JP2863546B2 - Flowmeter - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flow meter, and more particularly to a flow meter configured to be able to detect gas leakage downstream with good responsiveness.

2. Description of the Related Art Conventionally, a flexible membrane has been used as a flow meter for measuring the amount of gas used in each household in the middle of a pipe for supplying city gas (hereinafter simply referred to as gas) to each household. There is provided a so-called membrane meter which is configured to be displaced in accordance with the amount and measure a flow rate corresponding to the volume. Further, in a conventional gas pipe, the presence / absence of gas leakage is detected by using the membrane meter.

Problems to be Solved by the Invention For example, in a pipe measured downstream from a flow meter after an earthquake or the like has occurred, since the occurrence of gas leakage is detected by the flow meter, detection of the presence or absence of gas leakage in the downstream pipe is performed. The performance will depend on the performance of the flow meter itself. Therefore, when the above-mentioned membrane type meter is used, the presence or absence of gas leakage is detected before using the gas appliance at home.
However, in the above-mentioned membrane type meter, for example, a flow rate of 27
Since l / h leakage can be detected, gas leakage can be detected with high sensitivity when the flow rate of gas leakage is relatively large, but the gas intake time increases when the flow rate of gas leakage is low. However, there has been a problem that the leak detection flow rate is limited by the gas leak detection time.

In addition, in the gas supply line, as a flow meter other than the membrane type meter, adoption of a turbine type flow meter that measures a flow rate by rotation of a turbine rotor having a plurality of blades is being studied.

However, in an emergency such as an earthquake, the shutoff valve upstream of the turbine rotor must be closed once, and then when the shutoff valve is opened again, it is necessary to perform a return safety check to see if the piping or the like is damaged. Therefore, when the turbine type flow meter is provided in the middle of the pipe, the gas passing through the turbine rotor is rapidly filled into the downstream pipe together with the opening of the shut-off valve at the time of return safety confirmation, and the turbine rotor is operated at high speed. Rotate. Therefore, when the turbine type flow meter is used, the turbine rotor continues to rotate due to its inertia after the shut-off valve is opened, so that there is a problem that it takes time until the turbine rotor can detect a leak.

Therefore, an object of the present invention is to provide a flow meter that solves the above-mentioned problems.

Means for Solving the Problems According to the invention of claim (1), the main flow path provided in the flow meter main body and through which the fluid to be measured flows, and the main flow path is rotatably provided in accordance with the flow rate of the fluid to be measured. A rotating body that rotates, a rotation detection unit that detects the rotation of the rotating body, and a valve body that is provided in the main flow path on the upstream side of the rotation body and that shuts off the main flow path by sitting on the valve seat and the valve seat. A switching valve consisting of: one end opening to the main flow path on the upstream side of the switching valve, and the other end opening to face the outer periphery of the rotating body so as to rotate the rotating body, the fluid to be measured is A branching channel for supplying to the rotating body, a detecting unit provided downstream of the switching valve for detecting a pressure difference between the upstream side and the downstream side of the switching valve, and a valve of the switching valve based on a signal from the detecting unit. A valve drive unit for driving a body, and a valve drive unit provided upstream of one end of the branch flow path of the main flow path. A flowmeter comprising a shutoff valve that closes the main flow path only in an emergency, wherein after the shutoff valve is opened, the rotation of the rotating body accompanying the flow of the fluid to be measured flowing through the main flowpath is detected by a rotation detection unit. It is characterized by comprising means for detecting by a signal and judging the presence or absence of leakage of the fluid to be measured on the downstream side of the flow meter based on a change in the rotation frequency of the rotating body.

Further, the invention of claim (2) is characterized in that a main flow path provided in the flow meter main body and through which the fluid to be measured flows, and a rotating body rotatably provided in the main flow path and rotating according to the flow rate of the fluid to be measured. ,
A rotation detection unit that detects the rotation of the rotating body, a switching valve that is provided in the main flow path on the upstream side of the rotating body, and includes a valve seat and a valve body that shuts off the main flow path by sitting on the valve seat. One end is opened to the main flow path on the upstream side of the switching valve, and the other end is opened so as to face the outer periphery of the rotator so as to rotate the rotator to supply a fluid to be measured to the rotator. Road and
A detection unit that is installed downstream of the switching valve and detects a pressure difference between the upstream side and the downstream side of the switching valve, and a valve driving unit that drives a valve body of the switching valve by a signal from the detection unit. A flow meter that is provided upstream of one end of the branch flow path of the main flow path and includes a shut-off valve that closes the main flow path only in an emergency. Switching means for closing a switching valve to supply the fluid to be measured to the rotating body through the branch flow path; and detecting the rotation speed of the rotating body rotated by the supply of the fluid to be measured from the branch flow path. Means for detecting the leakage of the fluid to be measured on the downstream side of the flow meter based on the change in the rotation frequency.

