JP5297864B2 - Ultrasonic gas meter - Google Patents

Description

  The present invention relates to an ultrasonic gas meter in which a gas flow velocity is measured by an ultrasonic flow velocity sensor.

  Conventionally, as an ultrasonic gas meter using an ultrasonic flow velocity sensor, for example, there are those disclosed in Japanese Patent Publication No. 7-119638 (Patent Document 1) and Japanese Patent Application Laid-Open No. 2008-51562 (Patent Document 2).

  The ultrasonic gas meter disclosed in Patent Document 1 includes an ultrasonic flow rate sensor that includes two acoustic transducers, for example, piezoelectric transducers that operate at an ultrasonic frequency and are disposed at a predetermined distance in a gas flow path. Yes.

  Then, the ultrasonic signal generated by one transducer is received by the other transducer, the propagation time during which the ultrasonic signal is propagated between the transducers is measured, and the gas flow rate is intermittently determined based on the measured propagation time. The passage flow rate is obtained by multiplying the flow rate by the sectional area of the gas flow path and the intermittent time. Furthermore, an ultrasonic gas meter can be configured by displaying the integrated flow rate obtained by integrating the passing flow rate.

  As in Patent Document 2, the structure of a conventional ultrasonic gas meter (ultrasonic gas meter) is, for example, as shown in FIG. This gas meter 100 is a multilayer unit that rectifies the flow of gas in an intermediate flow path 5c formed between a gas inlet 5a connected to a gas supply source and a gas outlet 5b connected to a combustor or the like. 6 is provided. The flow velocity of the gas flowing in the multilayer unit 6 is measured by an ultrasonic flow velocity sensor (not shown) arranged on the side of the multilayer unit 6.

  By the way, especially in the case of city gas, although it is very rare, the gas piping cracks due to earthquakes, typhoons, land subsidence, etc., rainwater enters, and water enters the flow path of the ultrasonic gas meter. May end up. Even when water accumulates in the multi-layer flow path, even within the flow path, the flow speed increases due to narrowing of the flow path through which the gas passes, or the accumulated water undulates or jumps due to the gas flow. Water may adhere to the sonic flow velocity sensor. Ultrasound propagates uniformly in the same medium, but reflection, scattering, refraction, and attenuation occur at the interface between different media such as gas and water. Become. Therefore, erroneous measurement of the flow rate occurs.

  Therefore, when the amplification level of the ultrasonic signal received by the other transducer of the ultrasonic flow rate sensor is small and the propagation time is small, it is determined that the gas flow path is almost full. Sonic gas meters have been proposed.

Japanese Patent Publication No.7-119638 JP 2008-51562 A

  However, in the conventional ultrasonic gas meter, the ingress of water cannot be detected unless the gas flow path is almost full, and the ingress of a small amount of water cannot be detected.

  For example, in FIG. 8, when water enters the ultrasonic gas meter via the gas pipe, water droplets entering from the gas inlet 5 a shown in FIG. 8 fall near the upper surface 6 a of the multilayer unit 6. Then, the water droplets dropped near the upper surface 6a of the multilayer unit 6 hangs down to the nearby bottom 5d, accumulates near the bottom 5d, gradually accumulates, and when the water level gradually increases, the water becomes near the bottom 5d. It penetrates to the inside of the multilayer unit 6. If the water level further increases and, for example, about half of the multilayer flow rate unit 6 or an ultrasonic flow rate sensor (not shown) is submerged, the intrusion of water cannot be detected and an alarm cannot be issued unless this time is reached.

  In this way, in the conventional technology, if a large amount of water flows in at once, it can be detected immediately, but if water accumulates little by little, erroneous measurement of the flow rate can continue for a long period of time. Therefore, it is not preferable as a gas company and a user. It is desirable to detect a small amount of water entry and issue a warning at an earlier stage.

  The present invention has been made to solve such a conventional problem, and it is an object of the present invention to provide an ultrasonic gas meter capable of detecting and judging intrusion of a small amount of water at an early stage.

