JP4942254B2 - Gas meter - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to gas Sumeta.
[0002]
[Prior art]
The inventors of the present invention proposed in Japanese Patent Application No. 11-183112 (Japanese Patent Application Laid-Open No. 2001-12978) a gas flow meter that is small, inexpensive, and capable of accommodating a wide rangeability. This gas flow meter measures the flow rate of gas such as gas, and is arranged so that the flapper valve is opened and closed by the dynamic pressure of the gas and the valve differential pressure in the flow path. In addition, a bypass channel is provided in the channel to allow a small amount of gas to flow when the flapper valve is closed. The bypass channel includes a thermal flow sensor, and the flapper Estimated as a downstream flow path where the gas in the flow path section where the valve is disposed and the gas in the bypass flow path merge or an upstream flow path which supplies gas to the flow path section where the flapper valve is disposed and the bypass flow path section A gas flow meter was installed.
[0003]
Specific examples thereof are shown in FIGS. As shown in FIG. 12, a flow path area variable mechanism 2 and a speculative gas flow meter 3 are provided downstream of the flow path area. As shown in FIG. 13 and FIG. 14, the flow path forming body 4 that forms the flow path area variable mechanism portion 2 has one side wall 5 and the other side in a cross section (FIG. 14) perpendicular to the flow direction. It consists of a side wall 6, an upper wall 7, and a lower wall 8, and has a flow path 9 inside. The other side wall 6 is formed in a U-shaped cross section, and the flow path 9 is formed in a rectangular shape with a cross section in a direction orthogonal to the flow direction. Further, an inlet 10a is formed in the central portion of the upstream side wall 10, and a channel 12 for supplying gas to a main channel 16 and a bypass channel 17 described later is connected to the inlet 10a. An outlet 13a is formed at the central portion of the downstream side wall 13, and an outlet path 14 through which gas from a main channel 16 and a bypass channel 17 described later merge and flows out is connected to the outlet 13a.
[0004]
The inside of the flow path 9 is partitioned into a large flow rate circulation part and a micro flow rate circulation part by a partition plate 15, and the large flow rate circulation part is a main flow path 16 and the micro flow rate circulation part is a bypass flow path. The main flow path 16 is provided with a flapper valve 18 made of a light thin plate such as a plate material, for example, a foam material, so as to be opened and closed by the dynamic pressure of the flowing gas and the valve differential pressure. The flapper valve 18 is formed of a square plate having a size that fits substantially in the main flow path 16, and a horizontal support shaft 19 is fixed to a position that is eccentric upward from the center in the vertical direction. Both ends are fitted to the both side walls 5 and 6 so as to be rotatable, and the flapper valve 18 rotates about the support shaft 19.
[0005]
Further, the flapper valve 18 is inclined such that the lower part of the flapper valve 19 is located slightly downstream of the spindle 19 downstream of the flow path 9, and the upper end of the flapper valve 18 is located on the upper wall 7. As shown by the solid line in FIG. 13, when the gas flow rate is 0 to the set minute flow rate, the flapper valve 18 is brought into contact with the stopper 20 by its own weight and the contact with the stopper 20. The closed state is maintained at a predetermined inclination angle θ, and the flapper valve 18 is pushed open by the dynamic pressure of the gas and the valve differential pressure as shown by the chain line in FIG. It has become. A gap d in which the flapper valve 18 can be opened and closed is formed between both side ends of the flapper valve 18 and both side walls 5 and 6.
[0006]
The bypass flow path 17 is provided with a thermal flow sensor 21. In the example shown in the figure, it is provided at the center of the lower wall 8 side. The thermal type flow sensor 21 includes, for example, a fluid temperature detection unit disposed on the upstream side and the downstream side of the heat generation unit on the surface on which the flow on the silicon chip hits, and detects the fluid temperature on both sides of the heat generation unit according to the flow rate. Since the electrical resistance of the portion changes, this change is detected as an electrical signal, amplified, A / D converted, and the flow rate is obtained by a microcomputer. The speculation type gas flow meter 3 is, for example, a flow meter such as an ultrasonic type, a vortex type, a fluidic type, or a hot wire type.
