JPH10260155A - Sensor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a compact sensor device by which a heating type gas sensor and a temperature sensor can be housed together. SOLUTION: A sensor fitting metal 42 holds a gas sensor 20 and a temperature sensor 18 in approximate parallel with the supporting direction of a probe pipe 14, so that the width of a sensor device 10 is hardly made large even when the gas sensor 20 is arranged apart from the temperature sensor 18. In this case, since the gas sensor 20 is arranged a specified distance apart from the temperature sensor 18, the sensor 18 receives no influence of temperature in the gas sensor 20 heated by a heater.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sensor device, and more particularly, to a sensor device for measuring a concentration of oxygen, a humidity, and the like with a gas sensor having a built-in heater and a temperature sensor for temperature correction of the gas sensor. The present invention relates to a sensor device.

[0002]

2. Description of the Related Art A measuring apparatus for measuring gas concentration and temperature according to the prior art will be described with reference to FIG. The gas sensor 120 and the temperature sensor 130 are disposed on an insulating sensor pedestal 140, and the sensor pedestal 140
Is the connection fitting 11 provided at the tip of the metal pipe 114.
6 attached. In addition, the measurement device includes a dustproof cover 1 for the gas sensor 120 and the temperature sensor 130.
50 are provided. In such a configuration, the gas concentration and the temperature can be measured by one measuring device.

At present, the oxygen concentration in the exhaust gas of a gas boiler in a factory or the like is measured, for example, by measuring the oxygen concentration.
A fixed electrolyte sensor such as zirconia is used for controlling the air-fuel ratio, measuring humidity at a high temperature, or adjusting the humidity in a heating pot at a bread factory. Such a fixed electrolyte sensor can be measured only in an active state at a high temperature. Therefore, a heating device such as a heater is added and the sensor is heated to a set temperature of about 500 ° C. to 800 ° C. before use. Further, since the output value of a fixed electrolyte sensor deviates depending on the temperature of the atmosphere to be measured, it is necessary to measure the temperature of the atmosphere and perform temperature correction in order to perform accurate measurement.

[0004]

As shown in FIG. 7A, a gas sensor which needs to be heated and a temperature measuring sensor for correcting the value measured by the gas sensor are temperature-controlled. If the temperature sensor is attached to one of the sensor devices, the temperature sensor cannot properly measure the temperature of the surrounding atmosphere due to the thermal influence from the heated gas sensor. For this reason, the present inventor has proposed the gas sensor 2 as shown in FIG.
It has been devised to dispose the distance 20 and the temperature sensor 130 at a distance. However, arranging the gas sensor 220 and the temperature sensor 130 in this manner causes a problem that the sensor device becomes large.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problem, and an object of the present invention is to provide a sensor device having a compact configuration capable of simultaneously housing a heating-type gas sensor and a temperature sensor. It is in.

[0006]

According to the present invention, in order to achieve the above object, the sensor device according to the first aspect has a measuring element for measuring at least one of a gas concentration and a humidity, which has a built-in heater for heating. A temperature detecting element for correcting the temperature of the measuring element, a holding member that holds the measuring element and the temperature detecting element, and a supporting member that extends and supports the holding member in the atmosphere to be measured. In a sensor device, a technical feature is that the holding member holds the measurement element and the temperature detection element substantially parallel to a support direction of the support member and at a predetermined distance. .

According to a second aspect of the present invention, there is provided a sensor device according to the first aspect, wherein a separation distance between the measuring element and the temperature detecting element is 50 mm or more.

According to a third aspect of the present invention, in the first or second aspect, the holding member is formed in a cylindrical shape.
A technical feature is that the temperature detecting element is held inside.

According to the first aspect of the present invention, since the holding member holds the measuring element and the temperature detecting element, it is easy to exchange the measuring element and the temperature detecting element. Further, since the measuring element and the temperature detecting element are separated from each other by a predetermined distance, the temperature detecting element is not affected by the temperature of the measuring element heated by the heater. Further, since the holding member holds the measuring element and the temperature detecting element substantially parallel to the supporting direction of the holding member, the width of the sensor device is widened even if the measuring element and the temperature detecting element are arranged apart from each other. Nothing. Here, the holding member can hold the measuring element and the temperature detecting element via an insulating member or the like, or can directly hold the measuring element and the temperature detecting element. Further, the holding member may be composed of a plurality of members.

According to the second aspect of the present invention, since the measuring element and the temperature detecting element are separated by 50 mm or more, the value received by the temperature detecting element as an effect of the temperature of the measuring element heated by the heater is 1 ° C. or less. Thus, the temperature detecting element can accurately measure the ambient temperature.

