JPH0933473A - Gas detection sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a CO sensor capable of detecting the concentration of CO in an exhaust gas and a change of a flow velocity of a main flow of the exhaust gas. SOLUTION: A CO detection mechanism part 3 including a comparison element 4, a detection element 5 and a temperature detection element 12 is formed on a sensor base 1. A wind velocity detection element 50 of a heat beam type is set next the CO detection mechanism part 3. The wind velocity detection element 50 and CO detection mechanism part 3 are separated by a heat-shielding wall 51. The CD detection mechanism part 3, wind velocity detection element 50 and heat-shielding wall 51 are covered with a metallic cover 35. At a front end of the cover 35, an entrance orifice hole 36 is formed at the side of an upstream of an exhaust gas and an exit orifice hole 37 is formed at the side of a downstream. The exhaust gas is decelerated at the orifice holes 36, 37, entering a deceleration introduction chamber 38 in the cover 35 while decreasing a flow velocity. The exhaust gas is dispersed at a dispersing chamber 41 finally to reach the CO detection mechanism part 3. It is judged with reference to a concentration of CO detected by the CO detection mechanism part 3 and a wind velocity value detected by the wind velocity detection element 50 whether an increase of the concentration of CO results from influences of a headwind blowing at an exit of the exhaust gas.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention mainly relates to a carbon monoxide gas (CO) contained in exhaust gas provided on the exhaust side of a combustion device.
The present invention relates to a gas detection sensor for detecting the concentration of (gas).

[0002]

2. Description of the Related Art Exhaust gas (combustion exhaust gas) discharged from a combustion chamber is placed on the top of exhaust (exhaust side of combustion chamber) of a combustion device such as a water heater, a bath cooker, and a heater that uses gas or oil as a fuel. A CO sensor, which is a type of gas detection sensor that detects the CO concentration (CO gas concentration), is provided. The CO sensor detects the CO concentration in the exhaust gas, and the CO detected concentration exceeds a predetermined reference concentration. Occasionally, an alarm is issued and safety operations such as cutoff of fuel supply are performed.

An example of this type of CO sensor is shown in FIG. 11 and FIG.
Shown in 12. In these figures, the sensor base 1
3 pairs of terminal pins 2 are provided on the upper surface (front surface side) of the CO, and a CO element-insensitive comparison element 4 and a CO element are provided between each pair of terminal pins through a thin platinum wire having a diameter of, for example, 10 μm. The detection element 5 sensitive to gas and the temperature detection element 12 are provided to form the CO detection mechanism portion 3, and the comparison element 4 and the detection element 5 are provided.
Are separated by a partition plate 6. The comparison element 4 and the detection element 5 are incorporated in a resistance bridge circuit as shown in FIG.

As shown in FIG. 13, the detecting element 5 has a coil-shaped portion 13 formed at the center of a platinum wire which functions as a resistance wire, and the coil-shaped portion 13 is made of, for example, platinum, palladium, rhodium or the like. In the comparative element 4, similarly, the coil-shaped portion 13 formed in the central portion of the platinum wire is covered with the ceramic material containing the catalyst of No. 3 and is made of a ceramic material containing no catalyst. And is formed into a ball shape.

Around these comparison element 4 and detection element 5,
The upper and lower ends are covered with a cylindrical glass wool 7, which is open, and the outside is covered with a metal cover 21. A blade-shaped plate 20 is formed by cutting and raising on the inner surface of the peripheral wall of the metal cover 21, and the exhaust gas is formed so as to enter the inside through the raising and lowering opening 11.

A substrate on which a connection pattern of terminal pins is formed is provided on the back side of the sensor base 1, and a sensor signal is output to a circuit or the like for CO safe operation of the combustion device on the conductor connection pattern of this substrate. Lead wires for connection are connected, but illustration of these substrates is omitted.

When using this type of CO sensor,
The comparison element 4 and the detection element 5 are heated to about 200 ° C. by energization via the lead wire and the terminal pin 2. When CO gas comes into contact with the detection element 5 in this state, a catalytic combustion reaction by the catalyst occurs, Due to this reaction, the temperature of the detection element 5 rises to increase the electric resistance, and the resistance balance with the comparison element 4 which does not cause the catalytic combustion reaction is lost. In response to this resistance balance failure, it is taken out from the resistance bridge circuit of the CO sensor. A change in the applied voltage occurs, and based on the change, C
The O gas concentration is detected. At this time, the temperature of the CO sensor output is corrected based on the temperature information detected by the temperature detecting element 12.

FIG. 15 shows a sensor usage example in which a CO sensor 9 is installed on the exhaust side of a water heater generally known as a combustion device. The CO sensor 9 is installed in an exhaust gas flow velocity deceleration chamber 17 formed at a corner of the exhaust top 8. A combustion control device 33 is provided in this type of water heater, and fuel gas is supplied from the gas pipe 25 to the nozzle holder 24 in the combustion chamber 29 under the control of the combustion control device 33, while the combustion fan 23 Rotation causes air to enter the inside of the apparatus from the intake portion 30 as shown by an arrow B in the drawing, and is sent to the burner side (not shown), and the burner is burned by the air and the fuel gas. Water pipe 26 to heat exchanger
The water supplied to 22 is heated by burner combustion through the heat exchanger 22, becomes hot water, and is supplied from the hot water supply pipe 28 to a desired place such as a kitchen. Then, the combustion exhaust gas generated by such a combustion operation flows to the exhaust top 8 as described above, and the CO concentration in the exhaust gas is detected by the CO sensor 9.

[0009]

As described above, the CO concentration of exhaust gas is continuously detected during combustion operation to ensure safety against CO. However, during combustion operation, gust of wind exits the exhaust gas outlet. When the air is blown against the burner, the amount of air supplied from the combustion fan 23 to the burner decreases, and the CO concentration in the exhaust gas temporarily increases. As a result, even if there is no abnormality in the mechanism of the combustion system of the water heater, the CO concentration is temporarily increased by the gust and exceeds the reference concentration C
The safety operation of O works, the fuel supply is cut off, and the inconvenience that the burner combustion is stopped occurs.
The usability (convenience) of using the water heater becomes poor.