[0007]
[Problems to be solved by the invention]
The inventors of the present application have developed the above-mentioned prior art and conducted intensive research to put a speculative gas meter in place of a membrane gas meter into practical use. In the above-mentioned conventional flapper valve, Since the restoring force (valve load) of the valve increases, when the valve begins to open with fluid dynamic pressure and valve differential pressure, the valve load increases and the valve operation becomes unstable and hunting occurs. The existence of the first problem that causes fluid vibrations, there is a source of pressure fluctuation in the pipe, and the valve may vibrate in synchronization with the pressure fluctuation depending on the pipe condition. I noticed. In addition, if the dimensional accuracy of the contact portion between the flapper valve and the valve seat is not good, the sealing performance of the valve portion will deteriorate and valve leakage will occur, resulting in a large flow measurement error at low flow rates. In order to eliminate the leakage, extremely high machining accuracy was required, and the existence of a second problem such as an adverse effect on the production cost was noticed.
[0008]
Accordingly, the present invention aims at providing a gas meter wide ultrasonic method of and range catcher Stability small type that can solve these problems. In particular, the problem to be solved most in the present invention is to prevent hunting from occurring when the on-off valve starts to open.
[0009]
[Means for Solving the Problems]
In order to achieve the first object, the invention of claim 1 is characterized in that a main channel having a large channel cross-sectional area in which an on-off valve is disposed, and an upstream side and a downstream side of the on-off valve in the main channel, respectively. A bypass channel having a small channel cross-sectional area having an inlet port and an outlet port, an ultrasonic transducer provided in the bypass channel for measuring a flow velocity at a small flow rate less than a constant flow rate, and the main channel A gas meter provided with a main flow channel measurement unit communicating in series with an ultrasonic transducer for measuring a flow velocity at a flow rate of a predetermined flow rate or more provided in the main flow channel measurement unit,
The on-off valve is provided so as to be able to oscillate about a support shaft arranged substantially horizontally, and oscillates by a dynamic pressure of the fluid and a valve differential pressure within a predetermined angle range between a vertical plane including the support shaft and a horizontal plane. A stopper for determining the limit angle of the on-off valve toward the side closer to the vertical surface of the predetermined angle range,
The inlet port is opened to the valve seat inner diameter side of the portion farthest from the support shaft in the valve seat portion with which the on-off valve abuts,
The gas meter is characterized in that an inclined surface farther away from the support shaft is formed on the inner diameter side of the valve seat at a portion where the inlet port is opened toward the downstream side in the flow direction of the main flow path when the valve is opened.
[0010]
In the present invention, when the flow rate is small, the on-off valve of the main flow path is closed and gas flows through the bypass passage. The gas flow velocity in the bypass passage is measured by an ultrasonic vibrator provided in the bypass passage. When the flow rate exceeds a certain level, the on-off valve is pushed by the fluid dynamic pressure and the valve differential pressure, and swings and opens downstream. At this time, the on-off valve is not opened at a stroke and hunted. And the pressure loss by an on-off valve becomes small. The flow rate at medium to large flow rates is measured with an ultrasonic vibrator provided in the main flow path measurement unit.
Further, the larger the opening after opening, the closer the valve body is to the vertical surface, so the valve load for closing the on-off valve is reduced and the occurrence of hunting is suppressed. In addition, when the valve body moves (opens) to the vertical surface, the valve closing force (valve load) due to the weight of the valve body becomes zero, and the valve may not be recovered. Since the movement (swinging) of the valve body is limited, such a fear is completely eliminated. Therefore, there is no possibility that the on-off valve cannot be restored.
Furthermore, the faster the gas flowing through the valve opening of the on / off valve, the more difficult it is for gas to enter the bypass passage due to the presence of the inclined surface. To suppress.
[0011]
Furthermore , since the on-off valve starts to open from the place where the elastic body is likely to leak at the part farthest from the support shaft, and the inlet port of the bypass passage is provided near it, the on-off valve is arranged in a direction that reduces the hunting cycle that may occur Stable without being able to follow, and suppresses the occurrence of hunting.
[0012]
According to a second aspect of the present invention, in the gas meter according to the first aspect , at least a peripheral portion of the on-off valve is formed of an elastic material into a flexible lip shape.
In this invention, since the lip-shaped peripheral edge of the valve body bends smoothly and adheres closely to the valve seat at a small flow rate, the stability of the seal portion is good and the valve leakage is reduced.
[0024]
According to a third aspect of the present invention, in the gas meter according to the first or second aspect , an inlet and an outlet are provided at an upper portion of the case, the main flow path measurement unit is disposed immediately downstream of the inlet, and the on-off valve is disposed immediately upstream of the outlet. It is characterized by that.
