JPH11166848A - Flowmeter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flowmeter capable of taking accurate measurements by preventing an electronic counter from being incremented in excess because of environmental changes such as vibration or changes in pressure. SOLUTION: The electronic measuring part 10 of a gas meter has a magnet 11, which rotates and moves synchronizing with the expansion or contraction of a diaphragm, and first and second reed switches 12, 13 which sense the rotation and movement of the magnet 11 at respective remote positions. When the first and second reed switches 12, 13 alternately make opening and closing, the magnet 11 is regarded as having rotated and moved with the flow rate, and the electronic counter of the electronic measuring part 10 is incremented. When only one of the reed switches 12, 13 repeats opening and closing, the magnet 11 is regarded as having reciprocated at the place because of disturbance, and the electronic counter is not incremented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flow meter capable of monitoring a gas flow rate and the like from a remote place. More specifically, the present invention relates to a magnet that repeats movement each time a unit volume of fluid flows, and to a flow rate measurement technique using a reed switch that senses the movement of the magnet.

[0002]

2. Description of the Related Art A gas meter (flow meter) has two diaphragms (membrane) arranged in a measuring chamber for measuring a gas flow rate, and the two diaphragms expand and contract by the gas flowing into the measuring chamber. It has a repeating structure. The movement of the membrane is transmitted to a visual mechanical flow counter via an interlocking mechanism. At the same time, the built-in electronic counter counts up and automatic meter reading can be performed from a remote location.

As shown in FIGS. 7A and 7B, an electronic weighing means for controlling an electronic counter rotates and moves while drawing a predetermined trajectory by alternately expanding and contracting two diaphragms. And a single reed switch 12 arranged at a position close to the movement path R of the magnet 11, and the reed switch 12 opens and closes each time the magnet 11 passes near the switch. FIG. 7 (C)
As shown in FIG. 1, one terminal a2 of the reed switch 12 is connected to a pull-up resistor R1, and the other terminal a1 is a pull-down resistor R2 and an interrupt input of a microcomputer 14 (hereinafter, referred to as a microcomputer) having a built-in electronic counter. It is connected to terminal INT.

[0004] Therefore, as shown in FIG.
When 1 is apart from the reed switch 12, the magnitude of the magnetic field received by the reed switch 12 is equal to or smaller than the threshold value. Therefore, the reed switch 12 is in the cutoff state, and a low-level signal is input to the interrupt input terminal INT. As shown in FIG. 7B, when the magnet 11 approaches the reed switch 12, the magnitude of the magnetic field received by the reed switch 12 becomes equal to or larger than the threshold value.
2 is energized and Hi is applied to the interrupt input terminal INT.
A level signal is input. Therefore, every time the magnet 11 rotates, the interrupt input terminal INT is connected to the interrupt input terminal INT as shown in FIG.
As shown in (1), a signal P3 in which a low level (off) and a high level (on) are repeated is input.

The microcomputer 14 counts up a built-in electronic counter based on the signal P3. For example, the rising and falling edges of the pulse appearing in the signal P3 (edges,.
) Is detected, and the electronic counter is incremented, or only the rising edge (edge,...) Or the falling edge (edge,.

[0006]

However, in a gas meter, even when gas is not flowing, the diaphragm (membrane) performs irregular expansion and contraction operations due to mechanical vibrations and environmental changes such as temperature changes and pressure changes. Done, magnet 1
1 may reciprocate. Such reciprocal movement is on the boundary line for opening and closing the reed switch 12 (FIG. 7).
(B), the reed switch 12
Repeats the opening / closing operation, and the same pulse as when the gas is flowing appears in the signal P3. As a result, the microcomputer 14 counts up the electronic counter regardless of whether the pulse of the signal P3 is caused by the flow rate or the mechanical vibration. Counts the value at which the flow rate of.

It is an object of the present invention to provide a flowmeter capable of preventing an electronic counter from excessively moving due to environmental changes such as vibrations and pressure changes, and capable of accurate measurement.