According to the third aspect of the present invention, since the cylindrical holding member holds the temperature detecting element inside and is not exposed to the outside atmosphere, the temperature detecting element is unlikely to fail.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a sensor device according to the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing a sensor device according to the present embodiment, in which the left side of the dashed line is cut away. The sensor device 10 of the present embodiment includes a sensor unit
Is attached, and a wiring case 52 is attached to the rear end. As the probe pipe 14, a stainless steel pipe having a diameter of 25 mm and a length of 100 to 1000 mm is used. Around the sensor unit 12 side, a porous dust-proof protector 50 made of sintered stainless steel is attached to protect the gas sensor 20 attached to the tip of the sensor unit 12.

The sensor device 10 inserts the probe pipe 14 into a through hole 60a formed in the wall surface 60 of the exhaust duct to detect the oxygen concentration and humidity in the exhaust duct, and the sensor unit 12 is inserted into the exhaust duct. Is extended,
On the other hand, the wiring case 52 is disposed outside the exhaust duct. A lead wire described later from the sensor unit 12 passes through the inside of the probe pipe 14 and is drawn into the wiring case 52 side.

FIG. 2 is an enlarged view of the sensor unit 12 indicated by cycle C in FIG.
FIG. 3 shows a state in which the sensor unit 12 is removed from FIG. 4, and FIG. 4 shows a longitudinal section of the sensor unit 12 shown in FIG. As shown in FIG. 3, the sensor unit 12 is configured such that a gas sensor 20, which is a measuring element for simultaneously detecting oxygen concentration and humidity at the tip, is a cylindrical member that is a holding member via a gas sensor pedestal 40 made of an insulator such as ceramic. Is attached to the sensor mounting bracket 42. The sensor mounting bracket 42 is made of stainless steel and has a bolt portion 42b at the upper end.
However, a thread 42a is formed below the bolt portion 42b.

As shown in FIG. 4, as a sensor unit, a temperature sensor 18 as a temperature measuring element is mounted inside a sensor mounting bracket 42 via a temperature sensor pedestal 46 made of an insulator such as ceramic. I have. The temperature sensor is formed of a platinum-side temperature resistor having high detection accuracy. The distance between the gas sensor 20 and the temperature sensor 18 indicated by D in the figure is set to about 65 mm, and the temperature sensor 18 is configured so as not to be affected by the heat from the heated gas sensor 20. A lead wire from the gas sensor 20 is drawn out through a temperature sensor pedestal 46. Similarly, a lead wire from the temperature sensor 18 is also drawn out through the temperature sensor pedestal 46. This lead is connected to the probe pipe 14 as described above with reference to FIG.
Through the wiring case 52.

The inside of the sensor mounting bracket 42 is kept airtight by a gas sensor pedestal 40 and a temperature sensor pedestal 46, and the temperature sensor 18 is configured not to be exposed to an external atmosphere. Therefore, the temperature sensor 18
Does not directly measure the temperature of the gas to be measured for which the oxygen concentration is measured, but since the sensor mounting bracket 42 becomes equal to the temperature of the gas to be measured by heat conduction through a metal portion or an air portion, The temperature sensor 18 can accurately measure the temperature of the gas to be measured, and appropriately correct the temperature of the measurement value of the gas sensor 20.

Here, the platinum-side temperature resistor constituting the temperature sensor 18 can accurately measure the temperature, but is relatively susceptible to external mechanical shock, and if used under high humidity,
Corrosion occurs in the wiring and it easily breaks down. For this reason, in this embodiment, the temperature sensor 18 is housed in a sensor mounting bracket having an airtight structure so that no mechanical external force is applied and corrosion is not generated in the wiring and the like. In this embodiment, a platinum-side temperature resistor is used as the temperature sensor, but various temperature measuring elements such as a thermistor and a thermocouple can be used instead.

In the sensor unit 12 of this embodiment, a gas sensor 20 and a temperature sensor 18 are used as a pair. That is, the data for calibrating the characteristics of the gas sensor 20 and the characteristics of the temperature sensor 18 are calculated by an arithmetic circuit (not shown) for calculating the oxygen concentration and the humidity based on the outputs from both sensors so that accurate measurement can be performed. If the gas sensor 20 or the temperature sensor 18 is deteriorated, the sensor unit 12 is replaced together. In this case, the sensor unit 12 is individually adjusted in accordance with the characteristics of the sensor unit 12. Replace the existing arithmetic circuit or replace the configuration data in the memory.