[0025]
In this invention, the flow rate at the small flow rate is measured by the ultrasonic vibrator in the bypass passage, and the flow velocity at the medium to large flow rate is measured by the ultrasonic vibrator provided in the main flow path measurement unit, thereby reducing the size and rangeability. It is possible to realize an ultrasonic gas meter that operates stably and does not cause hunting of the on-off valve.
[0026]
According to a fourth aspect of the present invention, in the gas meter according to the third aspect , a shut-off valve is disposed in a flow path portion that communicates between the main flow path measuring section and the on-off valve.
[0027]
In the present invention, when the gas flow rate exceeds a predetermined flow rate, the shut-off valve is closed, and a small gas meter with a safety function having a function such as a so-called flow rate over cutoff can be realized.
[0028]
DETAILED DESCRIPTION OF THE INVENTION
Next, preferred embodiments of the present invention will be described with reference to examples of the drawings.
[0029]
[Example 1]
In the first embodiment shown in FIG. 1, the gas flowing in from the upper entrance 32 of the gas meter case 31 as indicated by the arrow A passes through the main flow path measurement unit 33 arranged immediately below (just downstream) of the entrance 32. It passes between the valve element 35 and the valve seat 36 of the shut-off valve 34 and flows into the main flow path 37. When the gas flow rate is less than the set minute flow rate, the flapper-like on-off valve 38 is urged counterclockwise around the support shaft 39 by its own weight, and is in contact with the valve seat 40 and closed. The gas passes through the bypass flow path 42 from the inlet port 41 that opens to the farthest distance from the support shaft 39 of the valve seat portion, and passes from the outlet port 43 that opens downstream of the on-off valve 38 of the main flow path 37 to the main flow path. It returns to 37 and flows out from the exit 44 provided in the upper part of the case 31 of a gas meter. The bypass channel 42 is provided with a pair of ultrasonic transducers (not shown). With respect to the gas flow in the bypass channel, transmission and reception of ultrasonic pulses in the same forward direction as the flow direction, The ultrasonic pulse is transmitted and received in the opposite direction, the propagation time of the ultrasonic wave in the forward direction and the reverse direction is measured by an electronic circuit (not shown), the flow velocity is calculated, and the flow path of the bypass flow path 42 is interrupted. Multiply the area to find the flow rate.
[0030]
When the gas flow becomes faster and exceeds the set minute flow rate, the on-off valve 38 swings clockwise around the support shaft 39 and opens due to the dynamic pressure of the gas and the valve differential pressure. Then, the left side of the on-off valve 38 in the drawing, that is, the area where the distance from the support shaft 39 is large, first leaves the valve seat 40. Since this area is just close to the inlet port 41 of the bypass flow path 42, the left end of the on-off valve 38 is separated from the valve seat 40, and when gas flows upward between the valve and the valve seat, the bypass from the inlet port 41 is bypassed. Gas becomes difficult to enter the flow path 42, and the on-off valve 38 opens more and more. And as it opens, it approaches the vertical plane including the support shaft 39 as indicated by reference numeral 38 ', so that the valve closing force due to its own weight is reduced and the opening degree increases. Thus, hunting is suppressed, the valve opening is smoothly increased, and an increase in pressure loss due to the on-off valve is prevented.
[0031]
Thus, the flow rate of the medium to large flow rate gas when the flow becomes faster is measured by a pair of ultrasonic transducers (not shown) arranged in the main channel measurement unit 33 and the channel of the main channel measurement unit 33 is measured. It is converted to flow rate by multiplying the cross-sectional area. The control and calculation for measuring the propagation time of the ultrasonic waves in the forward direction and the reverse direction by a pair of ultrasonic transducers (not shown) of the main channel measurement unit 33 to obtain the flow velocity are not shown. This is done by a driving electronic circuit. Then, the flow rate of the bypass channel 42 at the minute flow rate and the flow rate of the main channel measurement unit 33 at the middle to large flow rate are integrated and displayed as a gas usage amount on a display unit not shown.
[0032]
When the flow rate increases and the on-off valve 38 rotates further clockwise than the angular position indicated by reference numeral 38 ′, the vicinity of the tip of the on-off valve 38 hits a stopper portion (also referred to as a stopper) 45 of the case 31 and rotates. Movement (oscillation) is limited. By doing so, it is possible to prevent the on-off valve 38 from being opened to a vertical plane including the support shaft 39 or an angle beyond the vertical plane and becoming unable to be restored (closed). The electronic circuit (not shown) has a flow rate monitoring function by a microcomputer. When an abnormal flow rate is detected, the shutoff valve 34 is closed and the valve body 35 is brought into contact with the valve seat 36 to stop the gas flow. Shut off the gas supply to Thus, it works as a gas meter with a safety function (so-called microcomputer meter). A return mechanism 46 is manually operated from the outside of the gas meter to open (return) the shut-off valve 34.