The invention according to claim (3) is characterized in that a main flow path provided in the flow meter main body and through which the fluid to be measured flows, and a rotating body rotatably provided in the main flow path and rotating according to the flow rate of the fluid to be measured. ,
A rotation detection unit that detects the rotation of the rotating body, a switching valve that is provided in the main flow path on the upstream side of the rotating body, and includes a valve seat and a valve body that shuts off the main flow path by sitting on the valve seat. One end is opened to the main flow path on the upstream side of the switching valve, and the other end is opened so as to face the outer periphery of the rotator so as to rotate the rotator to supply a fluid to be measured to the rotator. Road and
A detection unit that is installed downstream of the switching valve and detects a pressure difference between the upstream side and the downstream side of the switching valve, and a valve driving unit that drives a valve body of the switching valve by a signal from the detection unit. A flow meter that is provided upstream of one end of the branch flow path of the main flow path and that shuts off the main flow path only in an emergency, and after a certain time has elapsed since the shut-off valve was opened. It is characterized by comprising means for detecting a change in the rotation frequency of the rotating body and determining whether or not there is leakage of the fluid to be measured on the downstream side of the flow meter based on an increase or decrease in the rotation frequency of the rotating body. Things.

According to the invention of claim (1), after opening the shut-off valve,
The rotation of the rotating body caused by the flow of the fluid to be measured flowing through the main flow path is detected by a signal from the rotation detecting unit, and based on a change in the rotating frequency of the rotating body, the presence or absence of leakage of the fluid to be measured on the downstream side of the flow meter is determined. Since the determination means is provided, a return safety check for checking whether there is a leak on the downstream side when the shutoff valve is opened can be determined in a short time with good responsiveness.

Further, according to the invention of claim (2), a switching means for closing the switching valve after a predetermined time elapses after the shut-off valve is opened, and supplying the fluid to be measured to the rotating body via the branch flow path; The number of rotations of the rotating body that is rotated by the supply of the fluid to be measured from the branch channel is detected by a signal from the rotation detection unit, and the presence or absence of leakage of the fluid to be measured on the downstream side of the flow meter is determined based on a change in the rotation frequency. Since the determination means is provided, the fluid to be measured is supplied to the rotating body through the branch flow path by the switching means,
The rotating body can be efficiently rotated.

Further, according to the invention of claim (3), a change in the rotation frequency of the rotating body is detected after a lapse of a predetermined time after the shut-off valve is opened, and the flow rate is determined based on the increase or decrease in the rotation frequency of the rotating body. The system is equipped with a means for determining the presence or absence of leakage of the fluid to be measured on the downstream side of the meter, so that the change in the rotation frequency of the rotating body is ignored until a certain time has elapsed since the shut-off valve was opened. It is not necessary to detect the frequency change due to the extreme flow rate fluctuation at the beginning of the valve.

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

The main flow path 3 includes an inflow path 3a, a diversion chamber 3b, a measurement chamber 3c, and an outflow path 3
d. A first valve seat 4 is provided between the inflow passage 3a and the flow dividing chamber 3b, and a second valve seat 5 is provided between the flow dividing chamber 3b and the measuring chamber 3c.

Reference numeral 6 denotes a shut-off valve, which is a valve body 6a which is seated on the valve seat 4 from the upstream side.
A coil spring 6b for urging the valve element 6a in the seating direction, and an electromagnetic solenoid 6c for driving the valve element 6a in the unseating direction by supplying a valve opening signal.

Reference numeral 7 denotes a switching valve, which is a valve element 7a that is seated on the valve seat 5 from the downstream side.
A coil spring 7b for urging the valve element 7a in the seating direction, and an electromagnetic solenoid 7c for driving the valve element 7a in the seating direction by supplying a valve opening signal. The valve element 7a is an electromagnetic solenoid 7c.
The disc-shaped valve plate 7a ₂ to the lower end of the rod 7a ₁ that fits within made by fixing with screws or the like. Further, the lower step of the valve plate 7a ₂ is mounted a ring-shaped rubber packing 7a _3.

The solenoids 6 of the shut-off valve 6 and the switching valve 7
c and 7c are mounted and fixed on a flat mounting base 8 that closes the openings 3e and 3f above the valve seats 4 and 5. The openings 3e, 3f and the mounting base 8 are sealed by O-rings 9, 10.

Here, the electromagnetic solenoids 6c and 7c will be described in detail.These electromagnetic solenoids 6c and 7c have a self-holding function, and when the solenoid is excited to attract the iron core, the current of the solenoid is thereafter It is a type that continues to adsorb the iron core even when it is opened. Explaining this according to the embodiment, when the electromagnetic solenoids 6c and 7c are excited, the rods 6a ₁ and 7a ₁ are pulled upward in the drawing. The rods 6a ₁ and 7a ₁ are attracted to permanent magnets (not shown) provided in the electromagnetic solenoids 6c and 7c, and in this state, even if the electromagnetic solenoids 6c and 7c are demagnetized, 6
a ₁ and 7a ₁ hold that position, that is, the position displaced upward.

