JP5909793B2 - Gas detector - Google Patents

Description

  The present invention is provided with a gas detection unit for determining the concentration of a gas to be detected and a display unit for displaying a determination result by the gas detection unit inside the casing, and measures for preventing flame escape to the outside are taken. Relates to the gas detector.

  There exists patent document 1 shown below as prior art document information relevant to this kind of gas detector. In the gas detector described in Patent Document 1, in order to make the explosion-proof container small, a necessary circuit board is divided into three boards including a liquid crystal display board, and they are spaced apart vertically. It is supported by a common support member in a stacked state.

  The liquid crystal display substrate is positioned in the uppermost layer as a display unit for the user to confirm the determination result by the gas detection unit, and this is transparent through a glass plate fitted inside the opening provided in the housing. You can see.

  A sufficient thickness of about 10 mm is given to the glass plate, and an O-ring that comes into contact with the outer peripheral surface of the glass plate is provided on the inner peripheral surface of the recess formed inside the opening of the housing to receive the glass plate. A groove for engaging is formed.

Japanese Patent Laying-Open No. 2007-127594 (paragraph 0009, FIG. 2)

  However, in the gas detector described in Patent Document 1, since a glass plate having low toughness is generally used as a protective member for the display unit, the glass is used when the internal pressure suddenly increases due to an explosion in the case. There also existed a problem that the protection member made from a plate might be damaged, and there existed a problem that the sealing inside a housing | casing might become inadequate due to aged deterioration of an O-ring.

  Accordingly, an object of the present invention is to provide a gas detector that is less likely to be damaged even in the event of a sudden increase in internal pressure due to an explosion in a housing, in view of the problems given by the conventional technology exemplified above. .

  Still another object of the present invention is to provide a gas detector in which the sealing inside the casing is easily secured over a long period of time in view of the problems given by the above-described prior art.

The characteristic configuration of the gas detector according to the present invention is as follows:
A gas detection unit that determines the concentration of the gas to be detected and the like, and a display unit that displays the determination result by the gas detection unit are provided inside the housing.
The display unit includes a circuit board that supports display elements, and a window plate member that is disposed inside the housing while supporting the circuit board,
The window plate member is made of a metal auxiliary housing having an opening for a display window, and a window forming portion made of a flame-retardant transparent resin that is insert-molded so as to cast at least the edge of the opening from the front and back sides. It is in the point that is composed of.

  In the gas detector according to the above characteristic configuration, the transparent portion that closes the opening for the display window is generally made of a transparent resin that is higher in toughness and flame retardant than glass. Thus, there is little risk of breakage even when the internal pressure suddenly increases due to an explosion in the housing.

  In addition, in the gas detector having the above-described characteristic configuration, the flame-retardant transparent resin that closes the opening for the display window is formed by insert molding with respect to the metal auxiliary casing, so that at least the edge of the opening of the auxiliary casing is front and back Since it is integrated with the auxiliary casing so as to be cast from, for example, a transparent plate-like member for windows is sealed inside the casing in comparison with a configuration in which the transparent plate member is simply fitted inside the opening of the auxiliary casing. It is easy to ensure the property over a long period of time, and the explosion-proof property is easily maintained.

  In another characteristic configuration of the present invention, the auxiliary housing includes a top plate portion provided with the opening, and support leg portions extending downward from an outer peripheral portion of the top plate portion, and It is fixed to the inside of the housing by a mounting plate that closes a space formed below the top plate by the support leg, and the circuit board is supported on the upper surface of the mounting plate. .

  In this configuration, since the auxiliary housing has acquired a container-like three-dimensional shape due to the presence of the support legs, the top plate can be used even in the event of a sudden increase in internal pressure due to an explosion in the housing. It becomes difficult to apply a large bending stress, and the insert-molded window-forming portion made of a flame-retardant transparent resin is less likely to be damaged due to deformation of the top plate portion. In addition, with this configuration, the circuit board is housed in a space surrounded by the inside of the auxiliary housing and the mounting plate, so it can be protected even if the internal pressure or temperature rises due to an explosion in the housing. It is easy to be done.

  Another characteristic configuration of the present invention is that a curved portion having an arc-shaped cross section projecting inwardly is formed at a lower end portion of the support leg portion.

  With this configuration, the lower end of the support leg has a sufficiently high rigidity, so even if it is made of a relatively thin plate material, the auxiliary housing will not be affected by a sudden rise in internal pressure due to an explosion in the housing. Since it becomes difficult to deform | transform a lower end part, the weight reduction of a gas detector is achieved as a result.

