JP7285169B2 - MEMBRANE GAS METER AND REPLACEMENT METHOD OF ITS MAGNETIC GAS FLOW DETECTION MECHANISM - Google Patents

Description

The present invention relates to a membrane gas meter equipped with a magnetic gas flow detection mechanism, and more particularly to a magnet mounting mechanism for the magnetic gas flow detection mechanism and a replacement method for the magnetic gas flow detection mechanism.

Membrane gas meters are generally equipped with a crank mechanism for opening and closing the open/close valve of the measuring chamber in conjunction with the reciprocating motion of the measuring membrane that partitions the measuring chamber for the gas flow rate. As shown in FIG. 5, the crank mechanism 100 of the membrane gas meter includes a rotary shaft 102 supported rotatably around a central axis 101 and a constant crank around the central axis 101 as the rotary shaft 102 rotates. and a crankshaft 103 that revolves around the radius. The reciprocating motion of the weighing membrane is transmitted to the crank mechanism 100 via a pair of crank arms (large and small elbows), and the crank mechanism 100 rotates around the central axis 101 . Rotational motion of the crank mechanism 100 is converted into opening/closing motion of an opening/closing valve that interlocks with the reciprocating motion of the weighing membrane via a link mechanism (not shown).

A magnetic sensor system is generally adopted as a gas flow rate detection mechanism in a film gas meter. In such a magnetic gas flow rate detection mechanism, the crank mechanism 100 is provided with a magnet mounting portion 107 for mounting a magnet 106 for gas flow rate detection. The magnet attachment portion 107 is arranged at a portion apart from the swing end 105 of the crank arm 104 (small elbow), and can be attached with, for example, a disk-shaped magnet 106 from above. The magnet 106 attached to the magnet attachment portion 107 is moved along an elliptical orbit by the crank arm 104 that swings as it rotates about the central axis 101 of the crank mechanism 100 . A reed switch (not shown) as a magnetic sensor is arranged in the meter case of the membrane gas meter at a position facing the passing position of the magnet 106 . During one revolution of the crank mechanism 100, the magnet 106 passes through the detection area of the reed switch once, and a detection signal of one pulse per cycle is output, and the gas flow rate is measured based on this detection signal.

In such a magnetic gas flow rate detection mechanism, the pulse output interval of the detection signal is wide, and the detection accuracy may not be sufficient. Patent Literature 1 proposes a method for increasing the accuracy of gas flow rate measurement by a magnetic gas flow rate detection mechanism in an existing film gas meter. In this method, a magnet for gas flow rate detection is arranged on the rotating shaft of the crank mechanism, and a magnetic sensor such as an MR sensor is used to detect the rotating magnetic field of the magnet rotating around the rotation center line of the rotating shaft. Detecting. As a result, a detection signal of 8 pulses per rotation can be obtained, and the detection accuracy can be improved.

Japanese Patent No. 6436642

In the method disclosed in Patent Literature 1, detection accuracy is improved by replacing the entire crank mechanism of an existing membrane gas meter with a crank mechanism that is an integrally molded plastic product with a magnet attached. That is, a set of parts of the crank mechanism 100 including the rotating shaft 102, the crank shaft 103, and the crank arm 104 on which the magnet 106 is mounted, which constitutes the crank mechanism 100 shown in FIG. 5, is replaced with a new crank mechanism. . Since it is necessary to replace a set of parts in this way, the replacement cost is high and the replacement work is not easy.

SUMMARY OF THE INVENTION An object of the present invention is to provide a membrane type gas meter equipped with a magnet attachment mechanism that can be replaced with a magnetic gas flow rate detection mechanism with high detection accuracy by simply replacing the minimum necessary number of parts in the crank mechanism of an existing membrane type gas meter. The object of the present invention is to propose a replacement method for a magnetic gas flow rate detection mechanism in a gas meter and a membrane gas meter.

In the magnet mounting mechanism for a membrane gas meter of the present invention, a holder arm is mounted along the crank arm using the magnet mounting portion of the crank arm (small arm) in the existing crank mechanism, and the magnet is attached to the holder arm. A magnet holder with a is attached so that the magnet is positioned on the central axis of the crank mechanism. A support shaft attached to the meter case (upper case) is fitted in a shaft hole provided in the portion of the holder arm to which the magnet is attached, and the holder arm is supported so that the magnet rotates around the central axis.

