JPH08210599A - Gas leakage detector - Google Patents

Abstract

PURPOSE: To provide a gas leakage detector intended for small size, low cost, and lightness. CONSTITUTION: When a gas flow rate is lessened, a main supply route 5 is closed, whereby gas is made so as to be feedable through only a sub supply route 6 installed in parallel with the route 5, and any gas leakage at the downstream side is detected by means of flow rate monitoring through a flow detecting means 3. A diaphragm 47e is installed in the point midway in the sub supply route 6 as closing a passage so as to make the gas flow through only a fine hole 47g1 . Differential pressure being produced by the flowing of gas into this fine hold is received on both surfaces, varying it to some extent, through which a judging means 4 judges the gas leakage by means of a flow signal that the flow detecting means 3 outputs in response to this variation. In this case, the specified value is set by dint of energizing force of a spring means 47k displacing the diaphragm and normally energizing it in the opposite direction. This flow detecting means 3 consists of a magnet 47i being displaced with the diaphragm and a proximity switch 48.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas leakage detection device, and more particularly to a group supply facility for supplying city gas or the like to each house of an apartment house, particularly in a portion of a gas supply pipe upstream of a microcomputer meter or a buried pipe. The present invention relates to a gas leakage detection device that detects the presence or absence of leakage without stopping gas supply.

[0002]

2. Description of the Related Art In a collective supply facility for LP gas, city gas, etc., a gas meter for measuring the amount of gas used is provided at each door. Recent gas meters have a gas flow rate that flows through the gas meter by a built-in microcomputer. A so-called microcomputer meter has come to be used, which is capable of monitoring leakage and determining leakage in a gas pipe between a gas meter and a gas device. Therefore, with respect to gas leakage on the downstream side of the microcomputer meter, safety can be secured by providing the gas meter with a detection function.

On the other hand, in order to detect gas leakage in the gas supply pipe leading to the gas meter of each house, a gas leakage detection device is also provided at the entrance of the gas supply pipe in the collective supply facility, and the gas meter of each house also functions as a gas monitoring device. It has also been proposed to detect the presence or absence of gas leakage in the gas supply pipe of the low pressure part including the buried pipe upstream of the above without stopping the gas supply. As a gas leak detection device installed in such a place, it is conceivable to use a device having the same structure as the gas meter of each house. But in this case,
Since it is necessary to use a large-capacity gas meter that allows a large amount of gas flow flowing into the inlet of the collective supply facility, the sensitivity for detecting a minute gas leak cannot be obtained and is not satisfied.

Therefore, when the gas flow rate decreases,
A flow path switching unit that automatically switches the flow path from the large flow path to the small flow path by closing the large flow path so that the gas flows only in the bypass flow path as a small flow path provided in parallel with the large flow path. In addition to the above, a small-capacity membrane gas meter is installed in the small flow channel, and by utilizing the function of this gas meter, the gas flow in the small flow channel can be monitored and minute gas leakage in the gas flow channel up to the microcomputer meter can be detected. Some have been proposed.

In the proposed leak detection device, when the gas consumption at night or at midnight is almost exhausted, the gas is made to flow only to the small flow path by the flow path switching means, and the gas is supplied through the gas supply pipe on the downstream side of the flow path switching means. The minute gas flow rate that flows can be monitored by a membrane gas meter with a small flow path. At this time, the membrane gas meter will not detect the gas flow rate if there is no gas consumption and no minute gas leakage occurs.

[0006] Then, it is premised that such a phenomenon occurs at least once during a relatively long predetermined period of 30 days, and if the membrane gas meter detects the gas flow rate during this predetermined period. When it is not eliminated, it becomes possible to determine that a minute gas leak has occurred.

As described above, the bypass flow path is provided in a part of the gas supply pipe, the gas is caused to flow in the bypass flow path when the flow rate is low, and the flow rate is monitored by the gas meter provided in the bypass flow path to detect the minute flow rate. Since the gas leakage is detected, it is possible to easily and surely detect the gas leakage of the gas supply pipe without forcibly stopping the gas supply.

[0008]

However, the membrane gas meter used for monitoring the minute gas flow rate in the above-mentioned conventional apparatus has a complicated structure originally having a measuring function and has a high performance. It is large and expensive. For this reason, there has been a problem that the gas leakage detection device becomes unnecessarily large and costly.

Therefore, the present invention has been made in view of the above problems.
It is an object of the present invention to provide a gas leakage detection device that is compact, low cost, and lightweight.