The increase in the CO concentration due to the gust does not continue continuously, and when the gust stops, a normal amount of air is supplied from the combustion fan 23, and the combustion is restored to clean combustion in which CO is hardly generated. Therefore, even if there is a temporary increase in CO concentration due to gusts, there is almost no problem with respect to CO safety, and it is desirable to continue combustion operation as it is and prioritize convenience.

However, the appliance itself cannot distinguish whether the increase in the CO concentration is due to the gust or the abnormality in the combustion mechanism, and when the CO concentration exceeds the reference concentration, the combustion operation is uniformly stopped. I had no choice but to carry out CO safe operation.

The present invention has been made in order to solve the above-mentioned problems, and an object of the present invention is to provide a wind speed near a CO concentration measuring field for determining whether or not a gust of wind is generated when the CO concentration increases. It is to provide a gas detection sensor that can obtain information.

[0013]

In order to achieve the above object, the present invention is constructed as follows. That is, according to the first aspect of the present invention, a test gas detection mechanism section for detecting the concentration of the test gas is formed on the sensor base, and the test gas detection mechanism section is covered by a cover having a gas introduction section. In the detection sensor, a heat ray type wind speed detecting element for detecting the flow velocity of the introduced gas containing the test gas introduced into the cover is accommodated in the cover.

According to a second aspect of the invention, in the structure of the first aspect of the invention, a deceleration introduction chamber for decelerating and introducing an external fluid gas to be measured is introduced into the cover, and the deceleration introduction chamber is introduced. A diffusion chamber for diffusing gas is formed, a test gas detection mechanism section is provided in the diffusion chamber, and a hot-wire wind velocity sensor is provided in the deceleration introduction chamber.

Further, a third invention is characterized in that, in the structure of the first or second invention, the deceleration introducing chamber and the diffusion chamber are partitioned by a partition wall having a communicating hole.

A fourth aspect of the invention is based on the configuration of the first or second aspect of the invention, and is characterized in that the test gas detection mechanism section and the wind speed detection element are partitioned by a heat shield wall. ing.

A fifth aspect of the present invention is the structure of any one of the first to fourth aspects of the invention, wherein a temperature detecting element for temperature compensating one or both of the detected gas detecting mechanism section and the wind speed detecting element is provided in the cover. Is provided.

Further, in a sixth aspect of the present invention, in the configuration of any one of the first to fifth aspects, the wind velocity detecting element is provided in a flow path from an inlet side to an outlet side of the fluid gas to be measured introduced into the cover. It is configured to be provided in the exit side area.

Further, a seventh aspect of the invention is provided with the configuration of any one of the first to sixth aspects of the invention, wherein the gas introduction portion provided in the cover is located upstream of the flow of the external measurement target fluid gas. And an outlet orifice hole provided on the downstream side. The size of the openings of the inlet and outlet orifice holes is the flow velocity of the fluid gas to be measured outside the cover. U _OUT and the inlet from the flow inside the cover through the orifice of the outlet flow rate U _iN and the ratio U _OUT: U _iN is (10-20):
It is configured to be set to 1.

Further, an eighth invention is characterized in that, in the construction of the first, fourth, fifth or sixth invention, the cover is formed of a metal mesh.

Further, a ninth invention is characterized in that the cover is formed of a laminated body of a metal mesh and a filter material in the structure having any one of the first to seventh inventions. ing.

Further, a tenth aspect of the present invention is characterized in that, in the ninth aspect, the filter material is provided with a plurality of through holes.

Furthermore, an eleventh aspect of the present invention is provided with the configuration of any one of the first to tenth aspects of the invention, wherein the test gas detection mechanism portion is a catalytic combustion type CO for detecting the CO gas concentration.
It is configured to be a detection mechanism section.

In the present invention having the above structure, the gas detection sensor of the present invention is installed in the flow path of the fluid gas to be measured such as exhaust gas.

The fluid gas to be measured enters the inside from the gas introduction section of the gas detection sensor, and the concentration of the test gas such as CO is detected and output by the test gas detection mechanism section. In the present specification, the test gas refers to a gas to be detected by the sensor (a gas to be detected). The measurement target fluid gas refers to the ambient fluid gas around which the gas detection sensor is installed.

On the other hand, the heat ray type wind speed detecting element provided inside the cover detects and outputs the flow velocity of the fluid gas to be measured introduced into the cover.

When a gas detection sensor is installed in the exhaust path of the combustion apparatus to detect the CO concentration in the exhaust gas, when a back wind due to gust blows against the exhaust outlet, the exhaust gas that is the fluid gas to be measured that passes through the exhaust path. The flow velocity of the main gas flow is reduced, and accordingly, the flow velocity of the exhaust gas introduced into the cover of the gas detection sensor and flowing inside the cover is also reduced. As a result of the change in the wind speed in the cover being detected by the wind speed detecting element, the detected value of the CO concentration detected by the test gas detecting mechanism section (CO gas detecting mechanism section) and the wind speed detected value of the wind speed detecting element are detected. It becomes possible to judge whether the CO detected concentration increased due to the gust by comparing with the above. When the CO concentration increased due to the gust, the CO detected concentration exceeds the reference concentration for performing the CO safety operation. Even if it does, it is possible to develop new products with improved usability of the combustion device such as not performing CO safe operation.

[0028]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a gas detection sensor according to the present invention will be described below with reference to the drawings. In each of the following embodiments, an example of detecting the CO concentration in the exhaust gas will be described as a representative example, the same names as those in the conventional example will be denoted by the same reference numerals, and duplicate description thereof will be omitted. .
FIG. 1 shows a first embodiment of the present invention. In this embodiment as well, similar to the conventional example shown in FIGS. 11 and 12, a plurality of pins 2 are projectingly provided on the front surface side of the sensor base 1, and the comparison element 4 is provided between the pair of terminal pins 2. The detection element 5 is disposed between the other pair of terminal pins, and the temperature detection element 12 is disposed between the other pair of terminal pins 2 to form the CO detection mechanism section 3. The comparison element 4 and the detection element 5 is a partition plate 6
The structure is divided by. In this embodiment, the glass wool 7 of the conventional example is omitted, but of course, the glass wool 7 may be provided if necessary.

A heat ray type wind velocity detecting element 50 is further provided on the surface side of the sensor base 1, and the wind velocity detecting element 50 is provided.
The CO detection mechanism section 3 is partitioned by a heat shield wall 51 that prevents heat of the heat ray of the wind speed detection element 50 from propagating to the CO detection mechanism section 3.