The configuration of the gas sensor 20 according to this embodiment will be described with reference to FIG. FIG. 5A is a perspective view of the gas sensor 20, and FIG. 5B is a cross-sectional view of the gas sensor 20 shown in FIG. The gas sensor 20
Has a width of about 5 mm, a height of about 20 mm, and a thickness of about 1 mm. The gas sensor 20 is a 3 to 4 W ceramic heater 2 having a built-in tungsten heater wire 23.
2, a stabilized zirconia plate (fixed electrolyte) 24,
26 are provided. The stabilized zirconia plate 24 has a positive electrode 26A and a negative electrode 2 made of a porous platinum layer.
8A is buried. Similarly, the stabilized zirconia plate 2
On the sixth side, a positive electrode 26B and a negative electrode 28B are embedded. A gas outlet hole 30A and a gas introduction part 32 are formed in the stabilized zirconia plate 24 side. Similarly, a gas outlet hole 30B and a gas introduction part (not shown) are formed in the stabilized zirconia plate 26 side. Are drilled.

The gas sensor 20 is heated to about 500 ° C. by a heater 22, and applied to one of the stabilized zirconia plates, for example, the stabilized zirconia plate 24, at which a limit current value proportional to the oxygen concentration is obtained. At the same time as measuring the oxygen concentration from the value, the other stabilized zirconia plate, for example, on the side of the stabilized zirconia plate 26, the humidity is measured from the oxygen concentration value obtained by decomposing water molecules. This gas sensor 20
Since the manufacturing method and operation of the present invention are described in detail in Japanese Patent Application Laid-Open No. Hei 5-87773 filed by the present applicant, the description is omitted here.

Next, a method of mounting the sensor unit 12 according to the present embodiment will be described with reference to FIG. At the tip of the probe pipe 14, a metal connection fitting 16 having a through hole 16b having a thread 16a formed at the center is attached by welding. First, the sensor unit 1
The second lead wire 48 is inserted into the through hole 16b of the connection fitting 16. Then, the screw thread 42a of the sensor mounting bracket 42 of the sensor unit 12 is replaced with the screw thread 16a in the through hole 16b.
The sensor unit 12 is fixed by screwing the sensor unit 12. The protector 50 is screwed into the thread 16c of the connection fitting 16 so as to cover the sensor unit 12. On the other hand,
The lead wire 48 of the sensor unit 12 is connected to the operation circuit side (not shown) in the wiring case 52 shown in FIG.
This arithmetic circuit is individually adjusted in accordance with the characteristics of the gas sensor 20 and the temperature sensor 18 attached to the sensor unit 12.

That is, in this embodiment, as described above,
When the gas sensor 20 or the temperature sensor 18 is deteriorated, or when a predetermined operation time elapses and the gas sensor 20 is periodically replaced, the sensor unit 12 is replaced with a new one, and a calculation which is individually adjusted according to the new sensor unit 12 is performed. Replace with a circuit or replace configuration data in the memory.

Subsequently, the gas sensor 20 and the temperature sensor 1
The relationship between the disposition distance D with respect to No. 8 and the thermal effect will be described with reference to the graph of FIG. In this experiment, gas sensor 2
The thermal effect from the gas sensor 20 on the temperature sensor 18 side was measured while changing the distance from 0 to the temperature sensor 18. Here, a rated current is applied to the heater (3 to 4 W) of the gas sensor 20 of the above embodiment to heat it to the set temperature of 500 ° C.
It shows a value measured at 0 ° C. (corresponding to the exhaust temperature of the boiler).

As shown in the graph, it was found that when the distance was 150 mm or more, there was almost no thermal effect. Also, if the distance is more than 50 mm, the thermal effect is 1 ° C or less,
That is, it was found that the measured temperature was the ambient temperature + 1 ° C, and that the temperature correction of the output value of the gas sensor 20 could be performed almost accurately. Therefore, in the configuration of the present embodiment, it is desirable that the gas sensor 20 and the temperature sensor 18 be separated by 50 mm or more.

In the above embodiment, the sensor mounting bracket 4
2 is a unit configuration that holds both the gas sensor 20 and the temperature sensor 18 so that replacement is easy. Further, since the gas sensor 20 and the temperature sensor 18 are separated by 65 mm, the temperature sensor 18 is not affected by the temperature of the gas sensor 20 heated by the heater. Furthermore,
Since the sensor mounting bracket 42 holds the gas sensor 20 and the temperature sensor 18 substantially parallel to the direction in which the probe pipe 14 is supported, unlike the arrangement example shown in FIG. Even if they are spaced apart, the width of the sensor device 10 does not increase.

