JP5778461B2 - Portable gas alarm - Google Patents

Description

  The present invention relates to a portable gas alarm device including a piezoelectric buzzer that operates when a detection target gas is detected.

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 From such a demand, a portable gas alarm device having an alarm notification mechanism by an alarm sound from an alarm buzzer that operates when a gas to be detected is detected by a gas sensor is widely used (patent) Reference 1).

  Normally, in such a portable gas alarm device, an opening for alarm sound emission is formed in the housing, and a buzzer arrangement portion is provided so as to communicate with the alarm sound emission opening, for example, a piezoelectric buzzer is arranged on this. In addition, a dustproof mesh with countless minute through-holes is provided to close the alarm sound emission opening, and water such as water droplets in the atmosphere is prevented from entering the inside of the housing through the hole of the dustproof mesh. Therefore, a waterproof sheet is provided.

  Thus, in a portable gas alarm device equipped with an alarm buzzer, it is desired that a large alarm sound be emitted, but the structure for opening the alarm sound emission opening is covered with a dustproof mesh and a waterproof sheet. In addition, there is a problem that an alarm sound having a sufficiently high sound pressure level (large sound volume) cannot be generated because the transmission of the buzzer sound is greatly hindered.

In addition, portable gas alarms are used in environments where flammable or explosive atmospheres may occur due to the presence of explosive atmospheres containing flammable gases or vapors, so the gas alarms themselves are not the ignition source. For example, when a piezoelectric buzzer is used, the energy generated in the piezoelectric buzzer when the weight is dropped is less than a specified value. There is a need to be.
However, when the piezoelectric buzzer is directly fixed to the housing, the energy generated in the piezoelectric buzzer when the weight is dropped exceeds the specified value defined in the above-mentioned explosion-proof specification standard. In addition to being able to be constructed as having an explosion-proof structure, there is a problem that the vibration of the piezoelectric buzzer itself is hindered and an alarm sound with a sufficiently high sound pressure level cannot be emitted.

JP 2007-200286 A

  The present invention has been made based on the above circumstances, and has a predetermined explosion-proof structure, and water such as water droplets in the atmosphere is disposed inside a housing in which electronic components such as a control circuit board are arranged. It is an object of the present invention to provide a portable gas alarm device that can reliably prevent entry into a space and can emit an alarm sound having a sufficiently large sound pressure level.

The portable gas alarm device according to the present invention includes a housing in which an alarm sound emitting opening is formed at least on an upper surface, and an acoustic sound chamber having an acoustic space formed in an upper surface side region in the housing. a piezoelectric buzzer which is arranged on the buzzer arrangement portion communicating with the sound emission opening, which is arranged on the rear side region in the housing, gas supply and a plurality of gas sensors, by sucking air in the environmental atmosphere to each of the gas sensor A suction means,
The piezoelectric buzzer is for positioning that extends in a direction perpendicular to the buzzer arrangement surface provided in the buzzer arrangement portion in the support hole formed in the tongue-like support portion provided in the outer peripheral surface of the case of the piezoelectric buzzer . The pin member is inserted and locked, and the support hole has an inner diameter larger than the outer diameter of the positioning pin member. It is supported in a possible state.

In the portable gas alarm device according to the present invention, a control circuit board having an opening at a position facing the buzzer arrangement portion is provided on the upper surface of the housing at a position above the piezoelectric buzzer. It is arranged facing the wall,
It is preferable that a buffer member is interposed between an outer edge portion on the upper surface of the piezoelectric buzzer and a peripheral edge portion of the opening portion on the lower surface of the control circuit board.

  Furthermore, in the portable gas alarm device of the present invention, a plate member in which a plurality of minute sound emission holes are formed is provided in the alarm sound emission opening so as to block the alarm sound emission opening. It is preferable to have a configuration.

  Furthermore, in the portable gas alarm device of the present invention, each of the minute sound emitting holes in the plate member is formed at a position displaced so as not to face the sound emitting port in the piezoelectric buzzer. It is preferable.

  Furthermore, in the portable gas alarm device of the present invention, it is preferable that an opening for alarm sound emission communicating with the acoustic space in the acoustic chamber is further formed on the back surface of the housing.