[0008]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a measuring chamber, a membrane that repeats expansion and contraction operations in conjunction with a flow rate of a fluid passing through the measuring chamber, In a flow meter having an electronic metering means for counting up the electronic counter based on the expansion and contraction operation,
The electronic weighing means includes a magnet that repeats movement while drawing a predetermined trajectory in conjunction with the expansion and contraction operation of the membrane, and a plurality of magnets respectively arranged at a plurality of locations where movement of the magnet in accordance with the flow rate can be detected. When all of the reed switches and the plurality of reed switches sequentially perform opening and closing operations, the electronic counter counts up. Even when some of the reed switches repeat the opening and closing operations, the electronic counter counts up. And control means not provided.

In the present invention, since the diaphragm (membrane) expands and contracts in response to the flow rate, the reed switches are respectively disposed at a plurality of positions where it is possible to detect the movement of the magnet. When the magnet performs a normal movement linked to the flow rate, all of the plurality of reed switches sequentially open and close. On the other hand, when the diaphragm (membrane) performs irregular expansion and contraction operations due to disturbances such as mechanical vibrations and environmental changes such as temperature changes and pressure changes even though the gas is not flowing. Since the range in which the magnet moves is narrow, only some of the plurality of reed switches open and close. As described above, in the present invention, focusing on the fact that whether the movement of the magnet is linked to the flow rate or the movement of the magnet due to disturbance differs depending on the movement form of the magnet, all of the plurality of reed switches are opened and closed. Is performed sequentially, that is, only when the magnet moves in conjunction with the flow rate, the electronic counter counts up, and when some reed switches repeatedly open and close, that is, the magnet moves due to disturbance. Is performed, the electronic counter is not incremented. Therefore, even with an electronic weighing unit using a magnet and a reed switch, it is possible to prevent the electronic counter from going too far due to disturbance such as vibration or pressure change, and to perform accurate weighing.

In the present invention, when the magnet is configured to repeat the rotational movement while drawing a predetermined trajectory in conjunction with the flow rate, the reed switch is arranged at the most distant position on the rotational trajectory of the magnet. It is preferable that the magnets are arranged at positions where the magnets can be detected as having moved. When configured in this way, the control means counts up the electronic counter when the two reed switches alternately open and close, and keeps the electronic counter counting even when one reed switch repeats the opening and closing operations. Do not count up. In the present invention, when the magnet performs a normal rotational movement based on the flow rate, the two reed switches open and close alternately, whereas the membrane expands and contracts due to disturbance despite no gas flow. When the operation is performed, since the magnet only reciprocates within a certain range, only one reed switch repeats the opening / closing operation. Therefore, 2
By counting up the electronic counter only when the two reed switches open and close alternately, it is possible to prevent the electronic counter from going too far due to disturbance and to perform accurate weighing.

In the present invention, the flow meter may include a mechanical counter in which the expansion / contraction operation of the membrane is transmitted through an interlocking mechanism. In this case, the magnet is
It is preferable that it is configured on a movable member constituting the interlocking mechanism.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a flow meter according to the present invention will be described below with reference to the drawings.

(Overall Configuration of Gas Meter) FIGS. 1 to 3
1A is a cross-sectional view of a gas meter to which the present invention is applied, as viewed from the back, a left-side cross-sectional view taken along line XX ′ of FIG. 1, and a plan cross-sectional view taken along line YY ′ of FIG.

As shown in these figures, the gas meter 1 of the present embodiment has a case body 20 composed of an upper case 201 and a lower case 202. The case body 20 has a gas inlet to which a gas pipe 221 is connected. 22 and gas pipe 211
Is formed with the gas outlet 21 to which is connected. The gas meter 1 is located at a position above the front of the case body 20.
A mechanical flow counter 23 for displaying the result of integration of the gas flow rates measured in the above is configured.

