JPH05302700A - Gas switching device - Google Patents

Abstract

PURPOSE:To provide a gas switching device that can supply gas only through a sub-supply duct with a main supply duct closed when a gas floe is decreased without large pressure loss and also reduce its size compactly. CONSTITUTION:A switching valve 24 provided in a gas duct 23 for forming a main supply duct, consists of a valve port 24d and a valve body 24b facing the valve port 24d from its upstream side, and opens and closes the gas duct. A throttling section 25 provided on the downstream side of the switching valve is communicated with a pressure regulating room 30 by a communicating means 25a, and the pressure in the throttling section is exerted on a diaphragm 28 so as to operate the valve body.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas switching device, and more particularly to a gas switching device in which a main supply passage is closed and a gas can be supplied only through a sub supply passage when the gas flow rate becomes small. ..

[0002]

2. Description of the Related Art Conventionally, as an apparatus of this type, for detecting a minute gas leak in a gas supply pipe including a buried pipe in an LPG supply facility without forcibly stopping the gas supply, for example, Japanese Patent Laid-Open No. 3-41300. There is one shown in FIG. 12 applied to the gas leakage detection device proposed in the publication.

FIG. 12 shows a gas supply facility for supplying gas to a housing complex such as a condominium in which a gas leak detection device is incorporated. In FIG. 12, a gas supply source 1 such as a propane gas cylinder and a gas inlet 3 of the condominium 2 are shown. And are connected by a gas supply pipe 4 as a main supply path,
The gas supply pipe 4 is provided with pressure regulators 5 and 6 and a gas meter 7. Further, the gas inlet 3 is provided with valves 8 and 9 for each floor, for example, and each house in the condominium 2 is supplied with gas to the gas consuming facility 13 via the valve 10 and the gas meter 11 through the pipe 12. It

A parent regulator 6 is provided in a gas supply pipe 4b between a main regulator 5 on the side of a propane gas cylinder 1 which is a gas supply source and a parent gas meter 7 which integrates the amount of gas supplied to the entire condominium 2. Further, the gas supply pipe 4b is provided with a bypass gas flow passage 14 as a sub-supply passage that connects the inlet side and the outlet side of the parent regulator 6. The gas flow path 14 is provided with a child regulator 15 and a microcomputer gas meter (hereinafter referred to as M meter) 16 as a minute leak detecting means in order from the inlet side.

The adjusting pressure of the child adjuster 15 is set higher than the adjusting pressure of the parent adjuster 6. For example, when the adjusting pressure of the master adjuster 6 is set to 280 mmH ₂ O, the adjusting pressure of the slave adjuster 15 is set to about 300 mmH ₂ O. Further, as the M meter 16, a minute flow rate, for example, a flow rate of about 3 liters / hour can be accurately integrated, and monitoring is performed by a minute leak detection function, and when there is a flow rate of 3 liters / hour or more for 30 consecutive days, leakage occurs. It is determined that there is a problem and that is indicated by lighting a lamp.

In the above construction, when the gas consumption at night or at midnight is almost eliminated, the pressure of the gas supply pipe 4b becomes high, the parent regulator 6 is closed, and the child regulators 15 and M.
The gas flows only to the meter 16, which makes it possible to monitor the minute gas flow rate flowing through the gas supply path 4b. The parent adjuster 6 and the child adjuster 15 constitute a gas switching device that closes the main supply passage so that the gas can be supplied only through the sub supply passage when the gas flow rate becomes small. At this time, if there is no gas consumption and no slight gas leakage occurs, neither the parent gas meter 7 nor the M meter 16 will detect the gas flow rate.

It is premised that such a phenomenon occurs at least once during a relatively long predetermined period of 30 days, and if the main gas meter 7 and the M meter 16 both have a gas flow rate during this predetermined period. When it is not detected, it becomes possible to determine that a minute gas leak has occurred.

As described above, the bypass flow passage is provided in a part of the gas supply pipe, and the regulators having different adjustment pressures allow the gas to flow into the bypass flow passage at a low flow rate, and the minute flow amount provided in the bypass flow passage can be detected. Since the flow rate is monitored by the meter to detect the minute gas leak, it is possible to easily and surely detect the gas leak in the gas supply pipe without forcibly stopping the gas supply.

