minute. rotates at high speed. That is, by using gas in the starter of the gas water heater, the rotational speed of the turbine rotor 12 increases as shown by the diagram in FIG.
It rises from point a to point b.

Such rotation of the turbine rotor 12 is caused by the pickup 1
5, and as the pickup 15 passes the magnet 14 embedded in the turbine rotor 12,
Pulses having pulse intervals corresponding to the rotation speed of the turbine rotor 12 are output.

The control circuit 22 then integrates the pulses from the pickup 15 to calculate the gas flow rate. In addition, the control circuit 22
detects the pulse interval of the pulses input from the pickup 15.

Here, for example, you decide to turn on the water heater and use hot water. Therefore, the amount of gas used on the downstream side of the flow meter 1 will increase. Further, as the amount of gas used increases, the turbine rotor 12 rotates at a higher speed, and the rotational speed of the turbine rotor 12 reaches point b in FIG. 3.

Since the control circuit 22 monitors the pulse interval of the pulses output from the pickup 15, it is possible to determine whether the amount of gas used is
When the limit amount "Ql" of 0 is reached and the pulse interval becomes "D", a valve opening signal is output to the electromagnetic solenoid 7C.

As a result, the electromagnetic solenoid 7C is energized and the valve body 7a is attracted upward by the electromagnetic force and is removed from the valve seat 5. The valve body 7a either moves upward against the spring force of the coil spring 7b or cannot resist the upstream pressure, and as will be described later, the spring force of the coil spring 7b is set to the minimum force necessary to close the valve. Therefore, the valve body 7a moves upward with a relatively small driving force.

Due to the valve opening operation of the switching valve 7, the gas passes through the opening of the valve seat 5 and reaches the measurement chamber 3C, and the flow path 11b of the flow rate measurement section 11.
It passes through and is supplied to gas appliances downstream from the flow path 3d.

Due to the valve opening operation of the switching valve 7, the rotation speed of the turbine rotor 12 is temporarily reduced from point b of the linework to 0 as shown in FIG.
Go down to the point. However, due to the increase in the amount of gas used due to the use of the gas water heater, the flow rate of gas increases and the rotational speed of the turbine rotor 12 also increases from point C to point d in FIG. 3.

Note that between point a and point b of diagram I in FIG. 3, gas is blown onto the turbine rotor 12 forcefully from the nozzle hole 19, so the rotational speed of the turbine rotor 12 has a steep slope in FIG. In this case, the rotation speed of the turbine rotor 12 has a gentler slope than between a and b because the gas passes through the flow path 11b with a large flow path area from point 0 to point d. It will rise.

Further, the rotational speed of the turbine rotor 12 from point 0 to point d in the diagram I in FIG.
5, and the control circuit 22 calculates and integrates the flow rate based on the pulses output from the pickup 15.

At this point, I decided to stop using the gas water heater and return to lighting only the pilot flame to reduce the amount of gas used. As the amount of gas used in the gas water heater decreases, the flow rate of gas passing through the flow path 11b of the flow rate measuring section 11 also decreases. Therefore, the rotational speed of the turbine rotor 12 also decreases from point d in diagram I in FIG. 3 toward point 0.

In the control circuit 22, hysteresis is provided in the valve closing and opening operations of the switching valve 7 in order to prevent fluctuations in the opening and closing operations of the valve body 7a. That is, the control circuit 22 determines that the pulse interval of the pulses from the pickup 15 is equal to or greater than "DI" (however, DI > D, and for example, DI is equal to or greater than 2).
A time of 50 msec is stored in the control circuit 22, and this time D1 can also be changed arbitrarily. ) is detected.

Therefore, when the gas flow rate decreases to "Q2" and the rotation speed of the turbine rotor 12 drops further below the 0 point and reaches point e (shown in the diagram in Figure 3), the pulse interval becomes It detects this and outputs a valve closing signal to the switching valve 7.

