JP6325288B2 - Gas detector - Google Patents

Description

  The present invention relates to a gas detection device.

  In the conventional gas detection device, the gas in the casing of the gas detection device is replaced with the pressure of the gas introduced from the gas inlet (see Patent Documents 1 and 2).

International Publication No. 2009/148134 Pamphlet JP 2008-051709 A

  In the configuration of the conventional gas detection device, there is a problem that gas stays in the casing, thereby reducing the gas detection speed.

  In view of the above problems, an object of the present invention is to provide a gas detection device capable of reducing a decrease in gas detection speed by suppressing gas stagnation in a housing.

  In order to solve the above-described problem, an aspect of the present invention is a gas detection device including a housing including a gas introduction port and a gas discharge port, a light emitting unit, and a light receiving unit, the light emitting unit and the light emitting unit Each of the light receiving portions has an interface with the housing, and is arranged so that light emitted from the light emitting portion forms an optical path that enters the light receiving portion through a space inside the housing, The housing has a movable partition wall portion, and the partition wall portion includes a shaft portion, and a blade plate provided in the shaft portion so that a surface portion thereof is substantially opposed to the gas introduction port. The vane plate rotates around the shaft portion to carry the gas introduced into the casing from the gas inlet into the optical path and carry the gas in the optical path to the gas outlet. It is a gas detector characterized by being operable as described above.

  Another aspect of the present invention is the gas detection device, wherein the partition wall is configured to always separate the space in the housing into two or more.

  Another aspect of the present invention is the gas detection device, wherein the partition wall portion further includes a sliding portion that contacts an interface between each of the light emitting portion and the light receiving portion and the housing.

  Another aspect of the present invention is a gas detection device in which the partition wall portion can completely block the optical path.

  According to another aspect of the present invention, the first light-receiving unit signal is acquired when the partition wall portion is not blocking the optical path, and the second time is obtained when the partition wall portion is blocking the optical path. And a signal processing unit for calculating the presence or concentration of the gas to be measured based on the signals of the first and second light receiving units.

  ADVANTAGE OF THE INVENTION According to this invention, it can suppress significantly that the gas which exists in the space (in optical path) between the light emission part in the housing | casing of a gas detection apparatus and a light-receiving part stays. Thereby, the fall of gas detection speed can be reduced.

It is a schematic diagram which shows the structural example of the gas detection apparatus which concerns on the 1st Embodiment of this invention. It is a schematic diagram which shows the structural example of the gas detection apparatus which concerns on the 2nd Embodiment of this invention. It is a schematic diagram which shows the structural example of the gas detection apparatus which concerns on the 3rd Embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In each drawing referred to in the following description, parts equivalent to those in other drawings are denoted by the same reference numerals.

(First embodiment)
FIG. 1 is a schematic diagram illustrating a configuration example of a gas detection device according to the first embodiment.

  The gas detection apparatus 1 according to the present embodiment includes a housing 101 having a gas introduction unit 102 and a gas discharge unit 103, a light emitting unit 104 including a light emitting element 104a, a light receiving unit 107 including a light receiving element 107a, and two blades. A partition including a plate 110 and a brush 111 and capable of rotating.

  In the gas detection device 1, gas flows from the gas introduction unit 102 into the housing 101, and the gas inside the housing 101 is discharged from the gas discharge unit 103. In the example of FIG. 1, the casing 101 has a D-shape having a certain thickness as a whole (as a whole, a rectangular parallelepiped and a column with a semicircular bottom (hereinafter referred to as “half-cylinder”, “half-cylinder part”, etc. )).

  In the present embodiment, the light emitting unit 104 including the light emitting element 104 a and the light receiving unit 107 including the light receiving element 107 a are respectively installed on the outer surface of the curved portion of the semi-cylindrical portion of the housing 101. Interfaces 106 and 109 are respectively formed between the light emitting unit 104 and the light receiving unit 107 and the housing 101, and the internal space of the housing 101 and the internal space of the light emitting unit 104 and the light receiving unit 107 are Each is independent. The light emitting unit 104 and the light receiving unit 107 are disposed to face each other with the housing 101 interposed therebetween, and an optical path (not shown) in which light emitted from the light emitting unit 104 enters the light receiving unit 107 through the housing 101 is disposed. ) Is formed.

  The light emitted from the light emitting element 104a passes through the interface 106 and is partially absorbed by the detection gas in the housing 101 when passing through the inside of the housing 101, and then passes through the interface 109 to receive light. Incident on the element 107a. The interface 106 and the interface 109 prevent the detection gas in the housing 101 from flowing into the light emitting unit 104 and the light receiving unit 107, and at the same time transmit infrared rays having a predetermined wavelength in the NDIR (Non-Dispersive InfraRed) method. It may also serve as an optical filter. For example, in the case of a CO2 sensor, using Si and Ge as a base material can be mentioned. In addition, the gas detection device 1 includes a signal processing unit not shown in FIG. The signal processing unit has a function of performing signal processing on light received by the light receiving element 107a.

