JP3012960B2 - Combustion equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combustion apparatus using a limiting current type oxygen sensor arranged in an exhaust gas passage to detect oxygen concentration, and more particularly to a combustion device using a limiting current type oxygen sensor that can detect oxygen concentration. The present invention relates to a combustion apparatus for shortening the warming time of warm air.

[0002]

2. Description of the Related Art A conventional combustion apparatus calculates a ratio between an air supply amount and a fuel supply amount (hereinafter referred to as an air-fuel ratio) in advance so as to obtain complete combustion, and calculates an air supply amount based on the calculation. And the fuel was supplied.
However, when the combustion equipment is used in various environments, the air-fuel ratio fluctuates from the initially calculated value due to fluctuations in the outside air temperature, fluctuations in the atmospheric pressure, and fluctuations in the durability of the fuel supply means and air supply means. If the air-fuel ratio is used as originally calculated on a flat ground at a high altitude in an oxygen-lean environment of meters, incomplete combustion may occur due to lack of oxygen.

As a means for solving this problem, focusing on the fact that the air-fuel ratio has a correlation with the oxygen concentration in the flue gas, a limiting current type oxygen sensor for measuring the oxygen concentration is used. Attempts have been made to develop combustion equipment that is arranged to control the air-fuel ratio optimally.

FIG. 24 shows a block diagram of such a conventional combustion device. In the figure, a fuel supply unit 1 for supplying fuel
And a flue gas 5 that discharges exhaust gas after combustion in a combustion unit 3 that is supplied with fuel and air from an air supply unit 2 that supplies air required for combustion and burns fuel mixed with air. Is provided with a limiting current type oxygen sensor 4. Here, the limiting current type oxygen sensor 4 has a heating element 6 in the vicinity of the sensor element, is enveloped by a heat insulating material 7, and is further encased by a gas permeable frame 8 to mount the sensor. It has a body configuration.

A device driving voltage source for applying a constant voltage to electrode films (not shown) formed on both surfaces of an oxygen ion conductive solid electrolyte (not shown) constituting the limiting current type oxygen sensor 4. 9 and element current detection means 10 for detecting the generated current are connected in series to form a closed circuit.
The control signal reading means 15 connected to both ends of the element current detecting means 10 is connected so as to control the fuel supply unit 1 and the air supply unit 2 based on the read result. A heating voltage source 11 for applying a voltage for heating is applied to the heating element 6 constituting the limiting current type oxygen sensor 4.
Is connected.

[0006] The operation is described below. First, the element driving voltage source 9 and the heating voltage source 11 are operated at a constant voltage value together with or before the combustion operation. Then, the oxygen ion conductive solid electrolyte of the limiting current type oxygen sensor 4 is heated by the heating element 6 to perform an oxygen pumping action, and oxygen molecules pass through the solid electrolyte as oxygen ions. The movement of oxygen molecules is gradually restricted by the oxygen diffusion path (not shown), so that the passage of oxygen ions is restricted, and accordingly, the generated current gradually decreases. Eventually, the action of limiting the movement of oxygen molecules by the oxygen diffusion path becomes stable, so that the generated current also becomes stable and exhibits a limiting current. As described above, it takes a considerable time for the sensor to exhibit the limiting current characteristic. Therefore, the sensor stabilization time is measured in advance, and after the stabilization time has elapsed, the current detected by the element current detection means 10 is read and used as a control signal.

As another conventional example, a voltage value of an element driving voltage source applied to an electrode film is linked to a current generated by an ion-conductive solid electrolyte body, and when the current value is large, the voltage of the element driving voltage source is increased. In some devices, the value is increased, and when the current value is small, the voltage value of the element driving voltage source is also reduced. Another conventional operating device measures the sensor characteristics by linking the voltage value of the element driving voltage source with the generated current in this manner. The detected current is read and used as a control signal.

[0008] However, in a combustion apparatus that performs air-fuel ratio control using the above-described conventional limiting current type oxygen sensor,
There is a problem with the warm-up warming time during which the limiting current type oxygen sensor can detect the oxygen concentration. For example, in the case of petroleum combustion equipment using kerosene as fuel, the principle is that kerosene is vaporized into kerosene vapor and a mixture of this kerosene vapor and air is burned. The temperature is raised to a temperature of 240 to 300 ° C., and the kerosene is vaporized on the vaporization surface of the combustion part to form kerosene vapor, which is then mixed with air and burned. Therefore, it takes several minutes to start the combustion, and it is necessary for the limiting current type oxygen sensor to be able to detect the oxygen concentration by the start time of the combustion.

In order to shorten the sensor stabilization time and start the measurement of the oxygen concentration in a short time, a method of lowering the voltage value applied to the heater to reduce the power consumption value of the heater, There is a method of reducing the applied voltage value to be applied. However, none of these methods is preferable from the viewpoint of the durability and responsiveness of the sensor, and there is a problem that the durability and responsiveness of the sensor are reduced. As described above, the ability to measure the oxygen concentration in a short time and the durability and responsiveness of the sensor are contradictory matters. That is, in order to improve the durability and responsiveness of the sensor, the voltage value applied to the heating element should be as high as possible within a range that does not cause cracking or the like of the sensor so as to have a high heater power consumption value. It is necessary to set the applied voltage value as high as possible within a range that does not cause electrolysis of water to a high applied voltage value, but from the viewpoint of giving priority to the ability to measure the oxygen concentration in a short time, the heating element A method of reducing the power consumption value by lowering the voltage value applied to the electrode, or a method of lowering the applied voltage value applied to the electrode film is adopted.

On the other hand, a method of increasing the voltage applied to the heating element only at the beginning of use and applying a normal voltage after a predetermined time has elapsed to shorten the stabilization time is also conceivable. However, the time when the combustion equipment starts burning varies widely, and this combustion start time takes a relatively long time when starting to use the combustion equipment, but when temporarily suspending use and restarting again, The time is short because the combustion part is warm. Therefore, in this method, when the combustion starts in a short time, a high voltage is applied to the heating element at the start of the combustion, and the sensor is heated more than necessary by receiving the heat of the combustion exhaust gas. There is a problem that the generated current is not stable and the oxygen concentration in the combustion exhaust gas cannot be easily measured accurately. Therefore, it is necessary to devise a method for operating the sensor in consideration of the combustion start time (usage form) of the combustion equipment. In the standardized sensor operation method as described above, although the combustion is started, the oxygen concentration is stabilized. There is a problem that an undetectable state occurs.

Furthermore, since the exhaust gas heat is received during combustion, if the power applied to the heating element is constant, the sensor temperature will be higher than in the atmosphere, and this increase in sensor temperature will cause a decrease in the durability of the sensor. . Therefore, after the start of combustion, it is necessary to take measures to prevent the sensor temperature from rising more than necessary, and there is a problem that the reliability of the sensor is reduced if the method of supplying voltage to the heating element is standardized.