  Furthermore, in the portable gas alarm device of the present invention, an opening communicating with the buzzer arrangement portion is formed in a lower wall forming the acoustic chamber, and a waterproof sheet having sound permeability has an opening. It is preferable that the structure is arranged so as to be closed.

  According to the portable gas alarm device of the present invention, the piezoelectric buzzer is connected to the alarm sound emission opening through the acoustic chamber having the acoustic space formed in the upper surface side region in the housing. The piezoelectric buzzer itself is held by the positioning member provided in the buzzer arrangement portion and is supported and arranged in a minutely displaceable state, so that the vibration efficiency of the piezoelectric buzzer itself is not lowered. Since the sound pressure level of the alarm sound is increased by the action of the acoustic space and is emitted to the outside through the alarm sound emitting opening, an alarm sound with a sufficiently high sound pressure level can be emitted, Since the external impact can be absorbed by the small displacement of the piezoelectric buzzer relative to the housing member, the energy generated in the piezoelectric buzzer when the external impact is received is regulated. It can be suppressed to below the size value can be configured as satisfying the predetermined explosionproof standards.

  In addition, since the buffer member is interposed between the outer edge portion of the upper surface of the piezoelectric buzzer and the peripheral edge portion of the opening portion of the lower surface of the control circuit board, the piezoelectric buzzer in the event of an impact is applied. The piezoelectric buzzer can be placed in an appropriate position with respect to the acoustic space without hindering minute displacement, and when the shock is received from the outside by the cushion function (shock absorbing function) of the buffer member Can further reduce the energy generated.

Furthermore, since the plate member in which a plurality of minute sound emission holes are formed is provided so as to close the alarm sound emission opening, a part of the alarm sound is temporarily transmitted to the sound space by the plate member. After being reflected inside, it is emitted to the outside through the minute sound emitting hole, so that an alarm sound with a higher sound pressure level can be emitted.
Then, each of the minute sound emission holes in the plate member is formed at a position displaced so as not to face the sound emission opening in the piezoelectric buzzer, so that the above sound pressure level improvement effect can be obtained with certainty. be able to.

  Furthermore, an alarm sound emitting opening that communicates with the acoustic space is further formed on the back surface of the housing member, so that a louder alarm sound can be emitted outside the housing. The alarm sound emitting opening can also function as a drain opening, so that water that has entered the acoustic space can be discharged to the outside.

  Furthermore, the bottom wall that forms the acoustic chamber is configured such that a waterproof sheet having sound permeability is disposed so as to close the opening that leads to the buzzer placement portion formed in the bottom wall. Therefore, even if water such as water droplets in the atmosphere enters the acoustic chamber through the alarm sound emission opening without significantly impeding the transmission of the alarm sound, It is possible to completely prevent the part from entering the space in which the parts are arranged, and therefore, it can be configured to have a predetermined waterproof structure.

It is a top view which shows the structure in an example in the portable gas alarm device of this invention. It is a rear view which shows the structure of the portable gas alarm device shown in FIG. 1 in the state which removed the sensor chamber cover cover. It is a right view of the portable gas alarm device shown in FIG. It is the sectional view on the AA line in FIG. It is CC sectional view taken on the line in FIG. It is the elements on larger scale which expand and show a part of FIG. It is the elements on larger scale which expand and show a part of FIG. It is explanatory drawing which shows the positional relationship of the sound emission opening in a piezoelectric buzzer, and the micro sound emission hole in a plate member. It is a top view which shows the structure of a gas detection unit. It is a block diagram which shows roughly the piping structure in the portable gas alarm device shown in FIG. It is sectional drawing which cut | disconnects and shows the structure of a lithium ion battery power supply unit in the direction perpendicular | vertical to the longitudinal direction of a lithium ion battery. It is explanatory drawing which shows schematically the structure of the power circuit board in the lithium ion battery power supply unit shown in FIG. It is sectional drawing which cut | disconnects and shows the structure of the dry battery power supply unit used in the portable gas alarm device shown in FIG. 1 in the direction perpendicular | vertical to the longitudinal direction of a dry battery.