  Another characteristic configuration of the present invention is that an annular elastic seal member surrounding the opening is sandwiched between the inner surface of the casing and the window plate member.

  With this configuration, the opening of the housing is surely isolated from the annular gap extending between the inner surface of the housing and the outer peripheral surface of the auxiliary housing by the elastic seal member. The flame escape to the outside is also suppressed during an explosion in the housing.

  Another feature of the present invention is that an annular space extending outside the elastic seal member is filled with a resin or an adhesive.

  With this configuration, the annular gap extending between the inner surface of the housing and the outer peripheral surface of the auxiliary housing is permanently closed by resin or adhesive, so an explosion in the housing should occur. Sometimes flame escape to the outside is more reliably suppressed.

  Another feature of the present invention is that the flame retardant transparent resin is made of polycarbonate.

  If it is this structure, the flame retardance, impact resistance, and transparency required when closing the window of a gas detector can be implement | achieved cheaply compared with other flame-retardant transparent resins.

It is a top view which shows the gas detector which concerns on this invention. It is a fractured front view showing a gas detector concerning the present invention. It is a perspective view which shows the gas detector which concerns on this invention. It is a perspective view which shows the discharge opening part vicinity of a gas detector. It is a fracture | rupture front view which shows the opening part opening part of a gas detector. It is a perspective view which shows the pump unit of the state fixed. It is a perspective view which shows the pump unit of the state moved upwards. It is a perspective view which shows the pump unit of the state moved to the side. It is a perspective view which shows the gas detector from which the pump unit was taken out. It is a disassembled perspective view which shows the cover body of a gas detector. It is a perspective view which shows the window board member of a gas detector. It is a fracture front view showing a window board member of a gas detector.

EMBODIMENT OF THE INVENTION Below, the form for implementing this invention is demonstrated, referring drawings.
(Schematic structure of gas detector)
A pump-type gas detector 100 shown in FIGS. 1 to 3 includes a container-like casing 1, in which a gas detection unit 5 that detects the concentration of a gas to be detected and a sample gas are provided. A pump unit 6 for introducing into the gas detection unit 5 from the outside of the housing 1 and discharging it to the outside of the housing 1 again, a display unit 8 for displaying the concentration value of the gas detected by the gas detection unit 5, and the like A control unit 9 for controlling the operation of each unit is disposed.

In this specification, the terms indicating the front, rear, left, and right directions are defined with reference to FIG. 1, and the upper position in FIG. 1 is referred to as the front side, and the lower position is referred to as the rear side.
Further, the terms indicating the upward and downward directions are determined with reference to FIG. 2, and the upper position in FIG. 2 is referred to as the upper side and the lower position is referred to as the lower side.

  The gas detection unit 5 is provided with a sensor unit 52 including a plurality of gas detection elements for detecting different types of gases. The gas detector 100 includes hydrocarbons, alcohols, and the like as detection target gases. Therefore, even in the event of an explosion in the vicinity of the gas detection unit 5 or the like, the explosion-proof type is less likely to ignite the explosive gas outside the housing 1.

  The housing 1 includes a main housing 2 that houses a gas detection unit 5, a pump unit 6, and the like, and a lid 4 that is pivotally supported by a hinge 11 on a part of the main housing 2. An endless seal member 21 is engaged with the annular groove 2B formed around the opening 2A of the main housing 2, and the opening is closed with the lid 4 and provided at the four corners of the lid 4. When the four casings 12 inserted into the through holes 4H are tightened against the main casing 2, the inside of the casing 1 is maintained in a sealed state by the seal member 21.

  As shown in FIG. 6 and the like, an explosion-proof pressure-resistant packing land 82 is attached to a through-hole formed in the rear side wall of the main housing 2 and is drawn into the housing 1 through the pressure-resistant packing land. A terminal block 84 for connecting the power supply cable 36 (see FIG. 1) and the like is disposed.

(Configuration of gas inlet and gas outlet)
The left side of the main housing 2 is provided with a gas introduction unit 22 for introducing a gas to be detected into the gas detection unit, and the right side of the main housing 2 is once introduced into the gas detection unit. A gas discharge part 23 for discharging gas out of the housing 1 is provided. The gas introduction part 22 is connected to the gas detection part 5 by a flexible tube T1, and the gas discharge part 23 is connected to the exhaust part of the pump unit 6 by another flexible tube T4.

  As understood from FIG. 2, the gas introduced from the gas introduction unit 22 by the suction force of the pump unit 6 is first supplied to the gas detection unit 5 through the flexible tube T <b> 1, and then the other flexible From the outlet of the gas detector 5 to the pulsation buffer 7 via the flexible tube T2, and enters the pump chamber (not shown) of the pump unit 6 via the flexible tube T3 from the outlet of the pulsation buffer 7. From the exhaust part of the pump chamber to the gas discharge part 23 via the flexible tube T4, the gas is discharged out of the housing 1.