[0009]

In the above-mentioned conventional gas switching device, the differential pressure between the parent regulator 6 and the child regulator 15 for reducing the pressure in the gas supply passage from high pressure to low pressure or from medium pressure to low pressure. Is provided to provide a switching function for determining the preferential direction of gas supply, and the decompression means and the switching means are combined.

Therefore, an attempt was made to apply the conventional device utilizing the differential pressure of the regulator as described above to a place where gas is already supplied at a low pressure, such as city gas or simple gas equipment. In this case, there is a problem that the pressure loss when passing through the device becomes too large and the device becomes too large, and the switching function cannot be utilized.

Therefore, in view of the above-mentioned conventional problems, the present invention causes a large pressure loss because the main supply path is closed and the gas can be supplied only through the sub supply path when the gas flow rate becomes small. It is an object of the present invention to provide a gas switching device that is compact and can have a structure suitable for downsizing.

[0012]

In order to achieve the above-mentioned object of the present invention, a gas switching apparatus according to the present invention supplies a gas only through a sub-supply passage by closing a main supply passage when the gas flow rate becomes small. In the gas switching device that is made possible, a gas flow path that forms the main supply path, a valve hole and a valve element that faces the valve hole from an upstream side, and the gas for opening and closing the gas flow path A switching valve provided in the flow path, a throttle portion provided on the downstream side of the switching valve, and a pressure regulating chamber and an external pressure chamber which are provided so as to air-tightly partition and bias toward the pressure regulating chamber. The switching valve is provided with: a diaphragm connected to the valve body of the switching valve; and a communication means for communicating the pressure regulating chamber with the throttle section for applying the pressure of the throttle section to the diaphragm. Connect the sub supply path to the upstream side It is characterized in that the the like.

[0013]

With the above construction, by providing the throttle portion, a differential pressure that changes in proportion to the square of the flow rate can be obtained. When the flow rate decreases, the differential pressure decreases remarkably, whereas when the flow rate increases, the differential pressure decreases. The pressure in the pressure regulating chamber, which is rapidly increased and communicated through the communication means, is rapidly reduced. When a large amount of gas is flowing, the gas flow velocity becomes faster and the pressure in the throttle acts to reduce the pressure in the pressure regulation chamber, which causes the diaphragm to move in the urging direction and the valve opening of the switching valve. Is rapidly expanded. Therefore, when the switching valve opens once, almost no pressure loss occurs here.

Further, since the back pressure is applied to the valve body from the upstream side in the switching valve which has been once closed, the force applied to the valve body should be increased even if the valve hole is enlarged in order to reduce the pressure loss. Therefore, the valve closed state can be reliably maintained.

Therefore, when the gas flow rate decreases and reaches a certain flow rate, the switching valve, which has been open with a sufficient opening until that point, closes immediately, and thereby the upstream side of the switching valve. Therefore, the gas is allowed to flow only to the sub supply path. That is, it is possible to realize both the so-called flow rate division function and the automatic flow path switching function of switching the flow path with a predetermined flow rate as a boundary only by a simple mechanical structure.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 3 show an embodiment of a gas switching device according to the present invention, FIG. 1 is a plan view, FIG. 2 is a sectional view taken along line AA, and FIG.
FIG. 6 is a sectional view taken along line BB.

In these figures, an inlet hole 21 and an outlet hole 22 to which the main supply passages are connected are formed in the case body 20, and an inlet hole of a gas flow path 23 between the inlet hole 21 and the outlet hole 22 is formed. A switching valve 24 for opening and closing the gas flow path 23 is provided near 21 and a venturi portion 25 as a throttle portion is provided near the outlet hole 22. An opening 26 is formed in the case main body 20 adjacent to the gas flow path 23, and a cover 27 is fixed to the opening 26.

Further, the case body 20 and the outside air vent 27a
A peripheral edge of a diaphragm 28 is fixed between the cover 27 and the cover 27 so as to close the opening 26, and the diaphragm 28 hermetically seals the atmospheric pressure chamber 29 on the cover 27 side and the pressure adjusting chamber 30 in the case body 20. It is partitioned. The pressure regulation chamber 30 communicates with the venturi portion 25 via a communication hole 25 a formed in the wall of the gas flow path 23. An actuating bar 31 is vertically provided at the center of the diaphragm 28, and a compression spring 32 is interposed between the diaphragm 28 and the cover 27 so that the diaphragm 28 is always located below, that is, on the pressure adjusting chamber 30 side. Is urged to.