[0010]

In order to achieve the above-mentioned object, the gas leakage detection device according to the present invention is provided in parallel with the main supply passage when the main flow passage is closed when the gas flow rate becomes small. In the gas leakage detection device, which allows gas to be supplied only through the sub supply path, and detects gas leakage on the downstream side by flow rate monitoring by the flow rate detection means provided in the sub supply path, having a fine hole,
A diaphragm that is provided in the middle of the sub supply passage so that gas flows only through the fine holes and that receives a differential pressure of a predetermined value or more generated by the gas flowing through the fine holes on both sides and is displaced. The present invention is characterized by including flow rate detecting means for outputting a flow rate signal in response to the displacement of the diaphragm, and determining means for determining gas leakage based on the flow rate signal from the flow rate detecting means.

The predetermined value is set by an urging force of spring means for constantly urging the diaphragm in a direction opposite to the displacement direction.

[0012] The flow rate detecting means is provided on the diaphragm and is displaced along with the diaphragm.
It is characterized by comprising a proximity switch which is turned on or off by the displacement of the magnet.

Counting means for counting the number of times the proximity switch is turned off or on for a fixed period;
It is characterized in that it has a comparing means for comparing a count value by the counting means with a predetermined number, and judges the possibility of gas leakage when the count value becomes equal to or less than the predetermined number.

The gas leakage detection device closes the main supply path when the gas flow rate becomes small, and supply path switching means for supplying gas only through the sub supply path provided in parallel with the main supply path, An opening / closing means having a valve body for opening / closing a valve opening provided at the inlet of the sub supply path,
The valve body of the opening / closing means and the valve body of the supply path switching means are simultaneously restrained in a valve closed state.

The restraint means forcibly presses the valve body of the supply path switching means against the valve opening so as to close the valve opening of the main supply path and maintains the valve closed state, and the inlet of the sub supply path. It is characterized in that the valve port provided in the is closed by the valve body of the opening / closing means to maintain the valve closed state.

[0016]

With the above structure, the valve body of the supply path switching means provided in the middle of the main supply path in parallel with the sub supply path opens the valve when the gas flow rate is high and closes it when the gas flow rate is low. Since the flow path is switched depending on the magnitude of the flow rate, a large pressure loss does not occur.

When the flow rate becomes small, the gas that has flowed only to the sub-supply path flows through the fine holes, and when a minute gas having a predetermined value or more flows into the fine holes, Due to the action, a differential pressure of a predetermined value or more is generated, and the diaphragm that receives it on both sides is displaced, and in response to this displacement, the flow rate detection means outputs a flow rate signal, and based on this flow rate signal, the determination means detects gas leakage. Since the determination is made, it is possible to detect whether or not a minute gas of a predetermined value or more is flowing in the sub supply passage by a simple configuration of a diaphragm provided to block the sub supply passage and a fine hole provided in this diaphragm. However, the possibility of gas leakage can be determined by this detection, and the predetermined value for determining the presence or absence of a minute gas flow can be easily and freely set by setting the diameter of the fine holes. It has become to so that.

Further, since the diaphragm is constantly biased by the spring means in the direction opposite to the displacement direction, the predetermined value for judging the presence or absence of the minute gas flow can be set easily and freely by the biasing force of the spring means. be able to.

Further, since the flow rate is detected by turning on or off the proximity switch by the displacement of the magnet provided on the diaphragm and displaced together with the diaphragm, the flow rate detecting means is compact.

Furthermore, the counting means counts the number of times the proximity switch is turned off or on for a certain period of time, the comparing means compares this count value with a predetermined number, and when the count value becomes less than the predetermined number, gas leakage occurs. Since it is determined that there is a possibility of gas leakage, a differential pressure always occurs when there is a gas leak, the differential pressure almost never disappears, the count value becomes small, and the possibility of a gas leak can be reliably determined. You can

Further, when the gas flow rate becomes small, the main supply passage is closed, and the supply passage switching means for supplying the gas only through the sub supply passage provided in parallel with the main supply passage, and the sub supply passage. The valve means of the opening / closing means and the valve body of the supply path switching means are simultaneously restrained in the valve closed state by the restraining means and the opening / closing means having a valve body for opening / closing the valve opening provided at the inflow port. , Forcibly pressing the valve body of the supply path switching means against the valve opening so as to close the valve opening of the main supply path, and closing the valve opening provided at the inlet of the sub supply path with the valve body of the opening / closing means. Since the valve closed state is maintained, it can be used as a switching valve in cooperation with the supply path switching means, and the gas flow can be completely blocked or not blocked arbitrarily. The gas supply pipe and inner pipe were changed significantly , Or when necessary to the construction of or repair occurs, can be completely shut off the gas flow, it is possible to safely perform the work.

