JPS6234134Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a combustion appliance that detects the combustion state using an oxygen concentration battery type sensor.

Configuration of conventional example and its problems It has been known to detect the combustion state of the burner using an oxygen concentration battery type sensor, but as shown in Figure 1, an oxygen concentration battery type sensor is used for burner A. If a device with sensor B attached is enclosed in outer case C, combustion exhaust gas from burner A will leak into outer case C, which will change the oxygen partial pressure at inner electrode _B1 of sensor B, causing the sensor output to become unstable and malfunction. may occur. That is, the output generated from sensor B is the inner electrode B ₁ and the outer electrode B ₂ on the exhaust gas side of burner A.
An electromotive force is generated due to the difference in oxygen concentration between the inner electrode B1 and the outer case C. However, as mentioned earlier, exhaust gas leaks into the outer case C and the oxygen partial pressure at the inner electrode _B1 becomes unstable, making the sensor output unstable. In addition, since the terminals for taking out the inner electrode B ₁ and outer electrode B ₂ of sensor B are brazed or soldered, the sensor terminals are quite limited in heat resistance, and in order to insulate the terminals, insulation packing is required. It was necessary to adopt a complicated configuration such as providing D.

Purpose of the invention The present invention was made in view of the above-mentioned problems, and is intended to stably obtain the output of an oxygen concentration battery type sensor and to lower the temperature of the terminal portion.

Structure of the invention In order to achieve the above object, the present invention has a structure in which air from a convection fan for indoor air circulation flows through the terminal part of an oxygen concentration battery type sensor, and one electrode surface of the sensor is connected to the exhaust gas passage of the burner, and the other is connected to the exhaust gas passage of the burner. are located on the air passage side of the convection fan.

Therefore, it is possible to stabilize the oxygen partial pressure on the other electrode surface of the sensor and to lower the temperature of the terminal portion of the sensor.

DESCRIPTION OF EMBODIMENTS One embodiment will be described below based on the drawings.
In FIG. 2, numeral 1 denotes a vaporizing cylinder, into which a preheater 2 is cast. 3 is a heating detection thermistor that detects the preheating temperature of the vaporizer cylinder 1. 4 is a burner head provided with a plurality of flame holes 5; a combustion tube 7 is provided on the outer periphery thereof so as to have a combustion exhaust gas passage 6; upper end openings of the burner head 4 and the combustion tube 7 are closed with a burner cap 8; ing. Reference numeral 9 denotes an oxygen concentration cell type sensor, which is mainly made of zirconia and formed into a hollow cylindrical shape.The outer and inner surfaces of the cylinder are each coated with platinum electrodes, and the outer surface electrode (also referred to as one electrode surface) 9a and the inner surface of the cylinder are coated with platinum electrodes. The outer electrode 9a having an inner surface electrode (also referred to as the other electrode surface) 9b is located in the combustion exhaust gas passage 6, and the tip 10 of the inner surface electrode 9b is sealed and the opening 11 at the other end is open to the atmosphere. . 12 is an exhaust pipe provided with an exhaust port 13. Reference numeral 14 denotes a combustion blower, which communicates with the vaporization cylinder via a blow pipe 15. Reference numeral 16 denotes an oil pump that sends fuel from the combustion tank 17 to the carburetor 1 through an oil pipe 18. Reference numeral 19 denotes a convection fan for circulating indoor air, which sucks indoor air from the suction port 21 of the main body case 20 and blows it out to the blowout port 22. This convection fan 19 includes the outer surface electrode 9a of the sensor 9, the extraction terminal portion of the inner surface electrode 9b, and the opening 11 of the inner surface electrode.
It is located in a position that blows indoor air towards the room. 23 indicates an igniter, and 24 indicates a stand for the main body case.

Next, the control circuit configuration of this embodiment will be explained with reference to the block diagram of FIG. 25 is an operation switch, 26 is a combustion circuit, and includes a preheater 2 and an igniter 2 shown in FIG.
3, includes an oil pump 16, a combustion blower 14, and a convection fan 19. 27 is a stabilized power supply circuit, which includes a sensor circuit 28, an ignition detection circuit 29, a timer circuit 30,
A stabilized DC power source is supplied to the combustion detection circuit 31 and the preheating heater control circuit 32. As shown in FIG. 4, the sensor circuit 28 is connected in series with the sensor 9 to a DC stabilized power source 27 via a resistor 33. Then output signals are output from output terminals a and b of the sensor,
A signal is sent to the ignition detection circuit 29 and the combustion detection circuit 31. The ignition detection circuit 29 detects the ignition signal from the sensor circuit 28 and cuts off the energization to the igniter 23 of the combustion circuit 26 or energizes the convection fan 19. The timer circuit 30 operates the combustion detection circuit 31 after a certain period of time after receiving the ignition signal from the ignition detection circuit 29. The combustion detection circuit 31 detects the output level of the sensor circuit 28 during combustion, and if there is an abnormal signal, stops the operation via the combustion circuit 26. Further, the preheating heater control circuit 32 controls the temperature of the vaporizing cylinder 1 using the heating detection thermistor 3 shown in FIG. 2, and sends a signal to operate the oil feed pump 16 of the combustion circuit 26 at the same time as preheating is completed.

