JP4691579B2 - Portable gas alarm - Google Patents

Description

  The present invention relates to a portable gas alarm.

In general, for example, in underground construction sites, tunnels, places where people enter, work areas, etc., there is a risk that dangerous gases such as carbon monoxide gas or hydrogen sulfide gas may be contained in the air of the environment. In many cases, there is a possibility that the air in the environmental atmosphere is in a dangerous state or in a dangerous state, such as when the oxygen gas concentration in the air may be lowered.
And when it becomes dangerous to humans due to the high concentration of dangerous gas contained in the air or low oxygen gas concentration, it is necessary to immediately know that In response to such demands, various types of portable gas alarms have been proposed so far, and some of these portable gas alarms detect different types of gas components. A plurality of gas sensors are provided so that a plurality of gas components can be detected simultaneously.

  Thus, in such a portable gas alarm device, for example, it may be used to measure the state of air in a gas measurement target space such as a place where water is accumulated such as in a manhole. In order to prevent water including water droplets in the atmosphere from entering the inside of the housing, it is desired that a waterproof structure be adopted. For example, in the gas detection unit, the flow of the test gas is prevented. In order to prevent water from coming into contact with the gas sensor while securing the filter, a filter having a waterproof function is mounted (for example, see Patent Document 1).

FIG. 8 is a cross-sectional view schematically illustrating the configuration of a gas detection unit in an example of a conventional portable gas alarm.
In the gas detector of this portable gas alarm device, for example, four button-type gas sensors 75A, 75B, 75C, and 75D are held side by side on one side surface (left side surface in FIG. 8) of the housing 70. The sensor holding part 71 is formed, and these gas sensors 75A to 75D are detachably engaged with the gas sensor holding part 71 via the packing 77, and the gas flow paths for the respective gas sensors 75A to 75D. 76A, 76B, 76C, and 76D are fixed and held by a gas sensor fixing frame member 76 that is formed independently of each other.
Further, a sheet-like dustproof / waterproof filter 80 common to the gas sensors 75A to 75D that removes atmospheric dust flowing into the gas sensors 75A to 75D and prevents water and the like from entering is provided in each of the gas sensor fixing frame members 76. The filter fixing member 78 is detachably engaged with the gas sensor fixing frame member 76 via the seal member 79 in a state where it is arranged so as to cover the gas flow paths 76A to 76D.
In this portable gas alarm device, for example, a gas sensor 75B for detecting hydrocarbon gas and a gas sensor 75C for detecting carbon monoxide gas are used, and interference gas components related to the gas sensors 75B and 75C are detected. Interference gas removal filters 81 and 82 for removal are interposed between the gas sensor fixing frame member 76 and the dustproof and waterproof filter 80.

However, in the portable gas alarm device having the above configuration, as shown in FIG. 9, the dustproof waterproof filter 80 is simply placed in a recess formed on the outer surface of the gas sensor fixing frame member 76. Therefore, for example, the test gas supplied at the time of gas sensor calibration flows through the thickness of the dustproof waterproof filter 80 and flows out of the outer peripheral surface 80A of the dustproof waterproof filter 80. There is a problem that the gas sensor fixing frame member 76 flows out (leaks) into the surrounding environment through a gap between the inner surface of the recess.
Further, since the interference gas removal filter 81 is simply housed in the interference gas removal filter holding portion by the recess formed in the opening edge portion of the gas flow path 76B in the gas sensor fixing frame member 76, The test gas flows into the gas flow path 76B through a minute gap between the outer peripheral surface of the interference gas removal filter 81 and the inner surface of the interference gas removal filter holding portion, and the specific gas sensor 75B is connected to the gas sensor 75B. There is a problem that a stable operation cannot be obtained under the influence of the interference gas component.

JP 2002-116169 A

The present invention has been made based on the circumstances as described above, and its purpose is to have excellent dustproof and waterproof performance, and reliably prevent the test gas from leaking outside during sensor calibration. It is to provide a portable gas alarm that can be used.
Another object of the present invention is to provide a portable gas alarm capable of obtaining a stable operation without being affected by interference gas components for each of a plurality of gas sensors.