Further, since the temperature sensor 18 is held inside the cylindrical sensor mounting bracket 42, when the sensor unit 12 is mounted, the temperature sensor 18 comes into contact with other members and receives a mechanical shock. There is no. Further, even in a high temperature and high humidity such as a boiler, or a highly corrosive gas including a sulfurous acid gas, the gas is not exposed to an external atmosphere.
No failure occurs in the temperature sensor 18 due to corrosion.

In this embodiment, the gas sensor 20 for simultaneously measuring the oxygen concentration and the humidity is exemplified. However, the present invention can be applied to a sensor for detecting only the gas concentration or only the humidity. Further, in this example, the case where the oxygen concentration is measured by the gas sensor 20 of the fixed electrolyte is described as an example, but the present configuration can be applied to the case where the concentration of NOx, SOx, and the like is measured. Further, in this example, the gas sensor of the fixed electrolyte is used, but the configuration of the present embodiment can be applied to a sensor of a semiconductor type using a metal oxide, for example, as long as the sensor includes a heater.

Further, in this embodiment, the temperature sensor 18 is housed in the sensor mounting bracket 42, but it is also possible to mount the temperature sensor 18 outside. For example, as shown in FIG. 4, the temperature sensor 18 attached upward from the temperature sensor pedestal 46 can be attached to the outside by pointing downward from the temperature sensor pedestal 46. Further, in this embodiment, the metal sensor mounting bracket 42 holds the gas sensor 20 and the temperature sensor 30 via the ceramic gas sensor pedestal 40 and the temperature sensor pedestal 46, but the sensor mounting bracket 42 is made of ceramic. Thus, the gas sensor 20 and the temperature sensor 30 can be directly held.

[0029]

As described above, according to the first aspect of the present invention, since the holding member integrally holds the measuring element and the temperature detecting element in a unit system, replacement is easy. Further, since the measuring element and the temperature detecting element are separated by a predetermined distance, the temperature detecting element is not affected by the temperature of the measuring element heated by the heater. Further, since the holding member holds the measuring element and the temperature detecting element substantially parallel to the supporting direction of the supporting member, the width of the sensor device is widened even if the measuring element and the temperature detecting element are arranged apart from each other. Nothing.

According to the second aspect of the present invention, since the measuring element and the temperature detecting element are separated from each other by 50 mm or more, the value received by the temperature detecting element as an effect of the temperature of the measuring element heated by the heater is 1 ° C. or less. Becomes For this reason, since the temperature detecting element can accurately measure the ambient temperature, it is possible to appropriately correct the detection value of the measuring element based on the ambient temperature measured by the temperature detecting element.

According to the third aspect of the present invention, since the cylindrical holding member holds the temperature detecting element inside and is not exposed to the outside atmosphere, the temperature detecting element is unlikely to fail.
Further, at the time of mounting, the temperature detecting element does not come into contact with other members or the like.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a sensor device of the present embodiment with a part cut away.

FIG. 2 is an explanatory diagram showing a cycle C in FIG. 1 in an enlarged manner.

FIG. 3 is a side view of the sensor unit of the embodiment.

FIG. 4 is a longitudinal sectional view of the sensor unit shown in FIG.

FIG. 5A is a perspective view of a gas sensor according to the present embodiment, and FIG. 5B is a cross-sectional view taken along the line AA of FIG. 5A.

FIG. 6 is a graph showing a relationship between a distance from a gas sensor to a temperature sensor and a temperature difference.

FIG. 7A is a cross-sectional view illustrating a sensor according to the related art, and FIG. 7B is a cross-sectional view illustrating a configuration example of a sensor device.

[Explanation of symbols]

 Reference Signs List 10 sensor device 12 sensor unit 14 probe pipe (supporting member) 20 gas sensor (measuring element) 30 temperature sensor (temperature measuring element) 40 gas sensor pedestal 42 sensor mounting bracket (holding member) 46 temperature sensor pedestal 48 lead wire

Claims (3)

[Claims] A measuring element for measuring at least one of a gas concentration and a humidity having a built-in heater for heating; a temperature detecting element for correcting the temperature of the measuring element; and the measuring element and the temperature detecting element. A sensor device comprising: a holding member for holding; and a supporting member that extends and supports the holding member in an atmosphere to be measured, wherein the holding member includes the measurement element and the temperature detection element, It is almost parallel to the support direction by the support member,
And a sensor device which is held at a predetermined distance. 2. The apparatus according to claim 1, wherein a distance between the measuring element and the temperature detecting element is 50 mm or more.
The sensor device according to claim 1. 3. The sensor device according to claim 1, wherein the holding member is formed in a cylindrical shape, and holds the temperature detecting element inside.