[0022]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of the gas leakage detection device of the present invention. In the figure, the gas leakage detection device 1 is configured as a flow path switching type that incorporates a function of a shutoff valve and also serves as a main valve of an outer lamp inner tube branched from a low pressure branch pipe 11. The gas leakage detection device 1 is connected in the middle of the outside lamp inner tube 13 with its inlet on the supply side of the outside lamp inner tube 13 and its outlet on the downstream side of the outside lamp inner tube 13, and is connected to a supply path switching means. The switching unit 2 includes a flow path switching valve 2a as an element and an opening / closing valve 2b as an opening / closing unit, a flow rate detection unit 3, and a gas leakage determination unit 4.

The flow path switching valve 2a of the switching unit 2 has a switching valve inlet 22 on the supply side of the outer lamp tube 13 and a switching valve outlet 23.
Is connected to the downstream side, and constitutes the main supply path 5 together with the external lamp inner tube 13. A sub-supply pipe 6 as a sub-supply passage having an inflow port 24 and an outflow port 25 on the upstream side and the downstream side thereof is connected in parallel to the flow path switching valve 2a forming a part of the main supply path 5. There is.

Between the inflow port 24 and the outflow port 25 of the sub supply pipe 6, an on-off valve 2b as an opening / closing means for opening and closing the sub supply pipe 6 and a flow rate detecting section for detecting the gas flow rate flowing through the sub supply pipe 6. 3 are sequentially connected from the upstream side. The flow path switching valve 2a and the on-off valve 2b are adapted to be closed by interlocking with each other by a restraint means described later. The on-off valve 2b and the flow rate detection unit 3 together with the sub supply pipe 6 form a sub supply path. The gas leakage determination unit 4 determines gas leakage based on the flow rate detection signal from the flow rate detection unit 3.

The LP gas and city gas used in the housing complex 14 are supplied from a gas supply source (not shown) to the low pressure branch pipe 1.
1, the light is supplied to the collective supply facility 15 of the housing complex 14 through the outer pipe 13 of the lamp. The equipment 15a corresponding to each door of the collective supply equipment 15 includes a microcomputer meter (not shown),
This microcomputer meter can be provided with a function of judging gas leakage on the downstream side thereof. The low-pressure branch pipe 11 is a pipe buried in the ground, and supplies gas that has already been brought to a low-pressure pressure state. The outer lamp inner pipe 13 is a pipe branched and connected from the low-pressure branch pipe 11 and is buried in the ground like the low-pressure branch pipe 11.

2 and 3 show specific structures of the switching section 2 and the flow rate detecting section 3 of FIG. 1, in which a flow path switching valve 2a as a supply path switching means and an opening / closing valve 2b as an opening / closing means are provided. FIG. 2 is a cross-sectional view showing the unconstrained state of the switching portion and FIG. 3 showing the restrained state of the switching portion.

The switching section 2 is a light inner tube 13 which is a gas supply path.
Has a switching unit body 21 inserted and connected in the middle of the
The switching unit main body 21 is formed with an inlet 22 and an outlet 23 formed with female threads to which the ends of the upstream and downstream external lamp inner tubes 13 are respectively screwed. The switching unit main body 21 is also provided with a partition wall 26 for partitioning the upstream side and the downstream side between the inflow port 22 and the outflow port 23, and adjacent to the partition wall 26, two openings 21a and 21b are provided. Formed on the side. The switching unit body 21 is further provided with the inlets 24 and the outlets 25 of the sub supply passages.
Is formed on the side opposite to that on which is provided. The inflow port 24 and the outflow port 25 are also partitioned by the partition wall 26, and are provided slightly downstream of the inflow port 22 and slightly upstream of the outflow port 23, respectively.

The two openings 21a and 21b formed adjacent to the partition wall 26 have an airtight ring 28 on the switching unit body 21.
Are connected to each other through a distribution space S formed by the curved cover 27 attached by using the above-mentioned, and form a part of the main supply path. In addition, a bearing hole 27a is provided at the top of the cover 27.
An opening / closing rotary operating rod 45, the lower end of which is thrust-bearing to a support plate 45b fixed in the cover 27, is airtightly and rotatably attached to the bearing hole using an airtight ring 45a. An operation cam member 45c is fixed to the rotation operation rod 45 by a nut 45d.