As shown in FIG. 2, this gas meter 1
Among the gas passages (not shown) from the gas inlet 22 to the gas outlet 21, the diaphragms 241 and 242 (membrane) are arranged in each of two chambers formed on the lower case 202 side. This is a membrane-type gas meter having a general basic structure having a measuring chamber 24. Therefore, the measuring chamber 2
Detailed description of the structure and operation in 4 is omitted,
Each of the measuring chambers 24 sequentially enters a gas inflow state and a gas outflow state, and each time a predetermined volume of gas flows in and out, the two diaphragms 241 and 242 alternately expand and contract. The expansion and contraction operations of the diaphragms 241 and 242 are as follows.
The data is transmitted to the mechanical flow counter 23 via the interlocking mechanism.

That is, in the interlocking mechanism, the diaphragms 241 and 242 are provided at the lower ends of the blade shafts 251 and 252 provided upright along the inner peripheral side surface of the case body 20 via the blades 253 and 254, respectively. Respectively. These blade shafts 251 and 252 are rotatable around their axes, and the diaphragms 241 and
Due to the expansion and contraction operation of 242, it reciprocates within a predetermined angle range. The base ends of the large elbows 261 and 262 are horizontally fixed to the upper ends of the wing shafts 251 and 252, respectively, and the rotation of the wing shafts 251 and 252 is transmitted to the large elbows 261 and 262.

The two large elbows 261 and 262 are arranged so as to intersect with each other.
The base ends of the small elbows 271 and 272 are connected by pins. The distal ends of the small elbows 271 and 272 are connected to each other and connected to the crank 28 located below the small elbows 271 and 272, and the expansion and contraction operations of the diaphragms 241 and 242 are transmitted to the crank 28. ing. Base ends of horizontally disposed valve rods 291 and 292 are connected to a crankshaft 281 of the crank portion 28, and distal ends of the valve rods 291 and 292 are fixed to the valve shafts 301 and 302. Here, since the valve shafts 301 and 302 are configured to rotate around their vertical axes around the valve guides 303 and 304 integrally with the valves 305 and 306, the expansion and contraction of the diaphragms 241 and 242 are performed. The operation is performed by the crank 28
And valve 3 via valve rods 291, 292.
05 and 306 are converted into a motion of reciprocating rotation about the valve guides 303 and 304. Therefore, diaphragm 2
In conjunction with the expansion and contraction operations of the valves 41 and 242, each valve 30
5 and 306 are operated, and the respective measuring chambers 24 are sequentially switched to a gas inflow state and a gas outflow state.

The crank section 28 includes a diaphragm 241,
The expansion / contraction operation of the crankshaft 242 is converted into a reciprocating rotation operation of the crankshaft 281, and the worm wheel 282 formed on the crank portion 28 is rotated about a horizontal axis.
When the worm wheel 282 rotates, the change gear 32 rotates via the horizontal shaft gear 31 to rotate the counter gear 33 connected to the mechanical flow counter 23. The display on the mechanical flow counter 23 is switched by the rotating operation of the counter gear 33. In this way, the display on the mechanical flow counter 23 can be performed in conjunction with the expansion and contraction operations of the diaphragms 241 and 242.

(Electronic Metering Means) The gas meter 1 is provided with an electronic metering unit 10 for performing automatic meter reading from a remote place. The electronic weighing unit 10 includes a magnet 11 attached to a small elbow 271 which is one of movable members constituting an interlocking mechanism, and a control board 1 disposed above the magnet 11.
5 and 1st reed switch 1 attached to
2 and 13 and a microcomputer 14 (hereinafter, referred to as a microcomputer / control means) that counts up a built-in electronic counter 140 based on opening and closing operations of these reed switches 12 and 13. Since the electronic counter 140 is counted up according to the flow rate,
The value of the electronic counter 140 is transmitted to a communication device (not shown).
By monitoring via, meter reading can be performed from a remote location.