According to the present invention, in order to change an existing membrane gas meter to a magnetic gas flow rate detection mechanism with high measurement accuracy, the existing magnet and magnetic sensor are removed, and the holder arm, magnet holder with magnet, support shaft and All you have to do is attach a magnetic sensor. There is no need to modify the components of the existing power transmission mechanism, including the crank mechanism for opening and closing the on-off valve according to the reciprocating motion of the metering membrane. Therefore, the replacement cost can be suppressed, and the replacement work is simplified.

1 is a schematic perspective view of a membrane-type gas meter to which the present invention is applied, viewed obliquely from the rear with the upper case removed; FIG. FIG. 2 is a schematic cross-sectional view of the membrane gas meter of FIG. 1; 3A and 3B are a perspective view, a plan view, a front view, and a side view showing main parts of a crank mechanism and a magnetic gas flow rate detection mechanism of the film gas meter of FIG. 1; FIG. FIG. 4 is a perspective view showing a reference example of a crank mechanism and a magnetic gas flow rate detection mechanism of a membrane gas meter; 1 is a perspective view showing a crank mechanism and a magnetic gas flow rate detection mechanism of a typical film gas meter; FIG.

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic perspective view of a membrane-type gas meter according to an embodiment, with the upper case removed, when viewed obliquely from the rear. FIG. 2 is a schematic cross-sectional view of the membrane gas meter cut along line AA' in FIG. Since the basic structure of the membrane gas meter 1 is the same as that of the conventional one, only the parts related to the present invention will be explained.

A meter case 2 of the membrane gas meter 1 is composed of an upper case 3 and a lower case 4. Inside the lower case 4, a pair of front and rear gas flow metering chambers 5F and 5R are arranged. Inside the upper case 3, opening/closing valves 7F and 7R of the front and rear measurement chambers 5F and 5R are opened and closed in conjunction with the reciprocating motion of the front and rear measurement films 6F and 6R that partition the front and rear measurement chambers 5F and 5R. . Inside the upper case 3, a crank mechanism 20 is arranged for opening and closing the on-off valves 7F, 7R of the front and rear weighing chambers 5F, 5R in conjunction with the reciprocating motion of the front and rear weighing membranes 6F, 6R.

As is known, the reciprocating motion of the front and rear metering membranes 6F, 6R is converted into rotational motion of the front and rear blade shafts 8F, 8R. Rotational motion of the blade shafts 8F, 8R is converted into rotational motion of the crank mechanism 20 via a pair of crank arms 9A, 9B (large elbows) and a pair of crank arms 10A, 10B (small elbows). The crank mechanism 20 is connected to the on-off valves 7F, 7R of the front and rear measuring chambers 5F, 5R via the front and rear links 11F, 11R. A crank mechanism 20 alternately opens and closes the on-off valves 7F and 7R in conjunction with the reciprocating motion of the metering membranes 6F and 6R.

The crank mechanism 20 is provided with a magnetic gas flow rate detection mechanism 40 for detecting the gas flow rate using the rotation of the crank mechanism 20 . As shown in FIG. 2 , the magnetic gas flow rate detection mechanism 40 of this example includes a magnet 41 and a magnetic sensor 42 . A magnet 41 is attached to the crank mechanism 20 . The magnetic sensor 42 is arranged at a position facing the magnet 41 from the upper side with a substantially horizontally extending partition wall portion 3a formed inside the upper case 3 interposed therebetween. 2, the portions of the crank mechanism 20 and the magnetic gas flow rate detection mechanism 40 are shown in gray.

(crank mechanism)
FIG. 3(a) is a perspective view showing the main parts of the crank mechanism 20 and the magnetic gas flow rate detection mechanism 40, and FIG. 3(b) is a plan view when viewed from the direction of arrow b. c) is a front view when viewed from the direction of arrow c, and FIG. 3(d) is a side view when viewed from the direction of arrow d.