  As shown in FIGS. 4 and 5, the openings 2 </ b> C and 2 </ b> D formed on the left and right side portions of the main housing 2 to form the gas introduction part 22 and the gas discharge part 23 have a generally cylindrical gas distribution sleeve. 24 is detachably attached. A small-diameter portion 24A protruding radially inward is formed at an intermediate position in the axial direction inside the gas distribution sleeve 24, and an explosion-proof filter 25 formed of sintered metal is formed outside the small-diameter portion 24A. The hose nipple 26 which is connected to one end of the flexible tubes T1 and T4 is screwed into the small diameter portion 24A.

The explosion-proof filter 25 is filled with stainless steel particles having an average particle diameter of 500 to 700 μm in a disk shape by a press device or the like inside the gas distribution sleeve 24, and then the entire gas distribution sleeve 24 is heat-treated in a predetermined temperature range. By doing so, it is formed integrally with the gas distribution sleeve 24. In order to perform an appropriate explosion-proof function, the explosion-proof filter 25 has a disk shape with a thickness exceeding 2 mm, a dry density of 5.0 g / cm ³ , and a maximum pore diameter of 50 μm.

  The left and right openings 2C and 2D of the main housing 2 have a small diameter portion 2P that abuts and supports the inner end face of the gas distribution sleeve 24. The gas distribution sleeve includes the small diameter portion 2P and the left and right sides of the main housing 2. It is clamped and fixed between an annular pressing member 27 fixed to the side with a screw.

  An annular groove 2E that surrounds the outer periphery of the gas distribution sleeve 24 is formed on the left and right side surfaces of the main housing 2, and the outer surface of the main housing 2 and the inner side of the pressing member 27 are formed in the annular groove 2E. An O-ring 28 made of an elastic member for sealing between the end faces is engaged.

  In addition, a female screw (not shown) for connecting a hose nipple (not shown) or the like is formed on the inner peripheral surface of the pressing member 27, so that the detection target gas is supplied to the gas detector 100 with respect to the hose nipple. On the other hand, a hose 30 (see FIG. 1) for introducing or discharging from the gas detector 100 can be connected.

  The gas detection unit 5 is disposed on the relatively bottom side of the main housing 2, that is, below, and the pump unit 6 is positioned adjacent to the upper side of the gas detection unit 5 in order to make the gas detector 100 compact. Arranged so as to at least partially overlap the gas detector 5 when viewed in the axial direction intersecting the bottom surface of the main housing 2.

(Pump unit mounting structure)
Maintenance of the gas detection unit 5 can be performed by releasing the fixation of the pump unit 6 and moving it in advance. As understood from FIG. 6 to FIG. 9, as specific configurations, plate-like fixed members 61 </ b> A and 61 </ b> B extending laterally are provided at the front end and the rear end of the lower surface of the pump unit 6, On the other hand, the support brackets 29A and 29B, which have an L-shaped section standing from the bottom of the main housing 2, are provided with generally horizontal support plate portions 29S that can support the fixed members 61A and 61B of the pump unit 6. It has been.

  A relatively short notch opened rightward is formed at the right ends of the fixed members 61A and 61B, and a long hole 63 extending in the left and right direction is formed on the left side of the notches of the fixed members 61A and 61B. ing. The width of the notch 62 and the long hole 63 in the front-rear direction is set to a dimension that exceeds the outer diameter of the leg portion of the mounting bolt 64 that is screwed into the female screw 29H of the support plate portion 29S.

The vicinity of the left and right ends of the fixed members 61A and 61B is fixed to the support plate 29S using a specially shaped mounting bolt 64 inserted through the notch and the long hole 63.
The mounting bolt 64 has a relatively long overall length, a first male screw portion 64B extending downward from the lower end of the head portion 64A, and a smooth small diameter portion 64C having no screw extending downward from the lower end of the first male screw portion 64B. And a second male screw portion 64D extending downward from the lower end of the small diameter portion 64C.

  When the pump unit 6 is fixed, the mounting bolts 64 are inserted into the front and rear cutouts 62 and the long holes 63 from above, and the first male screw portions 64B of the mounting bolts 64 are connected to the female screws 29H of the support plate portion 29S. What is necessary is just to clamp | tighten the edge part of a notch and the long hole 63 with respect to the support plate part 29S by screwing. FIG. 6 shows a state where the fixing is completed.

