JPH0989250A - Combustion equipment - Google Patents

Abstract

(57) [Summary] [Objective] To provide a combustion device that prevents the occurrence of incomplete combustion by verifying the sensor output of a limiting current type oxygen sensor arranged for performing air-fuel ratio control. [Structure] A limiting current type oxygen sensor 5 is arranged in an exhaust gas flow path 4, and air-fuel ratio control means 8 performs air-fuel ratio control.
The sensor output A when the limiting current type oxygen sensor 5 is operated at the combustion voltage and exposed to the atmosphere is measured by the sensor output detection constant means 10. The applied voltage determining means 11 compares the sensor output A with the threshold value E stored in advance and determines the applied voltage value based on the comparison value. Limiting current type oxygen sensor 5 in the atmosphere
The sensor output B when the voltage change means 12 is operated with the increased voltage value is measured by the sensor correction output detection means 13. The limiting current characteristic judging means 14 compares the sensor output B with the sensor output A to judge the limiting current characteristic. When it is determined that the current is the limit current, the air-fuel ratio target value correction means 15 corrects the air-fuel ratio target value based on the sensor output B.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combustion device for controlling an air-fuel ratio by arranging a limiting current type oxygen sensor for detecting oxygen concentration in an exhaust gas flow path, and more specifically, to generate incomplete combustion. The present invention relates to a combustion device having means for verifying whether or not the sensor output of a limiting current type oxygen sensor is normal in order to burn without combustion.

[0002]

2. Description of the Related Art When a combustion device is used in various environments,
Due to fluctuations in the outside air temperature, fluctuations in atmospheric pressure, and fluctuations in the durability of the fuel supply means and the air supply means, the fuel supply amount and the air supply amount fluctuate from the initially calculated values. For example, 20 above sea level
The air supply amount (oxygen supply amount) in the high altitude of the oxygen-diluted environment of 00 meters is greatly different from that in the flat land, and incomplete combustion occurs if the initial calculated value obtained in the flat land is used. In order to prevent the occurrence of incomplete combustion, the combustion equipment is devised in the structure of the combustion section so that it burns well even if the air amount fluctuates slightly, and a combustion state monitoring means is also provided.

On the other hand, focusing on the fact that the excess air ratio correlates with the oxygen concentration in the combustion exhaust gas passage, an oxygen sensor for measuring the oxygen concentration was developed, and this oxygen sensor was placed in the combustion exhaust gas passage. JP-A-3-330 proposes a combustion device that performs control so that the optimum oxygen concentration, that is, the excess air ratio is achieved.
No. 225 publication. As shown in FIG. 19, the proposed combustion apparatus has a configuration in which a limiting current type oxygen sensor 5 is arranged in the exhaust gas flow path 4 and the fuel supply means 1 or the air supply means 2 is controlled by the air-fuel ratio control means 8. is there. Since the limiting current type oxygen sensor 5 is used to control the oxygen concentration in the combustion exhaust gas to be always constant, there is an advantage that the excess air ratio is always kept constant and incomplete combustion can be prevented. Then, in order to prevent erroneous measurement of the oxygen concentration due to the deterioration of the limiting current type oxygen sensor 5, the oxygen concentration in the exhaust gas passage is detected after adjusting the oxygen sensor output in the atmosphere to a predetermined value.

In recent years, various proposals have been made to prevent erroneous measurement of oxygen concentration due to deterioration of the limiting current type oxygen sensor in this type of combustion equipment. For example, Japanese Patent Laid-Open No. 6-307628 discloses an oxygen concentration. Method for applying the monitoring voltage only at the time of measurement, Japanese Patent Application Laid-Open No. 6-307627 discloses a method for correcting the output of the air supply means 2 using estimated information, and Japanese Patent Application Laid-Open No. 7-27334 discloses detection of combustion of a frame rod or the like. There is a method of correcting the air-fuel ratio target value by using the section. Regarding the limiting current type oxygen sensor itself,
Japanese Patent Application Laid-Open No. 7-55760 proposes a method of inspecting deterioration over time by applying a voltage at a specific speed.