The surface side of the sensor base 1 is covered with a cylindrical metal cover 35, and the CO detection mechanism 3, the wind speed detection element 50 and the heat shield wall 51 are housed in the cover 35. . The tip of the cylindrical hole of the cover 35 is closed by a top wall 46, and an inlet orifice hole 36 is formed on the peripheral wall on the tip side of the cover 35 at a position on the upstream side of the flow path of the main flow of exhaust gas, and the downstream side. Outlet orifice hole at the side
37 is formed, and the orifice holes 36, 37 constitute a gas introducing portion for introducing the exhaust gas, which is the fluid gas to be measured, into the cover 35, and the inner space at the tip side of the cover 35 is the deceleration introducing chamber 38 Has become. The deceleration introduction chamber 38 has the same function as the flow velocity deceleration chamber 17 provided on the water heater side.

The wind speed detecting element 50 has an inlet orifice hole 36.
Is provided in the exit side region of the flow path of the introduced exhaust gas in the deceleration introducing chamber 38 from the inside of the cover to the outlet orifice hole 37. The internal space of the cover 35 is divided into a deceleration introduction chamber 38 on the tip side of the cover and a diffusion chamber 41 on the base end side of the cover, and the CO detection mechanism section 3 is provided in the diffusion chamber 41.

In this embodiment, the temperature detecting element 12 is a sensor output of the CO concentration detected by the CO detecting mechanism section 3 and the deceleration of the cover 35 from the inlet orifice hole 36 detected by the wind speed detecting element 50. The sensor output of the flow velocity of the introduced exhaust gas flowing through the introduction chamber 38 to the outlet orifice hole 37 is used as a shared element for temperature correction, but of course, the temperature detection element for correcting the sensor output of CO detected concentration. It is also possible to separately provide a temperature detection element for correcting the sensor output of the wind speed and the sensor output.

In the present embodiment, the size of the openings of the inlet orifice hole 36 and the outlet orifice hole 37 is determined by the flow velocity U _OUT of the main flow of exhaust gas and the flow velocity U _{IN of the} introduced exhaust gas flowing through the deceleration introduction chamber 38. Is set to be (10 to 20): 1, and the wind speed detected by the wind speed detection element 50 (or the value obtained by multiplying the wind speed detection value detected by the wind speed detection element 50 by a coefficient). Is configured to have a proportional relationship with the flow velocity of the main flow of the exhaust gas, and the flow velocity of the main flow of the exhaust gas can be obtained from the wind speed detection value detected by the wind speed detection element 50. .

On the back side of the sensor base 1, a substrate for outputting the signals of the comparison element 4, the detection element 5, the temperature detection element 12 and the wind speed detection element 50 to the outside through a lead wire and the gas detection sensor (CO). Although a sensor attachment plate for attaching the detection sensor) to the exhaust path of the combustion device such as the water heater is provided, these are not shown.

The gas detection sensor (CO detection sensor) of the present embodiment example has a deceleration introduction chamber 38 in the inner space on the tip side of the cover 35.
Therefore, the gas detection sensor can be attached at an appropriate desired position in the exhaust passage without requiring the flow velocity deceleration chamber 17 shown in FIG. 15 in the exhaust path of the combustion apparatus such as the water heater.

When the CO sensor 9 is installed in the water heater, as shown in FIG. 16, the configuration shown in FIG. 11 is used without providing the flow velocity deceleration chamber 17 shown in FIG. 15 in the exhaust passage. The CO sensor 9 was attached. However, C
When the O sensor 9 is directly attached to the exhaust passage in a bare state, the flow of the exhaust gas hits the CO sensor 9 strongly, and the CO sensor 9 cuts and elevates from the opening 11 to flow into the metal cover 21 at a high speed. Moreover, since the flow of the exhaust gas flows along the plate 20 of the cut-and-raised opening 11, it becomes a flow accompanied by a vortex and contacts the comparison element 4 and the detection element 5 of the CO detection mechanism section 3.

At this time, the flow of exhaust gas is fast, and
Since the flow is disturbed, the comparison element 4 and the detection element 5
There is a large difference in the flow velocity of the contact between the exhaust gas and the comparison element 4 due to the difference in the flow velocity. And the difference in resistance change between the comparison element 4 and the detection element 5 due to this is taken out as a CO detection component, so that there is a problem that an accurate CO detection concentration cannot be detected.

Therefore, recently, as shown in FIG. 15, the flow velocity reduction chamber 17 is provided at the corner of the exhaust top 8 of the water heater.
Is formed, the flow of the exhaust gas is decelerated and taken into the chamber 17, and then the decelerated flow of the exhaust gas is cut and raised and guided from the opening 11 to the CO detection mechanism section 3.
A large difference in flow velocity does not occur between the detection element 5 side and the detection element 5 side.

However, the deceleration flow velocity chamber 17 becomes a complicated work of joining the partition plate 34 to the inner wall surface of the exhaust top 8 by welding or the like, which lowers the productivity of the water heater and increases the cost of the water heater. There was a problem of inviting.

Further, the flow velocity deceleration chamber 17 has a disadvantage that the CO sensor 9 cannot be installed at a desired position because the place where it is produced is limited, such as the corner of the exhaust top 8.

The gas detection sensor of this embodiment has a cover 35.
By forming the deceleration introduction chamber 38 having the same function as the flow velocity deceleration chamber 17 provided on the exhaust side of the water heater, the flow velocity deceleration chamber 17 of the conventional example is provided at a desired position on the exhaust side of the combustion device such as the water heater. Can be installed without requiring. The flow of exhaust gas generated by the combustion operation hits the gas detection sensor.At this time, the exhaust gas is throttled from the inlet orifice hole 36 and enters the flow velocity introduction chamber 38, and is throttled again from the deceleration introduction chamber 38 and exit orifice. Outflow through hole 37. Since the flow velocity of the exhaust gas is restricted by the inlet orifice hole 36 and the outlet orifice hole 37, it is decelerated and introduced into the deceleration introduction chamber 38.

