JPH065621Y2 - Incomplete combustion detection sensor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to an incomplete combustion detection sensor capable of detecting an incomplete combustion state in combustion equipment.

(Prior Art) Conventionally, carbon monoxide, hydrogen monoxide, and other gas detectors such as an infrared type and a catalytic combustion type have been known, but they are large and expensive. Therefore, its use was limited to large combustion equipment.

(Problems to be solved by the invention) However, since such an unburned gas detector cannot be used in a small combustion facility, oxygen concentration is supplied at a high level to prevent generation of unburned gas. Therefore, developing an inexpensive unburned gas detector to improve combustion efficiency has been an important issue to be solved.

The present invention has been made in view of the above points, and an object thereof is to effectively solve the problems of the prior art, to provide an incomplete combustion detection sensor having a simple configuration, a small size, and easy handling.

(Means for Solving Problems) In order to achieve such an object, the present invention provides a stabilized zirconia, which is an oxygen ion conductive solid electrolyte, and two stabilized zirconia provided on both sides of the stabilized zirconia. A sensor having an electrode and a lid that covers one of the electrodes and is provided with a minute diffusion hole, and the sensor current generated in a predetermined region of the voltage applied between the electrodes is proportional to the oxygen concentration around the electrodes. And a sensor having a power supply circuit for applying a voltage of 1.3 V or more between the electrodes, the output current value of the sensor according to the voltage application of 1.3 V or more between the electrodes A comparator circuit is provided to compare with the set value set based on the limiting current value corresponding to the concentration, and when the output current value of the sensor exceeds the above set value, the presence of carbon monoxide is detected and incomplete. To detect combustion It was done by.

(Example) Next, the Example of this invention is described in detail based on drawing.

FIG. 1 shows a schematic configuration diagram of an embodiment of the present invention. In the figure, the incomplete combustion detection sensor 1 is mainly composed of a zirconia sensor section (zirconia element) 2 and an electronic circuit section 3. Of these, the zirconia sensor section 2 is composed of a stabilized zirconia 4, an electrode 5, a lid 6, a minute diffusion hole 7 and a heater 8.

Further, the electronic circuit section 3 includes a heater power supply 9 and an electrode power supply 1
0, a sensor detection resistor 11, an output circuit 12, and a comparison circuit 13.

By the way, the stabilized zirconia 4 is yttria (Y ₂ O
₃ ) or calcia (CaO) -stabilized zirconia ceramics, when heated to a high temperature of about 350 ° C. to 900 ° C. by the heater 8, only oxygen ions become a movable solid electrolyte. A catalytic electrode 5 made of platinum or the like is baked on both surfaces of the stabilized zirconia 4, and an electrode voltage capable of converting oxygen in contact with the electrode 5 into O ²⁻ ions is applied. One of the electrodes 5 and 5 is covered with a lid 6 having a minute diffusion hole 7, and even if there is no difference in oxygen concentration between the electrodes 5 and 5, a current (using oxygen ions as carriers by the pumping action ( (Sensor current) flows, and oxygen molecules in the lid 6 are discharged. This amount of discharge increases with the applied voltage. Oxygen in the lid 6 is replenished by diffusion through the minute diffusion holes 7, but the inflow of oxygen is restricted because the diffusion holes 7 are minute holes. Therefore, this sensor current is proportional to the oxygen concentration around the zirconia sensor section 2.

At this time, when carbon monoxide generated in the incomplete combustion atmosphere (reducing atmosphere) is present together with residual oxygen, the carbon monoxide burns due to the catalytic action of the electrode 5. This combustion contributes to an increase in the carbon monoxide sensor current, and this sensor current increases with increasing electrode voltage.

Next, FIG. 2 shows a relationship diagram between the sensor current and the electrode voltage in an incomplete combustion atmosphere. In the figure, the zirconia sensor unit 2 shown in FIG. 1 is used for the gas composition of an incomplete combustion atmosphere, for example, carbon monoxide (CO) 3.5%, oxygen (O ₂ ).
When installed in 0.2% residual nitrogen (N ₂ ), the sensor current in this atmosphere is abruptly over a certain range of electrode voltage, that is, about 1.3 to 1.4 V (DC) or more. It shows that it increases.

Next, FIG. 3 shows a comparison diagram of the sensor current due to the residual CO concentration and oxygen in the atmosphere. In the figure, when CO starts to remain in the atmosphere by applying an electrode voltage of about 1.3 to 1.4 V (DC) or more to the electrode power source 10, the sensor current B due to oxygen in the oxidizing atmosphere B A much larger sensor current A is suddenly generated as compared with Therefore, the sensor current A due to this residual CO is
As an output signal a through the output circuit 12 of the electronic circuit section 3 or as an atmospheric oxygen concentration of the comparison circuit 13 (20% by volume)
It is possible to detect the occurrence of the incomplete combustion state by comparing with the comparison value set based on the limiting current value corresponding to the above and determining and transmitting as the output signal b.

(Effect of the Invention) As described above, according to the present invention, the sensor current due to residual carbon monoxide generated in a predetermined region of the voltage applied between the electrodes of the zirconia sensor unit corresponds to the oxygen concentration in the atmosphere. The presence of carbon monoxide is detected when the set value exceeds the set value set based on the limiting current value, and the incomplete combustion is detected. It is possible to detect the incomplete combustion state in the equipment, the structure is simple, the size is small, the handling is easy, and it is particularly suitable for use in a small combustion equipment.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an embodiment of the present invention, FIG. 2 is a relational diagram of electrode voltage and sensor current in an incomplete combustion atmosphere,
FIG. 3 is a comparative diagram of the sensor current depending on the residual CO concentration and oxygen. 1: Incomplete combustion detection sensor, 2: Zirconia sensor part,
3: electronic circuit part, 4: stabilized zirconia, 5: electrode,
6: lid, 7: minute diffusion hole, 10: power supply for electrode, 12: output circuit, 13: comparison circuit, A: sensor current by CO,
B: Sensor current due to oxygen.

Continued Front Page (72) Inventor Masahiko Masuda 1-1 Tanabe Nitta, Kawasaki-ku, Kawasaki-shi, Kanagawa Fuji Electric Co., Ltd. (56) References JP-A-58-61455 (JP, A) JP-A-59- 217151 (JP, A) JP-A-60-91251 (JP, A)

Claims (1)

[Scope of utility model registration request] 1. Stabilized zirconia, which is an oxygen ion conductive solid electrolyte, two electrodes provided on both sides of the stabilized zirconia, and one of these electrodes is covered with a minute diffusion hole. A sensor having a lid, in which a sensor current generated in a predetermined region of a voltage applied between the electrodes is proportional to an oxygen concentration around the electrodes, and a voltage of 1.3 V or more is applied between the electrodes. In the power supply circuit having the above-mentioned power supply circuit, the output current value of the sensor according to the voltage application between the electrodes of 1.3 V or more is compared with the set value set based on the limiting current value corresponding to the oxygen concentration in the atmosphere. An incomplete combustion detection sensor comprising a comparison circuit that detects the presence of carbon monoxide when the output current value exceeds the set value and sends an output signal.