JPS60236059A - Sensor for combustion safety device - Google Patents

Abstract

PURPOSE:To detect stably the quantity of oxygen by providing a pair of detecting parts for detecting the quantity of oxygen in a burner combustion flame, and the quantity of oxygen of a position separated from the combustion flame, on a plate-shaped sintered body of an oxygen ion conductive solid electrolyte. CONSTITUTION:A combustion safety device use sensor 7 is constituted by forming a pair of electrodes 3, 4 on the surface of one side of a plate-shaped sintered body 5 of zirconia stabilized by yttria, and providing a protective film on its surface. This sensor 7 is placed on a burner 9 in a combustion chamber, a detecting part 4a goes into a combustion flame 6, a detecting part 3a is separated from the combustion flame 6 and installed, and an electromotive force based on an oxygen partial pressure between both the detecting parts is measured. At the normal combustion time when the oxygen density is >=20%, a high electromotive force is shown, but when the oxygen density in the chamber drops, the electromotive force drops, and it drops suddenly when the oxygen density becomes about 18%, and an incomplete combustion can be detected.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to improvements in sensors for combustion safety devices in combustion equipment.

(Prior art) For example, a combustion safety device sensor (hereinafter referred to as a sensor) that detects when combustion stops due to flame extinguishment or incomplete combustion occurs due to lack of oxygen in household combustion equipment and activates a safety device. ) as shown in Figure 4 (al(b
)K Heat-resistant electrodes (hereinafter referred to as electrodes) 2a, 2 are placed on both surfaces of a plate-shaped sintered body 5 of an oxygen ion conductive solid electrolyte as shown in FIG.
There is a sensor 1 formed with b. This sensor generates an electromotive force E based on the well-known Nernst equation due to the difference in oxygen partial pressure between the two electrodes through the partition wall of the oxygen ion conductive solid electrolyte.
occurs. In other words, the starting force is E-(RT/4F)l
It is expressed by the formula n(PI/P2). Here, R is a gas constant, F is a Faraday constant I Pl+ P2 is an oxygen partial pressure at each electrode, and T is a supply temperature of the detection section.

When the sensor 1 is installed in the burner 9 as shown in Fig. 5, the electrode 2a as shown in Fig. 5(a) under normal conditions
is in contact with the atmosphere, and one electrode 2b is in contact with the combustion flame 6, so that the difference in oxygen partial pressure between the two electrodes becomes large, and a high electromotive force is generated. In addition, in the event of oxygen deficiency, as shown in Fig. 5 tb+, the mixture 8 of unburned gas and primary air produced by extension of the combustion flame comes into contact with the electrode 2b, resulting in a difference in oxygen partial pressure between the two electrodes. becomes smaller and the electromotive force decreases. In the same figure, 6a has internal inflammation, 6b Fi, and external inflammation. Incomplete combustion was detected using such changes in electromotive force. However, the combustion flame fluctuates due to wind etc., and the combustion flame 6 is on the electrode 2a side K.
Because of this, the combustion flame 6 may come into contact with the electrode 2a, resulting in a decrease in electromotive force, making it impossible to obtain a stable electromotive force, and frequently causing malfunctions. In FIG. 5, 11 is a lead wire for connection to an external meter.

(Object of the Invention) An object of the present invention is to provide a sensor for a combustion safety device that solves the above-mentioned problems.

(Means for Solving the Problem) As a result of various studies regarding the above-mentioned drawbacks, the present inventors have found that a
We investigated a combustion safety device sensor that has electrodes with more than one pair of detection parts.

It was confirmed that incomplete combustion due to lack of oxygen, flame extinction, etc. can be detected without malfunction.

The present invention provides at least one pair of oxygen ion conductive solid electrolyte plate-shaped sintered bodies, each of which is provided with at least one pair on the same side surface, one of which is located within the combustion flame of a burner and the other located at a position away from the combustion flame. The present invention relates to a sensor for a combustion safety device formed with a heat-resistant electrode having a detection portion.

In the present invention, the beam plate-shaped sintered body (hereinafter referred to as plate-shaped sintered body) of the oxygen ion conductive solid electrolyte is made of zirconia stabilized with ittria, calcia, magnesia, ceria, strontia, etc.

Doria or the like is used to form the material into a temporary shape and sinter it.

The electrodes are made of platinum, rhodium, palladium, or an alloy thereof, and are made into a paste and applied to the surface of the plate-shaped sintered body by a printing method or the like and baked. A pair of detection parts, which are part of the electrodes, are provided on at least the same side surface of the plate-shaped sintered body.

One of the pair of detection parts is provided so that it enters the combustion flame of the burner, and the other one is provided at a position away from the combustion flame. For example, in FIG. 2, the detection parts 4a, 3a for the combustion flame 6 are
Set it up like this. The size, shape and position of the detection part depend on the fuel and burner used.