A cylindrical nozzle 31 serving as a valve port is attached to the opening 21a in an airtight and slidable manner using an airtight ring 32. A float guide 33 that guides a float 38 is integrally formed with the nozzle 31 via a flange 34 that laterally extends from the nozzle 31. The float guide 33 is formed in a shape in which 3 to 4 support columns 33b standing upright from the flange 34 are connected by a ring 33a so that gas can freely pass through S ₁ between the support columns 33b when the float 38 floats. Has become. The lower portion of the nozzle 31 mounted at equal angular upper end of three or four arms 35a to the gas passage S ₂ are formed, and the lower end of the arms 35a nozzle 3
It is attached to a cylindrical portion 35b having a diameter smaller than that of 1 and concentric with the nozzle 31.

A valve rod 36 is slidably inserted into the cylindrical portion 35b in the thrust direction, and is protruded and held downward by a coil spring 36b provided between the stop ring 36a and the cylindrical portion 35b. Has been done. The arm 35a and the cylindrical portion 35b are integrally formed to form a valve rod support 35 that supports the valve rod 36. A spring 37 is contracted between the upper surface of the switching unit body 21 outside the nozzle 31 and the lower surface of the flange 34 so as to push up the flange 34 from below. As a result, the float guide 33 integrally formed with the flange 34 is also pushed up until a part of the flange 34 contacts the stopper 34a.

The float 38 arranged inside the float guide 33 is formed in a shape in which a cylindrical projection is provided on the lower surface of a cylinder whose upper and lower end surfaces are closed, and the inside is hollow.
A packing 39, which closes the opening of the nozzle 31 and acts as a part of the valve body, is attached around the cylindrical projection on the lower surface. The float 38 can move up and down inside the float guide 33, and when the gas flow is large, the float 38 is pushed by the gas flow and floats up, and the packing 39 causes the nozzle 31 to move.
Away, the gas flows into the flow space S through the nozzle 31, and when the gas flow is small, the gas falls by its own weight, and the packing 39 contacts the periphery of the upper end of the nozzle 31.
The nozzle 31 is closed to shut off the gas flow. That is, the float 38 has both the two functions of floating and a part of the valve body of the supply path switching means. Therefore, the float 38 and the packing 39 form a valve body of the supply path switching means.

A nozzle 41 is provided as a valve port at the upper end of the inflow port 24 of the sub supply pipe. The valve body 42 that opens and closes the nozzle 41 is made into a nail shape, and the needle portion is the nozzle 41.
Threaded inside. A spring 43 is provided outside the nozzle 41 and supports the nail head of the valve body 42 from below. Disc 4
2 is normally lifted by a spring 43 and the nozzle 41
Is open, but when pushed down by the valve stem 36, the nozzle 4
1 is closed.

A guide retainer 46 is provided in the cover 27 adjacent to the opening / closing rotary operation shaft 45. The guide retainer 46 has a sliding rod 46a protruding upwardly inserted into and guided by a sliding hole 45b ₁ of the support plate 45b in a vertically slidable manner, and also has a retaining ring 46b at its protruding end. Coil spring 4 compressed between support plate 45b
The upward biasing force is always applied and held by 6c. With this configuration, the tip of the sliding rod 46a is elastically contacted with the cam surface 45c ₁ of the cam member 45c. The guide retainer 46 is a disc member 46 that pushes the upper end of the float guide 33.
d and the float holding member 4 that pushes the upper surface of the float 38
6e and a supporting member 46f for supporting the disk member 46d and the float pressing member 46e, and the float pressing member 46e is a substantially L-shaped lever member made of a spring material rotatably supported by a bent portion. The one end is elastically contacted with the upper end edge of the float guide 33, and the other end is displaced downward by the clockwise rotation and is elastically contacted with the upper end surface of the float 38.

When the opening / closing rotary operation rod 45 is rotated, the cam member 45c is also rotated, and the tip of the sliding rod 46a elastically contacted with the cam surface 45c ₁ rides on the high portion of the cam surface and slides. Rod 46a and guide retainer 46 integral with this
Moves down against the coil spring 46c. Due to the lowering of the guide retainer 46, the float retainer member 46e rotates first in the clockwise direction, and the other end hits the upper surface of the float 38 and pushes down the float 38, and the packing 39
Is contacted with the periphery of the upper end of the nozzle 31, and the nozzle 31 is closed. Then, the disc member 46d abuts on the float guide 33 at a timing when the float 38 cannot be lowered any more, but when the guide retainer 46 further lowers against the coil spring 46c by this, the disc member 46d causes the float guide 33 to move toward the float 38. With coil spring 3
7, the valve stem 36 of the valve stem support 35 simultaneously pushes down the valve body 42 against the spring 43. When the valve element 42 is pushed down, the valve element 42 closes the nozzle 41. When the valve body 42 hits the nozzle 41 and cannot be lowered further, the coil spring 36b compresses and the valve rod 36 escapes. Therefore, even if the float guide 33 further descends, an unnecessarily large force is exerted on the valve body 42 and the nozzle 41. It's gone.