As shown in FIG. 3B, the magnet 11 attached to the small elbow 271 rotates in an elliptical shape. That is, when the two diaphragms 241 and 242 perform the expansion and contraction operations alternately, as shown by arrows A and B,
Since the two large elbows 261 and 262 swing regularly and alternately, the portion of the small elbow 271 to which the magnet 11 is attached rotates and moves as shown by the arrow R.

First and second reed switches 12, 1
Numerals 3 are located at the farthest positions from each other on the movement path R of the magnet 11, and are arranged so that the magnets 11 approach each other.

As shown in FIG. 4, one terminal a1 of the first reed switch 12 is connected to a pull-down resistor R2 and an interrupt input terminal INT1 of the microcomputer 14, and the other terminal a2 is connected to a pull-up resistor R1. Have been. One terminal b1 of the second reed switch 13 is connected to a pull-down resistor R3 and an interrupt input terminal INT of the microcomputer 14.
2 and the other terminal b2 is connected to a pull-up resistor R1. These two reed switches 12, 1
3 is configured to perform an opening and closing operation by sensing a magnetic field change accompanying the rotational movement of the magnet 11. When the magnet 11 approaches, both terminals are energized, and when the magnet 11 separates, both ends are energized. The child is cut off. Therefore, when the magnet 11 is 1
By performing the rotational movement for the number of cycles, the terminals a1 and b1 of the first and second reed switches 12 and 13 are connected to the terminals a1 and b1.
Pulse signals (first and second signals) corresponding to the opening and closing operations of these reed switches appear, and these signals are input to the interrupt input terminals INT1 and INT2 of the microcomputer 14.

FIGS. 5A to 5D are schematic views showing the manner in which the magnet 11 moves, and FIG. 6A is a time chart showing signals generated by the reed switches 12 and 13. is there. In FIG. 6A, the voltage at the terminal a1 of the first reed switch 12 is represented as a first signal P1, and the voltage at the terminal b1 of the second reed switch 13 is represented as a second signal P2.

As shown in FIG. 5A, when the magnet 11 is separated from the two reed switches 12 and 13,
The two reed switches 12 and 13 are both in the cutoff state, and as shown in FIG.
1 and P2 are both at the low level (period T0).
From this state, when the magnet 11 moves and the magnet 11 approaches the first reed switch 12, as shown in FIG. 5B, the first reed switch 12 is energized, and FIG. ), The first signal P1 becomes Hi level (period T1). Then, as shown in FIG.
When the magnet 11 separates from the first reed switch 12,
The first reed switch 12 is turned off, and FIG.
As shown in (A), the first signal P1 returns to a low level (period T2). Then, as shown in FIG.
When the magnet 11 approaches the second reed switch 13, the second reed switch 13 is energized, and FIG.
, The second signal P2 becomes Hi level (period T3). When the magnet 11 is separated from the second reed switch 13 again, as shown in FIG. 5A, the second reed switch 13 is turned off, and as shown in FIG. The signal P2 goes low (period T
4). In a state in which gas flows in the measuring chamber 24, expansion and contraction operations of the diaphragms 241 and 242, which are proportional to the gas flow rate, are transmitted to the magnet 11 via the interlocking mechanism.
Keeps rotating, the first and second reed switches 12 and 13 alternately repeat the on / off operation described above (periods T5, T6, and T7), and the first and second signals P1, P2
In 2, a pulse appears alternately.

The microcomputer 14 operates as follows based on a program stored in a ROM or the like.
When the first and second reed switches 12 and 13 are opening and closing alternately, a built-in electronic counter 14 is provided.
The count-up of 0 is performed. That is, the first and second
Microcomputer 14 counts up the electronic counter 140 based on the rising and falling edges (edges) of the first and second signals P1 and P2.

In order to realize such an operation, after detecting the rising edge of the first signal P1, the microcomputer 14 does not accept any input other than the falling edge of the first signal P1. After detecting the falling edge of the first signal P1, no input other than the rising edge of the second signal P2 is accepted. After detecting the rising edge of the second signal P2, inputs other than the falling edge of the second signal P2 are not accepted. Further, after detecting the falling edge of the second signal P2, no input other than the rising edge of the first signal P1 is accepted.