[0012]

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned problems of the conventional combustion apparatus. In the present invention, a voltage applied to a heating element for heating a limiting current type oxygen sensor is controlled by various parts including a combustion part. A combustion device that stabilizes the limiting current type oxygen sensor in a short time by changing the temperature according to the magnitude of the temperature, accelerates the start of oxygen concentration detection, and does not reduce the durability and responsiveness of the limiting current type oxygen sensor The purpose is to provide.

[0013]

According to a first aspect of the present invention, there is provided a combustion apparatus, comprising: a fuel supply unit for supplying fuel; an air supply unit for supplying air; A combustion section for burning a mixed gas of fuel and air, a flue through which flue gas from the combustion section flows, and a heating element disposed in the flue and disposed in close proximity to the sensor element, are enclosed by a heat insulating material. A limiting current type oxygen sensor, a heating voltage source for applying a heating voltage to a heating element of the limiting current type oxygen sensor, a heating voltage changing means for changing a voltage applied to the heating voltage source, and a combustion unit disposed in the combustion unit. And a temperature detecting means for applying the temperature detection result to the heating voltage changing means. In addition to the structure of claim 1, the temperature of the sensor element is included in the limiting current type oxygen sensor. To detect heating voltage The temperature sensor according to claim 3 is provided in a closed circuit for connecting a heating element and a heating voltage source of the limiting current type oxygen sensor in addition to the structure of claim 1. And a heater current detecting means for supplying the detection result to the heating voltage changing means, and a fuel supply unit for supplying fuel, an air supply unit for supplying air, A combustion section that burns a gas mixture of air and air, a flue through which flue gas flows from the combustion section, and a heating element disposed in the flue and disposed in close proximity to the sensor element. A current-type oxygen sensor, a heating voltage source for applying a heating voltage to a heating element of the limiting current-type oxygen sensor, heating voltage changing means for changing a voltage applied to the heating voltage source, Heating voltage changing means based on temperature detection results And a temperature detecting means provided in the flue in which the flue gas from the combustion section flows, instead of the temperature detecting means in the structure of claim 4. And a flue gas temperature detecting means for providing the heating voltage changing means to the heating voltage changing means. As a structure corresponding to claim 6, the flue gas temperature detecting means is arranged in the combustion flame of the combustion part instead of the flue gas temperature detecting means in the structure of claim 5, It has an ion current detecting means for giving a detection result to the heating voltage changing means.

[0014]

According to the first aspect of the present invention, there is provided a combustion apparatus comprising:
The temperature detecting means detects the temperature of the combustion section, and if it is equal to or higher than a predetermined temperature value stored in advance, the heating voltage changing means operates the heating voltage source at a normal voltage value, and if the temperature is lower than the predetermined temperature value, In the initial stage of use, the heating voltage source is operated at a voltage value higher than the normal voltage value, and after a predetermined time stored in advance, the heating voltage source is lowered to the normal voltage value to operate.

Further, in the configuration of claim 2, the temperature detecting means detects the temperature of the combustion section, and if the temperature is equal to or higher than a predetermined temperature value stored in advance, the heating voltage changing means switches the heating voltage source to a normal voltage value. When the temperature is lower than the predetermined temperature value, the heating voltage source is operated at a voltage value higher than the normal voltage value in the initial stage of use, and the sensor temperature detected by the sensor temperature detection unit becomes higher than the predetermined sensor temperature stored in advance. If it does, it will be operated with the voltage lowered to the normal voltage value. Further, in the configuration of claim 3, the temperature detecting means detects the temperature of the combustion section, and if the temperature is equal to or higher than a predetermined temperature value stored in advance, the heating voltage changing means operates the heating voltage source at a normal voltage value. When the temperature is lower than the predetermined temperature value, the heating voltage source is operated at a voltage value higher than the normal voltage value in the initial stage of use, and the heater current value detected by the heater current detecting means becomes equal to or less than the predetermined heater current value stored in advance. In this case, the operation is performed with the voltage lowered to the normal voltage value.

Further, in the configuration of claim 4, the heating voltage changing means operates the heating voltage source at a voltage value lower than the normal voltage value when the temperature of the combustion section obtained from the temperature detecting means is higher than a predetermined temperature stored in advance. Will work as follows.

In a fifth aspect of the present invention, when the exhaust gas temperature obtained from the exhaust gas temperature detecting means is equal to or higher than a predetermined exhaust gas temperature stored in advance, the heating voltage changing means switches the heating voltage source to a voltage value lower than the normal voltage value. To actuate.

In the configuration of claim 6, the heating voltage changing means sets the heating voltage source lower than the normal voltage value when the ion current value obtained from the ion current detecting means is equal to or more than a predetermined ion current value stored in advance. It will act to operate at the voltage value.

[0019]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a combustion apparatus according to an embodiment of the present invention. FIG. 1 is a block diagram showing a basic configuration of a combustion apparatus according to one embodiment of the present invention.

In FIG. 1, components having the same functions as those in FIG. 24 of the conventional example are denoted by the same reference numerals, and detailed description thereof will be omitted. A heating voltage source 11 for applying a voltage for heating is connected to the heating element 6 which constitutes a part of the limiting current type oxygen sensor 4 and is arranged close to the sensor element. Is provided with heating voltage changing means 12 for changing the voltage applied to the heating element 6.

A temperature detecting means 13 is arranged in the combustion part 3 and a temperature (A ₁ ) of the combustion part obtained from the temperature detecting means 13 by electrical connection with the heating voltage changing means 12 is stored in advance at a predetermined value (A ₁ ). In the above case, the heating voltage source 11 is operated at the normal voltage value (V ₀ ), and when the temperature of the combustion part is lower than the predetermined value (A), the heating voltage source 11 is initially set to a voltage value higher than the normal voltage value (V ₀ ). V ₁ ), and when the following conditions are met, the voltage is rapidly or gradually reduced to the normal voltage value. The time at which the voltage applied to the heating voltage source 11 is reduced to the normal voltage value (V ₀ ) is at least (A) after a lapse of a predetermined time (t) stored in advance.
(A) A sensor temperature (α ₁ ) obtained from a sensor temperature detecting section (not shown) arranged in the limiting current type oxygen sensor 4 and electrically connected to the heating voltage changing means 12 is equal to or higher than a predetermined sensor temperature (α). In the case of (c), the heating element 6 and the heating voltage source 11
The heater current value (a ₁ ) obtained from the heater current detecting means 14 arranged in the closed circuit electrically connected to the heating voltage changing means 12 is equal to or less than the predetermined heater current value (a). It is configured as follows.

The element current detecting means 10 is provided with a control signal reader 15 for utilizing the detected current from the element current detecting means 10 as a read control signal after a predetermined time (X) at which the sensor characteristics are stabilized. .

Further, when the combustion starts and the following conditions are satisfied, the heating voltage changing means 12 is operated to operate the heating voltage source at a voltage value (V ₂ ) lower than the normal voltage value (V ₀ ). This condition means that (d) when the temperature of the combustion part obtained from the temperature detecting means 13 is equal to or higher than a predetermined temperature value (B) higher than the predetermined temperature value (A), (e) during the combustion flame of the combustion part 3 When the ion current value obtained from the disposed ion current detecting means 16 is equal to or more than the predetermined ion current value (I), (f) the exhaust gas temperature obtained from the exhaust gas temperature detecting means 17 disposed in the exhaust gas flow path 5 becomes the predetermined exhaust gas temperature value. (T) and above.

