JPH0726659Y2 - Flowmeter - Google Patents

Description

TECHNICAL FIELD The present invention relates to a flow meter, and in particular, is configured to prevent erroneous measurement due to an external magnetic field applied to a rotating body provided with a magnet for rotation detection. Flow meter.

2. Description of the Related Art In a flow meter that measures the flow rate of a fluid to be measured by rotating a rotating body such as a turbine rotor, for example, a magnet is provided in the turbine rotor, and the rotation of the turbine rotor is magnetically detected by a pickup such as a magnetic sensor. . Therefore, in this type of flow meter, the presence of an external magnetic field is affected by, for example, the rotational sensitivity of the turbine rotor being reduced. For example, in the case of an industrial turbine meter or a water meter, the rotational force when the fluid rotates the turbine rotor is sufficiently large, and the ultra-low speed rotation range, that is, the minute flow rate is small, the external magnetic field The decrease in the rotational sensitivity of the turbine rotor due to the influence did not pose a problem.

However, in the case of city gas used in ordinary households, when a gas appliance, for example, a gas water heater is ignited, the amount of gas used is extremely small, and a plurality of gas appliances,
For example, when a water heater, a bath kettle, a gas stove, etc. are used at the same time, the amount of gas used increases. Therefore, since the flow meter used to measure city gas measures a wide range of flow rates from a minute flow rate to a large flow rate, the turbine rotor should be as lightweight as possible and the rotation resistance of the turbine rotor should be reduced. It supports the rotating shaft. Therefore, in the above-mentioned flowmeter, when an external magnetic field acts on the magnet provided in the turbine rotor, the rotational resistance of the turbine rotor increases, and the effect thereof is likely to appear remarkably.

Therefore, in the conventional flowmeter, due to the influence of the external magnetic field, the rotation speed of the turbine rotor decreases or the rotation resistance increases and the turbine rotor starts rotating due to the influence of the external magnetic field. In that case, the measurement sensitivity is lowered.

However, since the conventional flowmeter is not provided with any means for detecting that an external magnetic field is applied,
For example, a device with magnetic force is installed near the flow meter,
Alternatively, even if the magnets are used in the vicinity of the flow meter, the flow rate is often measured without knowing that the leakage magnetic field from these magnets acts on the magnet of the turbine rotor. In that case, the conventional flowmeter has a problem that a measurement error occurs or measurement becomes impossible due to the above reason.

Then, this invention aims at providing the flow meter which solved the said problem.

Means and Actions for Solving Problems The present invention provides, in the above-mentioned flowmeter, a detection member for detecting that an external magnetic field is applied in the vicinity of the rotating body, and a means for issuing an alarm by the output of the detection member. It is provided to prevent erroneous measurement by detecting and notifying when the rotating body is affected by an external magnetic field.

Embodiment FIG. 1 and FIG. 2 show an embodiment of the flowmeter according to the present invention. In FIG. 1, the flow meter 1 is arranged in the middle of a pipe (not shown) for feeding gas such as city gas. A main flow path 3 is formed inside the flowmeter main body 2 of the flowmeter 1.

Further, the main flow path 3 includes an inflow path 3a, a diversion chamber 3b, a measurement room 3c, and an outflow path 3d.
And consists of. 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.

6 is a shutoff valve, and a valve body 6a seated on the valve seat 4 from the upstream side,
It has a coil spring 6b for urging the valve body 6a in the seating direction and an electromagnetic solenoid 6c for driving the valve body 6a in the seating direction by supplying a valve opening signal.

7 is a switching valve, and a valve body 7a seated on the valve seat 5 from the downstream side,
It has a coil spring 7b for urging the valve body 7a in the seating direction and an electromagnetic solenoid 7c for driving the valve body 7a in the seating direction by supplying a valve opening signal. Incidentally, the valve body 7a is formed by a disc-shaped valve plate 7a ₂ to the lower end of the rod 7a ₁ that fits within the solenoid 7c secured by screws or the like. Further, the lower step of the valve plate 7a ₂ is mounted a ring-shaped rubber packing 7a _3.

The electromagnetic solenoids 6c, 7 of the shutoff valve 6 and the switching valve 7 are
The c is mounted and fixed on a mounting base 8 on a flat plate that closes the openings 3e and 3f above the valve seats 4 and 5. Further, a space between the openings 3e, 3f and the mounting base 8 is sealed by a 0 ring 9.