Also, be added to the opposite direction of the current in lowering the rod 6a _1, 7a ₁ held above <so as to cancel the magnetic field of the permanent magnet> electromagnetic solenoid 6c, 7c from the rod 6a _1, 7
a ₁ is released and descends. After this, electromagnetic solenoids 6c and 7
Even if c is demagnetized, the valve bodies 6a and 7a are valve seats by the coil springs 6b and 7b.
Energized to 4,5 and closes. As described above, the electromagnetic solenoids 6c and 7c of this type are used only at the beginning of the operation, and when the current is supplied, the state can be maintained without supplying the current thereafter, thereby saving power.

In normal flow measurement, and the rod 6a ₁ is moved upward since the electromagnetic solenoid 6c is initially energized, the result is held above, the valve element 6a of the shut-off valve 6 has been lifted. Therefore, if the shut-off valve 6 supplies current only instantaneously so that the magnetic field of the electromagnetic solenoid 6c is canceled only in an emergency, the valve 6a is closed by the coil spring 6b.

Reference numeral 11 denotes a flow rate measuring unit as a detecting means (this detecting means detects a pressure drop on the downstream side such that the valve element 7a is unseated and will be described later in detail). It is attached and fixed to the part 3g.

The flow rate measuring unit 11 has a flow path 11b in a cylindrical main body 11a, and an upstream cone 11c and a downstream cone 11d are supported by a support 11e in the flow path 11b.

Reference numeral 12 denotes a turbine rotor (rotating body) having a plurality of blades 12a on the outer periphery of a hub and provided between an upstream cone 11c and a downstream cone 11d.
It is rotatably supported by bearings 13a and 13b so as to rotate in accordance with the flow rate flowing through the inside. Also, the turbine rotor 12
A magnet 14 is embedded in the hub.

Reference numeral 15 denotes a rotation detection pickup composed of a magnetic sensor or the like, which is embedded in the downstream cone 11c so as to face the magnet 14 of the turbine rotor 12. This pickup 1
5 detects the rotation of the turbine rotor 12, and outputs a pulse corresponding to the rotation to the control circuit 22.

The control circuit 22 is connected to the electromagnetic solenoids 6c and 7c, detects a pulse from the pickup 15, accumulates the flow rate, and opens or closes the switching valve 7 according to the pulse interval.

O-rings 16 and 17 are provided on the outer periphery of the main body 11a of the flow rate measuring section 11, and the space between the inner wall of the mounting portion 3g and the main body 11a is sealed by the O-rings 16 and 17. In addition, mounting part 3g
The inner wall has a first stepped portion 3 g ₁ and the second step portion 3 g _2.
Therefore, the body 11a together with contact with the first stepped portion 3 g _1, to form a nozzle chamber 18 between the second step portion 3 g _2.

Reference numeral 19 denotes a small-diameter nozzle hole, which is formed in the main body 11a so that one end opens to the flow path 11b and the other end opens to the nozzle chamber 18. 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 to the branch chamber 3b and the other end opens to the nozzle chamber 18.
Therefore, the gas passing through the branch channel 20 reaches the nozzle chamber 18 and is injected into the blades 12 a of the turbine rotor 12 through the nozzle holes 19. In this way, the nozzle hole 19 allows the turbine rotor 12
As a result, the turbine rotor 12 rotates at a high speed.

Further, the flow rate measuring section 11 is mounted so as to fit into the mounting section 3g from above, and is easily mounted by removing the lid 21 for closing the mounting section 3g.

Further, a safety device 23 is connected to the control circuit 22, and the safety device 23 is connected to a return safety confirmation switch 24, a seismic sensor 25, for example, a pressure sensor 26 for detecting pressure in the downstream pipe. ing. 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 having a seismic intensity higher than a predetermined level occurs. The seismic sensor 25 detects the occurrence of an earthquake and outputs a signal indicating the occurrence of the earthquake to the safety device 23. The pressure sensor 26 detects the gas pressure in the pipe and outputs the signal to the safety device 23.
Output to

Therefore, the safety device 23 outputs an emergency closing signal to the control circuit 22 so as to urgently close the shutoff valve 6 when the gas pressure is abnormal due to the signal from the seismic sensor 25 or the signal from the pressure sensor 26. I do. When the return safety confirmation switch 24 is closed, the signal is sent to the control circuit 22 via the safety device 23.
The control circuit 22 performs a return safety confirmation operation after opening the shutoff valve 16 as described later.

FIG. 2 shows a schematic configuration of the control circuit 22. 2, a frequency measuring unit 27 is supplied with a pulse from the pickup 15, measures its frequency, and supplies the measured signal to a comparing and judging unit 28. The setting signal from the frequency setting unit 29 and the frequency measuring unit 27 for setting the judgment reference frequencies f ₁ and f ₂ in advance in the comparing and judging unit 28
The comparison signal is supplied to the return safety confirmation control unit 30. The measurement signal from the frequency measurement unit 27 is also supplied to a frequency increase / decrease determination unit 31.The frequency increase / decrease determination unit 31 determines whether the rotation frequency of the turbi rotor 12 is increasing or decreasing, and confirms the return signal to confirm safety. It is supplied to the control unit 30.

The time measurement unit 32 is provided as a timer, and measures, for example, the times T ₁ , T ₂ , T _{3, and the} like after the shut-off valve 6 is opened.

