JPS6157527B2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a combustion control device.

In recent years, there has been a rapid increase in the number of combustion devices that supply air from outside, exhaust air outside, and supply fuel with a pump. Due to changes in temperature, etc., stable combustion conditions cannot always be maintained.

In particular, when the supply air temperature is low, the oxygen concentration per unit volume is high and the combustion flame of the burner becomes a lifting flame, causing uneven combustion. Conversely, when the supply air temperature is high, the oxygen concentration per unit volume is low and the combustion flame becomes red. It becomes a fire and incomplete combustion occurs. Therefore, compensation based on the supply air temperature is required.

The present invention has been made in view of the above points, and is composed of an O ₂ sensor, a supply air temperature sensor, and a storage/arithmetic device, and the computing device has the O 2 _2. The range of the electromotive force of the sensor is memorized and set, and the memorized range corresponding to the detected temperature from the supply air temperature sensor is set.
A storage/arithmetic device compares and calculates whether the electromotive force detected by the O ₂ sensor is within the range of the electromotive force of the O ₂ sensor, and controls the combustion supply device based on the result. .

To explain the present invention with reference to the drawings, the combustion apparatus main body 1 includes a burner section 2, a combustion chamber 3, a heat exchanger 4, and an indoor air circulation fan 6 rotated by a motor 5.
A burner motor 9 which pivotally supports a fan 8 that supplies combustion air from an air supply pipe 7 is built into the burner section 2, and a fuel pipe 1 is connected to the burner motor 9.
Rotating body 11 that sprays fuel from 0, burner 1
2. A burner head 13 etc. are provided.

Furthermore, a supply air temperature sensor 14 is installed at a suitable location on the supply air pipe 7.
However, an O ₂ sensor 15 is fixed to the peripheral wall of the combustion chamber 3 with its tip protruding into the combustion chamber 3, and the fuel path to the fuel pipe 10 is connected to a fuel tank (not shown) installed outside the main body 1. It is supplied via a leveler 16 and a pump 17.

Reference numeral 18 denotes a control box that houses electronic components and the like.

Air supply pipe 7 and heat exchanger 4 guided to burner section 2
The exhaust pipe 19 led from the inside is integrated at its end and passes through the wall 20 to form an air supply/exhaust top 21 having a double pipe structure with its tip facing outdoors.

FIG. 2 is a detailed diagram of the O ₂ sensor 15, which uses ZrO ₂ -cao or ZrO ₂ -Y ₂ O ₃ ceramics as the electrolyte, and stabilized zirconia 24 with platinum films 22 and 23 on the inner and outer surfaces is made of graphite. A fixing fitting 26 is further housed in the outer cylinder 27 via a sealing material 25, and an electrode 31 is insulated from the outer cylinder 27 by an insulator 30 via a conductor 28 and a pressing spring 29.
is arranged. 32 is a lead wire, 33 is an insulating cover, and 34 is a protective cylinder having an appropriate number of through holes, and the conductive electrode 28 is hollow so that the atmosphere can circulate inside the stabilized zirconia 24.

Figure 3 shows the electromotive force vs. excess air ratio characteristic of the O ₂ sensor 15. For example, a good combustion state is achieved when the excess air ratio is in the range of 1.26 to 1.65 (4.5% to 8.7% in terms of O ₂ concentration in exhaust gas). For example, the electromotive force of the O ₂ sensor corresponding to this may remain at 10 to 100 mV.

Figure 4 shows the combustion characteristics of the burner that are related to the electromotive force of the O ₂ sensor and the supply air temperature.The most suitable fuel consumption is 4000Kcal/h, which is shown by curve A, and the burner has an optimal combustion allowable range. If it is between 4300Kcal/h and 3700Kcal/h shown by curves B and C, the electromotive force is 10mV according to Figure 3.
From the range of ~100mV, for example, supply air temperature -10℃~50
The range of supply air temperature corresponding to the excess air ratio is determined, such as °C.

FIG. 5 shows an example of an electric circuit, in which an AC power source 35 is connected to a DC constant voltage circuit 3 via a switch 36.
7. A series circuit between the fan motor 5 and the delay thermostat 39 via the room thermostat 38, a series circuit between the heater 40 and the heater thermostat 41, a series circuit between the burner motor control circuit 42 and the burner motor 9, an ignition control circuit 43 and the igniter 44 A series circuit between the pump control circuit 45 and the pump 17, a series circuit between the alarm switch 46 and the alarm 47 consisting of a buzzer, and a series circuit between the pump control circuit 45 and the pump 17 are connected in parallel, respectively. A signal from the flame detection circuit 48 is given to a storage/arithmetic unit 49, a burner motor control circuit 42, and a pump control circuit 45, and is sent to the supply air temperature sensor 1.
4 and the O ₂ sensor 15 are applied to a pump control circuit 45 and an alarm switch 46 via a storage/arithmetic unit 49.