An ultrasonic gas meter according to claim 1 is provided in a gas flow path, and a multi-layer unit in which rectifying plates are arranged in multi-layers in a rectangular parallelepiped cylindrical case, and the cylindrical case of the multi-layer unit joined to the cylindrical case, An ultrasonic flow rate sensor that detects the flow rate of the gas flowing in the multilayer unit with ultrasonic waves, and a determination unit that determines whether water has entered the gas flow path based on the output of the ultrasonic flow rate sensor An ultrasonic gas meter comprising: at least the upper surface of the cylindrical case of the multilayer unit, water from the inlet side opening of the multilayer unit to a sensor joint where the ultrasonic flow rate sensor is joined It is characterized by having a water guide structure consisting of a water channel surrounded by a bank part. In addition, you may make it comprise a water conveyance structure by the member separate from a cylindrical case, and fix this water conveyance structure to a cylindrical case.

The ultrasonic gas meter according to claim 2 is the ultrasonic gas meter according to claim 1, wherein the water guide structure is a bank portion formed on an upper surface of the cylindrical case, and the inlet side opening portion. It has a bank part extended from a sensor junction part, and the inside of this bank part is constituted as a channel.

The ultrasonic gas meter according to claim 3 is the ultrasonic gas meter according to claim 1, wherein the water guide structure extends from the opening on the inlet side where the upper surface of the cylindrical case is recessed to the sensor joint. It has a water channel.

The ultrasonic gas meter according to claim 4 is the ultrasonic gas meter according to claim 1, wherein the water guide structure forms an inclined surface that forms the water channel formed on an upper surface of the cylindrical case, and the inclined surface. It has the bank part formed in the circumference | surroundings of this invention, It is characterized by the above-mentioned.

The ultrasonic gas meter according to claim 5 is the ultrasonic gas meter according to claim 1, wherein the water guide structure includes a water channel formed in a side portion of the cylindrical case, the water channel and the cylindrical case. And a bank portion formed on the entrance side opening portion side of the upper surface.

  An ultrasonic gas meter according to claim 6 is the ultrasonic gas meter according to any one of claims 1 to 5, wherein the cylindrical case and an inner wall of the gas flow path are sealed at the sensor joint portion. It is characterized by having a packing to perform.

  According to the ultrasonic gas meter of the first aspect, the water droplets that have entered the gas flow path and dropped on the upper surface of the cylindrical case of the multilayer unit are guided to the sensor joint by the water guide structure formed in the cylindrical case. Therefore, the entry of a small amount of water can be detected at an early stage by the ultrasonic flow rate sensor. Further, since it is not necessary to newly provide an additional part such as a moisture sensor, it is possible to detect the entry of water without increasing the cost.

  According to the ultrasonic gas meter of the second aspect, even if water drops that have fallen on the upper surface of the cylindrical case of the multilayer unit gradually accumulate, the water drops do not hang down to the bottom near the bank, and this bank In addition to the effect of the first aspect, water intrusion can be detected at an earlier stage.

  According to the ultrasonic gas meter of the third aspect, even if water drops that have fallen on the upper surface of the cylindrical case of the multilayer unit gradually accumulate, the water drops enter the water channel that is recessed in the upper surface of the cylindrical case, In addition to the effects of the first aspect, intrusion of water can be detected at an earlier stage. .

  According to the ultrasonic gas meter of the fourth aspect, even if water drops that have fallen on the upper surface of the cylindrical case of the multilayer unit gradually accumulate, the water drops do not sag to the bottom near the bank, In addition to the effects of the first aspect, water intrusion can be detected at an earlier stage in addition to the effect of the first aspect.

  According to the ultrasonic gas meter of claim 5, even if water drops that have dropped on the upper surface of the cylindrical case of the multilayer unit gradually accumulate, the bank portion formed on the inlet side opening side on the upper surface of the cylindrical case. The water droplets do not hang down to the bottom of the vicinity, flow to the water channel formed on the side of the cylindrical case, and further, the water droplets reach the bottom of the vicinity by the bank portion formed on the inlet side opening side of the water channel. In addition to the effects of the first aspect, water intrusion can be detected at an earlier stage in addition to the effect of the first aspect.