Next, the operation of this embodiment will be explained with reference to the vaporization cylinder temperature increase graph in FIG. 5, the sensor output graph in FIG. 6, and the sequence time chart in FIG. 7.
When the operation switch 25 is turned on, the preheater 2 is turned on and the igniter 23 is heated to red. Preheating heater 2
The temperature of the vaporization cylinder 1 rises as shown in FIG. 5 by energization, and when the temperature of the vaporization cylinder reaches a temperature x at which the fuel can be sufficiently vaporized, the oil feed pump 16 is operated by the heater preheating control circuit 32 to start combustion. The blower 14 is also operated and ignited by the igniter 23 to start combustion.
At the same time, the power supply to the preheater 2 is cut off. At this time, as shown in FIG. 4, the output voltage of the sensor 9 is approximately the same as that of the stabilized power supply 27 because the temperature of the sensor 9 is low before ignition, and the internal resistance Ri is approximately 100 megohms, which is a much larger value than the resistor 33. The same high value will be obtained. After ignition, the sensor 9 is heated, so the internal resistance Ri gradually decreases and the output voltage decreases as shown in FIG. When the value falls to a certain value Y, the ignition detection circuit 29 cuts off the energization of the igniter 23, and the convection fan 19 is operated to detect ignition.
After that, the temperature of the sensor 9 further increases and the internal resistance continues to decrease, and during this time the output voltage of the sensor 9 decreases. When the temperature of the sensor 9 becomes stable, the internal resistance Ri becomes stable at about several tens of ohms, and the output voltage also becomes stable. After ignition is detected, the combustion detection circuit 31 is activated after a predetermined period of time for the sensor output to stabilize, and the output voltage of the sensor 9 is determined to be below a certain value Z as shown in FIG. Combustion continues while being detected. At this time, the convection fan 19 always sends indoor air into the opening 11 of the inner surface electrode 9b of the sensor 9 as shown by the solid line arrow in FIG. 2, so the oxygen partial pressure of the inner surface electrode 9b is in a stable state and the sensor output is The electromotive force ei (shown in FIG. 4) caused by the difference between the oxygen partial pressure of the room air and the oxygen partial pressure of the combustion exhaust gas passage 6 can be completely detected. Further, the convection fan 19 cools the terminal portion of the sensor 9, thereby improving the life of the sensor. If combustion air becomes insufficient, the oxygen partial pressure in the combustion exhaust gas passage 6 will drop extremely, and the oxygen partial pressure difference with indoor air will increase, so the oxygen concentration battery type sensor 9 will generate an electromotive force ei. As shown in FIG. 6, when the sensor output increases and exceeds a certain value Z, the combustion detection circuit 31 is activated and the combustion circuit 26 is stopped, making it possible to detect abnormal combustion.

Effects of the invention As described above, in the present invention, the other of the pair of electrode surfaces of the oxygen concentration battery type sensor is located on the air passage side of the convection fan, which stabilizes the oxygen partial pressure on the other electrode surface and stabilizes the sensor output. The combustion state can be completely detected without malfunction. In addition, since the terminal portion of the sensor is cooled by a convection fan, the sensor can be installed in a simple manner without requiring a complicated insulation structure, and the life of the sensor can be extended, which has great effects.

[Brief explanation of the drawing]

Figure 1 is a sectional view of a conventional combustion appliance;
The figure is a sectional view of a combustion appliance showing an embodiment of the present invention.
Figure 3 is a block circuit diagram showing the control system of the present invention.
Fig. 4 is a sensor circuit diagram of the main part, Fig. 5 is a graph showing the temperature rise durability, Fig. 6 is a graph showing the output of the sensor, and Fig. 7 is a combustion appliance showing an embodiment of the present invention. It is a time chart diagram of a sequence. 4...Burner head, 9...Oxygen concentration sensor,
9a... External electrode, 9b... Inner electrode, 6... Exhaust gas passage, 19... Convection fan, 31... Combustion detection circuit, 11... Opening.

Claims (1)

[Scope of utility model registration request] A burner, an oxygen concentration battery type sensor having a pair of electrode surfaces that detects the combustion state of the burner and generates an electromotive force, a convection fan that circulates indoor air, and a combustion sensor that detects the output signal of the sensor. A combustion appliance in which a circuit is provided, and the sensor has an electrode lead-out terminal portion located in the air passage of the convection fan, and one electrode surface is located in the exhaust gas passage of the burner, and the other electrode surface is located on the air passage side. .