[0033]
As described above, the main flow path measuring unit 33 for measuring a medium to large flow rate is disposed immediately below (immediately downstream) the inlet 32, the on-off valve 38 is disposed directly below (immediately upstream) the outlet 44, and the shutoff valve is the main flow path. Since the measuring unit 33 and the on-off valve 38 are disposed in the flow path portion, an ultrasonic type gas meter having a wide rangeability can be formed in a small size and a compact size.
[0034]
[Example 2]
In FIG. 2 to FIG. 7, elements having the same reference numerals as those of the first embodiment of FIG. 1 perform the same functions as those of the first embodiment, and thus redundant description is omitted. . In this second embodiment, as shown in FIGS. 2, 3 and 6 in particular, the on-off valve 38 includes a valve frame 38a that is swingably supported on a support shaft 39, and a thin plate-like circle made of NBR having a thickness of 0.3 mm. A valve rubber 38b made of a plate, receiving plates 38c, 38d sandwiching the valve rubber 38b from both sides, and rivets 38e, 38e for connecting and fixing the movable end of the valve frame 38a to the center of the valve rubber 38b and the two receiving plates 38c, 38d. It cooperates with the valve seat 40. The support shaft 39 is attached to the on-off valve base 47, and the on-off valve base 47 is housed and fixed at a predetermined location in the case 31 as shown in FIGS. It is arranged directly below (immediately upstream).
[0035]
When the flow rate of the gas flowing through the gas meter is less than the set minute flow rate, the on-off valve 38 is inclined as shown in FIGS. 2 and 3, the valve load due to its own weight acts as the valve closing force, and the peripheral edge of the valve rubber 38b The portion is flexibly elastically deformed and bent, and is in close contact with the seat surface of the valve seat 40 as shown in FIG. In FIG. 7, the valve frame 38a, the receiving plates 38c and 38d, and the rivet 38e are omitted without being shown, and the drawing is simplified. The central portion of the valve rubber 38b sandwiched between the receiving plates 38c and 38d forms a part of a spherical surface along the shape of the receiving plates 38c and 38d. In the free state as a single piece of valve rubber before assembling, etc., it is a thin disc-shaped flat plate made of NBR with a thickness of 0.3 mm, and the lip-shaped part on the periphery stabilizes the operation of the seal part of the on-off valve after assembly It works effectively to prevent valve leakage at minute flow rates.
[0036]
A main flow path 37 when the on-off valve 38 is opened is formed in an inlet port 41 portion of the bypass flow path 42 that opens most far from the support shaft 39 in an inner diameter portion (also referred to as an inner diameter) 40 a of the valve seat 40. An inclined surface 40b that is farther away from the support shaft is formed toward the downstream side in the flow direction (substantially shown in the right direction in FIGS. 2 and 3). As a result, the opening / closing valve 38 opens, and the faster the gas flows, the more difficult it is for gas to flow from the inlet port 41 to the bypass flow path 42, thereby suppressing the occurrence of hunting of the opening / closing valve 38. In FIG. 7A, a circle formed by a two-dot chain line of an imaginary line denoted by reference numeral 38b ′ indicates an outer circumferential circle when the valve rubber 38b closes to the valve seat 40. As apparent from FIG. 7A, the annular portion 48 having a radial width ΔR sandwiched between the outer circumferential circle 38b ′ and the inner diameter 40a of the valve seat 40 is directed to the valve seat 40 when the on-off valve 38 is closed. A close contact portion (seal portion) of the valve rubber 38b is shown. Since the inclined portion 40b is formed and a part of the valve seat 40 is notched as described above, the annular portion 48 where the valve rubber 38b is in close contact with the valve seat 40 is shown. The width ΔR is a small width Δr in a portion adjacent to the inclined portion (notch portion) 40b. In this way, when the flow rate exceeds the set minute flow rate and the on-off valve 38 starts to open, the portion with the small width Δr is farthest from the support shaft 39 and tries to leave the valve seat first, and Δr < Since it is ΔR, the valve rubber is easily separated from the valve seat with a small force. Thus, since the air is vented from this portion at a flow rate slightly exceeding the minute flow rate, the on-off valve 38 does not cause hunting. Since the valve load decreases as the on-off valve 38 opens, the pressure loss at the maximum flow rate of the gas meter due to the on-off valve is not increased.