A connecting pin 31 is provided at the lower end of the operating rod 31.
a is engaged with the long hole 33a, and the operation end at one end of the operation lever 33 is connected. The other end of the operating lever 33 is rotatably supported in the case main body 20 via a support shaft 34, and a connecting pin 24a is provided at an intermediate action point thereof with a long hole 33b.
Is connected to a valve rod 24c extending from the valve body 24b of the switching valve 24. The valve body 24b is arranged so as to face the valve hole 24d from the inlet hole 21 side, and the valve rod 24c
Is inserted into the valve hole 24d.

The valve hole 24d of the switching valve 24 is formed with a sufficiently large diameter so that a large pressure loss does not occur here, and the bearing 35 of the valve rod 24c is also sufficiently large as shown in FIG. 4 for the same purpose. It is formed so as to secure a gas passage 35a having an area.

Between the gas flow path 23 and the pressure adjusting chamber 30, a switching hole 24 and a flow hole 23a near the inlet hole 21 are provided.
And the sub outlet hole 30 is formed in the pressure adjusting chamber 30.
a (FIG. 3) is formed, and a bypass pipe (not shown) is connected between the sub outlet hole 30a and a main supply passage (not shown) connected to the outlet hole 22 to form the flow hole 23.
The pressure adjusting chamber 30, the sub outlet hole 30a, and the bypass pipe form a sub supply path that bypasses the switching valve 24.

The venturi portion 25 has a characteristic of changing the pressure difference between the inlet portion and the throttle portion in proportion to the square of the flow rate. Specifically, as shown in FIG. 5, when the flow rate decreases, the differential pressure decreases remarkably, whereas when the flow rate increases, the differential pressure rapidly increases and the inside of the pressure adjusting chamber 30 communicated through the communication hole 25a. Sharply reduce the pressure.

Therefore, when a large amount of gas is flowing, the gas flow velocity increases and the pressure of the venturi portion 25 acts in the direction of reducing the pressure in the pressure adjusting chamber 30, whereby the diaphragm 28 urges the compression spring 32. As it moves in the direction, the valve opening of the switching valve 24 is suddenly widened.
Therefore, when the switching valve 24 is opened once, almost no pressure loss occurs here.

On the other hand, when only a small amount of gas is flowing, the gas flow velocity becomes slow and the influence of the venturi portion 25 on the pressure adjusting chamber 30 is almost eliminated, whereby the diaphragm 28 resists the bias of the compression spring 32. When the valve body 24b is moved to close the valve hole 24d, the switching valve 24 is closed. The switching valve 24 that has been closed once is the valve body 2
Since the back pressure is applied to 4b from the upstream side, even if the valve hole 24d is increased in order to reduce the pressure loss, the valve body 24b
The valve closed state can be reliably maintained without increasing the force applied to the valve.

As described above, when the gas flow rate becomes small and reaches a certain flow rate, the switching valve 24, which has been open with a sufficient opening up to that point as a boundary, promptly closes the valve, whereby the flow hole 23a. From the sub outlet hole 3 via the pressure regulation chamber 30
The gas is made to flow only to 0a. That is, the above-described gas switching device can realize both so-called flow rate classification and automatic flow path switching functions, which switch the flow paths at a predetermined flow rate, by only a simple mechanical structure.

The above gas switching device, as shown in FIG.
The bypass pipe 40a connected between the sub outlet hole 30a of the pressure regulation chamber 30 and the main supply passage 40 connected to the outlet hole 22 is provided with the flow rate detection unit 41, which is applied to an apparatus for detecting a minute gas leak. be able to. By providing the bypass pipe 40 with the flow rate detection unit 41 as shown in the figure, the flow rate of the gas flowing through the flow rate detection unit 41 and its continuity can be monitored. Then, as a result of this monitoring, when it is detected that the flow rate above the level continues for a month, for example, when the flow rate is low, it can be determined that there may be a minute gas leak on the downstream side. This makes it possible to take measures such as issuing warnings and alarms.

As the flow rate detecting section 41, a flow rate sensor or the like in which a magnetic contact disposed in the vicinity of the bypass pipe 40 and a magnet or the like provided in a turbine type or float type operating portion can be used. Flow rate detector 41
In the case of, the controller 42 receives a non-voltage signal from a flow rate sensor that does not require a commercial power source, judges the presence or absence of a minute flow rate and the presence or absence of a minute gas leak due to this signal, and displays the result on the display unit. ..