As described above, the electromagnetic solenoid 7c of the switching valve 7 is a self-holding type solenoid, so a current in the opposite direction to the valve opening signal is applied to the electromagnetic solenoid 7c. Therefore, by supplying the valve closing signal, the electromagnetic solenoid 7c generates a reverse magnetic field that cancels the magnetic field of the permanent magnet that holds the valve body 7a in the valve open position. As a result, the valve body 7a held in the valve open position comes into contact with the valve seat 5 due to the spring force of the spring 7b, thereby closing the main flow path 3.

Therefore, the gas reaches the nozzle chamber 18 from the branch chamber 3b via the branch channel 20, and from the nozzle hole 19 to the turbine rotor 12.
is ejected from the blades 12a. Therefore, the turbine rotor 12 receives the gas injected from the nozzle hole 19 and rotates at a high speed.

That is, the rotational speed of the turbine rotor 12 is as shown in line diagram I in FIG.
will rise from point e to point f. Furthermore, when the starter of the gas water heater is turned off, the amount of gas used becomes zero, and the rotational speed of the turbine rotor 12 drops from point f to point a.

Here, the operation of the flow meter 1 after, for example, an earthquake will be explained with reference to FIGS. 4 and 5.

As mentioned above, when an earthquake of a predetermined magnitude or more occurs, the seismic sensor 25 is activated and its signal is input to the safety device 23, so the control circuit 22 operates the electromagnetic solenoid 6c of the cutoff valve 6.
energizes to close the cutoff valve 6. After the earthquake, the shutoff valve 6
The gas supply line is cut off by the valve closing operation, and the householder also closes the main valves of the gas appliances in the home.

When the earthquake stops and things calm down, the householder closes the return safety confirmation switch 24. As a result, the return safety confirmation control section 30 of the control circuit 22 executes the process shown in FIG. 4. still,
FIG. 5 is a diagram showing changes in the rotational wave number f of the turbine rotor depending on the presence or absence of gas leakage.

In FIG. 4, when a signal from the return safety confirmation switch 24 is input to the control circuit 22 via the safety device 23 (step $1), the safety confirmation control section 30 opens the cutoff valve 6 (step S2). ). - Therefore, the gas from the upstream pipe (not shown) passes through the valve seat 4.5 in the main flow path 3 and flows into the flow measurement section 11 (flow path 11 provided with the turbine rotor 12).
b), and is further filled into the downstream piping (not shown) from the outlet 3d.

It takes a certain amount of time mT2 (shown in FIG. 5) until the end of the downstream piping connecting the flowmeter 1 and the household gas appliance is filled with gas. Therefore, it is checked whether a time T preset by the time setting section 34 has elapsed since the cutoff valve 6 was opened (step S3).

When time T has elapsed in step S3, it is checked whether the frequency f of the pulse from the pickup 15 (rotational wave number of the turbine rotor 12) is lower than the reference frequency f1 preset in the frequency setting section 29 (step S
4).

In FIG. 5, when the frequency f>fl, there are roughly three types of patterns: lines [gI, L It].

When f>fl in step S4, the switching valve 7 is opened (step S5), and it is confirmed whether the frequency f is decreasing (step S6). Here, the switching valve 7 opens because the flow rate exceeds Q in FIG.
This is to switch from gas injection from the flow path 3b to gas supply from the flow path 3b. If the frequency does not decrease due to the opening of the switching valve 7 in step $6 (as shown by line I in Figure 5), this means that there is a leak when the gas appliance is open or the gas pipe is open. is extremely large, it is determined that there is a gas leak on the downstream side, and the shutoff valve 6 is closed (step S7).
).

Then, the display device 35 displays a message indicating that there is a gas leak. On the other hand, when the frequency f decreases in step S6 (indicated by lines m and m in FIG. 5), the time T, (indicated by lines m and m in FIG. When the frequency f becomes approximately constant within (shown in step S)
8. S9, shown by the line ■ in FIG.
Close the valve.

The diagram shown in the 5th WJ shows that after the shutoff valve 6 opens, as gas from the upstream piping is supplied to the downstream side, the rotation of the turbine rotor 12 increases to the extent that it is lost to the downstream piping. It is shown that when gas is filled, the rotational speed of the turbine rotor 12 peaks at point a and decreases until the switching valve 7 is closed at the time T.