Here, even when gas is not flowing in the measuring chamber 24, vibrations are applied to the case 20, environmental changes such as temperature changes and pressure changes occur, and the diaphragm 24
When the large elbows 261 and 262 described with reference to FIG. 3B swing when the first and second 242 irregularly expand and contract, the magnet 11 reciprocates on the spot. There is. When such reciprocating movement is performed at a position close to the first reed switch 12 or the second reed switch 13, a pulse appears repeatedly only in the first signal P1 or only in the second signal P2. Become.

For example, if the magnet 11 reciprocates in a state where the magnet 11 is close to the first reed switch 12,
As shown in FIG. 6B, a pulse repeatedly appears only in the first signal P1. However, in this example, after detecting the falling edge of the first signal P1,
Since only the rising edge of the second signal P2 is accepted, during the period (period Tb) in which a pulse due to reciprocation due to disturbance appears (period Tb), the electronic counter 14
No count-up of 0 is performed. Then, the weighing chamber 24
When the magnet 11 starts rotating and moving due to the flow of gas inside, when the second signal P2 rises, the electronic counter 1
The count up of 40 is restarted.

Similarly, when the magnet 11 reciprocates while the magnet 11 is close to the second reed switch 13,
As shown in FIG. 6C, a pulse repeatedly appears only in the second signal P2. However, in this example, after detecting the falling edge of the second signal P2,
Since only the rising edge of the first signal P1 is accepted, the electronic counter 140 does not count up during the period Tc in which the pulse appears due to the reciprocating movement caused by the disturbance. Thereafter, when the gas flows in the measuring chamber 24, the magnet 11 starts rotating and moving in accordance with the flow rate. When the first signal P1 rises, the electronic counter 140 restarts counting up.

As described above, in the gas meter 1 of the present embodiment, the two reed switches 12 and 13 are arranged so as to detect the magnetic field change accompanying the movement of the magnet at different positions. In addition, the two reed switches 12 and 13 are positioned at positions most distant from each other around the movement path R of the magnet 11 (positions corresponding to both ends of the long axis of the elliptical trajectory of the magnet 11). Is waiting for you to come. When the magnet 11 moves normally in accordance with the flow rate, it rotates and moves, and when it moves due to disturbances such as vibrations or environmental changes, it reciprocates on the spot. The behavior differs depending on the movement.
Therefore, in the microcomputer 14, the two reed switches 1
It is possible to determine whether the magnet 11 is rotating or reciprocating by the pattern in which the magnets 2 and 13 open and close. That is, when the reed switches 12 and 13 alternately open and close, pulses appear alternately in the two signals P1 and P2. Count up. When only one reed switch repeatedly performs the opening / closing operation, the electronic counter 140 does not count up assuming that the magnet 11 is reciprocating. As a result, the reciprocating movement of the magnet 11 due to vibration, environmental change, or the like is ignored, so that the electronic counter 14
Zero can be prevented from progressing excessively, and accurate measurement can be performed.

(Other Embodiments) In this embodiment, two reed switches 12 and 13 are used. However, three or more reed switches are used, and the electronic counter is used only when all of them are sequentially opened and closed. The count-up of 140 may be performed.

In this embodiment, the case where the magnet 11 performs the rotational movement has been described. However, the movement of the magnet 11 is not limited to the rotational movement but may be the reciprocating movement. In this case, the magnet 11
Moves in a wide range for normal movement linked to the flow rate, and moves in a narrow range for movement due to disturbance. Therefore, if a plurality of reed switches are used, each of which detects a magnetic field change due to the movement of the magnet 11 at a different position, all the reed switches sequentially open and close, or only some reed switches repeat the opening and closing operations. It can be determined whether the movement of the magnet 11 is a normal movement linked to the flow rate or a movement due to a disturbance.

Further, in the present embodiment, the gas meter 1 has been described, but the present invention can be applied to other flow meters.