[0037]
In FIG. 7, the inclined portion 40 b is formed in a part of the valve seat 40, particularly the portion farthest from the support shaft 39, and the valve seat is notched, thereby reducing the radial width of the seal portion to a narrow width Δr, When the on-off valve starts to open, gas is easily leaked (vented) due to the presence of the inclined portion (notch). This prevents hunting when the on-off valve starts to open. In the example of FIGS. 8A and 8B, a part of the outer periphery of the valve rubber 38b, in particular, the part farthest from the support shaft 39 is formed with the cutout part 38B, so that the annular part 48 as the seal part in the radial direction. The width [Delta] r is set to a narrow width [Delta] r ', and the same effects as in the case of FIGS. 7 (a) and 7 (b) are obtained. In the example of FIG. 8, the inclined portion 40b in the case of FIG. 7 is not formed.
[0038]
As shown in black in FIG. 5, the ultrasonic vibrators 49 and 50 are disposed in the bypass channel 42 at a certain distance in the longitudinal direction of the bypass channel 42. And it is driven and controlled by a battery-driven electronic circuit (not shown) to transmit and receive ultrasonic pulses between both transducers, measure the propagation time of ultrasonic waves in the forward and reverse directions of the flow, Based on the propagation time, the flow rate of the gas flowing through the bypass channel 42 is calculated, and the flow rate is obtained by multiplying the channel cross-sectional area of the bypass channel.
[0039]
The flow rate from the middle to the large flow rate after the opening / closing valve 38 is opened is measured by an ultrasonic method in the main flow channel measurement unit 33 between the inlet 32 and the main flow channel 37. In FIG. 2, the ultrasonic transducers 51 and 52 are arranged to face each other with a certain distance in the main channel measurement unit 33 as shown in black. As in the case of the bypass flow path, the two vibrators 51 and 52 are driven and controlled by a battery-driven electronic circuit (not shown), and ultrasonic pulses are transmitted and received between the two vibrators. The propagation time of sound waves in the forward and reverse directions is measured. Then, the flow velocity is calculated based on the measured both propagation times, and the flow rate is obtained by multiplying the flow path cross-sectional area.
[0040]
In FIG. 5, 53 is a liquid crystal display unit mounted on the printed wiring board 54, and displays the flow rate integrated with time by the electronic circuit as the amount of gas used. Reference numeral 55 denotes a glass window. In the second embodiment, as shown in FIGS. 2 and 3, the stopper 45 is formed by providing an inclined bulge on the side wall of the case 31.
[0041]
Example 3
The third embodiment shown in FIGS. 9 and 10 is different from the second embodiment in the detailed structure of the on-off valve 38 and the shape of the stopper 45. In FIGS. 9 and 10, the valve frame 38a, the valve rubber 38b, and the receiving plate 38c are not hatched in order to avoid complicated drawings. In the third embodiment, the lower receiving plate 38d used in the previous embodiment is not used. FIG. 10 shows a state in which the on-off valve is separated from the valve seat 40 and a closed state in which the on-off valve is in contact with the valve seat 40. In the valve-closed state, a part of the portion extending from the outer periphery of the receiving plate 38c, which is the peripheral portion of the valve rubber 38b, in the outer peripheral direction (longitudinal direction) is pressed against the valve seat surface of the valve seat 40 and flexed flexibly. You can see how it is deforming. Thus, a stable seal is ensured. FIG. 11 is a diagram for explaining the main parts of the valve seat and the valve rubber of the third embodiment, and since there are many portions overlapping with FIG. In FIG. 5B, when the valve rubber 38b, whose peripheral portion is in close contact with the valve seat surface of the valve seat 40 when the valve is closed, starts to open, the reference numeral 38b ″ is attached and indicated by a two-dot chain line. As shown, the valve first begins to open from the vicinity of the inclined surface 40b, and arrows B and C in Fig. 9 indicate the gas flow when the on-off valve 38 is in the closed state and the open state.
[0042]
【Effect of the invention】
Since gas Sumeta of the present invention is constructed as described above, the following effects can be obtained. That is, the open valve is closed to prevent hunting, and does not increase the pressure loss. Moreover, there is no possibility that it cannot be restored even if it is opened wide.
Furthermore, as the on-off valve is opened, gas is less likely to enter the bypass flow path, so that the on-off valve operates more stably and the metering accuracy of the gas meter is improved.