The time T ₁ is the time when the switching valve 7 is closed and the gas flow is switched from the main flow path 3 to the branch flow path 20, and the time T ₂
Is a sufficient time for the gas leakage detection in the nozzle area, time T ₃ is a time sufficient to fill the gas to the downstream side pipe. The comparison determination unit 33 compares the time measurement signal from the time measurement unit 32 with the setting signals of the times T ₁ , T ₂ , and T ₃ from the time setting unit 34, and is set when the measurement signal reaches the setting signal. The determination signal after the elapse of a predetermined time is supplied to the return safety confirmation control unit 30.

The return safety confirmation control unit 30 is connected to the shutoff valve 6, the electromagnetic solenoids 6c and 7c of the switching valve 7, and the display unit 35.

Next, the operation of the flow meter 1 having the above configuration will be described with reference to FIGS. 3 and 4.

As shown in FIG. 2, the control circuit 22 initially causes the shut-off valve 6 to open. Then, as described above, even if the current to the shutoff valve 6 is cut off while the valve element 6a is open upward, that state is maintained. The shut-off valve 6 closes only in an emergency, and in this case, as described above, if a short-time current is supplied to the shut-off valve 6, the shut-off valve 6 closes immediately. Generally, the shut-off valve 6 is held in an open state, and thus the description thereof is omitted.

Now, it is assumed that gas appliances have been started to be used on the downstream side.
For example, suppose that the ignition of the gas heater at home is ignited.
Since the gas usage at this time is very small, the switching valve 7 is in a closed state, and the gas flows from the branch chamber 3b to the blade 12a of the turbine rotor 12 through the branch channel 20, the nozzle chamber 18, and the nozzle hole 19. It is injected.

FIG. 3 shows the relationship between the rotation speed of the turbine rotor 12 and the gas flow rate. As shown in the middle diagram I in FIG. 3, when the ignition of the gas water heater is ignited, the flow rate is very small, but the gas flows through the nozzle.
Since the blades 12a of the turbine rotor 12 are vigorously blown from the 19 holes, the turbine rotor 12 rotates at high speed. That is, due to the use of gas at the ignition of the gas water heater, the number of revolutions of the turbine rotor 12 increases from the point a to the point b as shown by the diagram I in FIG.

The rotation of the turbine rotor 12 is controlled by the pickup 15
The pickup 15 outputs a pulse having a pulse interval corresponding to the rotation speed of the turbine rotor 12 as the magnet 14 embedded in the turbine rotor 12 passes. Then, the control circuit 22 calculates the gas flow rate by integrating the pulses from the pickup 15. Further, the control circuit 22 detects a pulse interval of a pulse input from the pickup 15.

Here, for example, the water heater is ignited and hot water is used. Therefore, the amount of gas used in the measurement downstream of the flow meter 1 increases. In addition, the turbine rotor 12 rotates at a higher speed as the amount of gas used increases,
The number of rotations of twelve reaches point b in FIG.

Since the control circuit 22 checks the pulse interval of the pulse output from the pickup 15, when the gas usage reaches the limit amount “Q ₁ ” of the branch channel 20 and the pulse interval becomes “T”,
A valve opening signal is output to the electromagnetic solenoid 7c.

As a result, the electromagnetic solenoid 7c is excited, and the valve body 7a is attracted upward by the electromagnetic force and is separated from the valve seat 5. Although the valve element 7a moves upward against the spring force of the coil spring 7b, it does not oppose the upstream pressure, and as described later, the coil spring 7b has the spring force set to the minimum force necessary for closing the valve. Therefore, the valve element 7a moves upward with a relatively small driving force.

By the valve opening operation of the switching valve 7, the gas passes through the opening of the valve seat 5, reaches the measurement chamber 3c, passes through the flow path 11b of the flow rate measurement unit 11, and is supplied to the gas appliance downstream from the outflow path 3d. Is done.

Due to the valve opening operation of the switching valve 7, the rotation speed of the turbine rotor 12 is temporarily changed from the point b in the diagram I to c as shown in FIG.
Go down to the point. However, the flow rate of the gas increases due to the increase in the gas usage accompanying the use of the gas water heater, and the rotation speed of the turbine rotor 12 also increases from the point c to the point d in FIG.

In FIG. 3, since the gas is blown from the nozzle holes 19 to the turbine rotor 12 from point a to point b in the diagram I, the rotation speed of the turbine rotor 12 is as shown in FIG.
Although the gas rises steeply, the gas passes through the flow passage 11b having a large flow passage area from the point c to the point d. In this case, the rotation speed of the turbine rotor 12 is slower than that between the points a and b. It will rise on a gradient.

The rotation speed of the turbine rotor 12 from the point c to the point d in the diagram I in FIG.
The control circuit 22 calculates and integrates the flow rate based on the pulse output from the pickup 15.

Here, the use of the gas water heater is stopped, and only the ignition is ignited to reduce the gas consumption.
As the gas usage in the gas water heater decreases, the gas flow rate passing through the flow path 11b of the flow rate measurement unit 11 also decreases.
Accordingly, the rotation speed of the turbine rotor 12 is also shown in FIG.
From point d to point c.