FIG. 2 is a flow chart showing an operation state of the heating voltage changing means 12 used in the combustion apparatus of the present invention, focusing on the detection result of the temperature detecting means 13 for detecting the temperature of the combustion section 3. When started, heating voltage changing means 1
The RAM in the control unit 2 is cleared. Next, the combustion part temperature (A ₁ ) is detected, a predetermined temperature value (A) of the combustion part temperature is called, and the combustion part temperature (A ₁ ) is compared with the predetermined temperature value (A). If the combustion section temperature (A ₁ ) is higher than a predetermined temperature value (A), the heating voltage source 1
1 is operated with a working voltage source (V ₀ ). On the other hand, when the combustion section temperature (A ₁ ) is lower than the predetermined temperature value (A), the heating voltage source 11 is initially operated at a voltage value (V ₁ ) higher than the normal voltage value. 11 is operated by rapidly or gradually reducing the applied voltage to the normal voltage value (V ₀ ). The time to decrease to this normal voltage value is
(A) In the case where a predetermined time (t) stored in advance has elapsed, (A) The sensor temperature obtained from the sensor temperature detecting unit disposed in the limiting current type oxygen sensor 4 and electrically connected to the heating voltage changing means 12 (Α ₁ ) is the predetermined sensor temperature (α)
In the above case, (c) the heater current value (a ₁ ) obtained from the heater current detecting means 14 which is disposed in the closed circuit between the heating element 6 and the heating voltage source 11 and is electrically connected to the heating voltage changing means 12 Is less than or equal to the predetermined heater current value (a). After this voltage change, the heating element 6 is connected to the heating voltage source 11
, Thereby operating at the normal voltage value (V ₀ ).

After a lapse of a predetermined time (t) stored in advance, the heating voltage changing means 12 measures a required time from the start. When the predetermined time (t) is reached, the heating element 6 is turned on by a normal voltage value ( V ₀ ). For test sensor temperature, first, if the sensor temperature (alpha ₁₎ of the detected sensor temperature (alpha ₁₎ is equal to or higher than a predetermined sensor temperature (alpha) is operated in a conventional voltage value (V _0), again the sensor if less This cycle is repeated until the temperature (α ₁ ) is detected and the temperature becomes equal to or higher than the predetermined sensor temperature (α). For verification of heater current value,
First, the heater current value (a ₁ ) is detected. If the heater current value (a ₁ ) is less than the predetermined heater current value (a), the heater current value (a ₁ ) is operated at the normal voltage value (V ₀ ). This cycle is repeated until (a ₁ ) becomes equal to or less than the predetermined heater current value (a).

FIG. 3 is a flowchart showing an operation state in the case where the heating voltage changing means 12 used in the combustion equipment of the present invention operates the heating voltage source 11 at a normal voltage value (V ₀ ) from the beginning. After the start, the heating voltage source 11 is operated at the normal voltage value (V ₀ ) to start combustion, and when the following conditions are met, the heating voltage changing means 12 is operated and the heating voltage source is rapidly or gradually changed from the normal voltage value. Operate at a low voltage value (V ₂ ). The timing for changing this voltage value is determined by (d) the combustion unit 3
When the temperature of the combustion part (B ₁ ) obtained from the temperature detecting means 13 disposed at the predetermined temperature value (B) or more, (E)
Ion current detecting means 1 arranged in the combustion flame of combustion part 3
When the ion current value (I ₁ ) obtained from the exhaust gas temperature (I ₁ ) is equal to or larger than the predetermined ion current value (I), the exhaust gas temperature (T ₁₎ obtained from the exhaust gas temperature detecting means 17 arranged in the flue (exhaust gas passage) 5 ) Is equal to or higher than the predetermined exhaust gas temperature value (T).

In the case of the test of the combustion section temperature, first, the combustion section temperature
(B₁) Is detected and compared with the predetermined temperature value (B).
(B₁) Is greater than the value (B), the heating voltage source 11 is commonly used
Voltage value lower than voltage value (V_Two) And the value (B₁)
Is less than the value (B), the combustion section temperature (B₁) Detected
Threshold (B₁) Is equal to or greater than the value (B).
repeat. In the case of the ion current value test, first, the ion current
Value (I₁) Is detected and compared with a predetermined ion current value (I).
Value (I₁) Is equal to or more than the value (I), the heating voltage source 11
Voltage value (V_Two) Actuated and the value
(I₁) Is less than the value (I), the ion current value (I
₁) Is detected and the value (I₁) Is equal to or greater than the value (I).
Repeat cycle. On the other hand, in the case of verification of exhaust gas temperature,
First, the exhaust gas temperature value (T ₁) Is detected and a predetermined temperature value (T) is detected.
Compare the value (T₁) Is greater than the value (T), the heating voltage source
11 is a voltage value (V) lower than the normal voltage value._Two),
Value (T₁) Is less than the value (T), the exhaust gas temperature again
(T₁) Is detected and the value (T₁) Is greater than (T)
This cycle is repeated.

In any of the above cases, the voltage of the heating voltage source 11 may be changed rapidly or gradually as needed.

FIG. 4 is a block diagram of a first embodiment of the configuration around the limiting current type oxygen sensor 4 and its operating circuit in the combustion equipment of the present invention.

The limiting current type oxygen sensor 4 includes an oxygen ion conductive solid electrolyte body 19 having electrode films 18a and 18b forming a pair on both sides, and a cathode electrode on one side of the oxygen ion conductive solid electrolyte body 19. A helical spacer 20 'surrounding the membrane 18a and having a start end and an end spaced from each other, a sealing plate 20 "disposed above the helical spacer 20', and a helical spacer 20" disposed above the helical spacer 20 ". The heating section 6 is arranged. A diffusion-controlling body 20 is formed by the spiral spacer 20 ′ and the seal plate 20 ″, and the oxygen diffusion passage 21 is formed by opposing partition walls of the spiral spacer 20 ′, the oxygen ion conductive solid electrolyte body 19, and the seal plate 20 ″. It is formed in a spiral space surrounded by. The heating element 6 may be provided along with the oxygen ion conductive solid electrolyte element 19. Components common to those in FIG. 1 are denoted by the same reference numerals, and description thereof is omitted.