[0045]
Further, a gas meter that is small and has a wide range can be realized, and the switching of the measurement flow rate can be performed stably without the risk of hunting of the on-off valve .
[0046]
Furthermore , the occurrence of hunting of the on-off valve can be further suppressed.
[0048]
In the invention of claim 2 , further, even when the valve is closed at a minute flow rate, the valve rubber is deformed flexibly and comes into close contact with the valve seat, so that a stable sealing property can be secured and the valve leakage is small.
In invention of Claim 3 , a gas meter can be put together compactly.
[0049]
In the invention of claim 4 , the gas meter achieved in claim 3 is added with a shut-off valve for stopping the supply of gas at an abnormal flow rate, and a gas meter with a safety function having a small size and a wide range can be realized.
[Brief description of the drawings]
FIG. 1 is a schematic vertical sectional view of an embodiment of the present invention.
FIG. 2 is a longitudinal front view of an embodiment of the present invention.
FIG. 3 is an enlarged view of a part of FIG.
FIG. 4 is a top view of an embodiment of the present invention.
FIG. 5 is a longitudinal side view of an embodiment of the present invention.
FIG. 6 is a perspective view of a main part of an embodiment of the present invention.
7A and 7B are diagrams of an on-off valve according to an embodiment of the present invention, in which FIG. 7A is a plan view of a valve seat, and FIG. 7B is a longitudinal sectional view when the valve is closed.
8A and 8B are diagrams of an on-off valve according to an embodiment of the present invention, in which FIG. 8A is a plan view and FIG. 8B is a longitudinal sectional view.
FIG. 9 is a longitudinal sectional view around an on-off valve according to an embodiment of the present invention.
10 is a longitudinal sectional view for explaining the operation of the on-off valve in FIG. 9;
FIGS. 11A and 11B are diagrams illustrating the on-off valve of FIGS. 9 and 10, wherein FIG. 11A is a plan view of the valve seat, FIG. 11B is a longitudinal sectional view when the valve is closed, and FIG. FIG.
FIG. 12 is a schematic vertical sectional view of the prior art.
FIG. 13 is a longitudinal sectional view around a flow path area variable mechanism portion in the prior art.
14 is a cross-sectional view taken along line AA in FIG. 13 of the prior art.
[Explanation of symbols]
31 Case 32 Inlet 33 Main flow path measurement part 34 Shut-off valve 37 Main flow path 38 On-off valve 38b Valve rubber 39 Support shaft 40 Valve seat 40a Inner diameter part 40b Inclined surface 41 Inlet port 42 Bypass flow path 43 Outlet port 44 Outlet 45 Stopper 48 Annular part 49, 50, 51, 52 Ultrasonic transducers ΔR, Δr, Δr ′ width

Claims (4)

A main channel having a large channel cross-sectional area in which the on-off valve is disposed, and a bypass channel having a small channel cross-sectional area having an inlet port and an outlet port respectively opened on the upstream side and the downstream side of the on-off valve in the main channel An ultrasonic transducer for measuring a flow velocity at a small flow rate less than a fixed flow rate provided in the bypass flow channel, a main flow channel measurement unit communicating in series with the main flow channel, and a main flow channel measurement unit. A gas meter comprising an ultrasonic transducer for measuring a flow velocity at a flow rate above a certain flow rate,
The on-off valve is provided so as to be able to oscillate about a support shaft arranged substantially horizontally, and oscillates by a dynamic pressure of the fluid and a valve differential pressure within a predetermined angle range between a vertical plane including the support shaft and a horizontal plane. A stopper for determining the limit angle of the on-off valve toward the side closer to the vertical surface of the predetermined angle range,
The inlet port is opened to the valve seat inner diameter side of the portion farthest from the support shaft in the valve seat portion with which the on-off valve abuts,
A gas meter, wherein an inclined surface farther away from the support shaft is formed on a valve seat inner diameter side of a portion where the inlet port is opened toward a downstream side in the flow direction of the main flow path when the valve is opened. Gas meter according to claim 1, characterized in that the at least peripheral portions of the on-off valve, is formed in a lip shape having flexibility in an elastic material. The gas meter according to claim 1 or 2 , wherein an inlet and an outlet are provided in an upper part of the case, the main flow channel measuring unit is arranged immediately downstream of the inlet, and the on-off valve is arranged immediately upstream of the outlet. The gas meter according to claim 3 , wherein a shutoff valve is disposed in a flow path portion that communicates between the main flow path measurement unit and the on-off valve.

Images