The flow direction of the exhaust gas entering the diffusion chamber 41 from the deceleration introduction chamber 38 is a direction orthogonal to the direction of the exhaust gas flow in the deceleration introduction chamber 38 connecting the inlet orifice hole 36 and the outlet orifice hole 37. Since it is facing, deceleration introduction room 38
The flow of the exhaust gas from the diffusion chamber 41 to the diffusion chamber 41 becomes a further decelerated flow, there is almost no flow velocity of the exhaust gas when entering the diffusion chamber 41, and the diffusion velocity in the diffusion chamber 41 is almost zero and diffuses. Touch the element 4 and the detection element 5.

Therefore, there is no difference in the flow of the exhaust gas coming into contact with the comparison element 4 and the detection element 5, and there is no error component caused by the flow velocity of the exhaust gas.
It is possible to obtain an excellent effect that the concentration can be accurately detected.

Further, in this embodiment, since the wind speed detecting element 50 is provided in the cover 35, the state of the main flow of exhaust gas outside the cover 35 can be detected. For example, in a state where the gas detection sensor of the present embodiment is attached to the exhaust path of a combustion device such as a water heater, when a backwind such as a gust of wind blows on the outlet of the exhaust gas, the flow velocity of the main flow of the exhaust gas decreases. Since the change in the flow velocity is detected by the wind velocity detecting element 50, by referring to the detected wind velocity (flow velocity) value of the wind velocity detecting element 50 and the CO concentration detected by the CO detecting mechanism unit 3, When the CO concentration temporarily increases, it can be determined that the increase in CO concentration is due to gusts of wind, and it is possible to take measures such as suspending safe operation such as combustion stop, etc. The convenience of the device can be improved.

In this embodiment, the orifice hole 3
The sizes of the openings of 6, 37 were set so that the ratio of the main flow of the exhaust gas and the flow velocity of the exhaust gas introduced into the cover 35 and flowing into the deceleration introduction chamber 38 was (10 to 20): 1. The flow velocity of the main flow of exhaust gas can be obtained based on the wind speed detection value of the wind speed detecting element 50. If the ratio of the flow velocities is too small, the effect of decelerating the flow velocities in the cover 35 is reduced, and if it is too large, it is difficult to obtain a proportional relationship between the flow velocities of the two (including obtaining a proportional relationship by multiplying a coefficient). Therefore, it is preferable that the flow rate ratio be the above.

Recently, in a combustion apparatus such as a water heater, the control of the air volume matching the combustion heat quantity is performed by detecting the air volume supplied from the combustion fan 23 to the burner by using an air velocity sensor or the like, and the fan air volume is burned. A method of controlling the fan rotation speed of the combustion fan 23 so as to obtain a target air volume determined by the amount of heat is being adopted, and in such an air volume control method, the fan air volume is detected using the wind speed detection element 50 provided in the cover 35. Can also be obtained by calculation processing. In this case, a dedicated air volume detection sensor for detecting the fan air volume can be omitted, which is very convenient.

Further, in this embodiment, the wind speed detecting element
Since 50 is provided on the outlet side of the introduced exhaust gas flowing through the deceleration introduction chamber 38, the heat generated from the hot-wire wind velocity detecting element 50 rides on the flow of the exhaust gas and is covered from the outlet orifice hole 37 to the cover 35.
Therefore, the heat generated from the wind speed detecting element 50 can be suppressed from propagating to the CO detection mechanism section 3 side. Moreover, in the present embodiment, since the heat shield wall 51 is arranged between the CO detection mechanism section 3 and the wind speed detection element 50, the heat generated by the wind speed detection element 50 propagates to the CO detection mechanism section 3 side. This can be prevented almost completely, and the CO detection mechanism section 3 can be prevented from being adversely affected by the heat generated by the wind speed detecting element 50 when detecting the CO concentration.

Further, in the present embodiment, the temperature correction of the CO concentration detection value of the CO detection mechanism section 3 and the wind speed detection value by the wind speed detection element 50 is performed by the single temperature detection element 12 which is also used. It is possible to reduce the number of parts and reduce the cost of the sensor as compared with the system in which the temperature correction of the CO detection mechanism section 3 and the temperature correction of the wind speed detection element 50 are performed using separate temperature detection elements.

FIG. 2 shows a second embodiment of the present invention. The characteristic of this embodiment is different from the first embodiment is that the inlet orifice hole 36 and the outlet orifice hole 37 on the tip side of the cover formed along the flow path of the exhaust gas are provided at the tip end of the cover 35. It is formed on the wall 46, and the other structure is the same as that of the first embodiment.

In general, the CO sensor 9 is almost always installed laterally in the space on the exhaust side, for example, as shown in FIG. 15, and in such a lateral installation state, the exhaust chamber is not operated during combustion operation. A temperature difference occurs between the inside and outside of the CO, and due to this temperature difference, the CO sensor mounting wall surface
Condensation may cause water droplets on 18. The first
In the case where the inlet orifice hole 36 and the outlet orifice hole 37 are provided in the peripheral wall of the cover 35 as in the embodiment of FIG. 3, the water droplets of dew condensation attach the outlet orifice hole 37 (gas detection sensor (CO sensor 9) sideways). In this case, there is a concern that the outlet orifice hole 37 will enter the deceleration introduction chamber 38 from the upper side), and that if the diameter of the outlet orifice hole 37 is reduced, water droplets may block the outlet orifice hole 37. Such a problem can be solved by providing the inlet orifice hole 36 and the outlet orifice hole 37 in the tip top wall 46 as in the second embodiment. Of course, in addition to this, the same effects as those of the first embodiment can be obtained. In addition,
Although not shown, when the inlet orifice hole is formed in the peripheral wall of the cover 35 as shown in FIG. 1 and the outlet orifice hole 37 is formed in the tip top wall 46 of the cover 35 as shown in FIG.
The same effect as that of this embodiment can be obtained.

FIG. 3 shows a third embodiment of the present invention. A feature of this embodiment is that the cover 35 has a double structure to form the deceleration introduction chamber 38 and the diffusion chamber 41 in the cover 35, and the other configurations are the same as those of the first and second embodiments. This is similar to the second exemplary embodiments. In the example shown in FIG. 3, the inlet orifice hole 36 and the outlet orifice hole 37 are provided on the peripheral wall on the front end side of the cover 35 as in the case of the first embodiment.
May be provided on the top wall 46 of the cover 35 as in the second embodiment. As shown in FIG. 3, the cover 35 has a double structure, and the short inner cover 35b is fitted inside the tall outer cover 35a to form a double structure cover 35a.
I am trying.