The portable gas alarm device of the present invention has a gas detection section in which a plurality of gas sensors are arranged on one side of the peripheral surface of a substantially box-shaped housing,
In the gas detection unit, the plurality of gas sensors are fixed and held by a sensor cap formed in a state where the gas flow paths for each of the gas sensors are independent from each other, and further the gas flow in the sensor cap is An opening is formed at a position corresponding to each of the paths, and a sheet-like packing in which a protruding edge protruding in the thickness direction is formed over the entire circumference of the outer peripheral edge, and is accommodated in a recess surrounded by the protruding edge of the packing. common sheet-shaped dustproof waterproof filter to each of the gas sensors was found by a filter cap which is detachably attached to the sensor cap, projecting edge of the packing together are held fixed in a pressed state is elastically deformed the A seal structure is formed along the outer periphery of the dustproof waterproof filter .

In the portable gas alarm device of the present invention, at the outer opening edge of at least one gas flow path in the sensor cap, a sheet-like shape that removes interference gas components related to the gas sensor corresponding to the gas flow path is provided. Interference gas removal filter is provided,
The packing is formed with a convex portion protruding inward along the peripheral edge of the opening corresponding to the gas flow path on the surface located on the gas sensor side, and the convex portion is the gas in the sensor cap. It is preferable that the interference gas removal filter is configured to be held in a state in which the peripheral edge portion on the outer surface thereof is pressed by the convex portion by being fitted in the flow path.

  According to the portable gas alarm device of the present invention, a sheet-like dustproof waterproof filter common to each gas sensor is provided on the entire outer peripheral edge of the sheet-like packing interposed between the dustproof waterproof filter and the sensor cap. It is provided in a state of being accommodated in a recess surrounded by a protruding edge formed over the circumference, and the filter cap holds and fixes the dustproof waterproof filter and packing in a pressed state, and the protruding edge of the packing is elastic. Since the seal structure is formed by being deformed, the seal is sealed along the periphery of the dustproof waterproof filter by the protruding edge of the packing. Gas can be prevented from flowing through the wall thickness of the dustproof waterproof filter and flowing out of its peripheral surface. There can be reliably prevented from leaking into the surrounding environment.

  In addition, on the gas sensor side surface of the packing interposed between the dustproof waterproof filter and the sensor cap, an annular protrusion is formed along the periphery of the opening corresponding to the gas flow path leading to the sensor holding portion for the specific gas sensor. The projection is fitted into the corresponding gas flow path of the sensor cap, so that the periphery of the interference gas removal filter is held in a pressed state by the projection. This makes it possible to prevent the test gas from entering between the peripheral surface of the interference gas removal filter and the inner surface of the gas flow path in the sensor cap, so that it is stable without being affected by the interference gas component. Can be obtained.

1 is a front view showing a configuration of an example of a portable gas alarm device according to the present invention, FIG. 2 is a top view of the portable gas alarm device shown in FIG. 1, and FIG. 3 is a cross-sectional view taken along line BB in FIG. 4 and 4 are sectional views taken along line CC in FIG. In the following, for the sake of convenience, the vertical direction in FIG. 1 is defined as “vertical direction”, but it does not limit the usage form of the portable gas alarm.
The portable gas alarm device 10 includes a housing 11 having a substantially box shape, which is sized so as to be held and held by hand. One surface of the peripheral surface of the housing 11, for example, the housing 11 is provided. On the lower surface, there is a gas detection unit in which a plurality of gas sensors are arranged in the surface direction.

The housing 11 is composed of a back-side housing member 12 and a front-side housing member 13 made of, for example, a transparent resin material that is connected and fixed to the back-side housing member 12 via a frame-shaped packing P.
Inside the housing 11, a flat operation control circuit board 30 on which various necessary functional elements are mounted is disposed so as to extend along the front and back surfaces of the housing 11, and this operation control circuit board is provided. A panel-like display mechanism 31 is provided in the central region on the front surface side of 30, and a cavity portion that is partitioned in a watertight manner from a space in which electronic components such as the operation control circuit board 30 are disposed on the back surface side. A compartment 25 having 25A is formed, and a columnar secondary battery (storage battery) 60 serving as a driving power source is disposed on the left and right sides of the compartment 25.

  The internal space of the compartment 25 is a dustproof net provided in an alarm sound emission opening (hereinafter referred to as “front sound emission opening”) 15 formed at a position below the display unit 18 in the front side housing member 13. An alarm sound emission opening (hereinafter referred to as “upper sound emission”) formed on the upper wall of the back side housing member 12 that communicates with the outside via a (not shown) and forms a part of the compartment 25. 16) and a dustproof net (not shown) provided in the upper sound emission opening 16 and communicates with the outside.