  Further, as shown in FIG. 1, in the gas detection device 1 of the present embodiment, two sides of the substantially rectangular blade plate 110 are fixed to one side of the two blade plates 110 in the axial direction of the shaft portion 112. In addition, the brush portion 111 is provided along the other side parallel to the side fixed to the shaft portion 112 of the two blades 110. Further, the two blades 110 are arranged so that the angle formed by the two plates is 180 degrees with the shaft portion 112 as the center. The two blades 110 can rotate inside the housing 110 around the shaft portion 112 (or rotate about a line dividing one blade into two equal rectangles. May be). Further, as described above, the tip of the two blade plates 110 is attached with the brush portion 111 that functions as a sliding portion, and when the blade plate 110 rotates, the tip of the brush portion 111 is While rotating in contact with a part of the inner surface of the housing 101 and also in contact with the interface 106 and the interface 109, it rotates.

  More specifically, in this embodiment, the total length of the two blades 110 and the brush part 111 (and the shaft part 112) forming an angle of 180 degrees is the D-shaped linear part of the housing 101. The length is almost the same. The two blades 110 are substantially rectangular, and the length of the shaft portion 112 and the length of each side of the two blade plates 110 fixed to the shaft portion 112 are the same length, and The thickness of the casing 101 is substantially the same. Further, a convex portion 114 exists between the gas introduction portion 102 and the gas discharge portion 103 inside the housing 101 (the gas introduction portion 102 and the gas discharge portion 103 are configured by the presence of the convex portion 114. It can also be said). With such a configuration, the inside of the housing 101 is always divided into two spaces by the two blades 110. As the vane plate 110 rotates, introduction and discharge of the gas inside the housing 101 are promoted, and as a result, new detection gas always flows into the housing 101 and old gas is discharged. Since the gas introduced into the housing 101 from the gas inlet 102 is transported all the way to the optical path, not only the response speed of gas detection is improved, but also the accuracy of gas detection is improved. sell.

  Further, in the gas detection device 1, dust or the like contained in the detection gas causes dust to adhere to the surface of the interface 106 and the interface 109 on the side of the housing 101, and the light emitted from the light emitting unit 104 or the light receiving unit As the light incident on 107 decreases, a problem that the sensitivity as a gas sensor decreases may occur. However, according to the gas detection device of the present embodiment, one of the two blades 110 is pushed by the detection gas flowing from the gas introduction unit 102, and the shaft portion 112 positioned at the center of the housing 101 is used as an axis. When the vane plate 110 rotates, the brush portion 111 at the tip of the vane plate 110 rotates while contacting the inner surface of the semi-cylindrical portion of the housing 101. As a result, it is possible to remove dust attached to the surface of the interface 106 and the interface 109 on the side of the casing 101, and it is possible to reduce a decrease in sensitivity as a gas sensor. In addition, there is an advantage that the durability of the gas detection device 1 is improved and maintenance is free.

  Hereinafter, each component of the gas detection device 1 of the present embodiment will be further supplemented.

(Casing)
As long as the housing 101 of the gas detection device 1 includes a gas introduction part for allowing gas to flow in and a gas discharge part for discharging the gas, the material, shape, and the like are not particularly limited. For example, in the example shown in FIG. 1, the casing 101 is provided with the convex portion 114, so that the gas introduction portion 102 and the gas discharge portion 103 are formed. For example, the whole is circular (cylindrical) Two pipes may be used as a gas introduction part and a gas discharge part by inserting two pipes into the case.

  For the housing 101, an appropriate material can be selected from metals, resins, and the like in consideration of corrosiveness to gas and transparency to light emitted from the light emitting unit 104.

(Partition wall)
In the present embodiment, the partition wall portion rotates to carry the gas introduced from the gas introduction unit 102 into the optical path in the housing 101 and exhaust the gas existing in the optical path of the housing 101. It is configured to be carried to the unit 103. In the present embodiment, the partition wall portion rotates so as to draw a circular locus, but is not limited to this. For example, it may be rotated so as to draw an elliptical trajectory, or may be rotated helically. Rotating operation improves gas introduction / extraction efficiency and space saving.

(Sliding part)
In the present embodiment, the sliding portion has a brush shape, but is not limited thereto. For example, the shape may be a spatula or the like. Moreover, as a material of the sliding part, a flexible member is preferable from the viewpoint of the efficiency of removing the deposits, and examples thereof include rubber, resin, thin film or fibrous metal. However, it is not limited to these, and various materials can be adopted.