Next, the materials and manufacturing methods of the limiting current type sensor 4 and its mounting body will be described based on specific examples. In the limiting current type oxygen sensor 4 of FIG. 4, zirconia (ZrO _{2) is used} as the oxygen ion conductive solid electrolyte body 19.
To which 8 mol% of Y ₂ O ₃ is added), the electrode film 18a
18b as platinum, spiral spacer 20 'as glass (having a thermal expansion coefficient substantially the same as zirconia and containing a small amount of heat-resistant particles having a predetermined particle size), forsterite as seal plate 20 ", and platinum as heating unit 6 First, the electrode films 18 a and 18 b were connected to the solid electrolyte plate 19.
Further, a helical spacer 20 'is formed on the oxygen ion conductive solid electrolyte body 19 by using a thick film printing technique and a firing technique. On the other hand, the heating unit 6 is formed on the seal plate 20 ″ by using a thick film printing technique and a baking technique.
Next, the spiral spacer 20 'on the oxygen ion conductive solid electrolyte member 19 and the sealing plate 20 "are laminated and heated and melted to form an oxygen diffusion passage 21. Then, a lead wire (not shown) is attached. The sensor element is completed by electrically connecting a lead wire to a lead terminal (not shown) provided on a ceramic bottom body (not shown), and then enclosing with a heat insulating material 7. Further, the heat insulating material 7 is wrapped around with a stainless steel mesh (not shown), and the ceramic bottom body and the stainless steel mesh are joined to form a gas-permeable frame 8 as a package.

The operation will be described below with reference to FIG. 4 and a timing chart of FIG. When started, first, the heating voltage changing means 12
The temperature of the combustion part (A ₁ ) at the start is detected by operating the temperature detection means 13 and the measured combustion part temperature (A ₁ ) is compared with a predetermined temperature value (A) stored in advance. . If the combustion section temperature (A ₁ ) is higher than a predetermined temperature value (A), the heating voltage source 1
1 is operated at a normal voltage value (V ₀ ). On the other hand, when the combustion part temperature (A ₁ ) is lower than the predetermined temperature value (A), the heating voltage source 11 is initially operated at a voltage value (V ₁ ) higher than the normal voltage value, so that the heating element 6 is temporarily operated. Apply a high power value to quickly warm the sensor. Simultaneously with the start, the element driving voltage source 9 and the element current detecting means 10 are operated. The oxygen ion conductive solid electrolyte 19 is heated by the heating element 6 to perform an oxygen pumping action, and oxygen molecules pass through the oxygen ion conductive solid electrolyte 19 as oxygen ions.
Since the movement of oxygen molecules is gradually restricted by the oxygen diffusion passage 21, the passage of oxygen ions is restricted, and accordingly, the generated current gradually decreases. Eventually, at a predetermined time (t), the heating voltage changing means 12 operates, and the voltage value applied by the heating voltage source 11 is rapidly or gradually reduced to the normal voltage value (V ₀ ). Then, when the element current becomes stable (X), the control signal reader 15 reads the current detected by the element current detection means 10 and uses the value as a control signal. Note that the heating voltage source 1
The voltage value applied by 1 is, for example, 1.2 times or less the normal voltage value. In addition, the predetermined time (t) is set to be at least longer than the time when the element current starts to decrease, and at least up to four times the time from the start of use to the start of the element current decrease.

Thereafter, the fuel supply unit 1 and the air supply unit 2
Operates and combustion starts at time (Y). When the combustion part temperature (B ₁ ) obtained from the temperature detecting means 13 at the time (Z) becomes equal to or higher than a predetermined temperature value (B) higher than the predetermined temperature value (A), the heating voltage changing means 12 is activated. Then, the heating voltage source 11 is operated at a voltage value (V ₂ ) lower than the normal voltage value (V ₀ ).

The limiting current type oxygen sensor 4 is connected to the fuel supply unit 1 or the air supply unit 2 via the control signal reading unit 15.
It is electrically associated with the fuel supply unit 1. The oxygen concentration in the combustion exhaust gas is measured, and the fuel supply unit 1 or the air supply unit 2 is controlled so that the oxygen concentration is stored in advance.

As described above, according to this embodiment, by temporarily applying a high power value to the heating element 6 and warming the sensor in a short time, the oxygen diffusion passage 21 restricts the movement of oxygen molecules and the oxygen pumping action. Is stabilized in a short time, the sensor stabilization time is shorter than in the case of operating at a normal voltage from the beginning of use, the oxygen concentration can be measured in a short time, and the temperature of the combustion unit 3 is detected by temperature detection. By lowering the voltage applied to the heating element 6 detected by the means 13 below the normal voltage value, the sensor element is prevented from being heated more than necessary.

FIG. 6 is a block diagram of a second embodiment of the configuration around the limiting current type oxygen sensor 4 and its operation circuit in the combustion equipment of the present invention. Although the basic configuration is the same as that of FIG. 4, the limiting current type oxygen sensor 4 is provided with a sensor temperature detecting unit 22 for detecting the temperature of the sensor element, and the exhaust gas temperature detecting means 17 detects the smoke from which the combustion exhaust gas flows. It is arranged on the road 5 and is electrically connected to the heating voltage changing means 12 and further to the control signal reading means 15.

The operation will be described below with reference to FIG. 6 and the timing chart of FIG. First, the heating voltage changing means 12 and the temperature detecting means 13 are operated to detect the combustion part temperature (A ₁ ).
The measured combustion section temperature (A ₁ ) is compared with a predetermined temperature value (A) stored in advance. If the combustion part temperature (A ₁ ) is a high temperature equal to or higher than the predetermined temperature value (A),
The heating voltage source 11 is operated at the normal voltage value (V ₀ ). On the other hand, when the combustion part temperature (A ₁ ) is lower than the predetermined temperature value (A), the heating voltage source 11 is initially operated at a voltage value (V ₁ ) higher than the normal voltage value, so that the heating element 6 is temporarily operated. Apply a high power value to quickly warm the sensor. At the start,
The element driving voltage source 9 and the element current detecting means 10 are operated. Oxygen ion conductive solid electrolyte body 19 by heating body 6
Is heated to cause an oxygen pumping action, and oxygen molecules pass through the oxygen ion-conductive solid electrolyte body 19 as oxygen ions. However, since the movement of oxygen molecules is gradually restricted by the oxygen diffusion passage 21, the oxygen ions pass through. And the generated current gradually decreases. Eventually, when the sensor temperature obtained from the sensor temperature detecting section 22 becomes equal to or higher than the predetermined sensor temperature (α), the heating voltage changing means 12 is activated, and the heating voltage source 11 sharply changes the voltage value applied to the heating element 6 to the normal voltage. Value (V ₀ ). Then, after the time (X) at which the element is stabilized, the control signal reader 15 reads the current detected by the element current detection means 10 and uses the value as a control signal. The voltage value applied by the heating voltage source 11 in the early stage of use is, for example, a normal voltage value of 1.2.
The voltage value was twice or less.

Thereafter, the fuel supply unit 1 and the air supply unit 2
Operates to start combustion at time (Y). Then, when the exhaust gas temperature (T ₁ ) obtained from the exhaust gas temperature detecting means 17 becomes equal to or higher than the predetermined exhaust gas temperature value (T) at the time (Z), the heating voltage changing means 12 operates and the heating voltage source 1
The voltage of 1 is a voltage value (V ₂ ) lower than the normal voltage value (V ₀ )
Operate with

As described above, according to the present embodiment, by temporarily applying a high power value to the heating element 6 and warming the sensor in a short time, the movement of oxygen molecules by the oxygen diffusion passage 21 and the oxygen pumping action are controlled. Is stabilized in a short time, so the sensor stabilization time is shorter than when operating at normal voltage from the beginning of use, oxygen concentration can be measured in a short time, and the exhaust gas temperature rises above a predetermined temperature. By lowering the heating voltage applied to the heating element 6 from the normal voltage value, the sensor element is prevented from being heated more than necessary.