Hereinafter, embodiments of the present invention will be described in detail.
FIG. 1 is a top view showing the configuration of an example of the portable gas alarm device of the present invention, and FIG. 2 is a rear view showing the configuration of the portable gas alarm device shown in FIG. 1 with the sensor chamber cover lid removed. 3 is a right side view of the portable gas alarm device shown in FIG. 1, FIG. 4 is a cross-sectional view taken along the line AA in FIG. 1, FIG. 5 is a cross-sectional view taken along the line CC in FIG. FIG. 7 is a partially enlarged view showing a part of FIG. 4 in an enlarged manner, and FIG. 7 is a partially enlarged view showing a part of FIG.
The portable gas alarm device 10 has a box (heavy box) shape as a whole, and includes a main unit 15 including a display unit 20 and a gas detection unit 40, and a power supply that is detachably attached to the main unit 15. For example, it is configured as a shoulder type that is used by being hung on an operator's shoulder by an appropriate mounting member. 1 and 3, reference numeral 11 denotes an operation button, 12 denotes, for example, a belt-like mounting member mounting portion, 13A denotes a gas introduction portion, 13B denotes a gas discharge portion, and 14 denotes a display portion.

The display unit 20 includes an upper surface side housing member 21 made of, for example, resin and having an opening at the lower side. Inside the upper surface side housing member 21, a control circuit board 30 is placed on the upper wall of the upper surface side housing member 21. A panel-like display mechanism (LCD) 35 is arranged at the center of the upper surface of the control circuit board 30.
In one side region (the left side region in FIG. 4) inside the upper surface side housing member 21, an acoustic chamber 25 that forms a square columnar acoustic space is formed, and the inner space of the acoustic chamber 25 is The upper surface side alarm sound formed on the upper surface of the upper surface side housing member 21 while communicating with the buzzer arrangement portion 43 in the gas detection unit 40 through the opening K formed in the lower wall 25B constituting a part of the acoustic chamber 25. The sound emission opening 23A and a slit-like back side alarm sound emission opening 23B formed on the back surface of the upper housing member 21 communicate with the outside. The lower surface of the sound emission passage 25A extending from the acoustic chamber 25 to the back side alarm sound emission opening 23B is formed so as to incline downward and extend toward the outer side.

A sound-permeable waterproof sheet 26 is provided on the upper surface of the lower wall 25B of the acoustic chamber 25 so as to close the opening K formed in the lower wall 25B.
The waterproof sheet 26 is made of a porous film made of, for example, polyester, and is fixed to the upper surface of the lower wall 25B of the acoustic chamber 25 by, for example, bonding an outer peripheral edge portion thereof.

In addition, a plurality of minute sound emission holes 28A each having an opening diameter smaller than the opening diameter of the sound emission opening 62 in the piezoelectric buzzer 60 described later are formed in the upper surface side alarm sound emission opening 23A. For example, a plate member 28 made of polycarbonate is provided so as to close the upper side alarm sound emitting opening 23A.
As shown in FIG. 8, each of the minute sound emission holes 28A in the plate member 28 is formed at a position displaced with respect to the sound emission opening 62 so as not to face the sound emission opening 62 in the piezoelectric buzzer 60 described later. .
The plate member 28 in this example is formed with four minute sound emission holes 28A having the same opening diameter, and one side region (portable gas alarm) of the rectangular plate member 28 is formed. For example, three small sound emission holes 28A are formed in a line at regular intervals in the region on the front side of the device 10), and at a position closer to the center than these minute sound emission holes 28A. One minute sound emitting hole 28A is formed.

  The gas detection unit 40 includes a cylindrical lower surface side housing member 41 made of, for example, resin that is connected to the lower end of the upper surface side housing member 21 of the display unit 20 via a frame-shaped packing 16 and is detachably fixed. A buzzer arrangement portion 43 in which the piezoelectric buzzer 60 is arranged is formed at an upper portion inside the lower surface side housing member 41 at a position below the acoustic chamber 25 in the display unit 20.

  As shown in FIG. 9, the piezoelectric buzzer 60 is a low-profile columnar member in which a piezoelectric vibrator (not shown) is disposed in a case 61 having a sound emitting port 62 that opens upward. The positioning pin member provided on the outer peripheral surface of the lower part of the case 61 at a diagonal position centered on the sound emission port 62 so as to extend in a direction perpendicular to the horizontal buzzer arrangement surface 43A in the buzzer arrangement portion 43. A tongue-like support portion 63 that is locked to 43B is formed.