The opening / closing rotary operating rod 45 is rotated to the end, and the tip of the sliding rod 46a has the cam surface 45c of the cam member 45c.
_When you get on the flattest highest cam surface part of ₁ , it will be held in that state. Therefore, the opening / closing rotary operation rod 45 and the guide retainer 46 serve as restraint means for restraining the movement of the float 38, the packing 39, and the valve body 42 as the valve body.

With the structure described above, the float 38 as a part of the valve body of the supply path switching means opens the nozzle 31 when the gas flow rate is large and closes the valve when the gas flow rate is small. Since the flow path is switched depending on the magnitude of the flow rate, a large pressure loss will not occur. Further, the switching gas flow rate can be set by selecting the weight of the float 38 forming a part of the valve body.

Inflow port 24 formed adjacent to partition wall 26
One ends of the connection pipes 41a and 41b are respectively screwed into the outflow port 25 and the other end of the connection pipes 41a and 41b, and the inlet 3a and the outlet 3b of the flow rate detection unit 3 are connected to the connection nut 44.
It is connected by a and 44b. The flow rate detection unit 3 includes a detection unit main body 47 having an introduction hole 47a communicating with a conduit 44c forming the inlet 3a, and a lid having the outlet 3b while forming a flow rate detection chamber 47c in cooperation with the detection unit main body 47. It consists of a body 47d. The lid 47d is the airtight ring 4.
The flow rate detection chamber 47c, which is attached to the detection unit main body 47 via 7b and is formed airtight, has an introduction hole at the inlet 3a by a diaphragm 47e whose peripheral portion is sandwiched between the detection unit main body 47b and the lid 47d. It is partitioned into an inlet pressure chamber 47c ₁ that communicates through 47a and an outlet pressure chamber 47c ₂ that communicates with the outlet 3b.

As shown in a partially enlarged view in FIG. 4, a reinforcing disk 47f is attached to the lower surface of the diaphragm 47e. Circular holes 47e ₁ and 47f ₁ are respectively formed in the centers of the diaphragm 47e and the reinforcing circular plate 47f, and the peripheral edges of the circular holes are erected on the upper surface side of the diaphragm 47e and fitted to each other. In the circular holes 47e ₁ and 47f ₁ ,
A fine hole 47g ₁ communicating the inlet pressure chamber 47c ₁ and the outlet pressure chamber 47c ₂ is inserted in the center, a collar 47g ₂ is inserted at one end, and a nozzle member 47g having a screw 47g ₃ formed on the outer periphery is inserted. The diaphragm 47e, the reinforcing disc 47f, and the nozzle member 47g are attached to the screw 47g ₃ at the insertion end.
The diaphragm 47e and the reinforcing disc 47f are sandwiched between the collar 47g ₂ and the cap-shaped nut 47h and integrated by screwing the cap-shaped nut 47h into the.

A magnet holder 47j for holding a magnet 47i with a gap directly below the fine hole 47g ₁ is caulked to the brim 47g ₂ of the nozzle member 47g. The magnet holder 47j has an inlet pressure chamber 47c.
A flow path 47j ₁ is formed to connect ₁ and the fine hole 47g ₁ .

A coil spring 47k is contracted between the lid 47d and the diaphragm 47e, and the diaphragm 4k
7e is urged downward in the drawing. As the urging force of the coil spring 47k is not changed by shift positions of the coil spring 47k, the projection 47d ₁ formed on the inner surface of the lid 47d, the coil spring 47k to the annular rib 47e ₂ formed on the upper surface of the diaphragm 47e Each end of is fitted.

In the detection unit main body 47, especially the magnet 4
A part of the wall forming the inlet pressure chamber 47c ₁ adjacent to 7i is thinly formed. A reed switch 48, which is turned on when the magnet 47i approaches, is fixed to the outside of the detection unit main body 47 that faces the magnet 47i with this wall interposed therebetween. Also, an on / off signal for the reed switch 48 is provided adjacent to the reed switch 48. Is provided as a flow rate detection signal, and a gas leakage determination unit 4 for determining gas leakage is provided. In the gas leakage determination unit 4, as shown in FIG. 5, a microcomputer (CPU) 4a that operates as described below according to a predetermined program is used as a reed switch 4.
8. A signal from the reset switch 4b or the like is input and processed, and an alarm signal is output when there is a leak. In addition to the control program, the CPU 4a functions as a ROM 4a ₁ storing various fixed data, a data area storing various data being processed, and timers T ₁ , T ₂ and counter n as shown in FIG. It has a built-in RAM 4a ₂ having a work area that constitutes the means. In addition, the reset switch 4b is installed in the gas cylinder when the supply gas is LPG, and is operated after the operator confirms the presence or absence of leakage by turning on / off the leakage warning indicator lamp when replacing the cylinder. In the case of city gas, it may be provided on the monitoring panel of the housing complex and operated after checking the leakage warning indicator lamp of the monitoring panel for every month, for example.

