JP2010145174A - Gas meter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gas meter wherein a pressure sensor is fixed to a bulkhead so that gas does not flow out of a through-hole of the bulkhead of a case made of die casting, and which has no risk of gas leak caused by a fixing structure of the pressure sensor. <P>SOLUTION: In this gas meter, the pressure sensor 10 for detecting a pressure of supply gas is mounted on a through-hole 3c provided in a front wall 3b of an upper case 3 made of die casting forming the bulkhead between a supply gas atmosphere and the atmosphere. The gas meter further includes a counter spacer 4 fixed to the upper case to cover a part positioned on the atmospheric atmosphere side of the pressure sensor 10, and an O-ring 31 or a sheet-shaped packing 32 for blocking a gas leakage route is laid between the pressure sensor 10 and the front wall 3b, and when the counter spacer 4 is fixed to the upper case 3, the pressure sensor 10 is clamped between the counter spacer 4 and the front wall 3b. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a gas meter, and more particularly to a gas meter in which a pressure sensor is attached to a partition wall of a die-cast case that separates a supply gas atmosphere from the atmosphere (atmosphere) so that a part of the pressure sensor is located in the supply gas atmosphere.

The gas meter includes a pressure sensor for detecting the pressure of the supply gas, and shuts off the gas supply when a supply gas pressure exceeding a predetermined value is detected. Such a pressure sensor detects a gas supply pressure (applied pressure) as a differential pressure with respect to atmospheric pressure. In order to enable this detection, one end is located in the gas atmosphere and the other end is in the atmosphere. The supply gas atmosphere and the air are fixed to the partition wall in a state of being inserted into the through holes of the partition wall. This fixing is conventionally performed by screwing the pressure sensor in the direction of the partition wall (see Patent Document 1). When the pressure sensor is pushed in the direction of the partition wall, the packing provided around the through hole is crushed by the pressure sensor, so that gas does not flow out through the through hole.
Note that many of the gas meter cases constituting the partition walls are manufactured by die casting.
JP 2004-333380 A

  However, there are cases where a nest is formed in the case of the gas meter when it is manufactured by die casting. However, screw holes provided in the case may cause gas leakage depending on the formation position of the nest. . For example, if a nest is formed at a position where a screw hole is provided, the screw hole may unintentionally penetrate the case, which may cause gas leakage.

  The present invention has been made in view of the above circumstances, and is a gas meter in which a pressure sensor is fixed to the partition wall so that gas does not flow out from a through hole of the partition wall of a die-cast case, and the pressure sensor fixing structure It aims at providing the thing without the fear of the gas leak resulting from.

  The invention of claim 1 includes a die-cast case that forms a partition wall between a supply gas atmosphere and an air atmosphere, and a pressure sensor that detects the pressure of the supply gas is attached to a through hole provided in the partition wall of the case. The gas meter has a cover that is fixed to the case so as to cover the part of the pressure sensor that is located on the atmosphere side, and a packing that closes the gas leakage path is laid between the pressure sensor and the partition wall, and the cover is fixed to the case When this is done, a pressure sensor is sandwiched between the cover and the partition wall.

  According to a second aspect of the present invention, in the first aspect of the invention, the pressure sensor has a convex portion protruding in a direction of the surface facing the partition wall of the cover, and the cover has a convex portion of the pressure sensor on the surface facing the partition wall. The convex part of the pressure sensor comes into contact with the opposing surface of the cover, the pressure sensor is sandwiched between the cover and the partition wall, and the convex part of the pressure sensor and the cover are engaged. The pressure sensor is positioned in a direction parallel to the partition wall by engagement with the portion.

  In the gas meter of the present invention, when a cover that covers a portion of the pressure sensor located in the atmosphere is fixed to the case, the pressure sensor is sandwiched and fixed between the cover and the partition wall of the case. In the sandwiched and fixed state, the pressure sensor is pressed in the direction of the partition wall, so that the packing between the sensor and the partition wall can be crushed, so that the outflow of gas from the through hole of the partition wall can be prevented. As described above, since the pressure sensor is fixed without opening the screw hole in the partition wall, it is possible to prevent gas leakage from other than the through-hole portion.

FIG. 1 is an exploded perspective view for explaining an outline of an example of a gas meter of the present invention.
The illustrated gas meter 1 includes a lower case 2, an upper case 3, a counter spacer 4, a counter display unit 5, a counter cover 6, and an electronic unit case 7.

  The lower case 2 constitutes a measuring chamber for measuring the gas flow rate, and the upper case 3 provided thereon constitutes a distribution chamber for distributing the supply gas to the four rooms of the measuring chamber. FIG. 2 is a diagram illustrating a state in which the upper case 3 of FIG. 1 is viewed from the front. The gas introduction path that is continuous from the distribution chamber and the gas supply source connecting pipe 3a formed by the upper case 3 is naturally in a gas atmosphere. A pressure sensor 10, a shut-off valve 20, a vibration absorber (not shown), and the like are fixed (attached) to the front wall 3 b constituting the partition wall. The structure for fixing the pressure sensor 10 that is a feature of the present invention will be described later.