Incidentally, here, when the electromagnetic solenoids 6c and 7c are described in detail, these electromagnetic solenoids 6c and 7c have a self-holding function. It is a type that keeps adsorbing the iron core even if it is opened. Explaining in correspondence with the embodiment, when the electromagnetic solenoids 6c and 7c are excited, the rods 6a ₁ and 7a ₁ are pulled up in the figure. And a permanent magnet (not shown) provided in the electromagnetic solenoids 6c, 7c
The rods 6a ₁ and 7a ₁ are adsorbed on. In this state, even if the electromagnetic solenoids 6c and 7c are demagnetized, the rods 6a ₁ and 7a ₁ maintain their positions, that is, the positions displaced upward. To lower the rods 6a ₁ and 7a ₁ held above, a current in the opposite direction to the above is applied (to cancel the magnetic field of the permanent magnet).
a ₁ , 7a ₁ is released and descends. After this electromagnetic solenoid
Even if 6c and 7c are demagnetized, the coil springs 6b and 7b urge the valve bodies 6a and 7a to the valve seats 4 and 5 to close them. As described above, the electromagnetic solenoids 6c and 7c of this type are used only in the initial stage of the operation, and if the current is supplied, the state can be maintained thereafter without supplying the current, which leads to power saving.

During normal flow rate measurement, since the electromagnetic solenoid 6c is initially excited, the rod 6a ₁ moves upward and is held above, so that the valve body 6a of the shutoff valve 6 is separated. Therefore, if the shutoff valve 6 supplies a current only momentarily so that the magnetic field of the electromagnetic solenoid 6c is canceled only in an emergency, the valve body 6a will be a coil spring.
The valve is closed by 6b.

Reference numeral 10 denotes a flow rate measuring unit, which is attached and fixed to a mounting portion 3g on the downstream side of the switching valve 7.

The lower end of the flow rate measuring unit 10 is a step 3h on the inner wall of the mounting unit 3g.
And its upper end is in contact with the protrusion 21a of the lid 21.
Therefore, by fixing the lid 21 to the flowmeter main body 2, the flow rate measuring unit 10 is held by the annular mounting portion 3g without rattling, and is mounted in a state in which upward and downward rattling is also suppressed. In addition, in FIG. 1, the step portion 3h in the mounting portion 3g seems to be in contact with the lower end of the flow rate measuring portion 10 at one point, but in reality, the step portion 3h is on the switching valve 7 side (upstream side). In order to secure a flow path from the right side of the flow rate measuring unit 10, the lower end of the flow rate measuring unit 10 is formed so as to come into contact with more than half of the right side (in FIG. 1) except for a part on the left side.

The flow rate measuring unit 10 has a flow passage 10b in a cylindrical main body 10a,
An upstream side cone 10c and a downstream side cone 10d designated by the support column 10e are screwed into the inside of 10b.

Reference numeral 11 is a reed switch (detection member), which is normally open, but has a structure in which internal contacts are magnetically attracted and brought into contact when an external magnetic field is applied. This reed switch
In FIG. 1, two 11 are arranged on both the left and right sides of the turbine rotor 12.

Further, recesses 10a ₁ for accommodating the reed switches 11 are provided at 180 ° intervals on the outer periphery of the main body 10a of the flow rate measuring unit 10, and the recesses 10a ₁ are pipes 10f fitted to the outer periphery of the main body 10a.
Is blocked by. Therefore, the reed switch 11 is held near the turbine rotor 12.

As shown in FIG. 2, the pair of reed switches 11 are signal lines.
A battery 24 and an alarm lamp 25 are connected in parallel via 23. The alarm lamp 25 lights up when either one of the pair of reed switches 11 is closed, and notifies that the turbine rotor 12 is affected by the external magnetic field. The alarm lamp 25 may be provided in the vicinity of the flowmeter 1, but the signal line 23 may be extended and installed in a home, for example, to give an alarm to a resident.

As shown in FIG. 1, the reed switch 11 is arranged in the radial direction of the turbine rotor 12 because the turbine rotor 12 is easily affected by the magnetic field from the radial direction.
This is because the rotation resistance increases.

The turbine rotor (rotating body) 12 has a plurality of blades on the outer circumference of the hub.
12a and is provided between the upstream cone 10c and the downstream cone 10d. Further, the rotating shaft 12b of the turbine rotor 12 has a bearing 13 so that the rotating shaft 12b rotates in accordance with the flow rate flowing in the flow path 10b.
It is rotatably supported by a and 13b. Two magnets 14 are held on the hub of the turbine rotor 12 at 180 ° intervals.

15 is a rotation detecting pickup including a magnetic sensor,
It is embedded in the downstream cone 10c so as to face the magnet 14 of the turbine rotor 12. This pickup 15 has a magnet 14
The rotation of the turbine rotor 12 is magnetically detected by the passage, and a pulse corresponding to the rotation is output to the control circuit 22.

The control circuit 22 is connected to the electromagnetic solenoids 6c and 7c,
The pulse from the pickup 15 is detected, the flow rate is integrated, and the switching valve 7 is opened or closed according to the pulse interval.

O-rings 16 and 17 are provided in the groove of the inner wall of the annular mounting portion 3g, and the O-rings 16 and 17 seal between the flow rate measuring unit 10 and the mounting portion 3g.