In the control circuit 22, hysteresis is given to the valve closing operation and the valve opening operation of the switching valve 7 in order to prevent the opening and closing operations of the valve element 7a from fluttering. That is, the control circuit 22 determines that the pulse interval of the pulse from the pickup 15 is equal to or longer than “T ₁ ” (where T ₁ > T, and for example, 250 msec is stored as T _{1 in the} control circuit 22. and detects whether the time T ₁ can be arbitrarily changed.). Therefore,
The gas flow rate is reduced to “Q ₂ ”, and the number of revolutions of the turbine rotor 12 is further reduced from the point c to the point e (in FIG.
When the pulse interval T ₁ has been reached, a valve closing signal is output to the switching valve 7.

As described above, since the electromagnetic solenoid 7c of the switching valve 7 is a self-holding type solenoid, a current in a direction opposite to the valve opening signal is supplied to the electromagnetic solenoid 7c. Therefore, the electromagnetic solenoid 7c generates a reverse magnetic field that cancels the magnetic field of the permanent magnet that holds the valve element 7a at the valve open position by supplying the valve closing signal. As a result, the valve element 7a held at the valve open position
Abuts against the valve seat 5 by the spring force of the spring 7b, and closes the main flow path 3.

Accordingly, the gas reaches the nozzle chamber 18 from the branch chamber 3b via the branch channel 20, and the blade 12 of the turbine rotor 12 from the nozzle hole 19.
Squirted into a. Therefore, the turbine rotor 12 rotates at high speed upon receiving the gas injected from the nozzle holes 19. That is, the rotation speed of the turbine rotor 12 rises from point e in the diagram I in FIG. 3 to point f. When the ignition of the gas water heater is stopped, the gas usage becomes zero, and the rotation speed of the turbine rotor 12 drops from the point f to the point a.

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

As mentioned above, when an earthquake larger than the specified magnitude occurs,
The control circuit 22 closes the shut-off valve 16 by energizing the electromagnetic solenoid 6c of the shut-off valve 6 because the seismic sensor 25 is activated and its signal is input to the safety device 23. After the earthquake, the gas supply line is cut off by closing the shut-off valve 6, and the family member closes the main valve of the gas appliance in the house.

When the earthquake stops and calms down, the family member closes the return safety confirmation switch 24. As a result, the return safety confirmation control unit 30 of the control circuit 22 executes the processing shown in FIG. The fifth
The figure shows the change in the rotation frequency 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 S
1), the safety confirmation control unit 30 opens the shutoff valve 6 (step S2). Therefore, gas from the upstream pipe (not shown) passes through the valve seats 4 and 5 in the main flow path 3 and flows into the flow rate measurement unit 11 (in the flow path 11b provided with the turbine rotor 12). The downstream side pipe (not shown) is filled from the outlet 3d.

A certain time T ₃ (fifth) until the gas is filled up to the end of the downstream pipe connecting the flow meter 1 and the household gas appliance.
(Shown in the figure). Therefore, the shut-off valve 6 see whether the T ₃ preset time has elapsed by the time setting unit 34 from the closed (step S3).

When the time T ₃ has elapsed at step S _3, to determine whether lower than the reference frequency f ₁ to f (rotational frequency of the turbine rotor 12) pulse frequency is preset by the frequency setting unit 29 from the pickup 15 (step S4).

Note that, in FIG. 5, as if the frequency f> f ₁ is roughly divided into the diagram I, II, can be considered three patterns of III.

F> is when the f ₁ in step S4, by opening the switching valve 7 (step S5), and checks whether the frequency f is decreasing (step S6). Here, as described above, the switching valve 7 is opened because the flow rate in FIG. 3 has exceeded Q ₁ , causing the transition from b to c, that is, the flow from the gas injection from the nozzle hole 19. This is for switching to gas supply from the path 3b. If the frequency does not decrease due to the opening of the switching valve 7 in step S6 (shown by a diagram I in FIG. 5), it is determined that there is a gas leak on the downstream side, and the shutoff valve 6 is closed (step S7). ).

Then, a display indicating that there is a gas leak is performed on the display device 35. However, when the frequency f decreases in step S6 (shown by the diagrams II and III in FIG. 5), first, the time T ₁ (FIG. 5) after the shut-off valve 6 is opened by the return safety confirmation operation. ) When the frequency f becomes substantially constant (step S).
8, S9), it is determined that there is a gas leak on the downstream side, and the shutoff valve 6 is closed.

In the diagram III shown in FIG. 5, after the shut-off valve 6 is opened, as the gas from the upstream pipe is supplied to the downstream side,
This indicates that when the rotation of the turbine rotor 12 increases and the downstream pipe is filled with gas to some extent, the rotation speed of the turbine rotor 12 decreases with the peak at the point a.