FIG. 8 is a diagram showing a configuration around the limiting current type oxygen sensor 4 in the combustion equipment of the present invention and a third circuit of its operation circuit.
FIG. 4 is a block diagram of an embodiment of FIG. The basic configuration is the same as that of FIG. 4, but a heater current detecting means 14 is disposed in a closed circuit between the heating element 6 and the heating voltage source 11. The means 16 is electrically connected to the heating voltage changing means 12, and is also electrically connected to the control signal reading means 15 from the heater current detecting means 14.

The configuration is as described above.
8 and FIG. 9 of the timing chart.
Will be explained. First, heating voltage changing means 12 and temperature detection
By operating the means 13, the combustion section temperature (A₁) Detection
The measured combustion section temperature (A ₁) And memorized in advance
The predetermined temperature value (A) is compared. If the combustion section temperature
(A₁) Is a higher temperature than the predetermined temperature value (A),
The heating voltage source 11 is switched to a normal voltage value (V₀). one
The combustion section temperature (A₁) Is less than the specified temperature value (A)
Means that the heating voltage source 11 is initially set to a voltage value higher than the normal voltage value.
(V₁) To temporarily provide high power to the heating element 6
Apply value and warm sensor quickly. At the start,
Activating the element driving voltage source 9 and the element current detecting means 10
You. Oxygen ion conductive solid electrolyte body 19 by heating body 6
Is heated and the oxygen pumping action works,
Through the oxygen ion conductive solid electrolyte body 19 as elementary ions
But the movement of oxygen molecules is slowed down by the oxygen diffusion passage 21.
Restrictions, the passage of oxygen ions is restricted,
As a result, the generated current gradually decreases. Eventually, the heater power
The heater current value obtained from the flow detecting means 14 is a predetermined heater.
When the current value becomes equal to or less than (a), the heating voltage changing means 12 operates.
Then, the voltage value applied by the heating voltage source 11 is suddenly changed to a normal voltage.
Value (V₀). And the time when the element stabilizes
(X) After that, the control signal reader 15
The current detected by the current detection means 10 is read, and the value is read.
Use it as a control signal. Note that, as an example,
The voltage value applied by the thermal voltage source 11 is 1.2 times or more the normal voltage value
The voltage value was as follows.

Thereafter, the fuel supply unit 1 and the air supply unit 2
Operates to start combustion at time (Y). Then, when the ion current value (I ₁ ) obtained from the ion current detecting means 16 becomes equal to or more than the predetermined ion current value (I) at the time (Z), the heating voltage changing means 12 is activated to use the heating voltage source in a normal state. Operate at a voltage value (V ₂ ) lower than the voltage value.

As described above, according to this embodiment, by temporarily applying a high power value to the heating element 6 and warming the sensor in a short time, the oxygen diffusion passage 21 restricts the movement of oxygen molecules and the oxygen pumping action. Is stabilized in a short time, the sensor stabilization time is shorter than in the case where the sensor is operated at the normal voltage (V ₀ ) from the beginning of use, and the oxygen concentration can be measured in a short time. When the ionic current obtained from the ionic current detecting means disposed in the combustion flame is equal to or more than a predetermined value, the voltage applied to the heating element is reduced from a normal voltage value to prevent the sensor element from being heated more than necessary. .

The components in the above three embodiments are not fixed, and may be used in combination with other embodiments.

Hereinafter, the effects of the present invention will be described based on experimental examples. (Experiment 1) In the experiment, a circuit having all the components shown in FIGS. 4, 6 and 8 was used, and a limiting current type oxygen sensor (10
(mm x 10 mm x 0.7 mm) was measured with a package in which the heat insulating material was wrapped around with 0.5 g of the heat insulating material.

The test was conducted in the atmosphere (oxygen 20.6%).
A 1000 Ω resistor was used as the element current detection means 10, and the voltage at both ends was measured to determine the element current. Further, a resistance of 1.0Ω was connected in series as a heater current detecting means 14 to the heating element 6 and the heating voltage source 11 to form a closed circuit. Further, an element temperature detecting section 22 (specifically, a platinum sensor) is disposed on the surface of the sealing plate 20 ″ on the side of the diffusion hole.
FIG. 10 shows the obtained transient characteristics of the element current, FIG. 11 shows the transient characteristics of the heater current, and FIG. 12 shows the transient characteristics of the sensor temperature.

First, the operation method will be described. Heating voltage source 1
1 and the heating voltage changing means 12 are operated to apply a voltage of 10.9 V (1.09 times the normal voltage value of 10.0 V) to the heating unit 6 via a lead wire, and oxygen is supplied through the heating unit 6. The ion conductive solid electrolyte plate 19 is heated. On the other hand, the element driving voltage source 9 is operated at the same time as the heating voltage source 11 is operated, and the applied voltage is operated at 1.0 V, so that the electrode films 18a,
A voltage is applied to 18b. Then, the oxygen pumping action of the oxygen ion conductive solid electrolyte 19 works, and oxygen molecules are converted into oxygen ions by the oxygen ion conductive solid electrolyte 19.
, The element current gradually increases. However, the movement of oxygen molecules is gradually restricted by the oxygen diffusion path 21, so that the passage of oxygen ions is restricted, and the element current gradually decreases with time. .

Although the device current decreases with time,
When a predetermined time (t) (1.5 minutes in this case) is reached, the heating voltage changing means 12 is activated, and the voltage value applied by the heating voltage source 11 is rapidly reduced to the normal voltage value of 10.0V. Then, the sensor element current stabilizes in 6 minutes, and when a predetermined time (X) (6 minutes in this case) is reached in which the element current stabilizes, the control signal generator 15 reads the current detected by the current detecting means 9, and It can be used as a control signal.

On the other hand, although the heater current decreases with time, the predetermined heater current value (a) of 275 mA
(1.5 minutes after the initial stage of use)
2 is operated, and the voltage value applied by the heating voltage source 11 is rapidly reduced to the normal voltage value of 10.0V. Then, the heater current sharply decreases, and a stable value of 250 mA is obtained in about 6 minutes.

Although the sensor temperature increases with time, when the temperature reaches a predetermined temperature (α) of 440 ° C. (1.5 minutes after the initial use), the heating voltage changing means 12 operates and the voltage applied by the heating voltage source 11 is applied. The value suddenly rises to the normal voltage of 10.0V
To lower. Then, the temperature of the element rapidly rises to about 6
A stable temperature of 450 ° C. is obtained in a minute.

For reference, in the case of the conventional example operated at the normal voltage from the beginning of use, the element current, the heater current and the sensor temperature were stabilized in about 14 minutes as shown by the broken lines in FIGS.