An inlet orifice hole 36 is formed on the upstream side of the exhaust gas flow path, and an outlet orifice hole 37 is formed on the downstream side of the outer peripheral wall of the outer cover 35a. An inner space on the front end side of the cover 35 surrounded by the inner cover 35b serves as a deceleration introduction chamber 38 for exhaust gas.

The boundary region between the front end side and the base end side of the cover 35 is partitioned by the top wall (partition wall) 40 of the inner cover 35b which functions as a partition wall, and the base end side space of the cover 35 is defined by the diffusion chamber 41. Has become. The CO detection mechanism section 3 is formed in the diffusion chamber 41, and the outlet orifice hole 37 in the deceleration introduction chamber 38 is formed.
The wind speed detecting element 50 is provided on the side.

A partition wall that partitions the deceleration introduction chamber 38 and the diffusion chamber 41
A plurality of minute communication holes 42 having a diameter of, for example, about 1 mm are opened in 40, and the exhaust gas introduced into the deceleration introduction chamber 38 enters the diffusion chamber 41 through these minute communication holes 42. Incidentally, 39 in FIG. 3 indicates a sensor mounting plate.

In the example of FIG. 3, the inner cover 35b is formed of a metallic cover, and the top wall (compartment wall) 40 of this metallic cover is formed with a minute communication hole 42, but The partition wall 40 and the minute communication hole 42 thereof can be configured in various forms. For example, as shown in FIG.
The inner cover 35b may be formed by using one or two or more superposed (two in the illustrated example) metal meshes 43 of fine meshes, and the mesh holes of the mesh 43 may be used as fine communication holes. Alternatively, or as shown in FIG. 4 (b), the partition wall 40 is provided with a metal mesh 43 on one surface or both front and back surfaces (both front and back surfaces in the illustrated example) of a filter material 44 such as glass filter paper.
May be formed of a laminated body, and the holes of the metal mesh 43 and the internal minute gap spaces of the filter material 44 may be configured as minute communication holes. Furthermore, as shown in FIG. It is also possible to form a laminated body in which both the front and back sides of the filter material 44 are sandwiched by the metal mesh 43 in a sandwich shape, and to form a plurality of small holes 45 having a diameter of about 1 mm, for example, in the filter material 44 to secure a plurality of cloggings. The partition wall 40 can be configured in various forms. Further, the hole shape is not limited.

In the third embodiment, the partition wall 40 can serve as the heat shield wall 51 in the first and second embodiments, so the heat shield wall 51 is omitted. There is a wind speed detecting element between the partition wall 40 and the wind speed detecting element 50.
It is also possible to provide a heat shield wall that prevents the heat on the 50 side from propagating to the partition wall 40 side.

This embodiment has the same effects as those of the first and second embodiments, but in particular, the deceleration introduction chamber 38 and the diffusion chamber 41 are partitioned by the partition wall 40 so that the deceleration introduction is performed. The flow velocity of the exhaust gas that enters the diffusion chamber 41 from the chamber 38 can be further reduced, and when the partition wall 40 is made of a metal mesh as shown in FIG. The effect of deceleration can be further increased. Further, when the partition wall 40 is configured as shown in FIG. 4B, the internal clearance space of the filter material 41 is very narrow, and the exhaust gas is filtered by the filter. Since it enters the diffusion chamber 41 so as to exude through the material 44, the effect of decelerating the exhaust gas is further improved, and the effect of the flow velocity of the exhaust gas can be completely prevented.

As described above, by using the filter member 44, the flow velocity of the exhaust gas can be completely reduced, but the filter material 44 may be clogged with dust or the like while the gas detection sensor is used for a long period of time. If this happens, if there is clogging, there is a risk that exhaust gas will hardly enter the diffusion chamber 41 from the deceleration introduction chamber 38. In this regard, as shown in FIG. 4C, the filter material 44 has a small diameter hole.
Even if the filter material 44 is clogged, the deceleration introduction chamber 38 is formed through the small-diameter hole 45 by adopting the configuration in which the 45 is formed.
The exhaust gas can enter the diffusion chamber 41 side from the side, and even in the worst case where the filter material 44 is clogged, the CO concentration of the exhaust gas can be detected without any trouble. .

Further, in this embodiment, the flow velocity introducing chamber can be obtained by simply fitting the inner cover 35b into the outer cover 35a.
Since the 38 and the diffusion chamber 41 can be formed by being partitioned by the partition wall 40, the exhaust top 8 of the combustion device such as a water heater is conventionally formed.
As compared with the case where the deceleration flow velocity chamber 17 is formed on the side, the manufacturing work thereof is extremely simple, which makes it possible to significantly improve the manufacturing efficiency and cost of the combustion device equipped with the gas detection sensor.

FIG. 5 shows the fourth embodiment and FIG. 6 shows the fifth embodiment. These embodiments are provided in the interior space covered with the cover 35, and further, CO
A cover 52 that locally covers the installation region of the detection mechanism unit 3 is provided. The example of FIG. 5 corresponds to FIG. 1 of the first embodiment.
The cover 52 covers the area of the CO detection mechanism 3 having the above-described structure, and the cover 52 covers the area of the CO detection mechanism 3 having the structure shown in FIG. 2 of the second embodiment. It is a composition. The cover 52 is composed of various cover members shown in FIG. 4 of the third embodiment, and by providing the cover 52, the same effect as that of the third embodiment can be obtained. it can.

FIG. 7 shows a sixth embodiment of the present invention. In this embodiment, a diameter-reduced step portion 49 is formed on the front side of the cylinder wall of the cover 35 having an opening at the tip, and the reduced-diameter step portion is formed.
The tubular wall extending from 49 to the tip side is a tubular portion having a reduced diameter, and the tip end opening of the radially reduced tubular wall 47 is closed by the flow velocity reduction member 53. The deceleration introduction chamber 38 and the diffusion chamber 41 on the base end side of the cover 35, which is adjacent to and communicates with the deceleration introduction chamber 38, are formed. The CO detection mechanism section 3 formed by the comparison element 4, the detection element 5, and the temperature detection element 12 is housed and formed in the diffusion chamber 41.