Referring to FIGS. 1 to 3, the crank mechanism 20 has a rotating shaft 21 which is vertically supported so as to be rotatable about a central axis 22 . Specifically, as shown in FIG. 1, a distribution chamber 12 is attached to the upper end of the lower case 4 above the front and rear weighing chambers 5F and 5R. , a rotating shaft 21 is vertically supported in a rotatable state. A lower crank plate 23 is horizontally fixed to the upper end of the rotating shaft 21 . A first crankshaft 24 is vertically attached to a portion of the lower crank plate 23 horizontally separated from the rotating shaft 21 by a predetermined distance. As shown in FIG. 1, one ends of front and rear links 11F and 11R are connected to the first crankshaft 24 so as to be capable of swinging. The other ends of the links 11F, 11R are connected to the opening/closing valves 7F, 7R of the front and rear weighing chambers 5F, 5R.

An upper crank plate 26 is horizontally fixed to the upper end of the first crankshaft 24 . A portion of the upper crank plate 26 horizontally separated from the center axis 22 by a predetermined distance and separated from the first crankshaft 24 by a predetermined angle around the center axis 22, for example, approximately 90°. A second crankshaft 27 is vertically fixed to.

As shown in FIG. 1, one ends of crank arms 10A and 10B (small armrests) are horizontally connected to the second crankshaft 27 . FIG. 3 shows only one crank arm 10A (small arm). A shaft hole 10a penetrating vertically is formed in one end of the crank arm 10A, and the second crankshaft 27 protrudes upward through the shaft hole 10a. Centering on the second crankshaft 27, the crank arm 10A can swing horizontally.

(Magnet attachment mechanism)
Next, a magnet attachment mechanism provided in the crank mechanism 20 for attaching the magnet 41 for gas flow rate detection will be described. The magnet mounting mechanism 60 of this example includes a first magnet mounting portion 61 provided on the crank arm 10A (small elbow), a holder arm 62, a magnet holder 63, and a second magnet mounting portion 64 provided on the magnet holder 63. and a rod shaft 65 (support shaft) attached to the partition wall portion 3 a of the upper case 3 .

The first magnet mounting portion 61 has a circular recess opening upward at a portion between the swing ends of both ends of the crank arm 10A (small elbow). A holder arm 62 is arranged horizontally along the crank arm 10A above the crank arm 10A. One end of the holder arm 62 is a mounting end provided with a connecting shaft 62a projecting vertically downward. The connecting shaft 62a is attached to the first magnet attachment portion 61 from above and fixed here. The other end 62b of the holder arm 62 is positioned directly above the second crankshaft 27, and has a shaft hole 62c extending therethrough in the vertical direction.

A magnet holder 63 is horizontally arranged above the holder arm 62 . At one end of the magnet holder 63, a cylindrical shaft 63a extending vertically downward is formed. The cylindrical shaft 63a is inserted into the shaft hole 62c of the holder arm 62 from above. The upper end of the second crankshaft 27 is rotatably inserted from below into the cylindrical shaft 63a inserted into the shaft hole 62c. The holder arm 62 is integrated with the crank arm 10A and is horizontally swingable about the second crankshaft 27 . Also, the magnet holder 63 can swing horizontally around the second crankshaft 27 .

A ring-shaped magnet 41 is horizontally mounted on the other end side of the magnet holder 63 . The magnet holder 63 is formed with a cylindrical shaft extending vertically upward as a second magnet mounting portion 64 . The cylindrical shaft is fitted into the center hole 41a of the magnet 41 from below. Here, the cylindrical shaft is positioned on the center axis 22 of the rotating shaft 21 of the crank mechanism 20 . A rod shaft 65 extending vertically downward is attached to a portion of the partition wall portion 3 a of the upper case 3 on the central axis 22 . The rod shaft 65 is inserted into the cylindrical shaft from above. As a result, the magnet 41 mounted on the magnet holder 63 rotates around the center axis 22 . A magnetic sensor 42, for example, an MR sensor is attached to a portion directly facing the magnet 41 with the partition wall portion 3a interposed therebetween.