Further, in step S9, if f# is not constant, the process returns to step S8 and continues to determine that f# is constant until time T has elapsed. If fs does not become constant within time T1, that is, if there is a possibility of a minute gas leak such as a leak from a gap in a pipe, the process proceeds to step 10, and the switching valve 7 is closed. This is to detect gas leakage with higher sensitivity by injecting gas from the nozzle hole 19. At this time, if there is a large amount of gas leakage on the downstream side,
As shown in , the rate of increase in the rotational speed of the turbine rotor 12 increases.

Next, the frequency f is a preset reference frequency f2 (however, f
s > ft ) is higher than or equal to (step 5ll). In this step Sll, if the frequency f exceeds T2 after the elapse of time T1 as shown in the frequency curve ■ (shown in Figure 5), as mentioned above, if the frequency It is determined that there is a slight gas leak, and the process proceeds to step S7, where the cutoff valve 6 is closed.

Step S! 2, the time T2 after switching valve 7 is closed
It is checked whether or not time (shown in FIG. 5) has elapsed, and the process of step Sll is repeated from time T1 to time T. Then, as shown in the diagram ■ (indicated by a broken line) in FIG. 5, even after time T2 has elapsed, the frequency f remains f! If it is less than that, it is assumed that there was no gas leak, and the process proceeds to step S13, where the return safety confirmation process ends. Additionally, the display device 35 will display that the process has been completed, and the family will be notified. After this, normal flow rate measurement is performed, and in this area in Fig. 5,
Depending on the usage status of the gas appliance, as shown in the diagram ■, for example, when the gas flow rate reaches the flow rate Q at which the switching valve 7 is opened, the flow rate will be shown as "axial flow °" in the same area. For example, when the flow rate of gas does not reach the flow rate Q1 at which the switching valve 7 opens, the same region is indicated by a "nozzle".

In addition, in step S4, if there is no leakage in the gas appliances, piping, etc., the gas pressure in the downstream piping increases, the gas is sufficiently filled, and the frequency f becomes < f < f as shown in the diagram ■ in Fig. 5.
t, it is determined that there is no gas leak, and the process moves directly to step 313, ending the recovery confirmation process. Thereafter, normal flow rate measurement is immediately performed without checking the above-described time T1.

By monitoring the rotation frequency of the turbine rotor 12 in this manner, the presence or absence of gas leakage on the downstream side can be detected with good responsiveness and in a short time.

FIG. 6 shows a modification of the first embodiment.

In Fig. 6, when the earthquake stops and there is a return input (step S1''), the switching valve 7 is first opened (step 82').Then, after the shutoff valve 6 is opened (step 53=) , check whether time T has elapsed since the start of the return operation.

After time T has elapsed, steps 86 to S13 are executed in the same way as the processing shown in FIG. 4 described above.

In this way, by opening the switching valve 7 in advance in step Sr, when the cutoff valve 6 is opened in step 31, the gas flow path area of the valve seat 5 becomes large, and the cutoff valve 6 opens. It is possible to shorten the time T3 required from when the valve is opened until the downstream piping is filled with gas. Therefore, the gas leak detection after the emergency cutoff operation can be performed in a shorter time than in the first embodiment, and the gas supply can be restored in a shorter period of time.

Furthermore, the determination in step S4 in FIG. 4 described above is no longer necessary, and the return processing of the control circuit 22 can be simplified accordingly.

A second embodiment of the present invention is shown in FIGS. 7 and 8.

In FIG. 7, the same parts as in the first embodiment are given the same reference numerals, and the explanation thereof will be omitted.

In FIG. 7, the flow rate pulse from the pickup 15 is supplied to the flow rate calculation correction unit 36, and the flow rate pulse is corrected for errors caused by temperature differences, for example, and input to the flow rate pulse output control unit 37. be done. This flow rate pulse output control section 37 includes a comparison determination section 285, a frequency increase/decrease determination section 31. A signal from the comparison/judgment section 33 is also input.