  On the other hand, when it is desired to move the pump unit 6 laterally for the purpose of maintenance of the gas detection part, the four mounting bolts 64 are removed until the entire length of the first male screw part 64B comes out of the female screw 29H of the support plate part 29S. Loosen. In this way, the first male screw portion 64B has a full length that has come out of the female screw 29H of the support plate portion 29S, and the second male screw portion 64D of the mounting bolt 64 is still positioned below the support plate portion 29S. The mounting bolt 64 can be freely moved up and down with respect to the support plate 29S within the range of the small diameter portion 64C without screws.

  Therefore, as shown in FIG. 7, the upper edge of the main housing 2 is cleared by moving the pump unit 6 slightly upward. Next, as shown in FIG. First, the edge of the notch is released from the front and rear right mounting bolts 64, and the front and rear left mounting bolts 64 can move freely to the left and right within the length of the long hole 63 with respect to the long hole 63. Therefore, the pump unit 6 can be moved laterally to the left side, and maintenance of the gas detection unit 5 can be performed. In this state, the second male screw portion 64D functions as a means for restricting the mounting bolt 64 from falling off the support plate portion 29S.

  When it is desired to remove the pulse buffer 7 for maintenance or for the purpose of replacing the pump unit 6 itself, as shown in FIG. 9, the upper end of the second male screw portion 64D of the mounting bolt 64 is connected to the support plate portion 29S. The entire mounting bolt 64 may be removed from the support plate portion 29S by screwing it into the female screw 29H and then pulling it upward from the female screw 29H.

(Configuration of gas detector)
As shown in FIG. 8, when the pump unit 6 is largely laterally moved to the left side, the lower gas detection unit 5 can be accessed. The gas detection unit 5 includes a socket-shaped sensor box 51 and a sensor unit 52 having a generally cylindrical outer shape that is detachably mounted on the sensor box 51 from above.

  The sensor unit 52 is fixed by screwing a sensor unit fixing plate 53 having a rectangular outer shape superimposed on the upper surface of the sensor unit 52 to the upper end surface of the sensor box 51. When the sensor unit fixing plate 53 is removed together with the screws, the sensor unit 52 can be replaced.

(Configuration of display unit)
As shown in FIG. 2, the back surface of the lid 4 supports a main circuit board 91 that constitutes the control unit 9 and an auxiliary circuit board 92 that serves to display the detected gas concentration value. . The auxiliary circuit board 92 is provided with a display element such as a 7-segment display that displays the detected gas concentration value, an LED that emits a message such as a warning, and the like. The light emission from the LED can be confirmed from the display unit 8 provided on the lid 4.

  As shown in FIG. 1, a relatively large rectangular main opening 4 </ b> A and a plurality of circular auxiliary openings 4 </ b> B arranged before and after the main opening 4 </ b> A are located at a position closer to the front side of the upper surface of the lid body 4. The numerical values displayed on the display elements and the light emitted from the LEDs are transmitted through these main openings 4A and the window plate member 41 (see FIG. 2) disposed on the back surface of the lid body 4. It can be confirmed through the auxiliary opening 4B.

The window plate member 41 casts a stainless steel window plate casing 42 having a horizontally long main display window 44A (an example of an opening) and at least a peripheral portion of the main display window 44A from the front and back sides (going round). ) And the window forming portion 43 made of a transparent flame-retardant resin, which is insert-molded as described above.
The window plate housing 42 is obtained by punching and bending a stainless steel plate using a press machine. The window plate housing 42 is generally formed from an oval top plate portion 42A and an outer peripheral portion of the top plate portion 42A downward. And an extended support leg 42B.
The above-described main display window 44A is formed at substantially the center of the top plate portion 42A, and a plurality of circular openings are formed through the front and rear of the main display window 44A as auxiliary display windows 44B.

  The support leg portion 42B extends from the outer peripheral portion of the top plate portion 42A, has a connection portion 42C having an arc-shaped cross section protruding outward, and a main leg portion 42D extending generally vertically from the lower end of the connection portion; A lower end portion 42E (an example of a curved portion) having an arc-shaped cross section that extends from the lower end of the main leg portion 42D and protrudes inwardly.

  The window forming portion 43 is provided only on the top plate portion 42A, and the transparent flame-retardant resin is formed on the main display window 44A by insert molding over a rectangular region excluding the outermost peripheral portion of the top plate portion 42A. In addition, the openings of all the auxiliary display windows 44B are filled. The part of the flame retardant resin integrally extended to the area including the auxiliary display window 44B outside the main display window 44A is sandwiched by a part of the top plate part 42A from both the front and back surfaces, thereby forming the window forming part 43. It plays the role of the clamping part which adheres to the top plate part 42A.