(Replacement of magnet mounting mechanism)
Here, the crank mechanism 20 of the membrane gas meter 1 of this embodiment has the same configuration as the crank mechanism 100 of the existing membrane gas meter shown in FIG. 5 described above. In addition, the magnetic gas flow rate detection mechanism in the existing membrane type gas meter is attached to the magnet 106 mounted on the magnet mounting portion 107 provided on the crank arm 104 (small elbow metal) and the portion of the meter case facing the magnet 106. It consists of a reed switch. The crank arm 104 and the magnet mounting portion 107 are the same as the crank arm 10A and the first magnet mounting portion 61 of this example.

Therefore, the magnet 106 and the reed switch, which are the magnetic gas flow rate detection mechanism in the existing membrane gas meter, are replaced with the magnet 41 and the magnetic sensor 42 that constitute the magnetic gas flow rate detection mechanism 40 of the membrane gas meter 1 of this embodiment. Therefore, in order to improve the accuracy of gas flow measurement, the following should be done.

As components of the magnet mounting mechanism, a holder arm 62 having a mounting end that can be mounted and fixed to the magnet mounting portion 107 of the crank arm 104 in an existing or existing membrane gas meter, and a magnet holder having a second magnet mounting portion 64 63 and a rod shaft 65 are prepared. As components of the magnetic gas flow detection mechanism 40, a magnet 41 and a magnetic sensor 42 are prepared.

In the existing membrane gas meter, the existing magnet 106 attached to the magnet attachment portion 107 of the crank arm 104 is removed. Instead, the connecting shaft 62a of the holder arm 62 of this example is mounted. The magnet holder 63 having the magnet 41 attached to the second magnet attachment portion 64 is attached to the holder arm 62 . Magnet 41 is rotatably supported around center axis 22 by rod shaft 65 attached to partition wall portion 3 a of upper case 3 of meter case 2 . Also, the reed switch is removed and the magnetic sensor 42 is attached instead.

Of course, it is also possible to remove the magnetic gas flow rate detection mechanism 40 of this example and return it to the existing magnetic gas flow rate detection mechanism. In this case, the holder arm 62, the magnet holder 63 and the rod shaft 65 on which the magnet 41 is mounted, and the magnetic sensor 42, which are components of the magnet mounting mechanism 60, are removed. The magnet 106 may be attached to the first magnet attachment portion 61 of the crank arm 10A, and a magnetic sensor such as a reed switch may be attached to the portion of the upper case 3 of the meter case 2 facing this.

In this way, the existing magnetic gas flow rate detection mechanism and the magnetic gas flow rate detection mechanism 40 according to this embodiment can be replaced with low cost and simple work.

( Reference example: Magnet attachment mechanism)
FIG. 4 is a perspective view showing a reference example of a magnet attachment mechanism. The magnet mounting mechanism 80 shown in this figure includes the crank arm 10C of the crank mechanism 20, the magnet holder 63, the second magnet mounting portion 64 provided on the magnet holder 63, and the partition wall portion 3a of the upper case 3 of the meter case. and an attached rod shaft 65 (see FIG. 3(c)). Note that the rod shaft 65 is omitted in FIG.

Unlike the existing crank arm 104 (FIG. 5) and the crank arm 10A (FIGS. 1 to 3), the crank arm 10C (small arm) does not have the first magnet mounting portion 61. As shown in FIG. One end of the magnet holder 63 is rotatably attached to the upper end of the second crankshaft 27 protruding upward from a shaft hole formed at one end of the crank arm 10C. The magnet holder 63 can swing horizontally around the second crankshaft 27 .

When using the magnet mounting mechanism 80 of this configuration, it is necessary to replace the crank arm 104, which is a component of the crank mechanism 100 shown in FIG. 5, but the holder arm 62 becomes unnecessary. Therefore, even in this case, the replacement cost can be reduced compared to the case where the entire crank mechanism 20 is replaced.