Further, the flow rate pulse output control section 37 outputs the flow rate pulse to the flow rate integration section 38 and the return safety confirmation control section 30. Then, the flow rate integrating section 38 integrates the flow rate pulses, and causes the display section 35 to display the flow rate.

The return safety confirmation control section 30 operates the cutoff valve 6. as will be described later in response to the flow rate pulse output from the flow rate pulse output control section 37. Open or close the switching valve 7.

The switching valve 7 is provided with an opening/closing sensor 39, and its opening/closing signal is output to the flow rate pulse output control section 37 and the return safety confirmation control section 30.

Further, the flow rate integration section 38 may be directly connected to the flow rate calculation correction section 36.

Next, the return safety confirmation control section 3 of the control circuit 22 shown in FIG.
0 and the processing executed by the flow rate pulse output control section 37 will be explained with reference to FIG.

First, after the earthquake has stopped, when the return safety confirmation switch 24 is closed (step 521), the return safety confirmation control section 3
0 opens the shutoff valve 6 (step 522). When the shutoff valve 6 is opened, the downstream side is filled with gas and the turbine rotor 12 starts rotating, as in the first embodiment (see FIG. 4).

Further, when the return safety confirmation switch 24 is closed and the cutoff valve 6 is opened, the flow rate pulse output control section 37 causes the comparison and judgment section 33 to start a time measurement process, and the comparison and judgment section 33 causes the cutoff valve 6 to open. Ignore the output state of the flow rate pulse until the time T, (see Figure 5) is determined after the valve closes (
Step 523). If the rotational wave number f of the turbine rotor 12 does not reach fl during this time T, the switching valve 7
Since the valve body 7a does not separate from the valve seat 5 and the switching valve 7 does not open, the open/close sensor 39 outputs a close signal.

Therefore, in step S324, when there is a closing signal for the switching valve 7, the state is shown in the middle line (■) in FIG. Then move on to complete the return safety confirmation.

If there is no close signal in step S24, the flow rate pulse output control section 37 determines whether the frequency f decreases (step 525). If the frequency f does not decrease in step S25 (as shown in diagram 1 in FIG. 5), a flow pulse is output from the flow pulse output control section 37 (step 52B), and the return safety confirmation control section 30 detects this. It is determined that there is a gas leak and the shutoff valve 6 is closed (step 5).
27). Then, the display section 35 displays that fact. or,
In step 325, when frequency f decreases,
The flow rate pulse output control unit 37 stops outputting the flow rate pulse (step 828).

Next, the flow rate pulse output control unit 37 checks whether the frequency f becomes substantially constant within time T1 after the switching valve 7 closes (step S29°830).

At this time, if the frequency f becomes approximately constant (line diagram in Figure 5
) The flow rate pulse output control unit 37 outputs a flow rate pulse, and the return safety confirmation control unit 30 detects this, determines that there is a gas leak, and closes the cutoff valve 6 (step S26).
．． 527).

Further, if fζ does not become constant within time 13, the flow rate pulse output control section 37 closes the switching valve 7 (step 5).
31). As a result, gas is ejected from the nozzle hole 19 toward the turbine rotor 12 . In this state, the frequency f
Check whether it is greater than or equal to 11 or equal to Step 53
2), f≧f.

If so, a flow rate pulse is output from the flow rate pulse output control unit 37, and the return safety confirmation control unit 30 detects this, determines that there is a gas leak on the downstream side, and closes the cutoff valve 6 (step 826). 527).

Also, in step S32, the frequency f is f! If it is below, the flow rate pulse output control unit 37 continues to monitor the change in frequency f until time T (step 533), and if the frequency f is below f during that time, it is determined that there is no leakage, and it is determined that the return is safe. The confirmation ends (step 534).

After this, the display section 35 displays the completion of the return safety confirmation, and the return safety confirmation control section 30 and the flow rate pulse output control section 37 return to the normal flow rate measurement state.

Therefore, as described above, gas leakage may be detected based on the change in the rotational wave number of the turbine rotor 12, and the presence of gas leakage may be determined based on the output of the flow rate pulse.