  Further, a sensor board 58 is disposed inside the lower surface side housing member 41 so as to extend in a direction perpendicular to the control circuit board 30. For example, five gas sensors 50 </ b> A and 50 </ b> B are provided on the back side of the sensor board 58. , 50C, 50D, 50E are detachably held, sensor holders 46A, 46B, 46C, 46D, 46E, and a sensor holder 45 having a gas inlet 48A and a gas outlet 48B are formed. A gas suction pump 66 that sucks air in the ambient atmosphere from the outside and supplies it to each of the gas sensors 50A to 50E is disposed in the other side region (the right region in FIG. 9) on the front side of One of the gas flow paths of the air in the ambient atmosphere that is sucked by the gas suction pump 66 and supplied to each of the gas sensors 50A to 50E. It is formed air reservoir (space buffer) 44 which forms a.

  An example of a combination of the gas sensors 50A to 50E is as follows. As the gas sensor 50A, a hydrogen sulfide gas detection gas sensor composed of a constant potential electrolytic gas sensor, and as the gas sensor 50B, a combustible gas such as a hydrocarbon gas composed of a catalytic combustion type gas sensor. The first combustible gas sensor for detection in the measurement range of% LEL (explosive lower limit concentration), the gas sensor 50C, a carbon monoxide gas detection gas sensor comprising a constant potential electrolytic gas sensor, and the gas sensor 50D as a heat conduction gas sensor As the second combustible gas sensor for detecting a combustible gas such as hydrocarbon gas in a volume% measurement range, the gas sensor 50E, an oxygen gas detection gas sensor composed of a galvanic cell type gas sensor can be exemplified. .

  As the gas suction pump 66, for example, a diaphragm pump driven by a motor is used. For example, the gas suction pump 66 has a performance capable of supplying air in an environmental atmosphere at a flow rate of 0.75 liter / min or more.

As shown in FIG. 10, the air reservoir 44 is a gas suction pump in a gas flow path of air in an ambient atmosphere that is sucked by the gas suction pump 66 through the dust filter 65 and supplied to each of the gas sensors 50A to 50E. The throttle part 68 is provided at a position downstream of the air reservoir 44.
A pressure sensor 67 is connected to the air reservoir 44, and the exhaust pressure from the air reservoir 44 measured by the pressure sensor 67 is monitored. A decrease in the gas flow rate due to the occurrence of clogging or the deterioration of the gas suction pump 66 over time is detected.

  In this portable gas alarm device 10, one selected power supply unit of a lithium ion battery power supply unit including a lithium ion battery and a dry battery power supply unit including a dry battery can be replaced with the other for the main unit 15. It is configured to be attached to. In this example, the lithium ion battery power supply unit 70 is mounted on the main unit 15, and the dry battery power supply unit, which is a power supply unit not selected, is stored in a predetermined aluminum trunk case, for example. Carried by.

  The lithium ion battery power supply unit 70 is connected to the lower end of the lower surface side housing member 41 constituting the gas detection unit 40 via the packing 18 and is detachably fixed, and is housed in the housing member 71. The battery pack 75 including the lithium ion battery 77, the power supply circuit board 73 disposed above the battery pack 75 inside the housing member 71, and the protection member 74 protecting the power supply circuit board 73. It has.

  As shown in FIG. 11, the battery pack 75 includes, for example, two rod-like lithium ion batteries 77 arranged in parallel with each other and connected in series, and a control circuit for preventing overcharge / overdischarge, for example. The formed protection circuit board 78 is embedded in a resin block 79 made of a thermosetting resin filled in the battery housing case 76, and the length direction of the lithium ion battery 77 (in FIG. A power supply (discharge) connection lead (not shown) is led out from one end side in the vertical direction, and a charge connection lead (not shown) is led out from the other end.

As shown in FIG. 12, the power supply circuit board 73 has a connector portion 73D electrically connected to the sensor board 58 in the main unit 15 and a limiting resistance element 73C, and the main unit via the limiting resistance element 73C. 15, and a charging circuit 73 </ b> A formed at a position separated from the region where the feeding circuit 73 </ b> B is formed.
The separation distance d between the region where the power feeding circuit 73B is formed and the region where the charging circuit 73A is formed is preferably set to, for example, 2.0 mm or more for reasons of explosion prevention.