1 Membrane gas meter 2 Meter case 3 Upper case 3a Partition wall portion 4 Lower case 5F, 5R Measurement chamber 6F, 6R Measurement membrane 7F, 7R Open/close valve 8F, 8R Wing shaft 9A, 9B Crank arm (large arm)
10A, 10B, 10C crank arm (small arm)
10a Shaft holes 11F, 11R Link 12 Distribution chamber 13 Crank base 20 Crank mechanism 21 Rotating shaft 22 Center axis 23 Lower crank plate 24 First crank shaft 26 Upper crank plate 27 Second crank shaft 28 Crank arm 40 Magnetic gas flow rate detection mechanism 41 magnet 41a center hole 42 magnetic sensor 60 magnet mounting mechanism 61 first magnet mounting portion 62 holder arm 62a connecting shaft 62b end portion 62c shaft hole 63 magnet holder 63a cylindrical shaft 64 second magnet mounting portion 65 rod shaft 80 magnet mounting mechanism 100 Crank mechanism 101 Center axis 102 Rotating shaft 103 Crank shaft 104 Crank arm 105 Swing end 106 Magnet 107 Magnet mounting part

Claims (2)

a crank mechanism that opens and closes an open/close valve of the measuring chamber in conjunction with the reciprocating motion of the measuring membrane that partitions the measuring chamber for the gas flow rate;
a magnet attachment mechanism for attaching a magnet for gas flow rate detection to the crank mechanism;
and
The crank mechanism is
a rotating shaft supported by the meter case so as to be rotatable about a central axis in conjunction with the reciprocating motion of the metering membrane;
a crankshaft that revolves around the central axis with a predetermined radius as the rotating shaft rotates;
a crank arm having an arm swing end rotatably connected to the crank shaft for converting the revolving motion of the crank shaft into the opening and closing motion of the on-off valve;
and
The magnet attachment mechanism includes:
a first magnet mounting portion disposed at a portion of the crank arm remote from the arm swinging end for mounting the first magnet as the magnet for detecting the gas flow rate;
a holder arm having a mounting end that can be mounted and fixed to the first magnet mounting portion;
a magnet holder having a holder swinging end connected to the holder arm so as to be swingable about the central axis and a second magnet mounting portion for mounting a second magnet as a magnet for detecting the gas flow rate;
a spindle attached to the meter case for supporting the second magnet attached to the second magnet mounting portion of the magnet holder so as to be rotatable about the central axis;
A membrane gas meter characterized by comprising: A method for replacing a magnetic gas flow rate detecting mechanism in a membrane gas meter having a crank mechanism for opening and closing an open/close valve of a gas flow metering chamber in conjunction with reciprocating motion of a metering membrane partitioning the gas flow rate metering chamber, comprising:
The crank mechanism is
a rotating shaft supported by the meter case of the membrane gas meter so as to be rotatable about a central axis in conjunction with the reciprocating motion of the metering membrane;
a crankshaft that revolves around the central axis with a predetermined radius as the rotating shaft rotates;
a crank arm having an arm swing end rotatably connected to the crank shaft for converting the revolving motion of the crank shaft into the opening and closing motion of the on-off valve;
and
The first magnetic detection mechanism, which is the magnetic gas flow rate detection mechanism before replacement,
a first magnet attached to a first magnet attachment portion disposed at a portion of the crank arm remote from the arm swinging end;
a first magnetic sensor attached to the meter case for detecting passage of the first magnet that moves with the swing of the crank arm;
and
A second magnet and a second magnetic sensor are prepared as a second magnetic detection mechanism which is the magnetic gas flow rate detection mechanism after replacement,
As a magnet attachment mechanism for attaching the second magnet to the crank mechanism,
a holder arm having a mounting end that can be mounted and fixed to the first magnet mounting portion;
a magnet holder comprising a holder swinging end connected to the holder arm swingably about the central axis and a second magnet mounting portion to which the second magnet is attached;
a spindle attached to the meter case for supporting the second magnet attached to the second magnet mounting portion of the magnet holder so as to be rotatable about the central axis;
prepare a
removing the first magnet from the first magnet mounting portion of the crank arm, and instead mounting the mounting end of the holder arm to the first magnet mounting portion;
The second magnet is rotatably supported around the central axis by the support shaft attached to the meter case,
A method for replacing a magnetic gas flow rate detection mechanism of a membrane gas meter, wherein the first magnetic sensor is removed and, instead, the second magnetic sensor is attached to a portion of the meter case facing the second magnet.

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