(Light emitting part)
The light emitting unit 104 only needs to be able to emit light including light in a wavelength band that can be absorbed by the gas to be detected. As the light emitting element 104a of the light emitting unit 104, an appropriate one may be selected according to the type of gas to be detected. Specific examples include tungsten light bulbs, LEDs, and laser diodes, but are not limited thereto.

(Light receiving section)
The light receiving element 107a of the light receiving unit 107 may be selected from those that can receive and detect light emitted from the light emitting element 104a of the light emitting unit 104. Specific examples of the light receiving unit 107 include a pyroelectric sensor, a thermopile, a bolometer, and a quantum infrared sensor. However, it is not limited to these.

  Further, when the light emitting unit 104 emits broadband light, the gas detection device 1 further allows light of a specific wavelength to selectively pass through the optical path from the viewpoint of improving detection sensitivity for the detection target gas. A low-pass filter, a high-pass filter, a band-pass filter and the like are preferably provided.

(Second Embodiment)
FIG. 2 is a schematic diagram illustrating a configuration example of the gas detection device according to the second embodiment. The gas detection device 1 according to the present embodiment includes a housing 101 having a gas introduction unit 102, a gas discharge unit 103, and a projection 114, a light emitting unit 204 including a light emitting element 204a, and a light receiving unit 207 including a light receiving element 207a. A partition wall portion including four blades 210 and a brush portion 211 capable of rotating.

  The difference between the gas detection device according to the present embodiment and the gas detection device according to the first embodiment is that the arrangement of the light emitting unit 204 and the light receiving unit 207 is different, and the blade plate 210 has four partition walls. And the position of the brush portion 211 is different.

  More specifically, as shown in FIG. 2, the partition wall portion is configured by arranging four blades 210 around the shaft portion 112 so as to form a cross shape. In the gas detection device according to the first embodiment, the light emitting unit 204 and the light receiving unit 207 are provided on the curved surface portion of the semi-cylindrical portion of the housing 101 so as to face each other. However, in the gas detection device according to the present embodiment, the light emitting unit 204 and the light receiving unit 207 are provided so as to face each other on the two D-shaped surfaces of the housing 101. Further, interfaces 206 and 209 exist between the light emitting unit 204 and the light receiving unit 207 and the housing 101, respectively.

  Furthermore, in the gas detection device of the first embodiment, the brush portion is provided along the other side parallel to the side fixed to the shaft portion of the two substantially rectangular blade plates. In the gas detection device according to the embodiment, the brush portion 211 is provided along each of two sides that are substantially perpendicular to the side fixed to the shaft portion 112 of the four substantially rectangular vanes 210. Further, the total length of the side fixed to the shaft portion 112 of the blade plate 210 and the length of the brush portion 211 is substantially the same as the D-shaped thickness of the housing 101. Thereby, when the blade 210 is rotated by the gas flowing into the housing 101 from the gas introduction unit 102, the brush 211 is in contact with the inside of the two D-shaped surfaces of the housing 101. Rotates. Therefore, dust attached to the surface of the interface 206 and the interface 209 on the housing 101 side can be removed, and a reduction in sensitivity as a gas sensor can be reduced.

  According to the gas detection device of the present embodiment, the light emitting unit 204 and the light receiving unit 207 are provided on the D-shaped surface of the casing 101 so as to face each other. The optical path between the light emitting unit 204 and the light receiving unit 207 is shorter than that of the gas detection device of the first embodiment. When the blade plate 210 blocks the optical path, the optical path is blocked by the surface portion of the blade plate in the first embodiment, whereas in the present embodiment, it is blocked by the thickness (line) of the blade plate 210. Thereby, since the time for which the partition wall blocks the optical path becomes shorter, detection noise that can be generated by blocking the optical path by the partition wall can be further reduced.

The shape of the partition wall is more preferably a shape that can completely block the optical path from the light emitting element 204a to the light receiving element 207a. Accordingly, the first signal in the light receiving unit 207 is acquired when the partition wall portion does not completely block the optical path, and the second signal in the light receiving portion 207 is acquired when the partition wall portion completely blocks the optical path. Can be easily obtained, and the offset can be removed based on the first and second signals. Thereby, the presence or absence or concentration of the gas to be measured can be detected with higher accuracy. Note that the blade plate 210 of the partition wall shown in FIG. 2 has a constant thickness as a whole, but is not limited thereto. The vane plate 210 may have any shape that can completely block the optical path from the light emitting element 204a to the light receiving element 207a. For example, the portion close to the tip of the blade 210 may have a thickness that completely covers the interface 206 and / or the interface 209, and the portion close to the shaft portion 112 of the blade 210 may be thinner. (The same applies to FIG. 3 described later.)
More specifically, for example, a signal processing unit (not shown) included in the gas detection device 1 outputs the signal of the light receiving unit 207 in a state that is not affected by the presence or concentration of gas in the housing 101, that is, the second signal. By obtaining and using this second signal as an offset signal, there is an effect that an offset such as a temperature drift component included in the first signal can be removed. In addition, when the partition wall portion of the gas detection device of the present embodiment can be operated continuously, the latest second signal can be sequentially acquired, and the offset signal can be removed with high accuracy. Is preferred.