Returning to the description of FIG.
The counter spacer 4 is a cover fixed to the upper case 3 so as to cover a portion located in the atmosphere such as a pressure sensor. The fixing is preferably performed by screwing (the reason will be described later). However, when fixing by screwing, the screw hole is formed at a position different from the partition of the upper case 3.

The counter display 5 disposed in front of the counter spacer 4 counts and displays the integrated value of the gas flow rate, and the counter cover 6 is for protecting the counter display 5. An electronic unit case 7 provided in front of the lower case 2 incorporates an electronic control unit. This electronic control unit is connected to a pressure sensor, shut-off valve, etc. with a cable (not shown), and monitors the signals of these parts and controls the operation of each part (function to control opening / closing of the shut-off valve, etc.). I have.
With the configuration as described above, in the gas meter 1, for example, when a supply gas pressure exceeding a predetermined value is detected, the gas supply can be shut off by closing the shutoff valve.

  Next, a pressure sensor mounting structure related to the characteristic part of the present invention and a more detailed structure of the sensor itself will be described with reference to FIG. FIG. 3 is a cross-sectional view taken along the line AA of FIG.

First, the structure of the front wall 3b of the upper case 3 which is a portion to which the pressure sensor 10 is attached and the member for sealing the gas meter will be described.
The front wall (partition wall) 3b of the upper case 3 is formed with a through hole 3c into which the pressure sensor 10 is inserted so that one end of the pressure sensor 10 is located in the gas atmosphere and the other end is located in the atmosphere. The through hole 3c leads to a continuous gas introduction path from the gas supply source connecting pipe 3a (see FIG. 2). A shoulder 3d is formed in the through hole 3c, and an O-ring (packing) 31 into which the pressure sensor 10 is inserted is attached to the shoulder 3d. A sheet-like packing 32 is attached around the through hole 3 c on the front surface side of the upper case 3.

Next, the structure of the pressure sensor 10 itself will be described.
The pressure sensor 10 includes a gas pressure detection element 11, a printed board 12, a board support member 13, and a protection member 14.
The gas pressure detection element 11 is an element that detects a gas supply pressure applied to the back surface as a differential pressure with respect to the atmospheric pressure applied to the front surface, and is bonded to the front surface side of the center of the printed circuit board 12 with an adhesive. A gas introduction hole 12 a is formed at the center of the printed circuit board 12 so that the gas supply pressure is applied to the back surface of the gas pressure detecting element 11.

The substrate support member 13 is for supporting and fixing the printed circuit board 12, and includes a tubular portion 13a extending in the front-rear direction and a flange portion 13b provided on the tubular portion 13a.
A boss 13c projects from the flange portion 13b. The printed board 12 is supported and fixed to the board support member 13 by fitting the boss 13c with a hole (not shown) of the printed board 12 and a silicon adhesive 33 described later.
The tubular portion 13a is inserted into the through hole 3c of the front wall 3b of the upper case 3 so that the gas supply pressure is applied to the back surface of the gas pressure detecting element 11 through the hole 13d (and the gas introduction hole 12a of the printed circuit board 12). Inserted. The tubular portion 13a has a small diameter portion 13e and a large diameter portion 13f. When the tubular portion 13a is inserted into the through hole 3c, the small diameter portion 13e is inserted into the inner periphery of the O-ring 31 and the large diameter portion 13f. The O-ring 31 is sandwiched between the shoulder 3d of the upper case 3. Further, a silicon adhesive 33 is applied around the hole 13d on the front surface side of the substrate support member 13 so that the gas does not flow out.

The protection member 14 protects the gas pressure detection element 11 and the like, covers the front surfaces of the gas pressure detection element 11, the printed circuit board 12, and the substrate support member 13, and constitutes the housing of the pressure sensor 10 together with the substrate support member 13. . An opening 14 a is formed in the protective member 14 so that atmospheric pressure is applied to the front surface of the gas pressure detecting element 11.
Further, the protective member 14 is formed with a convex portion 14 b protruding in the direction of the counter spacer 4.

  In this gas meter 1, since the convex portion 14 b is formed on the protective member 14, for example, a screw hole screw formed in a portion other than the partition wall of the upper case 3 is used to fix the counter spacer 4 to the upper case 3. When tightened, the convex portion 14 b comes into contact with the counter spacer 4. When the screws are further tightened and the fixing of the counter spacer 4 to the upper case 3 is completed, the pressure sensor 10 is sandwiched and fixed between the counter spacer 4 and the upper case 3. In this state, since the pressure sensor 10 is pressed toward the front wall 3b of the upper case 3, the sheet-like packing 32 is crushed between the flange portion 13b of the pressure sensor 10 and the front wall 3b of the upper case 3, and the pressure is reduced. The O-ring 31 is crushed between the large-diameter portion 13 f of the tubular portion 13 a of the sensor 10 and the shoulder portion 3 d of the upper case 3. Therefore, in the gas meter 1, the gas leakage path that leads from the supply gas atmosphere to the atmosphere is blocked.