The flow velocity deceleration member 53 closing the tip opening of the cover 35 is provided with a plurality of minute inflow holes 54 having a diameter of, for example, about 1 mm, and exhaust gas passes through these minute inflow holes 54 to the deceleration introduction chamber 38. It is designed to get in.

In the example of FIG. 7, the flow velocity reduction member 53 is formed by forming a minute inflow hole 54 in a metal plate, but the flow velocity reduction member 53 and the minute inflow hole 54 can be configured in various forms. For example, as shown in (a), (b), and (c) of FIG. 4, the partition wall 40 may be configured in the same form as the partition wall 40 in the third embodiment. In this sixth embodiment example,
In the exit side region of the flow path in the deceleration introduction chamber 38 of the exhaust gas that enters the inside of the cover from the flow velocity deceleration member 53 that functions as a gas introduction portion and goes out of the flow velocity deceleration member 53 again through the deceleration introduction chamber 38. The wind speed detection element 50 is provided, and the CO detection mechanism section 3 is housed and installed in the diffusion chamber 41. If necessary, as indicated by the chain line, a heat shield wall that prevents the heat generated by the wind speed detection element 50 from propagating to the CO detection mechanism section 3 side between the CO detection mechanism section 3 and the wind speed detection element 50. 51 is provided.
This embodiment example can also achieve the same effect as each of the above embodiment examples.

FIG. 8 shows a seventh embodiment of the present invention. This embodiment is different from the sixth embodiment in that a diffusion amount adjusting hole 48 for adjusting the diffusion amount of exhaust gas in the diffusion chamber is provided in the cylindrical wall of the diffusion chamber 41. The other configuration is the same as that of the sixth embodiment.

In the sixth embodiment, since the exhaust gas outlet opening is not provided in the cylindrical wall of the cover 35,
Due to the damper action of the inner space of the cover 35, the flow velocity reduction member 53
The exhaust gas that enters from the inside may not be able to enter deeply toward the base end side of the cover 35. Especially,
If the distance between the installation area of the CO detection mechanism section 3 and the deceleration introduction chamber 38 is too large, it becomes difficult for the exhaust gas to diffuse into the CO detection mechanism section 3, so the size of the reduced diameter of the deceleration introduction chamber 38 and the flow velocity deceleration are reduced. It is necessary to set the distance from the member 53 to the CO detection mechanism section 3 to an appropriate value.

On the other hand, in the seventh embodiment,
Since the diffusion amount adjusting hole 48 is provided in the cylinder wall of the diffusion chamber 41, the diffusion amount adjusting hole 48 functions as an outflow opening (exit orifice hole) of the exhaust gas that has entered the cover 35.
The exhaust gas that has entered the cover 35 can be introduced deeply.

Moreover, by adjusting the installation position of the diffusion amount adjusting holes 48, the number of holes to be installed, and the size of the holes, the amount of exhaust gas flowing from the flow velocity reduction member 53 toward the diffusion amount adjusting holes 48 and The momentum of the flow can be adjusted freely, and the diffusion of the exhaust gas touching the CO detection mechanism section 3 according to the shape of the deceleration introduction chamber 38, the distance between the CO detection mechanism section 3 and the flow velocity reduction member 53, and the like. The effect is that the amount of diffusion of exhaust gas can be freely adjusted so that the amount becomes optimal. The other effects are the same as those of the sixth embodiment. In the case of the seventh embodiment, the wind speed detecting element 50
Will be provided in a region near the diffusion amount adjusting hole 48 corresponding to the exhaust gas outlet side. Further, a heat shield wall 51 is provided between the wind speed detection element 50 and the CO detection mechanism section 3 as needed.

FIG. 9 shows an eighth embodiment of the present invention. The characteristic feature of this embodiment is that
With the cover 35 having a unique configuration, a front surface and a back surface of a filter material 44 such as a glass filter paper are sandwiched between metal meshes 43, and the cover 35 is composed of a composite material of the filter material 44 and the mesh 43. For example, the through holes 55 having a diameter of about 1 mm are formed scatteredly on the 44, or are formed with regularity such as having a constant straight line interval.

In the eighth embodiment, since the cover 35 is formed of the composite material of the filter material 44 and the mesh 43, the cover 35 is formed into a cap shape using a metal plate as in the conventional example, and the cut and raised opening is formed. The complicated manufacturing process of forming 11 is not necessary, the cap-shaped cover 35 can be manufactured very easily, the production efficiency of the cover 35 is improved, the cost can be reduced, and the mass production can be performed. It will be advantageous in trying.

Further, since the filter material 44 is sandwiched and held by the mesh 43 from both front and back surfaces, the cover 35 is not deformed (deformed). Further, the exhaust gas in the exhaust path is decelerated by the first stage when passing through the metal mesh outside the cover 35, and is then decelerated when passing through the filter material 44, but most of it passes through the filter material 44. Since the exhaust gas of (1) passes through the minute gap space inside the filter material 44, a large second stage deceleration at which the flow velocity is almost zero is made inside the filter material 44, and a state of leaching from the inside of the filter material 44 The exhaust gas discharged from these filter materials 44 is further decelerated in the third stage when passing through the inner metal mesh 43. As a result, at the time of entering the inside of the cover 35, the flow velocity of the exhaust gas becomes almost zero, and the exhaust gas has a CO detection mechanism portion in which the comparison element 4 and the detection element 5 are arranged in a state close to the zero flow velocity. CO diffuses to the 3 side
The concentration will be detected.

Therefore, according to the gas detection sensor (CO sensor 9) of the present embodiment example, even if it is exposed to the exhaust gas having a high flow velocity, it is not affected by the flow velocity, that is, as in the conventional example. It is possible to effectively prevent the problem that a difference occurs in the flow of exhaust gas that touches the comparison element 4 and the detection element 5, and the sensor output fluctuates due to the difference in the flow velocity.
Highly accurate and accurate CO concentration detection is possible.

Further, while the gas detection sensor is used for a long period of time, there is a possibility that dust, soot (carbon), etc. may cause clogging in the minute gap space inside the filter material 44. Even if clogging occurs, since the through holes 55 are formed in the filter material 44, the exhaust gas can be introduced into the cover 35 through these through holes 55 at a reduced flow rate without any trouble, so that the CO concentration can be detected. Can be performed without any trouble.