Reference numeral 19 denotes a small-diameter nozzle hole, which is formed in the main body 10a so that one end thereof opens into the flow path 10b and the other end thereof opens into a nozzle chamber 18 which is recessed in the inner wall of the mounting portion 3g. 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 in a tangential direction.

Reference numeral 20 denotes a branch flow passage, which is provided so that one end thereof opens into the flow dividing chamber 3b and the other end thereof opens into the nozzle chamber 18. Therefore, the gas passing through the branch flow passage 20 reaches the nozzle chamber 18 and is jetted to the blade a of the turbine rotor 12 through the nozzle hole 19. By doing so, even if the flow rate used on the downstream side is minute, the nozzle hole 19 causes the gas to be directly ejected to the turbine rotor 12, so that the turbine rotor 12 rotates at high speed.

Further, the flow rate measuring unit 10 is mounted so as to fit into the mounting portion 3g from above, and can be easily mounted by removing the lid 21 that closes the mounting portion 3g.

Next, the operation of the flow meter 1 having the above structure will be described with reference to FIG.

As shown in FIG. 3, the initial control circuit 22 opens the shutoff valve 6 in the open state. Then, as described above, even if the current to the shutoff valve 6 is cut off, the valve body 6a is kept open in the upward state. The shutoff valve 6 is closed only in an emergency and is normally opened.

Now, it is assumed that gas appliances have started to be used on the downstream side. For example, suppose the ignition of a gas water heater at home is ignited. Since the amount of gas used at this time is very small, the switching valve 7 is in the closed state, and the gas flows from the diversion chamber 3b to the diversion channel 20 and the nozzle chamber 1
8, it is injected to the blades 12a of the turbine rotor 12 through the nozzle holes 19.

Here, when the ignition of the gas water heater is ignited, the flow rate is very small, but the gas flows from the nozzle 19 holes to the blades of the turbine rotor 12.
The turbine rotor 12
Rotates at high speed.

The rotation of the turbine rotor 12 is magnetically detected by the pickup 15, and the pickup 15 has a pulse interval according to the rotation speed of the turbine rotor 12 as the magnet 14 provided on the turbine rotor 12 passes. Output pulse. Then, the control circuit 22 integrates the pulses from the pickup 15 to calculate the gas flow rate. Also the control circuit
22 detects the pulse interval of the pulses input from the pickup 15.

Here, for example, the hot water is ignited to use the hot water. Therefore, the amount of gas used on the downstream side of the flow meter 1 increases. Further, the turbine rotor 12 rotates at a higher speed as the amount of gas used increases.

Since the control circuit 22 is looking at the pulse interval of the pulses output from the pickup 15, when the gas usage reaches the limit of the shunt 20, the valve opening signal is output to the electromagnetic solenoid 7c.

As a result, the electromagnetic solenoid 7c is excited and the electromagnetic force causes the valve body 7a to be attracted upward and separated from the valve seat 5. In addition,
The valve body 7a moves upward against the spring force of the coil spring 7b, but does not oppose the upstream pressure, and as described later, the coil spring
Since the spring force of 7b is set to the minimum force required to close the valve, the valve body 7a moves upward with a relatively small driving force.

By the valve opening operation of the switching valve 7, the gas reaches the measurement chamber 3c through the opening of the valve seat 5, passes through the flow passage 10b of the flow rate measurement unit 10, and is supplied to the gas appliance downstream of the outflow passage 3d. To be done.

The flow rate of the gas supplied through the valve seat 5 is also measured by the turbine rotor 12, and the rotational speed of the turbine rotor 12 at this time is magnetically detected by the pickup 15 as described above. Then, the control circuit 22 calculates and integrates the flow rate based on the pulse output from the pickup 15.

Here, the flow meter 1 that measures the flow rate as described above
It is assumed that a device having magnetic force is placed near the. As a result, in the flow meter 1, as described above, the turbine rotor
12 is affected by the external magnetic field, and the number of rotations is reduced, and the measurement sensitivity in a minute flow rate range is reduced.

However, when a device that generates a leakage magnetic field is placed, the reed switch 11 is immediately closed to detect the generation of the external magnetic field. When the reed switch 11 is closed, the alarm lamp 25 is turned on to inform that the flowmeter 1 is erroneously measured due to the influence of the external magnetic field.

Thereby, the housekeeper can be careful not to place the device having the magnetic force in the vicinity of the flowmeter 1 that he or she notices abnormally, and the erroneous measurement of the flowmeter 1 is minimized.

FIG. 4 shows a modification of the present invention. In FIG. 4, when a device having a magnetic force is installed near the flowmeter 1, the reed switch 11 is closed as described above. The control circuit 22 receives a signal from the reed switch 11 and causes the speaker 26 to announce a notification that the device is excluded.