  In this manner, in the gas meter 1, the partition wall is provided so that the gas does not flow out from the through hole 3 c of the front wall 3 b of the upper case 3 without providing a screw hole in the front wall 3 b of the upper case 3 for fixing the pressure sensor 10. Since the pressure sensor 10 is fixed to 3b, there is no gas leakage due to the pressure sensor fixing structure. Therefore, the yield can be improved.

  In the above example, the counter spacer 4 and the convex portion 14b of the pressure sensor are in direct contact with each other, but an elastic member or the like may be sandwiched therebetween. By sandwiching the elastic member therebetween, it is possible to prevent the counter spacer 4 and the pressure sensor 10 from being deformed or damaged by the force pressing the pressure sensor 10 of the counter spacer 4.

  FIG. 4 is a cross-sectional view showing another example of the counter spacer. In addition, about the same structure as the structure of FIG. 3, the description is abbreviate | omitted by attaching | subjecting the same referential mark. The counter spacer 4 'in the example of FIG. 4 is different from that in FIG. Engaging portion 4a. In the gas meter having the counter spacer 4 ′, the pressure sensor 10 is positioned in the parallel direction with respect to the front wall 3 b by the engagement between the convex portion 14 b of the sensor 10 and the engaging portion 4 a.

  The counter spacer 4 (4 ′) is fixed to the upper case 3 by screwing because the force for pressing the pressure sensor against the upper case 3 (the front wall 3b) can be adjusted. It may be fixed by, for example.

Moreover, in the above-mentioned example, in order to sandwich the pressure sensor between the upper case and the counter spacer, the pressure sensor is provided with a convex portion, but the convex portion protruding in the pressure sensor direction is provided on the counter spacer side, You may enable it to hold | grip similarly to the above. In this case, it is preferable that an engaging portion that engages with the convex portion in a direction parallel to the front wall of the upper case is provided on a surface facing the counter spacer of the pressure sensor so that the alignment can be performed.
When the width between the counter spacer and the upper case is narrow, the pressure sensor can be clamped without providing the convex portion as described above. In this case, it is preferable to provide an engaging portion that directly engages with the main body portion of the protective member (a portion in which an opening for creating an air atmosphere) is formed so that the alignment can be performed.

It is a disassembled perspective view for demonstrating the outline of an example of the gas meter of this invention. It is a figure which shows a mode that the upper case of FIG. 1 was seen from the front. It is AA sectional drawing of FIG. It is sectional drawing which shows the other example of a counter spacer.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Gas meter, 10 ... Pressure sensor, 11 ... Gas pressure detection element, 12 ... Printed circuit board, 12a ... Gas introduction hole, 13 ... Substrate support member, 13a ... Tubular part, 13b ... Flange part, 13c ... Boss, 13d ... Hole , 13e ... small diameter portion, 13f ... large diameter portion, 14 ... protective member, 14a ... opening, 14b ... convex portion, 2 ... lower case, 20 ... shut-off valve, 3 ... upper case, 31 ... O-ring, 32 ... sheet shape Packing, 33 ... Silicone adhesive, 3a ... Gas supply source connecting pipe, 3b ... Front wall, 3c ... Through hole, 3d ... Shoulder, 4, 4 '... Counter spacer, 4a ... Engagement part, 5 ... Counter display part , 6 ... Counter cover, 7 ... Electronic unit case.

Claims (2)

In a gas meter provided with a die-cast case that forms a partition wall between a supply gas atmosphere and an air atmosphere, and a pressure sensor that detects the pressure of the supply gas is attached to a through-hole provided in the partition wall of the case,
A cover fixed to the case so as to cover a portion located on the atmosphere side of the pressure sensor;
Between the pressure sensor and the partition, a packing for closing a gas leakage path is laid,
The gas meter, wherein the pressure sensor is sandwiched between the cover and the partition when the cover is fixed to the case. The pressure sensor has a convex portion protruding in the direction of the surface facing the partition of the cover,
The cover has an engaging portion that engages with a convex portion of the pressure sensor on a surface facing the partition.
The convex portion of the pressure sensor abuts against the opposing surface of the cover, the pressure sensor is sandwiched between the cover and the partition wall, and the convex portion of the pressure sensor and the engagement portion of the cover are engaged. The gas meter according to claim 1, wherein the pressure sensor is positioned in a direction parallel to the partition wall.