Further, when a power consumption value of a normal heater, which does not cause any inconvenience in long-term continuous use of the sensor, was examined, it was found that the sensor power was practical if it was 2.5 to 2.9 W. The reason for this is that if it is 2.9 W or more, it becomes impractical due to heat shock accompanying intermittent use, and if it is 2.5 W or less, it becomes impractical due to electrode deterioration due to long-term use. Upon further detailed examination, it was found that the voltage value applied by the heating voltage source in a short period of time at the beginning of use was optimally 1.2 times or less the normal voltage value. The change time of the applied voltage is equal to or longer than the time when the element current starts to decrease, is within four times the time from the start of use to the time of the start of decrease, and the heater current value is 1.32 of the stable value.
The sensor stabilization time is shortened by setting the time when the element temperature becomes 1.04 times or more when the element temperature becomes 0.85 times or more and 1.0 times or less the stable temperature, and the durability is affected. It turned out there was no.

(Experiment 2) In the apparatus configuration of FIG.
An experiment was performed using a circuit having all the components shown in FIGS. The effect was determined with a combustion device using kerosene as fuel. In the flue 5 through which the flue gas of the combustion equipment passes, a mounted body of a limiting current type oxygen sensor having a heating element 6, wrapped with a heat insulating material 7, and further wrapped with a gas permeable frame 8.

Since the combustion equipment uses kerosene, it is necessary to vaporize the kerosene into steam. The combustion unit 3 is heated in advance to about 240 ° C. with a heater, and the kerosene is dropped on the heated portion. It is vaporized and turned into steam. The combustion part temperature is a value obtained by measuring the temperature of the vaporized surface part.

FIG. 13 shows the temperature transition of the combustion part 3. The temperature of the combustion section rises with time, and after about 7 minutes, the combustion starts, so that the temperature further rises and eventually stabilizes at around 300 ° C. In this combustion equipment, the predetermined temperature value (A) stored in advance is 100 ° C.
And The predetermined temperature value (B) was set to 260 ° C.

FIG. 14 shows the transition of the voltage applied by the heating voltage source 11 to the heating element 6. It can be seen from FIG. 13 that the temperature of the combustion part 3 is 30 ° C. in the initial stage of use and is equal to or lower than a predetermined temperature value (A) set to 100 ° C. Therefore, the applied voltage is
Initially, the voltage was set to 10.9 V (1.09 times the normal voltage of 10.0 V). Eventually, a predetermined time (t) (in this case, 1.5)
Min), the voltage is changed suddenly, and the normal voltage value becomes 10.
0 V is applied. Then, when the combustion starts and the temperature of the combustion section 3 becomes equal to or higher than the predetermined temperature value (B) of 260 ° C., the heating voltage changing means 12 operates to reduce the applied voltage to the heating element 6 to 9.0 V (normal voltage value 10). 0.0V (0.9 times). In addition,
Conventionally, 10.0 V is always applied.

FIG. 15 shows the transient characteristics of the element current generated from the limiting current type oxygen sensor 4. The element current increases with time in the early stage of use, but after about 1 minute, the movement of oxygen molecules is gradually restricted by the oxygen diffusion path, and thus gradually decreases with time. After about 6 minutes, a stable value is obtained. At this time, since the limiting current type oxygen sensor 4 is still in contact with the atmosphere, a limiting current value at the oxygen concentration in the atmosphere is obtained. For this reason, the limit current value measured in the atmospheric oxygen concentration is compared with the stored current value, and if they are almost the same value, it can be determined that the sensor has no abnormality. I can judge.

After the elapse of 7 minutes, the combustion starts, so that the oxygen concentration in the combustion exhaust gas decreases, and accordingly the element current also decreases, and a stable value can be obtained one minute after the combustion.

For reference, the transient characteristics of the element current in the case of the conventional method operated at the normal voltage from the initial stage of use are shown by broken lines. In the case of the conventional method, the element current was not stabilized by 7 minutes after the start of combustion, and was not quite stable even after the start of combustion. Therefore, the quality of the sensor cannot be determined based on the oxygen concentration in the atmosphere. Even if the sensor is abnormal, the sensor is used in an abnormal state, and erroneous measurement occurs. In addition, the sensor current cannot be used until the element current becomes stable because the element current is not stable even after the start of combustion, which is inconvenient.

FIG. 16 shows the transient characteristics of the sensor temperature. In the case of the present invention, the sensor temperature was stabilized at about 450 ° C. in about 6 minutes, and was substantially stabilized at about 455 ° C. even after 7 minutes from the start of combustion. On the other hand, in the case of the conventional method in which the sensor was operated at the normal voltage from the beginning of use, the sensor temperature did not reach the stable temperature even after 6 minutes had elapsed, and after the combustion was started, the temperature reached about 520 ° C.
It was almost stable. The sensor temperature of 520 ° C. is an upper limit temperature at which the sensor can be used for a short period of time, and is a temperature region where cracking of the sensor occurs when used for a long time. The reason why the sensor temperature increases after combustion in the conventional method is
This is because, when the combustion starts, the sensor is exposed to the combustion exhaust gas at about 260 ° C. and receives the combustion heat other than the original heating element supply heat. In this regard, the present invention reduces the voltage applied to the heating body after combustion and reduces the amount of heat supplied to the heating body assuming the reception of combustion heat, so that the sensor temperature becomes substantially the same regardless of before and after combustion. .

The heating voltage is changed before the start of combustion. When the predetermined time (t) is set to 1.5 minutes, the predetermined heater current value (a) is a time when the heater current value is 275 mA or less.

FIG. 17 shows the transient characteristics of the heater current flowing through the heater 6. In the case of the present invention, the heater current was stabilized at about 250 mA in about 6 minutes, and was substantially stabilized at about 225 mA even after 7 minutes from the start of combustion. In the present invention, the reason why the heater current value after the start of combustion is small even though the sensor temperature is substantially the same as compared to the value before the start of combustion is that the voltage applied to the heating element is reduced after the start of combustion. Therefore, while the temperature of the heating element decreases and the heater current value decreases accordingly, the sensor temperature is the temperature obtained by adding the temperature of the heat supplied by the heating element and the temperature of receiving the combustion heat.

On the other hand, in the case of the conventional method in which the heater was operated at the normal voltage from the beginning of use, the heater current value was not stable even after 6 minutes had passed, and even when combustion started, it was not quite stable. The reason why the heater current value after the start of combustion is smaller than the value before the start of combustion is that the sensor temperature increases after the start of combustion and the resistance of the platinum heater used for the heating element increases accordingly, resulting in a decrease in the heater current value. It is because it falls. The heating voltage is changed before the start of combustion. If the predetermined time (t) is 1.5 minutes, the predetermined sensor temperature (α) becomes 4
It was time to reach 40 ° C.

FIG. 18 shows the transient characteristics of the exhaust gas temperature obtained from the exhaust gas temperature detecting means arranged in the exhaust gas channel. The value of the exhaust gas temperature was obtained at the start of combustion, gradually increased, and eventually stabilized. When the temperature of the combustion section reaches a predetermined temperature value (B) of 260 ° C., the exhaust gas temperature is 80 ° C. When this 80 ° C. is set to a predetermined exhaust gas temperature value (T), an exhaust gas temperature of 80 ° C. or more is obtained. The voltage applied to the heating element was changed.