With the structure described above, the float 38, which is a part of the valve body of the switching means, opens the nozzle 31 when the gas flow rate is high and closes it when the gas flow rate is low. As long as it is present, in any case, the gas flows through the fine holes 47g ₁ of the flow rate detecting unit 3 in the sub supply path. When the gas flows through the fine holes 47g ₁ , the flow rate is Q (m ³ / h) and the diameter of the fine holes 47g ₁ is D (m
m), the differential pressure generated between the inlet pressure chamber 47c ₁ and the outlet pressure chamber 47c ₂ by the fine hole 47g ₁ is ΔP (mmH ₂
O), the gas density ρ (numerical value based on air), and the coefficient k (0.0092), the following equation holds, and the differential pressure ΔP between the inlet pressure chamber 47c ₁ and the outlet pressure chamber 47c ₂ is Occurs. Q = k × D ² × (ΔP / ρ) ^1/2

As is clear from the above equation, the fine holes 47g ₁
By appropriately setting the diameter of the gas, a minute gas flow generates a differential pressure ΔP of a predetermined value or more, and by utilizing this pressure difference, the diaphragm 47e is displaced upward against the biasing force of the coil spring 47k. You can The displacement of the diaphragm 47e can be detected when the magnet 47i which is displaced together with the diaphragm 47e is separated from the reed switch 48 and the reed switch 48 is turned off. Therefore, by setting the above-mentioned predetermined value according to the minute gas leakage to be detected, the reed switch 48 can be held in the off state even by the gas flow accompanying the minute gas leakage. Therefore, the leak determination unit 4 can determine a gas leak by inputting a signal indicating the presence or absence of a gas flow rate of a predetermined value or more from the flow rate detection unit 3 provided in the middle of the sub supply path.

In the above construction, when the gas is not used, the switching section 2 works so that the gas does not flow to the main supply passage. If there is a gas leak downstream of the leak detection device and the leak is minimal, the switching unit 2 still keeps the main supply path closed. Therefore, gas flows through the fine holes 46g ₁ in the sub supply path, the diaphragm 46e is displaced against the biasing force of the coil spring 46k under the differential pressure generated by this gas flow, and the magnet 47i is reed switch 47. The reed switch 47 is held in the off state. On the other hand, when there is no gas leakage, gas does not flow into the fine holes 47g ₁ and the diaphragm 47g ₁
The differential pressure that displaces e against its own weight and the coil spring 47k does not occur, and the magnet 47i comes closer to the reed switch 48 due to its own weight and the coil spring 47k, so that the reed switch 48 is turned on.

When the state of the flow rate 0 (the state where the reed switch is on) is generated continuously for, for example, 1 minute, this is counted, and this operation is performed for 30 days, and when the count value during this period is less than a predetermined number, leakage is caused. If there is more than a predetermined number, it is determined that there is no possibility of leakage. If it is determined that there is a possibility of leakage, the information is transmitted to the management center side via the telephone line so that leakage can be monitored at a remote location for the presence or absence of leakage.

Next, the details of the operation of the leakage determination unit will be described in detail by referring to the microcomputer (CPU) 4 of the leakage determination unit.
This will be described below with reference to the flowchart of FIG. The CPU 4a starts its operation when the power is turned on, and determines in the first step S1 whether or not the reset switch 4b has been turned on.
If S, the process proceeds to step S2, and timers T ₁ and T as shown in FIG. 6 configured in the work area of the RAM 4a ₂ are formed.
_{2. After} resetting all counters n, the process proceeds to step S3. When the determination in step S1 is NO, step S2 is skipped and the process proceeds to step S3.

In step S3, it is determined whether the reed switch 48 is on, and this determination is YES.
In this case, that is, when there is no gas flow in the fine holes 47g ₁ , the process proceeds to step S4, resets the timer T ₁ which is, for example, a one-minute timer, and then proceeds to step S7 described later. When the determination in step S3 is NO, that is, when there is a gas flow in the fine holes 46g ₁ , the process proceeds to step S5 and it is determined whether or not the timer T ₁ has timed out. When the determination in step S5 is NO, the process proceeds to step S7, which will be described later, and when the determination in step S5 is YES, that is, when the reed switch 48 remains on for one minute or more, the process proceeds to step S6 and the counter n is incremented. Then, the process proceeds to step S7.