[0005]

However, in the case of the conventionally proposed technique, since the limit current type oxygen sensor is verified whether it is normal or abnormal, the limit current in the atmosphere is exceeded. When the oxygen sensor does not work normally when the combustion voltage value is applied, this verification method erroneously determines that the control side is normal even if the limiting current oxygen sensor makes an erroneous measurement. Therefore, when the limiting current type oxygen sensor is used to control the oxygen concentration in the combustion exhaust gas to be constant, there is a problem that incomplete combustion occurs when the limiting current type oxygen sensor makes an erroneous measurement. The reason for this is that if the limiting current type oxygen sensor makes an erroneous measurement, the sensor output will be the same, but the oxygen concentration in the combustion exhaust gas will be a different concentration, so originally it should be controlled in the region where good combustion is obtained,
This is because the control is performed in the incomplete combustion region.

On the other hand, in the case of the proposal using a combustion detection unit such as a flame rod for the control by the limiting current type oxygen sensor,
If the flame rod signal value becomes small due to the deterioration of the material of the flame rod due to the use of combustion equipment,
Although the control by the limiting current type oxygen sensor is normal, the flame current signal has a value different from the preset value stored in advance, and the combustion device judges that incomplete combustion has occurred and stops the operation. This is because the controlled oxygen concentration by the limiting current type oxygen sensor exists in the immediate vicinity of the oxygen concentration corresponding to the threshold value of the flame current signal, so if there is deterioration of the material of the flame rod, the flame current signal at this controlled oxygen concentration This is because the value becomes smaller accordingly. Therefore, the proposed combustion device cannot be used immediately and has a problem that the life is extremely short. In addition, since this proposal constantly verifies the flame current signal value, if the flame current signal accidentally becomes a value different from the preset value during the control by the limiting current type oxygen sensor, the combustion equipment Had an adverse effect of judging that incomplete combustion had occurred and stopping the operation.

The present invention solves the above-mentioned conventional problems, and in order to burn without causing incomplete combustion, a combustion device having means for verifying whether or not the sensor output of the limiting current type oxygen sensor is normal. The purpose is to provide.

[0008]

In order to solve the above problems, a combustion device having an air-fuel ratio control means of the present invention is exposed to the atmosphere by applying a limiting current type oxygen sensor at a combustion voltage value during non-combustion. A sensor output detecting means for measuring the sensor output A at the time, and an applied voltage for comparing the sensor output A measured by the sensor output detecting means with a prestored threshold value E and determining an applied voltage value based on the comparison value. Deciding means, voltage changing means for changing the voltage applied by the element driving DC power supply to the applied voltage decided by the applied voltage deciding means, and limiting voltage type oxygen sensor A sensor correction output detecting means for measuring the sensor output B when the value is applied in the atmosphere, a sensor output B measured by the sensor correction output detecting means, and a sensor output A measured by the sensor output detecting means. An air-fuel ratio target based on the limiting current characteristic judging means for comparing and judging the limiting current characteristic and the sensor output B measured by the sensor correction output detecting means which operates when the limiting current characteristic is judged to be the limiting current. The air-fuel ratio target value correction means for correcting the air-fuel ratio target value set by the value setting means is provided.

Further, in order to solve the above-mentioned problems, in the combustion equipment having the air-fuel ratio control means of the present invention, the sensor output A when the limiting current type oxygen sensor is applied at the combustion voltage value at the time of non-combustion and exposed to the atmosphere When the sensor output detecting means for measuring, the voltage changing means for increasing the voltage applied by the element driving DC power supply, and the limiting current type oxygen sensor are applied with the voltage value changed by the voltage changing means and exposed to the atmosphere A sensor correction output detecting means for measuring the sensor output B, a sensor output B measured by the sensor output detecting means and a sensor output A measured by the sensor output detecting means are compared to determine a limit current characteristic. The air which is set by the air-fuel ratio target value setting means on the basis of the sensor output B measured by the sensor correction output detection means which is activated when it is determined to be the limit current by the determination means and the limit current property determination It has a structure obtained by applying the air-fuel ratio target value correcting means for correcting a ratio target value.