The speaker 26 is disposed in the vicinity of the flowmeter 1, and a person who carries the device by an announcement from the speaker 26 moves the device to another place without installing the device near the flowmeter 1. As a result, the turbine rotor 12 of the flow meter 1
The external magnetic field applied to is removed, and erroneous measurement is prevented.

The speaker 26 may be installed not only in the vicinity of the flow meter 1 but also inside the building, for example. In this case, the speaker
The family member who hears the announcement from 26 can caution the person carrying the above-mentioned device to separate the device from the flow meter 1.

FIG. 5 shows another modification.

Even if the announcement is made by the speaker 26 as described above, the announcement may not be effective if, for example, a child or the like is holding the magnet. In such a case, as shown in FIG. 5, the reed switch 11 is first closed by the external magnetic field, and when the signal is input to the control circuit 22, the control circuit 22 is separated from the flowmeter 1 by the speaker 26. Make an announcement.

The control circuit 22 energizes the electromagnetic solenoid 6c of the shutoff valve 6 when the signal from the reed switch 11 is input even after the announcement. As a result, the valve body 6a of the shutoff valve 6 held in the valve opening position is released from its self-holding by the excitation of the electromagnetic solenoid 6c, and is seated on the valve seat 4 by the pressing force of the spring 6b and the upstream pressure. Close the valve.

In this way, when the external magnetic field cannot be removed even by announcement from the speaker 26 due to mischief or the like, the shutoff valve 6 is closed to stop the gas supply and prevent the flow rate measurement from being erroneously measured.

Although the reed switch is used as the detecting member for detecting the external magnetic field in the above-described embodiment, the present invention is not limited to this.

Further, in the above embodiment, two reed switches are provided in the flow rate measuring unit, but the number of reed switches is not limited to two, and one or three or more may be used.

Further, the position of the reed switch is not limited to the flow rate measurement unit,
Other locations may be used as long as they are near the turbine rotor.

Further, in the above-described embodiment, the description has been made assuming that the flow rate of city gas is measured, but the present invention is not limited to this, and it is of course applicable to a flow meter that measures other fluids.

Effect of the Invention As described above, the flowmeter according to the present invention detects that an external magnetic field is applied and issues an alarm, so that even if a device having magnetic force is installed near the flowmeter, for example. , It is possible to be careful not to immediately issue an alarm from the display lamp or speaker to install such a device near the flowmeter, which can eliminate the influence of the external magnetic field and prevent erroneous measurement. Can be improved. Also, if the external magnetic field does not disappear even if it is tampered with by a magnet and the speaker announces, for example, the shutoff valve is closed based on the output signal from the detection member to force erroneous measurement. It has features such as prevention.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of an embodiment of a flow meter according to the present invention, FIG. 2 is a circuit diagram for detecting an external magnetic field and issuing an alarm, and FIG. 3 is a vertical section when a switching valve is closed. FIG. 4 is a circuit diagram of a modification of the present invention, and FIG. 5 is a circuit diagram of another modification of the present invention. 1 ... Flowmeter, 2 ... Flowmeter main body, 3 ... Main flow path, 6 ... Shut-off valve, 7 ... Switching valve, 10 ... Flow rate measuring unit, 11 ... Reed switch, 12 ... Turbine rotor, 14 ... Magnet, 15 ... Pickup, 22 ... Control circuit, 24 ... Battery, 25 ... Warning lamp, 26
… Speaker.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Creator Keiichi Miyamoto 1-17-20 Kitamachi, Kokubunji, Tokyo (72) Creator Hiroyuki Amemori 3-10-10 Masugata, Tama-ku, Kawasaki City, Kanagawa Prefecture (72) Creator Teruhisa Kojima 1-7-16 Weir, Tama-ku, Kawasaki-shi, Kanagawa (72) Inventor Masayuki Komaki 1188 Oshidate, Inagi-shi, Tokyo (72) Inventor Hiroshi Morita 3-2-95 Chiyosaki, Nishi-ku, Osaka-shi, Osaka (72) ) Inventor Takatoshi Murakami 3-2-95 Chiyozaki, Nishi-ku, Osaka City, Osaka Prefecture (72) Inventor: Yassei Sato 502-1 Shinhocho, Tokai City, Aichi Prefecture Toho Gas Co., Ltd. (72) Inventor: Yasushi Otoko 502-1 Shinhocho, Tokai City, Aichi Toho Gas Co., Ltd. (56) References

Claims (1)

[Scope of utility model registration request] 1. A flow rate including a rotating body that rotates according to a flow rate of a fluid to be measured, a magnet provided on the rotating body, and a pickup that detects rotation of the rotating body by passing through the magnet. A flowmeter, comprising a detecting member for detecting that an external magnetic field is applied in the vicinity of the rotating body, and means for issuing an alarm according to the output of the detecting member.