In step S7, it is determined whether or not the timer T ₂ including a 30-day timer has timed out. When the determination in step S7 is NO, the process returns to step S1 and the processes in steps S1 to S6 described above are repeated. When the determination in step S7 is YES, the process proceeds to step S8 and the count value of the counter is set to 3 for example. Is less than a predetermined number, and when this determination is NO, that is, when the count value of the counter n is, for example, 3 or more, it is determined that there is no gas leakage, the process proceeds to step S9, and the timer is started. returns to step S1 to T ₂ is reset and repeats the processing of step S1～8. When the determination in step S8 is YES, that is, when the count value of the counter n is less than 3, it is determined that there is a possibility of gas leakage, the process proceeds to step S10, a leak alarm signal is output, and then the process returns to the original. This leak warning signal is used to turn on a leak warning indicator provided in the gas cylinder storage or the monitoring panel, and is also used to notify the remote monitoring center.

As described above, when the gas consumption is almost exhausted, such as at night or midnight, the float 38 is lowered by its own weight and the packing 39 comes into contact with the nozzle 31, and the nozzle 3
The gas flow passing through 1 is blocked, and only the gas flowing from the inflow port 24 to the flow rate detection unit 3 through the nozzle 41 is blocked, whereby the minute gas flow rate flowing to the flow rate detection unit 3 can be monitored. Because. At this time, if there is no gas consumption and no minute gas leakage occurs, the flow rate detection unit 3 will not detect the gas flow rate. Then, as in the conventional case, on the assumption that such a phenomenon occurs at least three times during a relatively long predetermined period of 30 days, for example, if the flow rate detection unit 3 changes the gas flow rate during the predetermined period. If it is not detected three times or more, it is judged that a minute gas leak has occurred.

As described above, the CPU 4 which functions as a judging means for judging the gas leakage from the flow rate signal from the flow rate detecting means.
As shown in FIG. 5, a is a counting means 4a ₃ for counting the number of times the reed switch 48 is turned off or on for a certain period.
Then, it functions as a comparison means 4a ₄ for comparing the count value with a predetermined number, and judges the gas leakage when the count value becomes less than the predetermined number.

When it is necessary to significantly change or repair the existing gas supply pipe or inner pipe, even if it is a small amount of gas, it is uncomfortable and the gas flow is changed. Must be completely shut off. In such a case, as shown in FIG. 3, when the opening / closing shaft 45 is rotated to lower the guide retainer 46, the disc member 46a of the guide retainer 46 resists the elastic force of the spring 37 and the float guide 3
3 is pushed down, and the float pressing member 46b is float 3
Push 8 down. At this time, the nozzle 31 connected to the float guide 33 together with the airtight ring 32 has the switching unit main body 2
Sliding down the opening 1 while keeping airtight. Valve rod 3
6 is pushed down at the same time because it is connected to the nozzle 31, and the valve rod 36 pushes down the valve element 42. The valve body 42 closes the nozzle 41, which is the valve opening, completely shuts off the gas flow, and makes a large change to the existing gas supply pipe or inner pipe, or safely performs construction work. Will be able to.

After completion of the construction, when the opening / closing shaft 45 is rotated in the opposite direction to raise the guide retainer 46, the float guide 33 is lifted up by the elastic force of the spring 37, and the valve body 42 is also spring 4.
The elastic force of 3 raises the nozzle to open the nozzle 41.
Conventionally, it was necessary to separately provide a manual shutoff valve upstream of the gas flow, but the gas leakage detection device of the present embodiment has an opening / closing shaft 45.
And a guide retainer 46 are added, the function of the flow path shut-off valve is incorporated so that it does not have to be a switching valve, so there is no need for it. Therefore, the size and cost can be reduced as compared with the case where a separate shut-off valve is provided. And weight reduction.

Although the reed switch 48 which is turned on by the approach of the magnet is used as the proximity switch in the above embodiment, a reed switch which is turned off by the approach of the magnet may be used instead. .

[0054]

As described above, according to the present invention,
The valve body of the supply path switching means provided in the middle of the main supply path in parallel with the sub supply path is designed to open the valve when the gas flow rate is high and close the valve when the gas flow rate is low. Since the flow path is switched depending on the size of the pressure, a large pressure loss will not occur.

Further, the simple structure of the diaphragm provided so as to close the sub-supply passage and the fine holes provided in the diaphragm allows the sub-supply passage to have a predetermined value or more while achieving downsizing, cost reduction and weight reduction. Whether or not a minute gas is flowing can be detected, and the possibility of gas leakage can be judged by this detection, and the predetermined value for judging the presence or absence of a minute gas flow can be easily and freely set by setting the diameter of the fine holes. It can be set.