Further, in order to solve the above-mentioned problems, the combustion equipment having the air-fuel ratio control means of the present invention comprises a voltage changing means for increasing the voltage applied by the element driving DC power supply and a limiting current type oxygen sensor at the time of non-combustion. The sensor correction output detecting means for measuring the sensor output B when the warm-up is started by the voltage changing means at a voltage value higher than the combustion voltage value and exposed to the atmosphere, and the sensor output B measured by the sensor correction output detecting means are started at the time of starting. Limiting current characteristic judging means (II) for judging the limiting current characteristic by overshooting, and sensor measured by the sensor correction output detecting means which is activated when the limiting current characteristic judgment (II) judges that the limiting current characteristic An air-fuel ratio target value correction means for correcting the air-fuel ratio target value set by the air-fuel ratio target value setting means based on the output B is provided.

Further, in order to solve the above problems, the combustion device having the air-fuel ratio control means of the present invention has a sensor output A when a limiting current type oxygen sensor is applied at a combustion voltage value and exposed to the atmosphere during non-combustion. A sensor output detecting means for measuring the applied voltage, an applied voltage determining means for comparing the sensor output A measured by the sensor output detecting means with a prestored threshold value E, and determining an applied voltage value based on the comparison value. The voltage changing means for increasing the voltage applied by the element driving DC power supply to the applied voltage determined by the voltage determining means, and the limiting current type oxygen sensor at the time of non-combustion, the voltage changing means for increasing the voltage higher than the combustion voltage The sensor correction output detection means for measuring the sensor output B when warmed up by the value and exposed to the atmosphere, and the sensor output B measured by the sensor correction output detection means overshoot at the time of startup. Based on the sensor output B measured by the sensor correction output detection means that operates when the current limit is determined by the current limit determination means (II) and the current limit determination (II). And an air-fuel ratio target value correction means for correcting the air-fuel ratio target value set by the air-fuel ratio target value setting means.

Further, in order to solve the above problems, in the combustion equipment having the air-fuel ratio control means of the present invention, the sensor output A when the limiting current type oxygen sensor is applied at the combustion voltage value at the time of non-combustion and exposed to the atmosphere The sensor output detecting means for measuring, the sensor output good / bad test means for comparing the magnitude of the sensor output A measured by the sensor output detecting means with the prestored upper limit value E1 and lower limit value E2, and the sensor output good / bad detection means. When the value E1 or more or less than the value E2, an alarm generating means for issuing an alarm is provided.

Further, in order to solve the above-mentioned problems, the combustion apparatus having the air-fuel ratio control means of the present invention controls either the fuel supply means or the air supply means in a state where the control by the air-fuel ratio control means is released. And an abnormal output detecting means for measuring the sensor output Z from the limiting current type oxygen sensor in the combustion state by the abnormality detecting setting means, and an abnormal output An output abnormality detecting means for comparing the sensor output Z measured by the detecting means with the upper limit value H1 and the lower limit value H2 stored in advance and a sensor output Z from the limiting current type oxygen sensor by the output abnormality detecting means. When the value is equal to or more than H1 or less than the value H2, an alarm generating means for issuing an alarm is provided.

[0014]

Since the present invention is configured as described above, the voltage value when operating the limiting current type oxygen sensor at a voltage value higher than the combustion voltage value in the atmosphere is set to the optimum value, so that the sensor output B can be output in a short time. Since it is determined whether the sensor output B has the limiting current property, the accuracy is high. Since the air-fuel ratio target value is corrected based on the sensor output B, the correct air-fuel ratio target value is always obtained. Therefore, the air-fuel ratio can always be controlled with the correct oxygen concentration.