As the flow rate detecting section 41, other than the above, for example, a conventional gas meter of FIG. 12 in which a means for generating a flow rate pulse in response to a predetermined flow rate of gas is incorporated into a gas meter for integrating a minute gas flow rate is incorporated. The M gas meter used in the above can also be applied.

In the apparatus described above with reference to FIGS.
One diaphragm 28 to receive the pressure of the pressure regulation chamber 30.
Since it is only used, a large diaphragm 28 is required to enlarge the pressure receiving surface. However, in this case, the opening 30 and the cover 27 that covers the opening 30 become large, and the device becomes large.

To improve this point, the venturi section 2
It suffices that the pressure generated in 5 effectively acts on the diaphragm 28. As one method for this, the tip of the pipe 25b connected to the communication hole 25a may be brought close to the diaphragm 28 as shown in FIG. As shown in FIG. 8, it can be considered that the venturi portion 25 is formed by displacing it toward the diaphragm 28 side.

Another method is shown in FIGS.
As shown in (corresponding to FIG. 1 to FIG. 3), a single actuating bar 31 uses three diaphragms 28a to 28c having a central penetrating hole and is connected to each other by communicating holes 36 and 37. 3 pressure regulating chambers 30b to 30d and 3
Two atmospheric pressure chambers 29a to 29c are formed. It should be noted that, in order that the pressure of the Venturi portion 25 may efficiently act on the adjustment chambers 30c and 30d, the pipe 25b may be passed through the communication hole 25a.
Alternatively, the pressure may be directly introduced through the pipe, or alternatively, the pressure may be introduced through a pipe from a newly provided hole as shown by a dotted line. The other parts are almost the same as those shown in FIG. 1 to FIG. 3, etc., and the same parts are denoted by the same reference numerals and detailed description thereof will be omitted.

[0032]

As described above, according to the present invention, the back pressure is applied from the upstream side by the diaphragm that moves by utilizing the differential pressure, which becomes remarkably small when the flow rate becomes small and sharply increases when the flow rate becomes large. Is running,
When the switching valve is opened, the valve opening is suddenly widened, and even if the valve hole is made large, the valve closed state can be reliably maintained without increasing the force applied to the valve body, so there is almost no pressure loss. The effect that there is no occurrence of is obtained.

Further, the flow paths are switched at a predetermined flow rate,
Both the so-called flow rate classification and the automatic flow path switching functions can be realized only by a simple mechanical structure, so that it is compact and suitable for miniaturization.

[Brief description of drawings]

FIG. 1 is a plan view of an embodiment of a gas switching device according to the present invention.

FIG. 2 is a sectional view taken along line AA in FIG.

FIG. 3 is a sectional view taken along line BB in FIG.

FIG. 4 is an enlarged view of a part of FIG. 2 seen from another surface.

FIG. 5 is a graph showing a flow rate-differential pressure characteristic of a venturi portion.

FIG. 6 is a conceptual diagram of a minute gas leakage detection device configured by applying the gas switching device of the present invention.

FIG. 7 is a diagram showing a modified example of a part of FIG.

FIG. 8 is a diagram showing another modification of a part of FIG.

FIG. 9 is a plan view showing another embodiment of the gas switching device of the present invention.

10 is a cross-sectional view taken along the line AA in FIG.

11 is a cross-sectional view taken along the line BB in FIG.

FIG. 12 is a diagram showing an example of a conventional device.

[Explanation of symbols]

 23 gas flow path 24 switching valve 24b valve body 24d valve hole 25 throttle part (venturi part) 25a communication means (communication hole) 28 diaphragm 29 external pressure chamber 30 pressure regulation chamber

Claims (1)

[Claims] 1. A gas switching device in which a main supply passage is closed and gas can be supplied only through a sub-supply passage when the gas flow rate becomes small, wherein a gas passage forming the main supply passage and a valve hole are provided. A valve body facing the valve hole from the upstream side,
A switching valve provided in the gas flow passage for opening and closing the gas flow passage, a throttle portion provided on the downstream side of the switching valve, and provided so as to airtightly divide the pressure regulation chamber and the external pressure chamber. And a diaphragm connected to the valve body of the switching valve and urged toward the pressure regulating chamber, and the pressure regulating chamber and the throttle portion are communicated with each other in order to apply the pressure of the throttle portion to the diaphragm. A gas switching device, comprising: a communication means, wherein the sub supply path is connected to an upstream side of the switching valve.