Furthermore, in the second embodiment, since the flow rate integration section 38 and the return safety confirmation control section 30 are provided separately, the flow rate measurement process and the safety confirmation process are separated, and the input/output of the signal is "flow rate pulse". The configuration is simplified.

FIG. 9 shows a modification of the second embodiment.

In FIG. 9, when the earthquake stops and there is a return input (step S21''), the switching valve 7 is first opened (step 522-).Then, after opening the cutoff valve 6 (step S23''), It is checked whether time T has elapsed since the start of the return operation (step 524-).

After time T has elapsed, the processes of steps 325 to S34 are executed in the same way as the process shown in FIG. 8 described above.

In this way, by opening the switching valve 7 in advance in step 822', when the cutoff valve 6 is opened in step 823', the gas flow area of the valve seat 5 becomes large, and the cutoff valve 6 It is possible to shorten the time T3 required from when the valve is opened until the downstream piping is filled with gas. Therefore, the gas leak detection after the emergency cutoff operation can be performed in a shorter time than in the second embodiment, and the gas supply can be restored more quickly.

Furthermore, the determination in step S24 in FIG. 8 described above is no longer necessary, and the return processing of the control circuit 22 can be simplified accordingly.

A third embodiment of the present invention is shown in FIGS. 10 and 11. Note that the configuration of the image creation circuit 22 is the same as that shown in FIG. 7, so a description thereof will be omitted.

The return safety confirmation control section 30 controls the return safety confirmation switch 24.
When the circuit is closed, the signal is input and the processing shown in FIG. 10 is executed. After opening the cutoff valve 6, the rotational wave numbers of the turbine rotor 12 can be roughly divided into lines I and In as shown in FIG.

(2), and FIG. 11 is simplified compared to FIG. 5 in the case of the first and second embodiments described above.

In FIG. 1O, when the return safety confirmation switch 24 is closed (step 543), the cutoff valve 6 is opened (step 5).
44). Next, in step S45, it is checked whether time T4 has elapsed since the shutoff valve 6 was opened.
Ignore flow pulses until 4 (step 546)
. While this time T has elapsed, gas filling in the downstream piping is almost completed.

Time II! When T4 is reached, it is determined whether the frequency f of the turbine rotor 12 is decreasing (step 547).
. If the frequency f has not decreased in step S47 (see diagram in FIG. 11), it is assumed that there is a gas leak on the downstream side, and a flow rate pulse is output (step 548). Close valve 6 (step 5
49). Further, in step S47, when the frequency f decreases (diagrams II and III in FIG. 11), the output of the flow rate pulse is stopped (step 550). Then, it is monitored whether the frequency f is substantially constant until a time T has elapsed since the cutoff valve 6 was opened (step 551) (step 552).

If the rotational wave number f of the turbine rotor 12 does not decrease and becomes constant within time T6, this indicates that there is a continuous leak, and the process of step 348.49 is executed, and it is determined that there is a gas leak, and the cutoff valve 6 Close the valve. Also, within time Ti, f=
If q is not constant, the confirmation of return safety ends (step 553).

After this, a message to that effect is displayed on the display section 35, and the flow rate measurement state becomes normal. Note that the time T is set to a time sufficient to determine whether there is a gas leak for safety confirmation.

In this way, as in the second embodiment, the presence or absence of gas leakage can be detected with high sensitivity by monitoring changes in the frequency f, without using the switching valve opening/closing signals.

As another modification of the first and second embodiments, for example, the fourth embodiment
Step S11 in the figure. Instead of step S32 in FIG. 8, the slope of the frequency change after the switching valve 7 closes (differential coefficient d f/d t) is compared with a certain predetermined value (α),
f/dt)≧α, step S7 or S26.
The process of S27 may also be executed.

Further, as yet another modification, steps S11 and S
Instead of step S26.32, the change rate ε of the frequency after the switching valve 7 closes is compared with a certain predetermined value (β), and when ε≧β, step S7 is executed in step S26. The process of S27 may also be executed.