At the position corresponding to the compartment 25 on the back surface of the housing 11, a buzzer arrangement chamber 20 constituted by a stepped recess that forms a substantially cylindrical space portion having a smaller diameter toward the front side is formed. A lid 14 is provided to close the buzzer arrangement chamber 20.
The buzzer 21 is composed of a thin plate-like piezoelectric element made of a vibrator in which a disk-like piezoelectric ceramic is bonded to the central portion on one surface of a disk-like metal plate, for example, a film shape made of polycarbonate, for example. The buffer member 22 is not directly fixed to the housing 11.

  The secondary battery (storage battery) 60 that is a power source for driving uses, for example, an AAA size (single type) nickel-metal hydride (NiMH) battery, a nickel-cadmium (NiCd) battery, and the like, and is a sleeve-like heat dissipation member made of metal For example, 61 is disposed in the housing 11 in a state of being closely attached over the entire outer periphery of the secondary battery 60 and being held by the holding frame member 62.

  This portable gas alarm device 10 is configured to further include an alarm notification mechanism by light emission of the alarm light emitting element 32 and vibration by the alarm vibration generator 33 in addition to the alarm notification mechanism by the buzzer sound.

  In the above, reference numeral 55 in FIG. 1 is a first operation button that serves as both a main switch and a mode change switch in which “POWER” and “MODE” are displayed in two stages, and 56 is indicated as “AIR”. The second operation button 19 for adjusting the function for changing the alarm generation standard according to the type of gas sensor, that is, the type of gas to be detected by the gas sensor, 19 is the front surface of the housing 11 and the upper surface, both sides 2 in FIG. 2 is an infrared communication port for reading out gas concentration data detected by a gas sensor and recorded in a storage element of the operation control circuit board 30, for example. is there.

As described above, the sensor unit mounting portion 17 is formed on the lower surface of the housing 11 of the portable gas alarm, and the sensor unit mounting portion 17 has, for example, four buttons for detecting different types of gases. A sensor unit 35 having a gas sensor of the type is detachably attached, thereby forming a gas detection unit.
As the gas sensor, for example, a gas sensor 36A for oxygen gas detection composed of a galvanic gas sensor element, for example, a hydrocarbon gas composed of a catalytic combustion type gas sensor element is detected in a measurement range of% LEL (lower explosion limit concentration). A gas sensor 36B, for example, a gas sensor 36C for detecting carbon monoxide gas composed of a constant potential electrolytic gas sensor element, for example, a gas sensor 36D for detecting hydrogen sulfide gas composed of a constant potential electrolytic gas sensor element, and the like. .

As shown in FIG. 5, the sensor unit 35 includes a sensor holder 37 in which a sensor holding portion that holds four gas sensors arranged in the longitudinal direction is formed on the lower surface, and a configuration along the outer peripheral surface of the sensor holder 37. A sensor cap 38 formed with gas flow paths 38A, 38B, 38C, 38D that are independent from each other and that are detachably attached to the sensor holder 37 via a frame-shaped packing 40A having A ring-shaped packing 40B interposed between the gas sensor and the sensor cap 38, a filter cap 41 detachably attached to the sensor cap 38, and a laminated state between the sensor cap 38 and the filter cap 41. Corresponding to each of the gas flow paths 38A to 38D in the sensor cap 38. A substantially sheet-like packing made of, for example, rubber (hereinafter referred to as “external leakage prevention packing”) 45 having a circular opening 46 formed therein, and a sheet-like dust-proof made of, for example, PTFE common to the gas sensors 36A to 36D. A waterproof filter 50 and a sensor substrate 39 mounted on the upper surface of the sensor holder 37 are provided.
An interference gas component related to the gas sensor 36B for detecting hydrocarbon gas is formed at the lower opening edge of the gas flow path 38B in the sensor cap 38 that communicates with the sensor holding part for holding the gas sensor 36B for detecting hydrocarbon gas. And a gas flow path 38C in the sensor cap 38 that communicates with the sensor holding portion where the gas sensor 36C for detecting carbon monoxide gas is held, and a circular sheet-like interference gas removal filter 51 that removes the gas. A substantially columnar activated carbon filter 52 is inserted and provided in the opening 46 of the corresponding external leakage prevention packing 45.

  As shown in FIGS. 6A to 6D, the external leakage prevention packing 45 has a substantially oval planar shape along the inner peripheral surface of the recess formed in the lower surface of the sensor cap 38, and has a thickness. A vertical portion 47A extending in the direction and a strip-shaped portion 47B extending at an inclination toward the outer side in the surface direction of the substrate continuously at both ends of the vertical portion 47A; The projecting edge (rib) 47 is formed over the entire circumference of the outer peripheral edge.