  According to the ultrasonic gas meter of the sixth aspect, since the water guided to the sensor joint portion by the water guiding structure is further accumulated inside the packing, in addition to the effects of the first to fifth aspects, the water is further infiltrated. Further, it can be detected at an early stage.

It is a perspective view which shows the 1st Example of the multilayer unit in the ultrasonic type gas meter of embodiment of this invention. It is a perspective view which shows the 2nd Example of the multilayer unit in the ultrasonic type gas meter of embodiment of this invention. It is a perspective view which shows the 3rd Example of the multilayer unit in the ultrasonic type gas meter of embodiment of this invention. It is a perspective view which shows the 4th Example of the multilayer unit in the ultrasonic type gas meter of embodiment of this invention. It is a perspective view which shows the 5th Example of the multilayer unit in the ultrasonic type gas meter of embodiment of this invention. It is sectional drawing which shows the principal part of the ultrasonic type gas meter of embodiment of this invention. It is a principal part flock figure of the ultrasonic type gas meter concerning the embodiment of the present invention. It is sectional drawing which shows the principal part of the conventional ultrasonic gas meter.

Next, embodiments of the present invention will be described with reference to the drawings. 1 is a perspective view showing a first example of the multilayer unit 1 in the embodiment, FIG. 2 is a perspective view showing a second example of the multilayer unit 1 in the embodiment, and FIG. 3 is a multilayer unit 1 in the embodiment. FIG. 4 is a perspective view showing a fourth example of the multilayer unit 1 in the embodiment, and FIG. 5 is a perspective view showing a fifth example of the multilayer unit 1 in the embodiment. FIG. 6 is a cross-sectional view showing a main part of the gas meter according to the embodiment of the present invention, and FIG. 7 is a main part flock diagram of the ultrasonic gas meter 10 of the embodiment. In FIG. 6, the same members as those shown in FIG.

  As shown in FIG. 6, the ultrasonic gas meter 10 includes a multilayer unit 1 obtained by improving the conventional multilayer unit 6. The multilayer unit 1 shown in FIG. 6 is that of the first embodiment described later. Further, the meter body includes a gas inlet 5a that communicates with a pipe of a gas supply source, a gas outlet 5b that is connected to a combustor and the like, an inlet channel portion 51 that communicates with the gas inlet 5a, a gas flow An outlet channel portion 52 communicating with the outlet 5b, and an intermediate channel portion 5c formed between the meter body and the bottom lid 5e are communicated between the inlet channel portion 51 and the outlet channel portion 52. I have. Then, the multilayer unit 1 is provided in the intermediate flow path portion 5c, and the flow velocity of the gas flowing through the multilayer unit 1 is measured by an ultrasonic flow rate sensor (not shown) disposed on the side of the multilayer unit 1.

  The inlet flow channel portion 51, the outlet flow channel portion 52, and the intermediate flow channel portion 5c are fixed to each other in a state in which the space between them is kept airtight. In the inlet channel 51, the intermediate channel 5c, and the outlet channel 52, a gas as a fluid to be measured flows inward in order. For this reason, the space inside the inlet channel 51, the intermediate channel 5c, and the outlet channel 52 constitutes a gas channel. And the below-mentioned water conveyance structure 2 is formed in the upper surface part 1a which is an upper surface of the multilayer unit 1 arrange | positioned in the intermediate flow path part 5c. Furthermore, a part of the multilayer unit 1 is a sensor joint portion S that is joined to an ultrasonic flow rate sensor described later. A gas shut-off valve 20 that shuts off the gas flow path by closing the valve is provided upstream of the intermediate flow path portion 5c.