Effects of the Invention As described above, according to the flowmeter of the present invention, leakage of the fluid to be measured on the downstream side can be detected based on the change in the rotational wave number of the rotating body that rotates in accordance with the flow rate of the fluid to be measured. ,
It can detect leaks with good responsiveness without taking the time required to detect leaks at minute flow rates as with conventional model meters.Furthermore, since leaks can be detected while the rotating body is rotating, it is possible to detect leaks on the downstream side in a shorter time. It is possible to determine the presence or absence of a leak, and even when the turbine rotor rotates at high speed when the shutoff valve is opened, leakage can be detected even if the turbine rotor rotates at high speed, so it has features such as being able to improve the reliability of leak detection.

Further, according to claim (2), after the cutoff valve is closed in an emergency manner,
Since the switching valve 7 can be opened in advance by the return operation, a larger gas flow path area can be secured when the cutoff valve is opened. Therefore, the time required from when the shutoff valve is opened by the return operation until the downstream piping is filled with fluid can be further shortened, and leak detection after the emergency shutoff operation can be performed in a shorter time. .

Furthermore, according to claim (3), by closing the switching valve, the rotating body can be rotated more efficiently via the branch flow path, and even if the amount of leakage is relatively small, it is possible to ensure that there is a leak. It has features such as being able to detect

Further, according to claim (4), since the rotating body rotates rapidly when the shutoff valve is opened, leak detection cannot be performed at first due to an increase or decrease in the rotational wave number of the rotary body. By ignoring the rotational speed of the rotating body for a certain period of time after the rotation, there is no need to detect radically fluctuating frequency changes, and there is no need to perform unnecessary processing.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of a first embodiment of a flowmeter according to the present invention;
Fig. 2 is a schematic configuration diagram of the control circuit, Fig. 3 is a diagram showing the relationship between the flow rate and the rotation speed of the turbine rotor, Fig. 4 is a flowchart for explaining the processing executed by the control circuit, and Fig. 5 6 is a diagram showing changes in the rotational wave number of the turbine rotor after the shutoff valve is opened, FIG. 6 is a flowchart for explaining a modification of the first embodiment, and FIG. 7 is a diagram showing a second embodiment of the present invention. A block diagram of the example control circuit, FIG. 8 is a flowchart of the processing executed by the control circuit shown in FIG. 7, and FIG.
Flowchart for explaining a modification of the embodiment, first
FIG. 0 is a flowchart of the third embodiment of the present invention, and FIG. 11 is a diagram showing changes in the rotational wave number of the turbine rotor for reference when explaining the flowchart of FIG. 10. l...Flowmeter, 2...Flowmeter body, 3...Main flow path, 4...First valve seat, 5...Second valve seat, 6...
Shutoff valve, 7... Switching valve, 11... Flow rate measuring section, 12
... Turbine rotor, 14... Magnet, 15.
...Pickup, 18...Nozzle chamber, 19...Nozzle hole, 20...Diversion channel, 22...Control circuit, 24
...Return safety confirmation switch, 25...Seismic sensor, 26
... Pressure sensor, 30 ... Return safety confirmation control section, 3
7...Flow rate pulse output side wound. Patent applicant: Tokiko Co., Ltd. Figure 3 Figure 4 Figure 16 Figure 8 Figure 9 Figure 10

Claims (4)