In this embodiment, since the exhaust gas flows in the cover 35 through the small through holes 55, the wind speed detecting element 50 is arranged in the exhaust gas flow outlet region in the cover 35 to prevent the gust of wind. It is possible to detect changes in the flow velocity of the main flow of exhaust gas due to factors such as

Further, by setting the size of the opening of the small through hole 55, the flow velocity of the main flow of exhaust gas and the cover
Since it is possible to have a constant relationship with the ratio of the flow velocity flowing through the inside of 35, it is also possible to obtain the fan air flow rate by calculation analysis by the wind speed detection element 50.

The present invention is not limited to the above embodiments, but various embodiments can be adopted. For example, the entire cover 35 of each of the above-described embodiments (the flow velocity reduction member
(Including 53) may be composed of a metal mesh. In this case, the effect of decelerating the flow of the exhaust gas entering the cover 35 cannot be effectively obtained. Therefore, when the gas detection sensor is installed on the exhaust side of the combustion device such as the water heater, However, even in the case of this configuration, it is possible to detect the flow velocity change of the main flow of the exhaust gas due to the gust of wind or the like by the wind velocity detection element 50, and the CO detection mechanism unit 3 detects the CO flow. It is possible to distinguish whether or not the increase in concentration is due to the gust of wind.

Further, the cover 35 can take various forms other than those shown in the above-mentioned respective embodiments, and for example, as shown in FIG. A laminated body of mesh and filter material may be used, and the outlet side of the gas introduced into the cover 35 may be the outlet orifice hole 37, which can be formed in various forms.

Further, in each of the above embodiments, the CO detection mechanism section 3 is a contact combustion type CO detection mechanism. However, various other types of CO detection mechanisms different from this (for example, fixed electrolytic type, semiconductor type) CO detection mechanism).

Further, in each of the above embodiments, the case where the exhaust gas is used as an example of the fluid gas to be measured and the CO concentration is detected in the exhaust path of the combustion apparatus has been described. The CO concentration can be detected by being provided in the supply gas or other gas.

Further, although CO gas has been described as an example of the test gas in each of the embodiments, the gas detection sensor of the present invention uses a catalytic combustion type hydrocarbon (CmHn) or hydrogen (H ₂ ) gas. As a detection sensor, a heating type O ₂ sensor, or a semiconductor type CmHn, H
It can be applied as a _second detection sensor. In these cases, the detection mechanism corresponding to the test gas is built on the sensor base 1.

Further, the metal mesh in the above-mentioned embodiment may be any one in which metal fibers are laminated,
It is not necessarily limited to those folded into a mesh or the like.

[0081]

As described above, according to the present invention, the detected gas detecting mechanism and the wind speed detecting element are housed in the cover of the sensor, so that the detected value of the detected gas detecting mechanism is compared with the detected wind speed of the wind speed detecting element. Thus, for example, when the CO concentration detected by the test gas detection mechanism section temporarily increases, it can be determined whether or not the temporary increase in the CO concentration is due to the adverse wind such as gust of wind. In the case of the influence of a gust of wind, it is possible to take a control mode such as temporarily suspending a CO safety operation such as combustion stop to improve the convenience of the device.
It becomes possible to develop control of various combustion devices by checking the concentration and the change in the flow rate of exhaust gas.

Further, in the structure in which the deceleration introducing chamber and the diffusion chamber are provided inside the cover, the flow velocity of the fluid gas to be measured such as exhaust gas is decelerated and introduced into the deceleration introducing chamber inside the cover,
Since the test gas such as CO gas can be diffused to the test gas detection mechanism section with almost no flow velocity, when the test gas is detected by the test gas detection mechanism section, it is affected by the flow of the fluid gas to be measured. It is possible to prevent an error component from being generated in the detected gas detection value, and it is possible to detect the concentration of the detected gas in the fluid gas to be measured with high accuracy and high reliability.

In addition, in the structure in which the gas detection sensor itself has the deceleration means for the flow of the gas to be measured, as in the conventional example, a flow velocity deceleration chamber for decelerating the flow of the exhaust gas is provided on the exhaust side of the combustion device. You can omit the hand gap, which allows
Increasing the production efficiency of combustion equipment equipped with a gas detection sensor,
It is possible to reduce the cost of the device. Moreover, since it is not necessary to provide the flow velocity deceleration chamber on the side of the combustion device, the place where the gas detection sensor is installed is not limited, and the gas detection sensor can be installed at a desired position.

Further, in the structure in which the deceleration introducing chamber and the diffusion chamber are defined by the partition wall having the communication hole, the flow velocity of the gas entering the diffusion chamber from the deceleration introducing chamber is further decelerated when passing through the partition wall. As a result, the flow velocity of the gas can be brought to a state close to zero, whereby the influence of the flow velocity of the gas can be removed more reliably.

Further, in the structure in which the test gas detection mechanism section and the wind speed detection element are partitioned by the heat shield wall, the heat generated by the hot-wire type wind speed detection element propagates to the test gas detection mechanism section side. Therefore, it is possible to prevent the problem that the detection gas detection mechanism section side receives the heat from the wind speed detection element side and the detection accuracy of the detection gas is deteriorated.

Further, in the structure in which the wind speed detecting element is provided in the outlet side area of the gas flow path inside the cover,
Since the heat generated by the wind speed detection element can be carried on the gas flow and carried out to the outside of the cover, it is possible to suppress the heat generated by the wind speed detection element from propagating to the test gas detection mechanism side. It is possible to prevent a decrease in detection accuracy of the test gas detection mechanism section. In this case, the wind speed detecting element is provided in the outlet side area of the gas flow path in the cover, and,
By separating the wind speed detection element and the test gas detection mechanism section with a heat shield wall, it is possible to more reliably block the heat generated by the wind speed detection element from propagating to the test gas detection mechanism section side, and to detect the test gas It is possible to further improve the detection accuracy of the test gas in the mechanism section.

Further, the size of the opening of the inlet orifice hole and the outlet orifice hole of the gas introduction portion provided in the cover is determined by the flow velocity U _{OUT of the} fluid gas to be measured outside the cover and the flow velocity U _IN of the flow inside the cover. When the ratio is set to (10 to 20): 1, the main flow velocity of the fluid gas to be measured can be calculated by calculation analysis based on the detected wind speed value detected by the wind speed detection element. This makes it possible to control the air volume of the combustion fan, etc. based on the flow velocity detection value detected by the wind velocity detection element, and it is possible to omit the dedicated air volume sensor (wind velocity sensor) for air volume control. Therefore, it is possible to simplify the device configuration of the instrument such as the combustion device and reduce the cost of the instrument.