  As shown in FIG. 7, the ultrasonic gas meter 10 includes two gas meters that are spaced apart from each other by a distance L and that are opposed to each other so as to form a predetermined angle with respect to the gas flow direction Y. It has acoustic transducers TD1, TD2. The acoustic transducers TD1 and TD2 constitute an ultrasonic flow rate sensor.

  The two acoustic transducers TD1 and TD2 are, for example, piezoelectric vibrators that operate at an ultrasonic frequency, and each of the transducers TD1 and TD2 is transmitted through a transducer interface (I / F) circuit 11a and 11b, respectively, and a transmission circuit 12 and a reception circuit. 13 is connected. The transmission circuit 12 transmits a signal for generating an ultrasonic signal by driving one of the transducers TD1 and TD2 in the form of a pulse burst under the control of the control unit 14 constituted by a microcomputer or the like.

  The receiving circuit 13 includes an amplifier 13a that receives signals from the other transducers TD1 and TD2 that have received the ultrasonic signal that has passed through the gas flow path and amplifies the ultrasonic signal to a predetermined intensity. The amplification degree of the amplifier 13a can be adjusted by the control unit 14.

  The control unit 14 performs various processes according to the program. And it has the measuring function which measures gas flow velocity for every sampling time using two transducers TD1 and TD2, and measures the instantaneous flow rate by multiplying the measured gas flow velocity by the cross-sectional area of the gas flow path. Further, in the present embodiment, the control unit 14 includes a determination function (determination means) that determines whether water has entered the gas flow path based on the amplification degree of the received ultrasonic signal. The CPU 14a can distinguish and determine whether the intrusion is less than a predetermined amount of water or more than a predetermined amount of water in the gas flow path.

  Here, the amplification degree of the received ultrasonic signal varies depending on the amount of water that has entered. For example, when a small amount of water, such as 20 to 70 cc, enters the gas flow path, ultrasonic waves are scattered, refracted, attenuated, etc. at the interface between water and gas, and the propagation becomes unstable. For this reason, the received ultrasonic signal tends to be small, and the amplification degree tends to increase. On the other hand, when a large amount of water of 80 cc or the like enters the gas flow path and becomes almost full, the space between the acoustic transducers TD1 and TD2 is filled with the same medium. For this reason, there is no interface between water and gas, scattering, refraction, attenuation and the like are less likely to occur, and the degree of amplification tends to decrease. For these reasons, the degree of amplification tends to increase for the ingress of a small amount of water, and tends to decrease for the ingress of a large amount of water.

  Therefore, the control unit 14 can determine that less than a predetermined amount of water has entered by monitoring the amplification degree or that more than a predetermined amount of water has entered. Note that water intrusion may be detected by a change in the propagation time of the ultrasonic wave. Further, when the amount of water immersion is 0 cc, the instantaneous flow rate is measured almost accurately, and the difference between the maximum value and the minimum value of the instantaneous flow rate becomes very small. However, when water enters, the difference between the maximum value and the minimum value of the instantaneous flow rate is greater than or equal to a predetermined flow rate due to the influence of water. Therefore, the control unit 14 may detect the intrusion of water based on the difference between the maximum value and the minimum value of the instantaneous flow rate.

  Next, each example of the multilayer unit 1 will be described. As shown in FIGS. 1 to 4, the multi-layer unit 1 of each embodiment is formed by accommodating a rectifying plate 3 in a cylindrical case 1 </ b> A having a rectangular parallelepiped cylindrical shape, and is open to the inlet channel portion 51 side. It has an entrance-side opening 1-1 and an exit-side opening 1-2 that opens to the outlet channel 52 side. Moreover, the opening part 1b is formed in the location close | similar to the entrance side opening part 1-1 side of the side surface of the cylindrical case 1A, and the circumference | surroundings of this opening part 1b become the sensor junction part S (S '). Then, ultrasonic waves are emitted from the acoustic transducer TD2 to the internal gas via the sensor joint portion S. The rectifying plate 3 is formed in a flat plate shape, arranged in multiple layers in parallel to each other at intervals, and is accommodated in the central portion of the cylindrical case 1A. The rectifying plate 3 is arranged in parallel with the longitudinal direction of the cylindrical case 1A, and makes the flow velocity of the gas flowing through the multilayer unit 1 uniform. Thereby, the gas flow rate can be accurately measured.