Further, since the present invention is configured as described above, it is possible to judge whether the sensor output B when operating the limiting current type oxygen sensor at a voltage value higher than the combustion voltage value in the atmosphere has the limiting current characteristic. Since the air-fuel ratio target value is corrected based on the sensor output B with high accuracy, the correct air-fuel ratio target value can always be obtained. Therefore, the air-fuel ratio can always be controlled with the correct oxygen concentration.

Since the present invention has the above-mentioned structure, it is determined whether the sensor output B has the limiting current characteristic due to overshoot when the limiting current type oxygen sensor is operated at a voltage value higher than the combustion voltage value in the atmosphere. Therefore, the accuracy of the sensor output B is high. Since the air-fuel ratio target value is corrected based on the sensor output B, the correct air-fuel ratio target value can be obtained.
Therefore, the air-fuel ratio can always be controlled with the correct oxygen concentration.

Further, since the present invention is configured as described above, the voltage value when operating the limiting current type oxygen sensor at a voltage value higher than the combustion voltage value in the atmosphere is set to an optimum value, so that the sensor output can be output in a short time. B is obtained, it is determined whether the sensor output B has the limiting current characteristic due to overshoot, and the accuracy of the sensor output B is high. Since the air-fuel ratio target value is corrected based on the sensor output B, the correct air-fuel ratio target is always obtained. The value is obtained. Therefore, the air-fuel ratio can always be controlled with the correct oxygen concentration.

Further, since the present invention has the above-mentioned structure, the sensor output A when the limiting current type oxygen sensor is operated at the combustion voltage value in the atmosphere is judged to be larger or smaller than the upper limit value E1 and the lower limit value E2 stored in advance. Therefore, the life of the limiting current type oxygen sensor can be determined. Therefore, it is possible to prevent the air-fuel ratio control with an incorrect oxygen concentration.

Further, since the present invention is configured as described above, the sensor output Z of the limiting current type oxygen sensor in the combustion state in which the oxygen concentration in the exhaust gas is increased is judged to be larger or smaller than the upper limit value H1 and the lower limit value H2 stored in advance. The failure of the limiting current type oxygen sensor can be determined. Therefore, it is possible to prevent the air-fuel ratio control with an incorrect oxygen concentration.

[0020]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a block diagram of a combustion device which is an embodiment of the present invention. 1 is a fuel supply means for supplying fuel,
Reference numeral 2 is an air supply means for supplying air, and 3 is a combustion section for mixing fuel with air and burning it. Reference numeral 4 denotes an exhaust gas passage through which combustion exhaust gas passes, and a limiting current type oxygen sensor 5 is arranged therein. The limiting current type oxygen sensor 5 has a closed circuit configured by an element driving DC power source 6 for applying a voltage to its electrode (not shown) and a current detecting means 7 for obtaining a sensor output. Reference numeral 8 denotes an air-fuel ratio control means, which controls either one of the fuel supply means 1 and the air supply means 2 based on the sensor output from the current detection means 7 so that the air-fuel ratio target value is reached. Reference numeral 9 is an air-fuel ratio target value setting means,
The signal of the set air-fuel ratio target value is emitted.

Reference numeral 10 denotes a sensor output detecting means, which measures the sensor output A when the limiting current type oxygen sensor 5 is operated at the combustion voltage after the combustion is stopped and exposed to the atmosphere. Reference numeral 11 denotes an applied voltage determination means, which compares the sensor output A measured by the sensor output detection means 10 with a prestored threshold value E and determines the applied voltage value based on the comparison value. Reference numeral 12 is a voltage changing means, which changes the voltage applied by the element driving DC power supply 6 to a high value in order to make the applied voltage determined by the applied voltage determining means 11.