Further, in step S9, when it is not f ≒ constant returns to step S8, continuing to the f ≒ constant determined until time T ₁ is passed. When not the f ≒ predetermined time T ₁ within the leads to step 10, to close the switching valve 7. This is for detecting gas leak with higher sensitivity by injecting gas from the nozzle hole 19. At this time, if the amount of gas leakage is large in the downstream measurement, as shown by a-b in FIG.
The rate of increase of the number of rotations of 12 increases.

Next, it is determined whether the frequency f is higher than or equal to a preset reference frequency f ₂ (where f ₂ > f ₁ ) (step S11). In this step S11, to step S7 as when the frequency f after the frequency has passed the diagram III time T ₁ as shown in (5 shown in FIG.) Exceeds f _2, it is gas leak downstream Then, the shutoff valve 6 is closed.

Step switching valve 7, S12 is closed (shown in FIG. 5) time T ₂ from which look at whether elapsed time T ₁
Processing between step S11 in T ₂ is repeated Kaee from. Then, the return safety check leads to step S13 as well frequency f after time T ₂ as shown in the diagram in Figure 5 V (shown in dashed lines) has passed there was no gas leakage if f ₂ or less The process ends. In addition, the end is displayed on the display device 35 to inform the family.

Further, in step S4, the higher the gas pressure on the downstream side pipe, when sufficiently filled, because the frequency f is to be f <f ₁ as shown in the diagram IV of FIG. 5, when there is no gas leakage The process directly proceeds to step S13 as a determination, and the process of the return confirmation ends. Thereafter, normal flow rate measurement is performed.

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

6 and 7 show a second embodiment of the present invention. In FIG. 6, the same parts as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

In FIG. 6, a flow rate pulse from the pickup 15 is supplied to a flow rate calculating / correcting section 36, and the flow rate pulse is corrected to an error due to, for example, a temperature difference by the flow rate calculating / correcting section 36 and input to a flow rate pulse output control section 37. Is done. The flow rate pulse output control unit 37 also receives signals from the comparison determination unit 28, the frequency increase / decrease determination unit 31, and the comparison determination unit 33.

Further, the flow pulse output control unit 36 outputs a flow pulse to the flow integration unit 38 and the return safety confirmation control unit 30. Then, the flow rate calculator 38 integrates the flow rate pulses, and causes the display 35 to display the flow rate.

The return safety confirmation control unit 30 responds to the flow pulse output from the flow pulse output control unit 37,
The switching valve 7 is opened or closed. The switching valve 7 is provided with an opening / closing sensor 39, and the opening / closing signal is output to the flow rate pulse output control unit 37 and the return safety confirmation control unit 30. Further, the flow rate integrating section 38 may be directly connected to the flow rate calculating and correcting section 36.

Next, the return safety confirmation control unit 30 of the control circuit 22 shown in FIG.
Will be described with reference to FIG.

First, after the earthquake stops, when the return safety confirmation switch 24 is closed (step S21), the shutoff valve 6 is opened (step S22). By opening the shut-off valve 6, the gas is filled downstream as in the first embodiment, and the turbine rotor
12 starts rotating. After the shut-off valve 6 is opened, the output state of the flow pulse is ignored until time T ₃ (see FIG. 5) (step S23). Turbine rotor 12 during this time T ₃
When the rotation frequency f of not reach the f _1, not unseated valve body 7a of the switching valve 7 from the valve seat 5, the switching valve 7 does not open, opening and closing sensor 39 outputs a close signal.

Therefore, in step S24, when there is a closing signal of the switching valve 7, the state is as shown by the diagram IV in FIG. 5, it is determined that there is no gas leakage on the downstream side, and the process proceeds to step S33 to confirm the return safety. finish.

If there is no close signal in step S24, it is determined whether the frequency f decreases (step S25). Step S25
If the frequency f does not decrease (shown in the diagram I in FIG. 5), a flow rate pulse is output (step S26), and this is detected to determine that there is gas leakage, and the shutoff valve 6 is closed. (Step S27). Then, the display unit 35 displays that fact. If the frequency f does not decrease in step S25, the output of the flow pulse is stopped (step S2).
8).

Then, the switching valve 7 is to determine whether the frequency f from the closed within the time T ₁ is substantially constant (step S29, S3
0).

At this time, if the frequency f becomes substantially constant (the middle diagram in FIG. 5).
A flow pulse (shown in II) is output and detected, and it is determined that there is gas leakage (step S26), and the shutoff valve 6 is closed.

Further, when not a f ≒ constant within the time T _1, closing the switching valve 7 (step S31). As a result, gas is ejected from the nozzle hole 19 toward the turbine rotor 12.
In this state, it is checked whether or not the frequency f is equal to or more than f ₂ (step S32). If f ≧ f ₂ , a flow rate pulse is output, and by detecting this, it is judged downstream that there is a gas leak. The shutoff valve 6 is closed (steps S26 and S2).
7).

Further, when the frequency f is f ₂ or less in step S32, continues to monitor the change in the frequency f to the time T ₂ (step S33), also determines the frequency f is that no leakage if f ₂ or less therebetween, Finish the return safety confirmation (Step S3
Four).

After this, the end of the return safety confirmation is displayed on the display unit 35, and the normal flow rate measurement state is set.