[0034]

As described above, in the flow meter according to the present invention, the reed switches are respectively arranged at a plurality of positions where the membrane expands and contracts in accordance with the flow rate, whereby the movement of the magnet can be detected. Have been. For this reason, when the magnet performs a normal movement linked to the flow rate, all of the plurality of reed switches sequentially open and close, whereas the film is irregular due to disturbance despite no gas flow. When the expansion / contraction operation is performed, only a part of the plurality of reed switches performs the opening / closing operation because the moving range of the magnet is narrow. As described above, in the present invention, focusing on the fact that whether the movement of the magnet is linked to the flow rate or the movement of the magnet due to disturbance differs depending on the movement form of the magnet, all of the plurality of reed switches are opened and closed. Is performed sequentially, that is, only when the magnet moves in conjunction with the flow rate, the electronic counter is counted up. Therefore, even with an electronic weighing unit using a magnet and a reed switch, it is possible to prevent the electronic counter from going too far due to disturbance such as vibration or pressure change, and to perform accurate weighing.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a gas meter to which the present invention is applied, as viewed from the back.

FIG. 2 is a side sectional view taken along line XX ′ of the gas meter shown in FIG.

3A is a plan sectional view taken along line YY ′ of the gas meter shown in FIG. 1, and FIG. 3B is a schematic view of the interlocking mechanism shown in FIG.

FIG. 4 is a circuit diagram showing an electronic measuring unit in a gas meter to which the present invention is applied.

FIGS. 5A to 5D are explanatory diagrams showing a positional relationship between a moving path of a magnet and a reed switch in a gas meter to which the present invention is applied.

FIGS. 6A to 6C are time charts of signals generated by an electronic measuring unit in the gas meter to which the present invention is applied.

FIGS. 7A and 7B are explanatory diagrams showing a positional relationship between a magnet and a reed switch in a conventional gas meter, and FIG.
Is a circuit diagram of an electronic measuring unit in a conventional gas meter,
(D) is a time chart of a signal generated by an electronic measuring unit in a conventional gas meter.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Gas meter 10 Electronic measuring part (electronic measuring means) 11 Magnet 12 1st reed switch 13 2nd reed switch 14 Microcomputer (control means) 20 Case main body 23 Mechanical flow counter 24 Measuring chamber 140 Electronic counter 241, 242 Diaphragm (membrane) 261 262 Large elbow gold 271 272 Small elbow gold (movable member) R Moving path of magnet P1 First signal P2 Second signal

Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI G06M 3/12 G06M 3/12

Claims (3)

[Claims] 1. A measuring chamber, a film that repeats expansion and contraction operations in conjunction with a flow rate of a fluid passing through the measurement chamber, and an electronic measuring means that counts up an electronic counter based on the expansion and contraction operations of the film. In the flowmeter having, the electronic measuring means, a magnet that repeats movement while drawing a predetermined trajectory in conjunction with the expansion and contraction operation of the membrane, and a plurality of for detecting the movement of the magnet in conjunction with the flow rate A plurality of reed switches respectively arranged at a location, the electronic counter counts up when all of the plurality of reed switches sequentially perform opening and closing operations, and even if some reed switches repeat opening and closing operations. Control means for not counting up the electronic counter. 2. The magnet according to claim 1, wherein the magnet is configured to repeat a rotational movement while drawing a predetermined trajectory in conjunction with a flow rate, and wherein the reed switch is provided at two most separated positions on the rotational trajectory of the magnet. The control means counts up the electronic counter when the two reed switches alternately open and close, and the control means counts one of the two reed switches. The flowmeter is characterized in that the electronic counter does not count up even if the reed switch repeats opening and closing operations. 3. The apparatus according to claim 1, further comprising a mechanical flow counter to which the expansion / contraction operation of the membrane is transmitted via an interlocking mechanism, wherein the magnet is provided on a movable member constituting the interlocking mechanism. A flowmeter characterized in that it is configured as follows.