[Claims] (1) A main channel provided inside the flowmeter body through which the fluid to be measured flows, a rotating body rotatably provided in the main channel and rotated according to the flow rate of the fluid to be measured, and detection of the rotation of the rotating body. a rotation detection unit that is provided in the main flow path on the upstream side of the rotating body and opens due to a pressure difference between the upstream side and the downstream side due to a pressure drop on the downstream side; a branch channel that opens into the main flow channel on the upstream side of the valve seat, and whose other end opens to face the outer periphery of the rotating body so as to rotate the rotating body, and supplies the fluid to be measured to the rotating body; a detection means installed downstream of the valve body to detect a pressure drop that causes the valve body to leave its seat; and a valve drive unit that drives the valve body of the switching valve to the open position based on a signal from the detection means. and a cutoff valve that is provided upstream of the rotary body and closes the main flow path only in an emergency, the flowmeter comprising: a cutoff valve that closes the main flow path only in an emergency; The present invention is characterized by comprising means for detecting the accompanying rotation of the rotating body using a signal from a rotation detecting section, and determining whether or not there is leakage of the fluid to be measured on the downstream side based on a change in the rotational frequency of the rotating body. Flowmeter. (2) A main channel provided within the flowmeter body through which the fluid to be measured flows, a rotary body rotatably provided within the main channel and rotated according to the flow rate of the fluid to be measured, and detection of the rotation of the rotary body. a rotation detection unit that is provided in the main flow path on the upstream side of the rotating body and opens due to a pressure difference between the upstream side and the downstream side due to a pressure drop on the downstream side; a branch channel that opens into the main flow channel on the upstream side of the valve seat, and whose other end opens to face the outer periphery of the rotating body so as to rotate the rotating body, and supplies the fluid to be measured to the rotating body; a detection means installed downstream of the valve body to detect a pressure drop that causes the valve body to leave its seat; and a valve drive unit that drives the valve body of the switching valve to the open position based on a signal from the detection means. and a cutoff valve provided on the upstream side of the rotating body to close the main flow path only in an emergency, wherein after the cutoff valve is closed in an emergency, the cutoff valve is opened by a return operation. A valve opening means that outputs a valve opening signal to the valve drive unit to open the switching valve before opening the valve, and a rotating body that accompanies the flow of the fluid to be measured flowing in the main flow path after opening the shutoff valve. 1. A flowmeter comprising means for detecting the rotation of the rotating body based on a signal from a rotation detecting section and determining whether or not there is leakage of the fluid to be measured on the downstream side based on a change in the rotational frequency of the rotating body. (3) A main channel provided inside the flowmeter body through which the fluid to be measured flows, a rotary body rotatably provided in the main channel and rotated according to the flow rate of the fluid to be measured, and detection of the rotation of the rotary body. a rotation detection unit that is provided in the main flow path on the upstream side of the rotating body and opens due to a pressure difference between the upstream side and the downstream side due to a pressure drop on the downstream side; a branch channel that opens into the main flow channel on the upstream side of the valve seat, and whose other end opens to face the outer periphery of the rotating body so as to rotate the rotating body, and supplies the fluid to be measured to the rotating body; a detection means installed downstream of the valve body to detect a pressure drop that causes the valve body to leave its seat; and a valve drive unit that drives the valve body of the switching valve to the open position based on a signal from the detection means. and a shutoff valve that is provided upstream of the rotating body and closes the main flow path only in an emergency, the flowmeter closing the switching valve after a certain period of time has passed after the shutoff valve is opened. a switching means for supplying the fluid to be measured to the rotating body via the branch channel; and a switching means for supplying the fluid to be measured to the rotary body through the branch channel; 1. A flowmeter comprising: a means for detecting and determining whether or not there is a leakage of fluid to be measured on the downstream side based on a change in the rotational frequency. (4) A main channel provided inside the flowmeter body through which the fluid to be measured flows, a rotary body rotatably provided in the main channel and rotated according to the flow rate of the fluid to be measured, and detection of the rotation of the rotary body. a rotation detection unit that is provided in the main flow path on the upstream side of the rotating body and opens due to a pressure difference between the upstream side and the downstream side due to a pressure drop on the downstream side; a branch channel that opens into the main flow channel on the upstream side of the valve seat, and whose other end opens to face the outer periphery of the rotating body so as to rotate the rotating body, and supplies the fluid to be measured to the rotating body; a detection means installed downstream of the valve body to detect a pressure drop that causes the valve body to leave its seat; and a valve drive unit that drives the valve body of the switching valve to the open position based on a signal from the detection means. and a cutoff valve that is provided upstream of the rotating body and closes the main flow path only in an emergency, wherein the rotational frequency of the rotating body is determined after a certain period of time has elapsed since the cutoff valve was opened. 1. A flowmeter comprising means for detecting a change in the rotational wave number of the rotating body and determining whether there is a leakage of the fluid to be measured on the downstream side based on an increase or decrease in the rotational wave number of the rotating body.