As shown in FIG. 13, the dry battery power supply unit 80 includes a housing member 81 that is connected to the lower end of the lower surface side housing member 41 constituting the gas detection unit 40 via the packing 18 and is detachably fixed. The housing member 81 is provided with a battery receiving portion in which a cylindrical dry battery (for example, an AA type dry battery (AA size)) 86 having a battery insertion opening 81A that opens downward on the bottom surface is mounted from the lower side of the battery insertion opening 81A. A portion 81B is formed. In this example, for example, three AA batteries 86 are adjacent to each other, but the positive electrode and the negative electrode are arranged in parallel so that they face in opposite directions, and are attached to the battery receiving portion 81B and connected in series. It is said that. Reference numeral 83 in FIG. 11 denotes a battery receiving portion cover lid.
A power supply circuit board 85 is disposed at a position above the battery receiving portion 81 </ b> B inside the housing member 81, and a protection member 84 that protects the power supply circuit board 85 is provided.

In the portable gas alarm device 10, each of the display unit 20, the gas detection unit 40, the lithium ion battery power supply unit 70, and the dry battery power supply unit 80 is protected by, for example, an antistatic resin (antistatic resin). When the covers 22, 42, 72, and 82 are attached, and the protect covers 22, 42, 72, and 82 are attached, the size of the continuous resin surface portion of the housing member exposed to the outside is predetermined. The size is regulated to, for example, 400 mm ² or less, and as a result, the countermeasure against static electricity is sufficient and the explosion-proof property is high.

Thus, in the portable gas alarm device 10 described above, the piezoelectric buzzer 60 is inserted into the support hole (not shown) formed in the tongue-like support portion 63 and the positioning pin member 43B is inserted, The sound emission port 62 is positioned on the buzzer arrangement surface 43 </ b> A in a state where the sound emission port 62 is positioned with respect to the acoustic chamber 25, and the outer edge portion on the upper surface of the piezoelectric buzzer 60 is sound emission of the piezoelectric buzzer 60 on the control circuit board 30. It is pressed from above via a buffer member (cushion member) 31 provided at the peripheral portion on the lower surface side of the opening 30 </ b> A formed at a position facing the mouth 62.
The hole for supporting the tongue-like support portion 63 in the piezoelectric buzzer 60 has an inner diameter larger than the outer diameter of the positioning pin member 43B, so that the buzzer placement surface 43A is minute in the horizontal and vertical directions. It is supported so that it can be displaced.

In this portable gas alarm device 10, when ambient atmosphere air is sucked and introduced by the gas suction pump 66 through the dust filter 65, the gas sensors 50 </ b> A to 50 </ b> E pass through the air reservoir 44 and the throttle 68. The gas to be detected is detected by being sequentially supplied to each, and the type and concentration of the detected gas are displayed on the display unit 14 and the concentration of any of the gas to be detected exceeds the reference value. When is detected, an alarm operation signal is issued, whereby the piezoelectric buzzer 60 is activated.
For example, in the case of 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) in the case of hydrocarbon gas (HC gas), and is, for example, 25 ppm in the case of carbon monoxide gas (CO gas). In the case of hydrogen sulfide gas (H ₂ S gas), for example, it is 10 ppm, and an alarm operation signal is issued when the reference value is exceeded.

  Thus, according to the portable gas alarm device 10 configured as described above, the piezoelectric buzzer 60 is used for sounding the upper surface side alarm sound through the acoustic chamber 25 having the acoustic space formed in the upper surface side housing member 21. In the buzzer arrangement portion 43 leading to the opening 23A and the back side alarm sound emission opening 23B, the buzzer arrangement portion 43 is supported by the positioning pin member 43B provided in the buzzer arrangement portion 43 and supported in a minutely displaceable state. Therefore, the sound pressure level of the alarm sound from the piezoelectric buzzer 60 is increased by the action of the acoustic space without lowering the vibration efficiency of the piezoelectric buzzer 60 itself, and the upper surface side alarm sound is emitted. Since the sound is emitted to the outside through the opening 23A and the back side alarm sound emitting opening 23B, a sufficiently high sound pressure level alarm sound can be emitted, and the impact from the outside can be reduced. Since it can be absorbed by the minute displacement of the piezoelectric buzzer 60 relative to the housing member 41, the energy generated in the piezoelectric buzzer 60 when subjected to an external impact can be suppressed to a magnitude equal to or less than a specified value. It can be configured to satisfy a standard of a predetermined explosion-proof specification.