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

Further, in the second embodiment, since the flow rate integrating section 38 and the return safety confirmation control section 30 are separately provided, the flow rate measurement processing and the safety confirmation processing are separated, and the input / output of the signal is “flow rate pulse”. ”Alone to simplify the configuration.

8 and 9 show a third embodiment of the present invention. still,
The configuration of the control circuit 22 is the same as that of FIG.

When the return safety confirmation switch 24 is closed, the return safety confirmation control unit 30 receives the signal and executes the processing shown in FIG. After the shut-off valve 6 is opened, the turbine rotor
Twelve rotational frequencies can be roughly divided into diagrams I, II and III as shown in FIG. 9, and FIG. 9 is simpler than FIG. 5 in the case of the first and second embodiments described above. It has been turned.

In FIG. 8, when the return safety confirmation switch 24 is closed (step S43), the shutoff valve 6 is opened (step S4).
Four). Next, the shut-off valve 6 in Step S45 are to see if time has passed T ₄ from the opening, to ignore the flow pulses until the time T ₄ (step S46). Filling the gas is almost ended in the downstream side pipe during this time T ₄ has elapsed.

When the time reaches T _4, the frequency f of the turbine rotor 12 determines whether decreased (step S47). If the frequency f has not decreased in this step S47 (the ninth
In the diagram, a flow chart is output on the assumption that there is a gas leak on the downstream side (step S48), and the shutoff valve 6 is closed by detecting this (step S49). If the frequency f has decreased in step S47 (the ninth
The output of the flow rate pulse is stopped (steps S50). Then, the shut-off valve 6 is opened to the time T ₅ has elapsed (snap S51), the frequency f to monitor whether substantially constant (step S52).

When the time T ₅ within the rotation frequency f of the turbine rotor 12 is constant without decreasing executes the processing of step S48,49, it closes the shutoff valve 6 it is determined that there is a gas leak. or,
Return safety of the confirmation is finished when not time T ₅ within the f ≒ constant (step S53). After that, the fact is displayed on the display unit 35, and a normal flow rate measurement state is set. The time T ₅ is set to a time sufficient to determine the presence or absence of gas leakage to safely check.

Thus, as in the second embodiment, the presence or absence of gas leakage can be detected with high sensitivity by monitoring the change in the frequency f without using the switching valve open / close signal.

As a modification of the first and second embodiments, for example, instead of step S11 in FIG. 4 and step S32 in FIG.
Compares the gradient (differential coefficient df / dt) of the frequency change after the valve is closed with a predetermined value (α), and when (df / dt) ≧ α, executes the processing of step S7 or S26, S27 You may do it.

As another modified example, instead of the steps S11 and S32, the rate of change ε of the frequency after the switching valve 7 is closed is compared with a predetermined value (β). S7
May execute the processes of S26 and S27.

Effect of the Invention As described above, according to the invention of claim (1), after the shut-off valve is opened, the rotation of the rotating body accompanying the flow of the fluid to be measured flowing through the main flow path is detected by the signal from the rotation detection unit. The conventional membrane meter takes a long time to detect a leak at a very small flow rate because the conventional membrane meter has a means for determining the presence or absence of leakage of the fluid to be measured on the downstream side of the flow meter based on a change in the rotation frequency of the rotating body. On the other hand, in the present invention, it does not take much time to detect a leak at a very small flow rate, and a leak on the downstream side can be detected with good responsiveness. Further, in the conventional turbine type flow meter, after the shut-off valve is opened, the leak cannot be detected while the turbine rotor continues to rotate due to inertia, whereas in the present invention, the rotating body is rotating. Since the leak can be detected in the state, the leak on the downstream side can be detected in a shorter time, and the reliability of the leak detection can be improved.

Further, according to the invention of claim (2), a switching means for closing the switching valve after a predetermined time elapses after the shut-off valve is opened, and supplying the fluid to be measured to the rotating body via the branch flow path; The number of rotations of the rotating body that is rotated by the supply of the fluid to be measured from the branch channel is detected by a signal from the rotation detection unit, and the presence or absence of leakage of the fluid to be measured on the downstream side of the flow meter is determined based on a change in the rotation frequency. Since the determination means is provided, the fluid to be measured is supplied to the rotating body through the branch flow path by the switching means,
The rotating body can be efficiently rotated, and even if the amount of leakage is relatively small, leakage on the downstream side can be reliably detected.