FIG. 19 shows the transient characteristics of the ionic current obtained from the ionic current detecting means arranged in the combustion flame of the combustion section. The value of the ionic current was obtained at the start of combustion, gradually increased, and eventually stabilized. When the temperature of the combustion part reaches 260 ° C., which is the predetermined temperature value (B),
The ion current value was 6 μA, and this 6 μA was defined as a predetermined ion current value (I). When an ion current value of 6 μA or more was obtained, the voltage applied to the heating element was changed.

(Experiment 3) In a combustion apparatus using kerosene as a fuel, the effect was determined by increasing the temperature of the combustion section in the initial stage of use. The experiment was the same as in Experiment 2, except that the combustion equipment was burned, stopped, and burned again after 5 minutes to increase the temperature of the combustion section in the initial stage of use, and to raise the sensor temperature of the limiting current type oxygen sensor. did.

FIG. 20 shows the transition of the temperature of the combustion section 3. Since the combustion equipment was burned up to 5 minutes ago, the temperature of the combustion section was about 200 ° C in the initial stage of use, and after about 1 minute, the combustion started and the temperature rose further and eventually stabilized at about 300 ° C I do. In the combustion equipment, the predetermined temperature value (A) stored in advance is 100 ° C., and the predetermined temperature value (B) is 260 ° C.

FIG. 21 shows the transition of the voltage applied by the heating voltage source 11 to the heating element 6. The temperature of the combustion part 3 is 200 ° C. in the initial stage of use, and a predetermined temperature value (A) set to 100 ° C.
That is all. Therefore, the applied voltage was set to a normal voltage value of 10.0 V in the early stage of use. Then, when the combustion starts and the temperature of the combustion section 3 becomes equal to or higher than the predetermined temperature value (B) of 260 ° C.,
The heating voltage changing means 12 was activated to set the applied voltage to 9.0 V (0.9 times the normal voltage value of 10.0 V). In the reference example, 10.9 V (1.09 times the normal voltage value of 1.0 V) was applied in the initial stage of use, and the voltage suddenly increased for a predetermined time (t) (1.5 minutes in this case). This is an example in which a normal voltage value of 10.0 V is applied after being changed.

FIG. 22 shows the transient characteristics of the sensor temperature. The sensor was warm because the combustion equipment was burning up to 5 minutes ago, and the sensor temperature was about 380 ° C. at the beginning of use. The sensor temperature was about 420 ° C. about 1 minute after the start of combustion, and was almost stable at about 550 ° C. after about 3 minutes. On the other hand, in the initial stage of use, 10.9 V (a voltage value 1.09 times the normal voltage value of 10.0 V) is applied, and when a predetermined time (t) (1.5 minutes) is reached, the voltage is rapidly changed to a normal voltage. In the case of the reference example in which a value of 10.0 V is applied, the sensor temperature is about 550 ° C. after about 10 minutes.
It was almost stable. This is because the voltage change time is determined to be 1.5 minutes, so it is still 10.9V even when the combustion starts 1.0 minutes
Is applied, the sensor is warmed more than necessary, and it takes much time to be stabilized.

FIG. 23 shows the transient characteristics of the element current generated from the limiting current type oxygen sensor 4. The element current increases with time in the early stage of use, but immediately decreases with time because the movement of oxygen molecules is gradually restricted by the oxygen diffusion path.

At about one minute after the start of combustion, the oxygen concentration in the combustion exhaust gas decreases, and the element current decreases accordingly, and a stable value can be obtained in about three minutes.

In the reference example, 10.9 V (1.09 times the normal voltage of 10.0 V) is applied in the initial stage of use, and the voltage is rapidly changed when the predetermined time (t) reaches 1.5 minutes. Since a normal voltage of 10.0 V was applied, the device current was almost stabilized after about 10 minutes. This is because the voltage change timing is determined to be 1.5 minutes, and even after 1.0 minute of the start of combustion, 10.9 V is still applied, so the sensor is warmed more than necessary and stabilized accordingly. This takes a lot of time.

The numerical values presented above are merely examples, and show different values depending on the material and structure of the sensor and the structure of the combustion device, and this value does not limit the scope of the invention.

[0074]

As is apparent from the above description, the combustion apparatus of the present invention is configured such that the voltage value applied to the heating element for heating the limiting current type oxygen sensor is changed depending on the temperature of the combustion section. In the case of a relatively long combustion start time, such as when starting to use a combustion device, a voltage value to be applied to the heating element is only used in the initial period of use. After increasing the predetermined time, a method of applying a normal voltage is used.
When the combustion part is warm, such as when the use is temporarily interrupted and restarted, the voltage applied to the heating element is set to the normal voltage from the beginning of use. It is stable in a short time and oxygen concentration measurement can be started early.

Further, the combustion apparatus of the present invention is configured such that the voltage value applied to the heating element for heating the limiting current type oxygen sensor is reduced after the start of combustion, so that the sensor receives the heat of the combustion exhaust gas during the combustion. As a result, the heat supplied from the heating element can be reduced, so that the sensor temperature becomes almost the same as that in the atmosphere, and the durability of the sensor does not decrease.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a basic configuration of a combustion apparatus according to an embodiment of the present invention.

FIG. 2 is a flowchart showing an operation state of the heating voltage changing unit.

FIG. 3 is a flowchart showing an operation state of the heating voltage changing unit.

FIG. 4 is a block diagram of a first embodiment of a peripheral configuration and an operation circuit of a limiting current type oxygen sensor in the combustion equipment of the present invention.

FIG. 5 is a timing chart of the control flow.

FIG. 6 is a block diagram of a peripheral configuration of a limiting current type oxygen sensor and an operation circuit thereof in a combustion apparatus according to a second embodiment of the present invention.

FIG. 7 is a timing chart of the control flow.

FIG. 8 is a block diagram showing a peripheral configuration of a limiting current type oxygen sensor in a combustion apparatus according to a third embodiment of the present invention and an operation circuit thereof;

FIG. 9 is a timing chart of the control flow.

FIG. 10 is a diagram showing transient characteristics of element current of a sensor according to the present invention.

FIG. 11 is a transient characteristic diagram of a heater current of the heating element.

FIG. 12 is a diagram showing a transient characteristic of a sensor temperature of the sensor.

FIG. 13 is a graph showing a transient characteristic of a temperature in a combustion section of the combustion equipment.

FIG. 14 is a diagram showing a change in voltage applied to the heating element.

FIG. 15 is a diagram showing transient characteristics of element current of the sensor.

FIG. 16 is a diagram showing transient characteristics of the sensor temperature.

FIG. 17 is a transient characteristic diagram of a heater current flowing through the heating element.

FIG. 18 is a graph showing transient characteristics of exhaust gas temperature of the combustion equipment.

FIG. 19 is a diagram showing a transient characteristic of an ion current of the ion current detecting means of the combustion equipment.

FIG. 20 is a temperature transition characteristic diagram of a combustion section of the combustion device.

FIG. 21 is a transition characteristic diagram of a voltage applied to the heating element.