  The multilayer unit 1 of the first embodiment shown in FIG. 1 is formed on the upper surface 1a of the cylindrical case 1A from the upper side portion of the inlet side opening 1-1 to the opening 1b along both sides of the upper surface 1a of the cylindrical case 1A. An extending bank portion 21 is formed, and a water channel 22 is formed inside the bank portion 21 by the bank portion 21. The bank portion 21 and the water channel 22 constitute a water guide structure 2 that extends to the upper surface 1a of the cylindrical case 1A up to the sensor joint portion S and guides water to the sensor joint portion S. Further, a packing 4 is provided around the sensor joint portion S. And the water droplet which fell to the upper part (on the upper surface 1a) of the entrance-side opening 1-1 flows to the opening 1b, that is, the sensor joint portion S while being surrounded by the bank 21. Further, the water flowing out to the sensor joint portion S is accumulated inside the packing 4, and the water does not flow out to the periphery of the sensor joint portion S by the packing 4, and just into the ultrasonic sensor joint portion S of the multilayer unit 1. Accumulate. Thereby, even a small amount of water can be detected at an early stage. The multilayer unit 1 and the bottom cover 5e are not in close contact with each other in assembly, and are provided with a slight gap (play). And the packing 4 is provided so that it may just fit in the clearance gap. Further, the packing 4 may be formed of, for example, a self-foaming sponge that does not allow water to pass through, and may be attached to the multilayer unit 1 or the back cover 5e with a double-sided tape.

  In the multilayer unit 1 of the second embodiment shown in FIG. 2, a water channel 2 as a water guide structure is formed by recessing the upper surface 1a of the cylindrical case 1A. Note that the multilayer unit 1 of the second embodiment is also disposed in the intermediate flow path portion 5c shown in FIG. And the water channel 2 in 2nd Example is formed to the upper side part of the entrance side opening part 1-1, or the upper side of the opening part 1b, and comprises the water channel 2 extended to the sensor junction part S on the upper surface 1a of cylindrical case 1A. The water is led to the sensor joint S. Further, a packing 4 is provided around the sensor joint portion S. As a result, the water droplets falling on the upper part (on the upper surface 1a) of the inlet side opening 1-1 flow along the water channel 2 to the opening 1b, that is, the sensor joint portion S. Further, the water that flows out to the sensor joint portion S is accumulated inside the packing 4, and the water does not flow around the sensor joint portion S by the packing 4, and just the ultrasonic sensor joint portion S of the multilayer unit 1. It will be accumulated in. Thereby, even a small amount of water can be detected at an early stage.

  The multilayer unit 1 of the third embodiment shown in FIG. 3 has an opening 1b on the upper surface 1a of the cylindrical case 1A from the upper side one end of the inlet side opening 1-1 along the upper surface 1a of the cylindrical case 1A. An L-shaped bank portion 23 extending to one side is formed. The multilayer unit 1 of the third embodiment is also disposed in the intermediate flow path portion 5c shown in FIG. In the third embodiment, an inclined surface 24 and a bottom surface 25 that are slightly inclined from the upper side of the entrance-side opening 1-1 to the exit-side opening 1-2 are formed inside the bank portion 23. Has been. The bank portion 23, the inclined surface 24, and the bottom surface 25 constitute a water guide structure 2 that guides water to the sensor joint portion S to the upper surface 1 a of the cylindrical case 1 </ b> A inside the bank portion 22. Further, a packing 4 is provided around the sensor joint portion S. And the water droplet which fell to the upper part (on the upper surface 1a) of the entrance-side opening 1-1 flows to the opening 1b, that is, the sensor joint portion S while being surrounded by the bank 23. Further, the water that flows out to the sensor joint portion S is accumulated inside the packing 4, and the water does not flow around the sensor joint portion S by the packing 4, and just the ultrasonic sensor joint portion S of the multilayer unit 1. It will be accumulated in. Thereby, even a small amount of water can be detected at an early stage.