Further, even if the cover of the gas detection sensor is made of a composite material (laminate) of a filter material and a metal mesh, when the gas to be measured passes through the filter material of the cover, the fluid to be measured is The gas flow is decelerated to a state close to zero and enters the inside of the cover, and diffuses in a state where the flow velocity is close to zero to reach the test gas detection mechanism portion, so that the deceleration introduction chamber and the diffusion chamber are provided inside the cover. Similar to the configuration provided, the effect that the test gas can be detected with high accuracy by the test gas detection mechanism section without being affected by the gas flow rate inside the cover is obtained.

Moreover, in the case where the filter material has a plurality of through holes, even if the filter material is clogged, the fluid gas to be measured is introduced into the cover through the through holes. Even if the filter material is clogged, the concentration of the test gas in the fluid gas to be measured can be detected without any problem.

Further, in the structure in which the temperature detecting element is provided in the cover, the detection value of the test gas of the detection gas detecting mechanism portion and the wind speed detection value of the wind speed detecting element can be temperature-corrected to obtain. Therefore, the detected value of the test gas concentration and the detected wind speed can be accurately detected without being affected by the ambient temperature of the gas detection sensor. In this case, one temperature detection element is provided in the cover, and the temperature detection element for temperature compensation is used for the detection value of the gas to be detected and the wind speed detection value. The number of components can be reduced as compared with the case where separate temperature detection elements for the wind speed detection value are provided, and the gas detection sensor can be simplified in configuration and the sensor cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a configuration explanatory diagram of a first embodiment example of the present invention.

FIG. 2 is a configuration explanatory diagram of a second embodiment example of the present invention.

FIG. 3 is a configuration explanatory view showing a third embodiment example of the present invention.

FIG. 4 is an explanatory diagram of various configuration examples of the partition wall 40 in the embodiment example.

FIG. 5 is a configuration explanatory view showing a fourth embodiment example of the present invention.

FIG. 6 is a configuration explanatory view showing a fifth embodiment of the present invention.

FIG. 7 is a configuration explanatory view showing a sixth embodiment of the present invention.

FIG. 8 is a configuration explanatory view showing a seventh embodiment of the present invention.

FIG. 9 is a configuration explanatory view showing an eighth embodiment of the present invention.

FIG. 10 is an explanatory diagram showing another configuration example of the cover that constitutes the gas detection sensor.

FIG. 11 is an explanatory diagram of a configuration of a conventional CO sensor.

12 is an exploded perspective view of the CO sensor shown in FIG. 11.

FIG. 13 is a configuration explanatory diagram of a comparison element and a detection element.

FIG. 14 is a general circuit diagram of a CO sensor.

FIG. 15 is an explanatory diagram showing a usage example of a CO sensor in a water heater.

FIG. 16 is an explanatory diagram showing another example of how the CO sensor is attached to the water heater.

[Explanation of symbols]

 3 CO detection mechanism section 12 Temperature detection element 35, 35a, 35b Cover 36 Inlet orifice hole 37 Outlet orifice hole 38 Deceleration introduction chamber 41 Diffusion chamber 50 Wind speed production element 51 Heat shield wall

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[Procedure amendment]

[Submission date] September 22, 1995

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Correction target item name] All drawings

[Correction method] Change

[Correction content]

[Figure 3]

FIG. 4

FIG. 11

[Fig. 13]

FIG. 14

[Figure 1]

[Fig. 2]

[Figure 5]

[Figure 6]

[Fig. 12]

FIG. 7

[Figure 8]

[Figure 9]

[Figure 10]

FIG. 15

FIG. 16

Claims (11)

[Claims] 1. A gas detection sensor in which a test gas detection mechanism section for detecting the concentration of a test gas is formed on a sensor base, and the test gas detection mechanism section is covered by a cover having a gas introduction section. A gas detection sensor, characterized in that a heat ray type wind speed detecting element for detecting the flow velocity of the introduced gas containing the test gas introduced into the cover is housed in the cover. 2. A deceleration introducing chamber for decelerating and introducing an external fluid gas to be measured and a diffusion chamber for diffusing the gas introduced into the deceleration introducing chamber are formed inside the cover, and the diffusion chamber is covered with the decompression chamber. The gas detection sensor according to claim 1, wherein a test gas detection mechanism section is provided, and a hot-wire wind speed sensor is provided in the deceleration introduction chamber. 3. The gas detection sensor according to claim 1, wherein the deceleration introduction chamber and the diffusion chamber are partitioned by a partition wall having a communication hole. 4. The test gas detection mechanism section and the wind speed detection element are partitioned by a heat shield wall.
Alternatively, the gas detection sensor according to claim 2. 5. The temperature detecting element for temperature compensating one or both of the detected gas detecting mechanism section and the wind speed detecting element is provided in the cover. Gas detection sensor. 6. The wind speed detecting element is provided in an outlet side region of a flow path from the inlet side to the outlet side of the fluid gas to be measured introduced into the cover. 2. The gas detection sensor according to any one of 1. 7. The gas introduction part provided in the cover is composed of an inlet orifice hole provided at a position upstream of the flow of the fluid gas to be measured outside, and an outlet orifice hole provided at a position downstream thereof. The size of the opening of the inlet and outlet orifice holes is the ratio U _OUT of the flow velocity U _{OUT of the} fluid gas to be measured outside the cover and the flow velocity U _IN of the flow inside the cover from the inlet to the outlet orifice hole. : U _IN is set to be (10 to 20): 1, and the gas detection sensor according to any one of claims 1 to 6. 8. The cover according to claim 1, wherein the cover is formed of a metal mesh.
The gas detection sensor described. 9. The gas detection sensor according to claim 1, wherein the cover is formed of a laminated body of a metal mesh and a filter material. 10. The gas detection sensor according to claim 9, wherein a plurality of through holes are formed in the filter material. 11. The gas detection sensor according to claim 1, wherein the test gas detection mechanism unit is a catalytic combustion type CO detection mechanism unit that detects a CO gas concentration.