  The piece 47B of the external leakage prevention packing 45 is formed so as to decrease in thickness toward the tip, and as a result, has sufficient deformability due to the compressive force when the filter cap 41 is attached. It can comprise and a desired sealing property can be acquired reliably.

  Further, on the upper surface of the external leakage prevention packing 45, an annular shape is formed along the periphery of the opening 46 corresponding to the gas flow path 38B in the sensor cap 38 communicating with the sensor holding portion of the gas sensor 36B for detecting hydrocarbon gas. As shown in FIG. 7, the protrusion 48 is fitted into the corresponding gas flow path 38 </ b> B in the sensor cap 38, so that the interference gas removal filter 51 is formed at the peripheral edge on the lower surface thereof. The portion is held in a state of being pressed by the convex portion 48.

  In this sensor unit 35, the filter cap 41 is detachably attached to the sensor cap 38 in a state where the dustproof / waterproof filter 50 is disposed in the recess 45 </ b> A surrounded by the protruding edge 47 of the external leakage prevention packing 45. As a result, the external leakage prevention packing 45 and the dustproof / waterproof filter 50 are held and fixed in a pressed state, and the protruding edge 47 of the external leakage prevention packing 45 is elastically deformed in the thickness direction, thereby providing a sealing structure. Is formed.

In the portable gas alarm device 10 having the above configuration, air in the environmental atmosphere diffuses and reaches the gas sensors 36 </ b> A to 36 </ b> D, the concentration of the target gas is detected, and the result is displayed on the panel-shaped display mechanism 31. Is displayed. When the concentration of the detection target gas exceeds the reference value set for the gas, an alarm operation signal is issued, whereby the buzzer 21 is activated to open the front sound emission opening 15 and the upper sound emission opening 16. An alarm sound is emitted to the outside.
For example, when the detection target gas is oxygen gas (O ₂ gas), the reference value is, for example, 18.0% by volume (vol%), and an alarm operation signal is issued when the reference value is lower than that. The reference value is, for example, 10% LEL (gas concentration with respect to the lower explosion limit concentration) when the detection target gas is hydrocarbon gas (HC gas), and when the detection target gas is carbon monoxide gas (CO gas). For example, it is 25 ppm, and in the case of hydrogen sulfide gas (H ₂ S gas), for example, it is 10 ppm. When the reference value is exceeded, an alarm operation signal is issued.
In the portable gas alarm device 10, a plurality of types of alarm notification mechanisms are provided, but it is not necessary that all of them be driven all at once, and each alarm notification mechanism is sequentially driven for a predetermined time. Preferably, a cyclic alarm action is performed.

Thus, according to the portable gas alarm device 10 configured as described above, the sheet-like dustproof / waterproof filter 50 common to the gas sensors 36 </ b> A to 36 </ b> D is provided between the dustproof / waterproof filter 50 and the sensor cap 38. The sheet-like external leakage prevention packing 45 interposed is provided in a state of being housed in a recess 45A surrounded by a protruding edge 47 formed over the entire circumference of the outer peripheral edge. The waterproof filter 50 and the external leakage prevention packing 45 are held and fixed in a pressed state, and the protruding edge 47 of the external leakage prevention packing 45 is elastically deformed to form a seal structure. Since the sealing edge 45 is sealed along the periphery of the dustproof waterproof filter 50 by the protruding edge 47 in the prevention packing 45, for example The test gas supplied at the time of calibration of the gas sensor can be prevented from flowing through the thickness of the dustproof waterproof filter 50 and flowing out of the peripheral surface, and the test gas leaks to the surrounding environment. It can be surely prevented.
As described above, a sufficiently reliable seal structure is formed in the gas detection unit, and the portable gas alarm device 10 is configured to have excellent dustproof and waterproof performance by the performance of the dustproof and waterproof filter 50 itself. Can do.

  In addition, on the gas sensor side surface (upper surface) of the external leakage prevention packing 45, an annular shape is formed along the periphery of the opening 46 corresponding to the gas flow path 38B leading to the sensor holding portion of the gas sensor 36B for detecting hydrocarbon gas. A convex portion 48 is formed, and the convex portion 48 is fitted into the corresponding gas flow path 38 </ b> A of the sensor cap 38, whereby the interference gas removal filter 51 is pressed by the convex portion 48 at the peripheral portion on the lower surface thereof. By being configured to be held in such a state, it is possible to prevent the test gas from entering between the peripheral surface of the interference gas removal filter 51 and the inner surface of the gas flow path 38A in the sensor cap 38. In other words, the test gas can be supplied to the hydrocarbon gas detection gas sensor 36B via the interference gas removal filter 51. Since the, it is possible to obtain a stable operating state without being affected by the interference gas component.