  The window plate member 41 is pressed and fixed to a predetermined location on the back surface of the lid body 4 with a screw or the like via a generally rectangular metal fixing plate 45. The auxiliary circuit board 92 described above is disposed on the upper surface of the fixed plate 45, and the main circuit board 91 is supported on the lower surface of the fixed plate 45. Further, the fixing plate 45 is formed with a through hole 45H for inserting a cable connector (not shown) for electrically connecting the auxiliary circuit board 92 to the main circuit board 91 on the main housing 2 side.

  The main display window 44 </ b> A and the plurality of auxiliary display windows 44 </ b> B filled with a transparent flame-retardant resin emit light emitted from LEDs indicating characters, POWER, ALARM, TROUBLE, etc. displayed on the display element of the auxiliary circuit board 92. It plays the role of a window to make it visible from. The LED installed corresponding to ALARM constitutes an alarm means for notifying that the detected value has exceeded a predetermined level.

  From the upper and lower surfaces of the three auxiliary display windows 44B corresponding to the positions of the LEDs, solid and generally cylindrical light guide portions 44C made of a transparent flame-retardant resin are integrally formed projecting upward and downward. ing. These light guide parts 44C are arranged so that their lower end faces are close to the upper surface of the LED, and the light emitted from the LED is transmitted upward to confirm the light emission state from directions other than the front of the lid 4 It is easy to do.

  As shown in FIG. 10, an annular seal member 46 made of an elastic material is disposed on the back surface of the lid body 4, and the seal member 46 is based on the pressing and fixing of the window plate member 41 by the fixing plate 45. 4 and the top plate portion 42A of the window plate member 41. An annular space formed between the back surface of the lid 4 and the support leg portion 42 </ b> B of the window plate member 41 is filled with the epoxy resin 47.

  Further, as shown in FIG. 2, near the surface of the lid 4 is made of a transparent resin so as to face the window forming portion 43 of the window plate member 41 and close the main opening 4A and the auxiliary opening 4B. A protective plate is attached.

[Another embodiment]
<1> In the above embodiment, polycarbonate is used as the flame retardant resin constituting the window forming portion 43 of the window plate member 41, but it is transparent to clear the flame retardant grade: V-0 in the vertical combustion test. Any resin may be used.

<2> The present invention is applicable to gas detectors other than the explosion-proof type as long as it is a gas detector provided with a gas detection unit and a display unit for displaying a determination result by the gas detection unit. It is most effective when applied to a detector.

  The present invention is an invention that can be used as a technique for solving a problem that has been conventionally seen in a gas detector including a gas detection unit and a display unit that displays a determination result by the gas detection unit.

DESCRIPTION OF SYMBOLS 1 Case 2 Main housing 4 Lid 4A Main opening 4B Auxiliary opening 5 Gas detection part 6 Pump unit 8 Display part 41 Window plate member 42 Window plate housing 42A Top plate part 42B Support leg part 42C Connection part 42D Main Leg portion 42E Lower end portion 43 Window forming portion 44A Main display window 44B Auxiliary display window 45 Fixing plate 45H Through hole 46 Seal member 47 Epoxy resin (resin)
91 Main circuit board 92 Auxiliary circuit board 100 Gas detector

Claims (6)

A gas detection unit that determines the concentration of the gas to be detected and the like, and a display unit that displays the determination result by the gas detection unit are provided inside the housing.
The display unit includes a circuit board that supports display elements, and a window plate member that is disposed inside the housing while supporting the circuit board,
The window plate member is made of a metal auxiliary housing having an opening for a display window, and a window forming portion made of a flame-retardant transparent resin that is insert-molded so as to cast at least the edge of the opening from the front and back sides. A gas detector consisting of   The auxiliary housing includes a top plate portion having the opening and a support leg portion extending downward from an outer peripheral portion of the top plate portion, and the top plate portion is formed by the support leg portion. The gas detector according to claim 1, wherein the circuit board is supported on the upper surface of the mounting plate, and is fixed to the inside of the housing by a mounting plate that closes a space formed below the housing.   The gas detector according to claim 2, wherein a curved portion having an arc-shaped cross section protruding inward is formed at a lower end portion of the support leg portion.   The gas detector according to any one of claims 1 to 3, wherein an annular elastic seal member surrounding the opening is sandwiched between an inner surface of the casing and the window plate member.   The gas detector according to claim 4, wherein an annular space extending outside the elastic seal member is filled with a resin or an adhesive.   The gas detector according to any one of claims 1 to 5, wherein the flame-retardant transparent resin is made of polycarbonate.

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