The multilayer unit 1 of the fourth embodiment shown in FIG. 4 includes a water channel 26 extending from the upper side of the inlet side opening 1-1 on the side of the cylindrical case 1A, and the inlet side opening 1-1 side of the water channel 26. And a bank portion 28 formed on the inlet-side opening 1-1 side of the upper surface 1a of the cylindrical case 1A. The water channel 26 and the bank portions 27 and 28 constitute a water guide structure 2 that guides water to the sensor joint portion S ′. Thereby, the water droplet which fell on the upper surface 1a of the entrance-side opening 1-1. Due to the bank portion 28 formed on the upper surface 1a of the cylindrical case 1A on the inlet side opening 1-1 side, water droplets do not hang down to the bottom in the vicinity but flow into the water channel 26. Further, the bank portion 27 formed on the inlet-side opening 1-1 side of the water channel 26 does not cause the water droplet to drip to the nearby bottom, and the water channel 26 reliably guides the water droplet to the sensor joint S ′. be able to. Thereby, even a small amount of water can be detected at an early stage.

  Here, FIG. 4 shows side walls 5c1 and 5c2 that form a part of the intermediate flow path portion 5c. Transducer attachment portions 5c3 and 5c4 to which the acoustic transducers TD1 and TD2 are attached are formed on the side walls 5c1 and 5c2. Gas flows from the inlet-side opening 1-1 to the outlet-side opening 1-2, but the vicinity of the transducer attachment portion 5c4 that is upstream of the gas flow is the sensor joint portion S, and downstream of the gas flow. The vicinity of the transducer attachment portion 5c3 is the sensor joint portion S '.

  In the first to third embodiments, the water guide structure 2 is configured to guide water to the upstream sensor joint portion S. However, the water guide structure 2 of the fourth embodiment is connected to the sensor joint portion S ′ on the downstream side. It is configured to guide water. The water guide structure 2 may guide water to either the upstream sensor joint portion S or the downstream sensor joint portion S ′. Although it is conceivable to lead water to both sensor joint portions S and S ′, it is possible to collect water more reliably if the water is concentrated on one side and guided.

  In the fourth embodiment, since the width of the side water channel 26 and the cylindrical case 1A is matched to the width of the intermediate flow path portion 5c, no packing is provided, but the sensor joint portion S ' You may provide packing like the said Example in the circumference | surroundings. In the fourth embodiment, the bank portions 27 and 28 prevent the water droplets from dropping, but only the side water channel 26 may be used. Further, the water channel 26 may be inclined toward the sensor joint portion S ′.

  The multilayer unit 1 of the fifth embodiment shown in FIG. 5 includes a water guide structure 2 that forms a water guide structure on the upper surface 1a of the cylindrical case 1A. The water guide structure 2 is a separate member from the cylindrical case 1A, and is attached to the cylindrical case 1A by bonding or the like. The cylindrical case 1A and the water guiding structure 2 may be fixed by screwing. The water guide structure 2 has a bank portion 29 extending from the position of the upper side portion of the inlet side opening portion 1-1 to the opening portion 1b along both sides of the upper surface 1a of the cylindrical case 1A. A water channel 29a is formed in the water. The bank portion 29 and the water channel 29a constitute a water guide structure 2 that extends to the upper surface 1a of the cylindrical case 1A up to the sensor joint portion S and guides water to the sensor joint portion S. Although illustration is omitted, a packing similar to the above-described embodiment is provided around the sensor joint portion S. And the water droplet which fell on the upper part of the entrance side opening part 1-1 flows to the opening part 1b, ie, the sensor junction part S, surrounded by this bank part 29, and the water which flowed out to the sensor junction part S is the inner side of packing. Accumulate. As a result, similar to the above embodiments, even a small amount of water can be detected at an early stage.