FIG. 22 is a diagram showing transient characteristics of the sensor temperature.

FIG. 23 is a diagram showing transient characteristics of an element current generated from the sensor.

FIG. 24 is a block diagram of a peripheral configuration of a limiting current type oxygen sensor of a conventional combustion device and an operation circuit thereof.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fuel supply part 2 Air supply part 3 Combustion part 4 Limit current type oxygen sensor 5 Flue 6 Heating body 7 Insulation material 8 Gas permeable frame 9 Element driving voltage source 10 Element current detection means 11 Heating voltage source 12 Heating voltage Changing means 13 Temperature detecting means 14 Heater current detecting means 16 Ion current detecting means 17 Exhaust gas temperature detecting means

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI G05D 23/20 G01N 27/46 325Q (56) References JP-A-6-265139 (JP, A) (58) Fields investigated ( Int.Cl. ⁷ , DB name) F23N 5/00 F23N 5/12 F23N 5/14 340 F23N 5/20

Claims (6)

(57) [Claims] A fuel supply unit for supplying fuel; an air supply unit for supplying air; a combustion unit for burning a mixed gas of fuel and air; a flue through which combustion exhaust gas from the combustion unit flows; A limiting current type oxygen sensor having a heating element disposed in the flue and disposed in close proximity to the sensor element and enclosed by a heat insulating material, and a heating voltage source for applying a heating voltage to the heating element of the limiting current type oxygen sensor A heating voltage changing unit that changes a voltage applied to the heating voltage source, and a temperature detecting unit that is disposed in the combustion unit and provides a temperature detection result of the combustion unit to the heating voltage changing unit. The temperature detecting means detects the temperature of the combustion section, and if the temperature is equal to or higher than a predetermined temperature value stored in advance, the heating voltage changing means operates the heating voltage source at a normal voltage value, and the heating voltage changing means operates at a normal voltage value, and In the case of the above, the heating voltage A combustion device in which the power source is operated at a voltage value higher than the normal voltage value in the initial stage of use, and is operated by lowering the voltage to the normal voltage value after a predetermined time stored in advance. 2. A fuel supply unit for supplying fuel, an air supply unit for supplying air, a combustion unit for burning a mixed gas of fuel and air, a flue through which combustion exhaust gas from the combustion unit flows, A limiting current type oxygen sensor having a heating element disposed in the flue and disposed in close proximity to the sensor element and enclosed by a heat insulating material, and a heating voltage source for applying a heating voltage to the heating element of the limiting current type oxygen sensor Heating voltage changing means for changing a voltage applied to the heating voltage source; temperature detecting means disposed in the combustion section to provide a temperature detection result of the combustion section to the heating voltage change means; and A sensor temperature detecting section for detecting the temperature of the sensor element in the oxygen sensor and applying the temperature to the heating voltage changing means, wherein the temperature detecting means detects the temperature of the combustion section and stores the predetermined temperature stored in advance. If the value is greater than or equal to The heating voltage changing means operates the heating voltage source at a normal voltage value.If the heating voltage source is lower than a predetermined temperature value, the heating voltage source is operated at a voltage value higher than the normal voltage value in an initial stage of use, and the sensor temperature is increased. Combustion equipment configured to operate by lowering to a normal voltage value when the sensor temperature detected by the detection unit becomes equal to or higher than a predetermined sensor temperature stored in advance. 3. A fuel supply unit for supplying fuel, an air supply unit for supplying air, a combustion unit for burning a mixed gas of fuel and air, a flue through which combustion exhaust gas from the combustion unit flows, A limiting current type oxygen sensor having a heating element disposed in the flue and disposed in close proximity to the sensor element and enclosed by a heat insulating material, and a heating voltage source for applying a heating voltage to the heating element of the limiting current type oxygen sensor Heating voltage changing means for changing a voltage applied to the heating voltage source; temperature detecting means disposed in the combustion section to provide a temperature detection result of the combustion section to the heating voltage change means; and A heater current detecting means for providing a detection result to the heating voltage changing means provided in a closed circuit between the heating element of the oxygen sensor and the heating voltage source, wherein the temperature detecting means detects the temperature of the combustion unit. Detect and it is When the temperature is equal to or higher than the predetermined temperature value stored in advance, the heating voltage changing means operates the heating voltage source at a normal voltage value, and when the temperature is lower than the predetermined temperature value, the heating voltage source uses the normal voltage value at the beginning of use. Combustion configured to operate at a higher voltage value, and to operate by lowering to a normal voltage value when the heater current value detected by the heater current detection means becomes equal to or less than a predetermined heater current value stored in advance. machine. 4. A fuel supply unit for supplying fuel, an air supply unit for supplying air, a combustion unit for burning a mixed gas of fuel and air, a flue through which combustion exhaust gas from the combustion unit flows, A limiting current type oxygen sensor having a heating element disposed in the flue and disposed in close proximity to the sensor element and enclosed by a heat insulating material, and a heating voltage source for applying a heating voltage to the heating element of the limiting current type oxygen sensor A heating voltage changing unit that changes a voltage applied to the heating voltage source, and a temperature detecting unit that is disposed in the combustion unit and provides a temperature detection result of the combustion unit to the heating voltage changing unit. Combustion equipment wherein the heating voltage changing means operates the heating voltage source at a voltage value lower than a normal voltage value when the temperature of the combustion section obtained from the temperature detecting means is equal to or higher than a predetermined temperature stored in advance. 5. A fuel supply unit for supplying fuel, an air supply unit for supplying air, a combustion unit for burning a mixed gas of fuel and air, a flue through which combustion exhaust gas from the combustion unit flows, A limiting current type oxygen sensor having a heating element disposed in the flue and disposed in close proximity to the sensor element and enclosed by a heat insulating material, and a heating voltage source for applying a heating voltage to the heating element of the limiting current type oxygen sensor Heating voltage changing means for changing a voltage applied to the heating voltage source, and an exhaust gas temperature detecting means disposed in a flue through which flue gas from a combustion section flows, and providing a detection result to the heating voltage changing means. When the exhaust gas temperature obtained from the exhaust gas temperature detecting means is equal to or higher than a predetermined exhaust gas temperature stored in advance, the heating voltage changing means operates the heating voltage source at a voltage value lower than a normal voltage value. Combustion equipment configured in. 6. A fuel supply unit for supplying fuel, an air supply unit for supplying air, a combustion unit for burning a mixed gas of fuel and air, a flue through which combustion exhaust gas from the combustion unit flows, A limiting current type oxygen sensor having a heating element disposed in the flue and disposed in close proximity to the sensor element and enclosed by a heat insulating material, and a heating voltage source for applying a heating voltage to the heating element of the limiting current type oxygen sensor And a heating voltage changing means for changing a voltage applied to the heating voltage source, and an ion current detecting means arranged in a combustion flame of a combustion unit and providing a detection result to the heating voltage changing means, The heating voltage changing means operates the heating voltage source at a voltage value lower than the normal voltage value when the ion current value obtained from the ion current detecting means is equal to or more than a predetermined ion current value stored in advance. Baking equipment.