If the supply air temperature is low, the oxygen concentration per unit volume will be high and the combustion flame of the burner will become a lifting flame, causing uneven combustion. Conversely, if the supply air temperature is high, the oxygen concentration per unit volume will be low and the combustion flame will turn red. Since this will result in fire and incomplete combustion, the memory/arithmetic unit 49 is made to store and set the range of the electromotive force of the O ₂ sensor 15 that corresponds to the stable combustion range between the lifting flame state and the red fire state. put. That is, the memorized range is as shown in Fig. 4. For example, when the supply air temperature is 20°C, the electromotive force of the O ₂ sensor 15 is
It is 35-60mV.

The present invention is constructed as described above, and the switch 3
6 is closed, the burner 12 is turned on by the heater 40.
When the burner 12 is heated and the temperature of the burner 12 exceeds a certain value, the burner motor 9, the igniter 44, and the pump 17 are activated to ignite the flame, and when the flame detection circuit 48 detects a flame, the burner motor 9 and the pump 17 are activated.
continues to operate to continue combustion, and when the combustion chamber 3 reaches a certain temperature or higher, the fan motor 5 is operated and hot air is supplied into the room.

In this case, the combustion air exchanges heat with the exhaust gas in the supply/exhaust top 21 and gradually begins to rise in temperature, but it is assumed that the outside air temperature will rise sufficiently above -10°C as shown in Fig. 4 as a result of heat exchange ( For example, after 5 minutes have elapsed, the memory/arithmetic device 49 starts operating in response to a signal from the flame detection device 48.

The signal detected by the supply air temperature sensor 14 is input to the storage/arithmetic unit 49. For example, if it is 20°C, the range of the electromotive force of the O ₂ sensor 15 is 35mV to 35mV as shown in a in FIG. 4. It is confirmed that the voltage is 60mV.

The O ₂ sensor 15 installed in the combustion chamber 3
The stabilized zirconia 24 senses the oxygen concentration PO ₂ in the room and the oxygen concentration PO ₂ ′ in the room led into the stabilized zirconia 24 through the electrode 31 and the conductor 28, and controls the movement of oxygen ions. The electromotive force thus generated is output from the electrode 31, but the O ₂ sensor 15
and the range 35mV to 60m shown above.
It is compared with V in the storage/arithmetic unit 49, and if it is within that range, combustion continues with the fuel amount unchanged.
If it is not within that range, a signal is sent to the pump control device 45 to bring it within that range, and the pump 17
is controlled.

That is, if the electromotive force detected by the O ₂ sensor 15 is lower than the above range, the discharge amount of the pump 17 is increased to increase the electromotive force, and conversely, if it is higher, the discharge amount of the pump 17 is decreased to reduce the electromotive force. Stable combustion is performed within the range.

Once the memory/arithmetic unit 49 is activated, the supply air temperature detected by the supply air temperature sensor 14 is -10°C to 50°C.
If it is out of the range, a signal is sent from the storage/arithmetic unit 49 to the alarm switch 46, and the alarm 47 is activated.

It can be assumed that such a situation occurs due to the blockage of the air supply route or the exhaust route, but the alarm 47
In addition to activating the burner and asking the user to inspect the device, the combustion may be stopped along with a lamp display to prompt the user to inspect the device.

As described above, according to the present invention, the memory/arithmetic device has a memory that corresponds to the stable combustion range at the supply air temperature.
A range of electromotive force of the O ₂ sensor is set, and the storage/arithmetic unit compares whether the electromotive force detected by the O ₂ sensor is within the set range corresponding to the temperature detected by the supply air temperature sensor. By calculating and controlling the combustion supply device based on the result, stable combustion can be performed even if the supply air temperature changes.

Furthermore, an alarm or combustion stop can be issued even in combustion at conditions other than a good excess air ratio.

In addition, the combustion characteristics related to the electromotive force of the O ₂ sensor and the supply air temperature should be determined as appropriate depending on the shape of the burner, the existence and degree of heat exchange between the supply air and exhaust air at the top of the supply and exhaust, etc. Therefore, the optimum range of supply air temperature corresponding to the excess air ratio is -10℃.
It is not limited to ~50°C.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of the present invention, Fig. 2 is a sectional view of the O ₂ sensor, Fig. 3 is a characteristic diagram showing the relationship between the electromotive force generated by the O ₂ sensor and the excess air ratio, and Fig. 4 is the O ₂ sensor. FIG. 5 is an electric circuit diagram showing one embodiment of the combustion characteristic diagram, which is related to the electromotive force and the supply air temperature. 14... Supply air temperature sensor, 15... O ₂ sensor, 49... Memory calculation device.

Claims (1)

[Claims] 1 O ₂ sensor installed in the combustion exhaust gas passage,
A supply air temperature sensor provided in the supply air passage and the O ₂ temperature sensor that corresponds to the stable combustion range at the supply air temperature.
Is the electromotive force range of the sensor set, and is the electromotive force detected by the O ₂ sensor within the set electromotive force range of the O ₂ sensor that corresponds to the detected temperature from the supply air temperature sensor? A combustion control device comprising a storage and calculation device that performs a comparison calculation to determine whether or not the fuel is present and controls the fuel supply device based on the result.