Further, it is possible to easily and freely set the predetermined value for judging the presence or absence of the minute gas flow by the urging force of the spring means, and to make the flow rate detecting means compact. And, when there is a gas leak, a differential pressure is always generated, the differential pressure almost never disappears, and the count value becomes small,
The possibility of gas leakage can be reliably determined.

Further, the switching gas flow rate can be easily set by selecting the weight of the member that descends along the valve guide member by its own weight to close the valve opening, float by a large gas flow rate, and open the valve opening.

Furthermore, by simultaneously restricting the main supply path and the sub supply path to the valve closed state, it is possible to completely block or not block the gas flow in the flow path. When it is necessary to significantly change or repair the gas supply pipes and inner pipes, the gas flow can be completely shut off, and the work can be performed safely. .

Furthermore, the work of greatly changing or repairing the existing gas supply pipe or inner pipe can be safely carried out without providing a separate shutoff valve, which has high mountability and can be installed in existing equipment. It is very easy to handle.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a gas leakage detection device of the present invention.

FIG. 2 is a cross-sectional view showing an open state of a switching unit in FIG.

3 is a cross-sectional view showing a closed state of a switching unit in FIG.

FIG. 4 is an enlarged cross-sectional view of a part of the flow rate detection unit of FIG.

5 is a diagram showing a circuit configuration of a gas leakage determination unit in FIG.

6 is a diagram showing a part of a work area in a RAM shown in FIG.

FIG. 7 is a flowchart showing a process performed by the CPU in FIG.

[Explanation of symbols]

1 Gas Leakage Detector 2a Supply Path Switching Means (Supply Path Switching Valve) 2b Opening / Closing Means (Opening / Closing Valve) 3 Flow Rate Detection Means (Flow Rate Detection Section) 4 Judgment Means (Gas Leakage Judgment Section) 4a ₃ Counting Means (CPU) 4a ₄ Comparison means (CPU) 5 Main supply path 6 Sub supply path 31 Valve mouth (nozzle) 33 Valve body guide member (float guide) 36 Valve rod 38, 39 Valve body (float, packing) 42 Valve body 45 Restraining means (for opening and closing) Rotation operation axis) 46 Restraint means (guide retainer) 47g ₁ Micro hole 47e Diaphragm 47k Spring means (coil spring) 47i Magnet 48 Proximity switch (reed switch)

Claims (6)

[Claims] 1. A main supply passage is closed when the gas flow rate becomes small, and gas can be supplied only through a sub supply passage provided in parallel with the main supply passage. A gas leakage detection device configured to detect a gas leak on a downstream side by monitoring a flow rate. The gas leakage detection device has a fine hole and is provided in the middle of the sub supply passage so that gas flows to the sub supply passage only through the fine hole. ,
A diaphragm that is displaced by receiving a differential pressure equal to or higher than a predetermined value generated by the gas flowing through the fine holes, a flow rate detection unit that outputs a flow rate signal in response to the displacement of the diaphragm, and a flow rate detection unit A gas leakage detection device comprising: a determination unit that determines gas leakage based on a flow rate signal. 2. The gas leakage detection device according to claim 1, wherein the predetermined value is set by an urging force of spring means that constantly urges the diaphragm in a direction opposite to the displacement direction. 3. The flow rate detecting means comprises a magnet provided on the diaphragm, which is displaced together with the diaphragm, and a proximity switch which is turned on or off depending on the displacement of the magnet. Gas leak detector. 4. The determining means includes counting means for counting the number of times the proximity switch is turned off or on for a certain period, and comparing means for comparing a count value by the counting means with a predetermined number. 4. The gas leakage detection device according to claim 3, wherein the gas leakage is judged when the numerical value becomes a predetermined number or less. 5. A supply path switching means for closing the main supply path when the gas flow rate becomes small so that the gas can be supplied only through the sub supply path provided in parallel with the main supply path, and the sub supply path. An opening / closing means having a valve body for opening and closing a valve opening provided at the inlet of the valve, and a restraining means for simultaneously restraining the valve body of the opening / closing means and the valve body of the supply path switching means in a valve closed state. The gas leakage detection device according to any one of claims 1 to 4. 6. The restraint means forcibly presses the valve element of the supply passage switching means against the valve opening so as to close the valve opening of the main supply passage and maintains the valve closed state, and the sub supply passage 6. The gas leakage detection device according to claim 5, wherein the valve opening provided at the inflow port is closed by the valve body of the opening / closing means to maintain the valve closed state.