(Third embodiment)
FIG. 3 is a schematic diagram illustrating a configuration example of the gas detection device according to the third embodiment. The gas detection apparatus 1 according to the present embodiment includes a casing 101 having a gas introduction unit 102, a gas discharge unit 103, and a projection 114, a light emitting / receiving unit 304 including a light emitting element 304a and a light receiving element 307a, and a reflector 305. And a partition wall portion that includes four blades 210 and a brush portion 211 and can be rotated.

  The difference between the gas detection device according to the present embodiment and the gas detection devices according to the first and second embodiments is that the light emitting unit and the light receiving unit are integrated (light emitting / receiving unit 304), and the light receiving / emitting unit. The difference is that a reflecting plate 305 is provided at a position facing the interface 309 between 304 and the casing 101. In the present embodiment, as shown in FIG. 3, the light emitting / receiving unit 304 and the reflecting plate 305 are respectively provided on the two D-shaped surfaces of the housing 101 as in the second embodiment. However, it is not limited to this. As in the first embodiment, the housing 101 may be provided so as to face each other at the curved surface portion of the semi-cylindrical portion.

  Infrared light emitted from the light emitting element 304 a passes through the interface 309 and is partially absorbed by the gas in the housing 101 when passing through the housing 101, then reflected by the reflecting plate 305, and again in the housing. Part of the gas is absorbed by the gas in the body 101 and enters the light receiving element 307a. Therefore, as compared with the gas detection device according to the second embodiment, it is possible to further reduce the size, and the optical path length is doubled, so that the detection sensitivity is improved.

  Also in the gas detection device according to the present embodiment, as in the gas detection device according to the second embodiment, the partition wall portion is configured to be able to completely block the optical path. Thus, the first signal is acquired by the light emitting / receiving unit 304 when the partition wall does not completely block the optical path, and the second signal is received and emitted when the partition wall completely blocks the optical path. Obtained by the unit 304. Thereby, based on the first and second signals, the presence or absence or concentration of the gas to be measured can be detected with higher accuracy. Further, the material of the brush part 211 and the blade plate 210 is made of a material having a high reflectance with respect to the light emitted from the light emitting element 304a, so that the second signal indicates an output when the gas concentration is zero. This is more preferable because it is possible to cancel the offset corresponding to the change in the output due to the deterioration of the element over time or the environmental temperature.

  The present invention is suitable as a gas detection device.

DESCRIPTION OF SYMBOLS 1 Gas detection apparatus 101 Case 102 Gas introduction part 103 Gas discharge part 104,204 Light emission part 104a, 204a, 304a Light emitting element 106,206 Interface 107,207 Light reception part 107a, 207a, 307a Light reception element 109,209,309 Interface 110 , 210 Blades 111 and 211 Brush part 114 Convex part 304 Light emitting / receiving part 305 Reflecting plate

Claims (5)

A housing having a gas inlet and a gas outlet;
A gas detector comprising a light emitting part and a light receiving part,
Each of the light emitting unit and the light receiving unit has an interface with the housing, and is arranged so that light emitted from the light emitting unit forms an optical path that enters the light receiving unit through a space inside the housing. Has been
The housing has a movable partition wall,
The partition wall portion, blades provided so as to be rotatable with the shaft portion installed in a substantially vertical direction, by flowing gas pre Kijiku portion as an axis with respect to the inflow direction of the gas flowing from said gas inlet A plate, and the vane plate rotates around the shaft portion to carry gas introduced into the housing from the gas introduction port into the optical path, and the gas in the optical path to the gas path. A gas detection device that is operable to be carried to a gas discharge port.   The gas detection device according to claim 1, wherein the partition wall is configured to always separate the space in the housing into two or more.   The gas detection device according to claim 1, wherein the partition wall portion further includes a sliding portion that contacts an interface between each of the light emitting unit and the light receiving unit and the housing.   The gas detection device according to any one of claims 1 to 3, wherein the partition wall is capable of completely blocking the optical path. When the partition portion does not block the optical path, obtains a signal of the first light receiving portion; and
When the partition wall is blocking the optical path, a signal of the second light receiving unit is obtained,
A signal processing unit for calculating the presence or concentration of the gas to be measured based on the signals of the first and second light receiving units;
The gas detection device according to claim 4.

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