  Further, the shock absorber 31 is interposed between the outer edge on the upper surface of the piezoelectric buzzer 60 and the peripheral edge of the opening 30A on the lower surface of the control circuit board 30, so that an impact is applied. The piezoelectric buzzer 60 can be disposed at an appropriate position with respect to the acoustic space without hindering the minute displacement of the piezoelectric buzzer 60 that is generated. Further reduction in energy generated at the time can be achieved.

  Furthermore, since the plate member 28 in which the plurality of minute sound emission holes 28A are formed is provided so as to close the upper surface side alarm sound emission opening 23A, a part of the alarm sound is plate member. 28 is once reflected in the acoustic space and then released to the outside through the minute sound emitting hole 28A, so that an alarm sound with a higher sound pressure level can be emitted. Each of the minute sound emission holes 28 </ b> A in the plate member 28 is formed at a position displaced so as not to face the sound emission opening 62 in the piezoelectric buzzer 60, thereby improving the sound pressure level. Can be definitely obtained.

  Furthermore, since the waterproof sheet 26 having sound permeability is arranged so as to close the opening K communicating with the buzzer arrangement portion 43 formed in the lower wall 25B forming the acoustic chamber 25, an alarm is provided. When water such as water droplets in the atmosphere enters the acoustic chamber 25 through the upper-side alarm sound emission opening 23A and the rear-side alarm sound emission opening 23B without significantly impeding sound transmission. Even so, it is possible to completely prevent the electronic component such as the control circuit board 30 from entering the space in which the electronic component is disposed, and therefore, it can be configured to have a predetermined waterproof structure.

  Further, the back side alarm sound emission opening 23B that opens to the back surface of the upper surface side housing member 21 has a slit shape, and is used for sound emission from the acoustic chamber 25 to the back side alarm sound emission opening 23B. Since the lower surface of the passage 25A is formed so as to incline downward and extend toward the outer side, the back side alarm sound emission opening 23B can also function as a water draining opening. Even when water such as water droplets inside enters the acoustic space, it can be discharged to the outside through the rear side alarm sound emission opening 23B.

  Hereinafter, experimental examples performed for confirming the effects of the present invention will be described.

<Experimental example 1>
According to the above example, a portable gas alarm device (10) according to the present invention was produced.
The upper surface side alarm sound emission opening (23A) in the upper surface side housing member (21) has a dimension in the vertical direction (vertical direction in FIG. 1) of 16.5 mm and a dimension in the horizontal direction (horizontal direction in FIG. 1) of 13 mm. It is a square shape.
The acoustic chamber (25) in the upper housing member (21) has a volume of about 1800 mm ³ .
The piezoelectric buzzer (60) has an oscillation frequency of 3.0 to 3.7 kHz and an opening diameter of the sound emission port (62) of φ4 mm.
The waterproof sheet (26) is a sheet-like sheet made of polyester and having a thickness of 0.03 mm.
The plate member (28) is made of polycarbonate, has a thickness of 1 mm, the number of minute sound emitting holes (28A) is four, the diameter of the minute sound emitting holes 28A is 2 mm, and the adjacent minute sound emitting holes 28A The center-to-center distance (separation distance) is about 4 mm.
The piezoelectric buzzer (60) has a hole diameter for supporting the tongue-like support portion (63) of φ2.2 mm, and the buzzer arrangement portion (43) has an outer diameter of the pin member (43B) of φ1.9 mm. (60) is supported and arranged so as to be minutely displaceable with respect to the lower surface side housing member (41).

With respect to this portable gas alarm device, when the sound pressure level of an alarm sound emitted to the outside was measured, the sound pressure level of the alarm sound was 95 to 100 dB.
Further, when an explosion-proof test was performed in which a 1 kg iron ball was dropped from a height position of 70 cm with respect to the upper surface of the portable gas alarm (10), the energy generated in the piezoelectric buzzer (60) It was confirmed that the size was less than the specified value.