Further, according to the invention of claim (3), a change in the rotation frequency of the rotating body is detected after a lapse of a predetermined time after the shut-off valve is opened, and the flow rate is determined based on the increase or decrease in the rotation frequency of the rotating body. The system is equipped with a means for determining the presence or absence of leakage of the fluid to be measured on the downstream side of the meter, so that the change in the rotation frequency of the rotating body is ignored until a certain time has elapsed since the shut-off valve was opened. It is not necessary to detect the frequency change due to the extreme flow rate fluctuation at the beginning of the valve, and it is not necessary to execute useless arithmetic processing.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a first embodiment of a flow meter according to the present invention,
FIG. 2 is a schematic configuration diagram of a control circuit, FIG. 3 is a diagram showing a relationship between a flow rate and a rotation speed of a turbine rotor, FIG. 4 is a flowchart for explaining processing executed by the control circuit, and FIG. Is a diagram showing a change in the rotation frequency of the turbine rotor after the shut-off valve is opened, FIG. 6 is a block diagram of a control circuit according to the second embodiment of the present invention, and FIG. 7 is a control circuit shown in FIG. FIG. 8 is a flowchart of a process executed by the third embodiment of the present invention.
FIG. 9 is a flow chart of the embodiment, and FIG. 9 is a diagram showing a change in the rotation frequency of the turbine rotor which is referred to when explaining the flow chart of FIG. 1 ... Flow meter, 2 ... Flow meter body, 3 ... Main flow path, 4 ...
... first valve seat, 5 ... second valve seat, 6 ... shut-off valve, 7 ...
... Switching valve, 11 ... Flow measurement unit, 12 ... Turbine rotor,
14 ... magnet, 15 ... pickup, 18 ... nozzle chamber, 19 ... nozzle hole, 20 ... shunt channel, 22 ... control circuit,
24 ... Return safety confirmation switch, 25 ... Seismic sensor, 26 ... Pressure sensor, 30 ... Return safety confirmation control unit, 37 ... Flow pulse output control unit.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G01F 1/00 G01F 1/10 G01F 1/06 G01F 3/22

Claims (3)

(57) [Claims] 1. A main flow path provided in a flow meter main body and through which a fluid to be measured flows, a rotating body rotatably provided in the main flow path and rotating according to the flow rate of the fluid to be measured, and a rotation of the rotating body. A rotation detection unit for detecting, a switching valve provided in the main flow path on the upstream side of the rotator, the switching valve including a valve seat and a valve body that shuts off the main flow path by sitting on the valve seat; A branch passage for supplying a fluid to be measured to the rotating body, the branch path being open to the main flow path on the upstream side of the rotating body, and the other end being opened so as to face the outer periphery of the rotating body so as to rotate the rotating body; Detecting means for detecting a pressure difference between an upstream side and a downstream side of the switching valve, a valve driving unit for driving a valve element of the switching valve by a signal from the detecting means, A shutoff valve that is provided upstream of one end of the branch flow path and closes the main flow path only in an emergency A flowmeter comprising: after opening of the shut-off valve, detects rotation of the rotating body due to the flow of the fluid to be measured flowing through the main flow path by a signal from a rotation detecting unit, and changes the rotation frequency of the rotating body. A means for determining the presence or absence of leakage of the fluid to be measured on the downstream side of the flow meter based on the flow rate. 2. A main flow path provided in a flow meter main body, through which a fluid to be measured flows, a rotating body rotatably provided in the main flow path and rotating in accordance with a flow rate of the fluid to be measured, and a rotation of the rotating body. A rotation detection unit for detecting, a switching valve provided in the main flow path on the upstream side of the rotator, the switching valve including a valve seat and a valve body that shuts off the main flow path by sitting on the valve seat; A branch passage for supplying a fluid to be measured to the rotating body, the branch path being open to the main flow path on the upstream side of the rotating body, and the other end being opened so as to face the outer periphery of the rotating body so as to rotate the rotating body; Detecting means for detecting a pressure difference between an upstream side and a downstream side of the switching valve, a valve driving unit for driving a valve element of the switching valve by a signal from the detecting means, A shutoff valve that is provided upstream of one end of the branch flow path and closes the main flow path only in an emergency A switching means for closing the switching valve after a lapse of a predetermined time after the shut-off valve is opened, and supplying the fluid to be measured to the rotating body through the branch flow path; and The number of rotations of the rotating body that is rotated by the supply of the fluid to be measured from the branch channel is detected by a signal from the rotation detection unit, and leakage of the fluid to be measured on the downstream side of the flow meter is detected based on a change in the rotation frequency. A flow meter comprising means for judging the presence or absence. 3. A main flow path provided in the flow meter main body, through which a fluid to be measured flows, a rotating body rotatably provided in the main flow path and rotating in accordance with the flow rate of the fluid to be measured, and a rotation of the rotating body. A rotation detection unit for detecting, a switching valve provided in the main flow path on the upstream side of the rotator, the switching valve including a valve seat and a valve body that shuts off the main flow path by sitting on the valve seat; A branch passage for supplying a fluid to be measured to the rotating body, the branch path being open to the main flow path on the upstream side of the rotating body, and the other end being opened so as to face the outer periphery of the rotating body so as to rotate the rotating body; Detecting means for detecting a pressure difference between an upstream side and a downstream side of the switching valve, a valve driving unit for driving a valve element of the switching valve by a signal from the detecting means, A shutoff valve that is provided upstream of one end of the branch flow path and closes the main flow path only in an emergency A flow meter comprising: after the shut-off valve is opened, a change in the rotation frequency of the rotating body is detected after a lapse of a predetermined time, and the downstream of the flow meter is determined based on an increase or decrease in the rotation frequency of the rotating body. A means for judging the presence or absence of leakage of the fluid to be measured on the side.