The selection is made after considering the performance of the combustion equipment, and there are no particular restrictions.

The detection units may be provided in one pair on one side of the plate-shaped sintered body and in two pairs on the other side.

Further, as shown in FIG. 2(b), it is preferable to provide a spacer 10 made of a heat-resistant material between the detection parts 4a and 3a to prevent the combustion flame from penetrating. Furthermore, it is preferable to provide a protective film formed by spraying zirconia powder or the like on the electrode surface, since this improves the corrosion resistance of the electrode.

(Function) When the sensor is configured as described above, during normal combustion, the detection part 3a comes into contact with the atmosphere, and the detection part 4a comes into contact with the combustion flame, so the difference in oxygen partial pressure between the detection parts of one car becomes large. High electromotive force is generated. On the other hand, when there is a lack of oxygen, combustion flames attack the detection part 4.
Since a comes into contact with the mixture of unburned gas and primary air, the difference in oxygen partial pressure between both detection parts becomes smaller and the electromotive force decreases.
Detects incomplete combustion. Conventional sensors utilize the conduction of oxygen ions through the partition wall of the oxygen ion conductive solid electrolyte, but the sensor of the present invention utilizes the conduction of oxygen ions near the surface of the oxygen ion conductive solid electrolyte. Ruru.

(Example) Next, embodiments will be described with reference to the drawings.

Embodiment 1 5- Fig. 1 shows a sensor 7 for a combustion safety device according to an embodiment of the present invention. is a plate-shaped sintered body made by molding and sintering Intoria-stabilized zirconia into a size of 6 x 50 mm + 0.8 mm in thickness. Platinum paste is applied to one surface of the plate using a printing method and then baked to form a pair of electrodes 3. .4, and a protective film (not shown) was formed on the surface by spraying zirconia powder. 3a.

Reference numeral 4a denotes a pair of detection parts provided in the longitudinal direction from the left end of the plate-shaped sintered body 5.

Next, as shown in FIG. 2(a)K, the detection part 4a of this sensor 7 is placed above the burner 9 in the combustion chamber and enters the combustion flame 6.
After the detection unit 3a is installed away from the combustion flame 6 and connected to an external instrument via a lead wire 11.

When the oxygen concentration in the room was changed and the resulting electromotive force was measured, as shown in Figure 3, during normal combustion when the oxygen concentration was 20% or more, a high electromotive force of 0.8 V or more was observed, indicating a decrease in the oxygen concentration in the room. At the same time, the electromotive force decreased and the oxygen concentration suddenly decreased to around 18%, making it possible to detect incomplete combustion.

6- Example 2 The sensor of Example 1 was made of alumina with a dogleg-shaped cross section and a thickness of 1 mm, which blocked the detection parts 3a and 4a and provided a window through which the sensor 7 could pass, as shown in FIG. A similar diaphragm 10 was attached and the same test as in Example 1 was conducted, and the relationship between the oxygen concentration in the room and the electromotive force was almost the same as that shown in FIG. 3, and incomplete combustion could be detected.

(Effects of the Invention) According to the present invention, since one of the detection parts is provided in the combustion flame and the other part is provided in a position away from the combustion flame, malfunctions are eliminated and the electromotive force according to the amount of oxygen is stabilized. It can be obtained by Furthermore, if the sensor deteriorates or is damaged, the electromotive force will decrease, so abnormalities in the sensor can be detected without relying on other sensors. Furthermore, if the Kim electrode is provided only on one side of the plate-shaped sintered body, the process can be shortened.

[Brief explanation of drawings]

FIG. 1 is a sensor for a combustion safety device according to an embodiment of the present invention, fa) is a plan view, and (b) is a sectional view taken along line A-A of fa). Figure 2 is a schematic diagram showing how the combustion safety device sensor shown in Figure 1 is used, and Figure 3 shows the relationship between oxygen concentration and electromotive force when the combustion safety sensor of the present invention is fully used [7]. graph,
Fig. 4 shows a conventional combustion safety sensor (a top view, (b) is a side view, and Fig. 5 is a schematic diagram showing how the sensor for combustion safety device shown in Fig. 4 is used. Description 1...Sensor 2a, 2b...Electrode 3.4...Electrode 3a, 4a...Detection part 5...Plate-shaped sintered body 6...
- Combustion flame 6a...Inner flame 6b...Outer flame 7...Sensor 8...Mixture 9...Burner 10...Partition plate-34:

Claims (1)

[Claims] 1. At least one pair of detectors provided on a plate-shaped sintered body of an oxygen ion conductive solid electrolyte such that one side of the same side surface is located in the combustion flame of the burner and the other one is located at a position away from the combustion flame. A sensor for a combustion safety device comprising a heat-resistant electrode having a heat-resistant electrode.