As mentioned above, although embodiment of this invention was described, this invention is not limited to said embodiment, A various change can be added.
For example, the support structure of the piezoelectric buzzer is not limited to the above example as long as the piezoelectric buzzer is supported so as to be capable of minute displacement without being directly fixed to the housing member.
Further, the number of minute sound emitting holes, the opening diameter, and the formation position in the plate member are not limited to those in the above example, and can be appropriately changed.
Furthermore, the portable gas alarm device of the present invention may be used by being mounted on the body with an appropriate mounting tool, or may be used in a state where it is placed on a horizontal plane in the detection target space, for example.

DESCRIPTION OF SYMBOLS 10 Portable gas alarm device 11 Operation button 12 Mounting member attachment part 13A Gas introduction part 13B Gas discharge part 14 Display part 15 Main unit 16 Packing 18 Packing 20 Display unit 21 Upper surface side housing member 22 Protect cover 23A Upper surface side alarm sound Sound emission opening 23B Rear side alarm sound emission opening 25 Acoustic room 25A Sound emission passage 25B Lower wall K opening 26 Waterproof sheet 28 Plate member 28A Micro sound emission hole 30 Control circuit board 30A Opening 31 Buffer member (cushion) Element)
35 Panel display (LCD)
40 Gas detection unit 41 Lower surface side housing member 42 Protect cover 43 Buzzer arrangement portion 43A Buzzer arrangement surface 43B Positioning pin member 44 Air reservoir (buffer space portion)
45 Sensor holder 46A to 46E Sensor holding part 48A Gas introduction part 48B Gas discharge part 50A to 50E Gas sensor 58 Sensor substrate 60 Piezoelectric buzzer 61 Case 62 Sound outlet 63 Tongue piece support part 65 Dustproof filter 66 Gas suction pump 67 Pressure sensor 68 Diaphragm part 70 Lithium ion battery power supply unit 71 Housing member 72 Protect cover 73 Power supply circuit board 73A Charging circuit 73B Power feeding circuit 73C Limiting resistance element 73D Connector part 74 Protection member 75 Battery pack 76 Battery housing case 77 Lithium ion battery 78 Protection circuit Substrate 79 Resin block 80 Dry battery power supply unit 81 Housing member 81A Battery insertion port 81B Battery receiving portion 82 Protect cover 83 Battery receiving portion cover lid 84 Protective member 85 Power supply circuit base 86 batteries

Claims (6)

A buzzer arrangement portion that communicates with the alarm sound emission opening via a housing having at least an upper surface formed with an alarm sound emission opening, and an acoustic chamber having an acoustic space formed in the upper surface side region in the housing. A piezoelectric buzzer disposed; a plurality of gas sensors disposed in a rear side region in the housing; and gas suction means for sucking air in an environmental atmosphere and supplying the air to each of the gas sensors,
The piezoelectric buzzer is for positioning that extends in a direction perpendicular to the buzzer arrangement surface provided in the buzzer arrangement portion in the support hole formed in the tongue-like support portion provided in the outer peripheral surface of the case of the piezoelectric buzzer . The pin member is inserted and locked, and the support hole has an inner diameter larger than the outer diameter of the positioning pin member. A portable gas alarm characterized by being supported in a possible state. In the upper surface side region in the housing, a control circuit board having an opening at a position facing the buzzer arrangement portion is disposed facing the upper wall of the housing at a position above the piezoelectric buzzer,
The portable gas alarm device according to claim 1, wherein a buffer member is interposed between an outer edge portion of the upper surface of the piezoelectric buzzer and a peripheral edge portion of the opening portion of the lower surface of the control circuit board.   3. The alarm sound emitting opening is provided with a plate member in which a plurality of minute sound emitting holes are formed so as to close the alarm sound emitting opening. The portable gas alarm device described in 1.   4. The portable gas alarm device according to claim 3, wherein each of the minute sound emission holes in the plate member is formed at a position displaced so as not to face the sound emission opening in the piezoelectric buzzer.   The portable gas alarm device according to any one of claims 1 to 4, further comprising an alarm sound emitting opening that communicates with the acoustic space in the acoustic chamber on the rear surface of the housing. .   The lower wall forming the acoustic chamber is formed with an opening communicating with the buzzer arrangement portion, and a waterproof sheet having sound permeability is arranged so as to close the opening portion. The portable gas alarm device according to any one of claims 1 to 5.

Images