  Moreover, in this 5th Example, since the water conveyance structure 2 is comprised by the cylindrical case 1A and another member, there exist the following effects. In order to provide a bank portion, a hollow portion, and an inclined portion in the cylindrical case 1A of the multilayer unit 1, it is necessary to provide a slider in the molding die of the multilayer unit 1 in a direction perpendicular to the mold drawing direction. There are problems that the molding of the multilayer unit 1 becomes complicated, takes man-hours for molding, and the quality is not stable. However, if a separate water-conducting structure is produced as a molded product as in the fifth embodiment, the molding of the multilayer unit 1 itself does not increase the man-hour and the quality is stabilized.

  Various combinations of waterways and bank portions in each of the above embodiments can also be made. For example, in addition to the configuration of the second embodiment shown in FIG. 2 and the configuration of the third embodiment shown in FIG. 3, the first embodiment or the fourth embodiment is provided at the inlet side opening 1-1 side end of the upper surface 1a. Structures such as bank portions 22 and 26 may be provided. In addition to the configuration of the fourth embodiment shown in FIG. 4, a water channel having the upper surface 1a recessed may be formed on the upper surface 1a.

  Moreover, although the water conveyance structure 2 of 5th Example is a type which provided only the bank part 29, you may combine the structure of each said Example variously. For example, a separate water guide structure may be recessed to form a water channel, an inclined surface may be provided on the top surface of the separate water guide structure, and a bank portion may be formed around it. You may form a water channel in the side part of a cylindrical case with a water guide structure.

  The ultrasonic gas meter of the embodiment detects the intrusion of water using the output of the ultrasonic flow rate sensor. However, if the output of the ultrasonic flow rate sensor is used, the ingress of water is detected. The detection method is not limited to that of the embodiment, and other methods may be used.

DESCRIPTION OF SYMBOLS 1 Multilayer unit 1A Cylindrical case 2 Water conveyance structure, water conveyance structure 21 Bank part 22 Water channel 23 Bank part 24 Inclined surface 25 Bottom surface 26 Water channel 27, 28, 29 Bank part 3 Current plate 4 Packing S, S 'Sensor junction part

Claims (6)

A multi-layer unit provided in the gas flow path and in which a rectifying plate is arranged in multiple layers in a rectangular parallelepiped cylindrical case, and a flow rate of the gas flowing in the multi-layer unit joined to the cylindrical case of the multi-layer unit is exceeded. An ultrasonic gas meter comprising an ultrasonic flow rate sensor that detects sound waves and a determination unit that determines whether water has entered the gas flow path based on the output of the ultrasonic flow rate sensor. And
A water guide composed of a water channel surrounded by a bank that guides water from at least an upper surface of the cylindrical case of the multilayer unit to a sensor joint to which the ultrasonic flow rate sensor is joined from an opening on the multilayer unit. An ultrasonic gas meter having a structure.   The water guide structure is a bank part formed on the upper surface of the cylindrical case, and has a bank part extending from the inlet side opening part to the sensor joint part, and the inside of the bank part is configured as a water channel. The ultrasonic gas meter according to claim 1.   2. The ultrasonic gas meter according to claim 1, wherein the water guiding structure has a water channel extending from the inlet-side opening having a recessed upper surface of the cylindrical case to a sensor joint portion.   2. The ultrasonic wave according to claim 1, wherein the water guide structure includes an inclined surface that forms the water channel formed on an upper surface of the cylindrical case, and a bank portion that is formed around the inclined surface. Gas meter.   The water conveyance structure includes a water channel formed on a side portion of the cylindrical case, and a bank portion formed on the inlet side opening side of the upper surface of the water channel and the cylindrical case, respectively. Item 2. The ultrasonic gas meter according to Item 1.   The ultrasonic gas meter according to any one of claims 1 to 5, further comprising a packing that seals the cylindrical case and an inner wall of the gas flow path at the sensor joint portion.

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