As mentioned above, although preferred embodiment which concerns on this invention was described, this invention is not limited to said embodiment, A various change can be added.
For example, specific configurations such as the height and thickness of the protruding edge and the convex portion in the external leakage prevention packing can be appropriately changed according to the thickness of the dustproof waterproof filter and interference gas removal filter used.

It is a front view which shows the structure in an example of the portable gas alarm device of this invention. It is a top view of the portable gas alarm device shown in FIG. It is the BB sectional view taken on the line in FIG. It is CC sectional view taken on the line in FIG. It is a disassembled perspective view which shows the structure of the sensor unit in the portable gas alarm device shown in FIG. It is explanatory drawing which shows the structure of an external leakage prevention packing, Comprising: It is (A) top view, (B) AA sectional view, (C) X part detailed drawing, (D) Y part detailed drawing. It is an expanded sectional view which expands and shows a part of FIG. It is sectional drawing which shows the outline of a structure of the gas detection part in an example of the conventional portable gas alarm device. It is an expanded sectional view which expands and shows a part in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Portable gas alarm device 11 Housing 12 Back surface side housing member 13 Front surface side housing member 14 Cover 15 Opening for alarm sound emission (front opening for sound emission)
16 Alarm sound emission opening (Upper sound emission opening)
DESCRIPTION OF SYMBOLS 17 Sensor unit mounting part 18 Display part 19 Alarm light emission part 20 Buzzer arrangement room 21 Buzzer 22 Buffer member 25 Compartment room 25A Cavity part 30 Operation control circuit board 31 Panel-shaped display mechanism 32 Alarm light emitting element 33 Alarm vibration generator 35 Sensor unit 36A, 36B, 36C, 36D Gas sensor 37 Sensor holder 38 Sensor cap 38A, 38B, 38C, 38D Gas flow path 39 Sensor substrate 40A Packing 40B Ring-shaped packing 41 Filter cap 45 External leakage prevention packing 45A Recess 46 Open 47 Protruding edge (rib)
47A Vertical portion 47B Strip portion 48 Convex portion 50 Dust-proof waterproof filter 51 Interference gas removal filter 52 Activated carbon filter 55 First operation button 56 Second operation button 57 Infrared communication port 60 Secondary battery (storage battery)
61 Sleeve-shaped heat radiation member 62 Holding frame member 70 Housing 71 Gas sensor holding portion 75A, 75B, 75C, 75D Gas sensor 76 Gas sensor fixing frame member 76A, 76B, 76C, 76D Gas flow path 77 Packing 78 Filter fixing member 79 Seal member 80 Dustproof waterproof filter 80A Dustproof waterproof filter outer peripheral surface 81, 82 Interference gas removal filter P Packing

Claims (2)

It has a gas detection part in which a plurality of gas sensors are arranged on one side of the peripheral surface of a substantially box-shaped housing,
In the gas detection unit, the plurality of gas sensors are fixed and held by a sensor cap formed in a state where the gas flow paths for each of the gas sensors are independent from each other, and further the gas flow in the sensor cap is An opening is formed at a position corresponding to each of the paths, and a sheet-like packing in which a protruding edge protruding in the thickness direction is formed over the entire circumference of the outer peripheral edge, and is accommodated in a recess surrounded by the protruding edge of the packing. common sheet-shaped dustproof waterproof filter to each of the gas sensors was found by a filter cap which is detachably attached to the sensor cap, projecting edge of the packing together are held fixed in a pressed state is elastically deformed the portable gas alarm, characterized in that the sealing structure along the periphery of the dustproof waterproof filter is formed . At the outer opening edge of at least one gas flow path in the sensor cap, a sheet-like interference gas removal filter for removing interference gas components related to the gas sensor corresponding to the gas flow path is provided,
The packing is formed with a convex portion protruding inward along the peripheral edge of the opening corresponding to the gas flow path on the surface located on the gas sensor side, and the convex portion is the gas in the sensor cap. 2. The portable gas alarm according to claim 1, wherein the interference gas removal filter is held in a state where a peripheral edge portion of the interference gas removal filter is pressed by the convex portion by being fitted in the flow path. vessel.

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