Reference numeral 13 is a sensor correction output detecting means, which operates the limiting current type oxygen sensor 5 in the atmosphere at a voltage value raised by the voltage changing means 12, and measures the sensor output B at that time. Reference numeral 14 is a limiting current characteristic determining means, which compares the sensor output B measured by the sensor correction output detecting means 13 with the sensor output A measured by the sensor output detecting means 10,
Determine the limiting current property. Reference numeral 15 denotes an air-fuel ratio target value correction means, which operates when the limiting current property determination 14 determines that the current is a limit current, and based on the sensor output B measured by the sensor correction output verification means 15, an air-fuel ratio target value. The air-fuel ratio target value set in the setting means 9 is corrected.

A heating DC power source 16 is a power source for heating the limiting current type oxygen sensor 5 to a predetermined temperature.

The sensor output is basically generated by the current detecting means 7. Therefore, the sensor output detection means 10 for measuring the sensor output A and the sensor correction output detection means 13 for measuring the sensor output B have sensor output values A and B at respective voltage values in the atmosphere generated by the current detection means 7. Is a means for measuring (reading). Hereinafter, various kinds of output detecting means of the same kind will be expressed as means for measuring (reading) various sensor output values generated by the current detecting means 7.

FIG. 2 is a flow chart of the control flow of the combustion equipment according to the first embodiment of the present invention. It starts when the combustion stops and the atmosphere flows in, and the limiting current type oxygen sensor operated at the combustion voltage value is exposed to the atmosphere. First, in step 1, the limiting current type oxygen sensor is exposed to the atmosphere for a predetermined time in an operating state. After a lapse of a predetermined time, in step 2, the sensor output A of the limiting current type oxygen sensor in the atmosphere A
Read. In step 3, sensor output A in the atmosphere
And the threshold value E stored in advance are compared, and the applied voltage is determined according to the magnitude of the sensor output A and the threshold value E. In step 4, the voltage value applied to the limiting current type oxygen sensor is changed to a high value. In step 5, the applied voltage is changed and then exposed to the atmosphere for a predetermined time. In step 6, the sensor output B in the atmosphere of the limiting current type oxygen sensor with the applied voltage changed is read. In step 7, the sensor output A in the applied voltage state at the time of combustion is compared with the sensor output B in which the applied voltage is changed to a high value, and it is determined whether or not the current is the limit current. When it is determined that the current is the limit current, the routine proceeds to step 8, where the air-fuel ratio target value is corrected based on the sensor output B. In step 9, the corrected new air-fuel ratio target value is set. On the other hand, if it is determined that the current is not the limit current, the process proceeds to step 10 to issue an alarm.

FIG. 3 is a partially cutaway perspective view of an element used in a limiting current type oxygen sensor of a combustion device according to an embodiment of the present invention. Reference numeral 30 denotes a plate-shaped oxygen ion conductive solid electrolyte, and a cathode electrode 31a is formed on one side and an anode electrode 31b (not shown) is formed on the other surface side. On one upper side of the solid electrolyte plate 30, a single spiral glass film 32 is arranged which surrounds the cathode electrode 31a and is arranged so that the starting end and the terminating end are spaced from each other. Then, a sealing plate 33 is arranged on the spiral glass film 32 to form a diffusion limiting body with the spiral glass film 32 and the sealing plate 33, and the oxygen diffusion holes 34 serve as partition walls of the spiral glass film 32 facing each other. It was formed in a spiral type space surrounded by the solid electrolyte 30 and the seal plate 33. Oxygen diffuses into the cathode electrode 31a via the oxygen diffusion hole 34. A heating unit 35 is arranged above the seal plate 33. This element is used as a limiting current type oxygen sensor by surrounding it with a heat insulating material and further surrounding this heat insulating material with a stainless wire mesh case.

Next, a description will be given based on a concrete experimental example.
The materials used for the device are as follows. The solid electrolyte plate 30 is a sintered plate of stabilized zirconia (hereinafter, referred to as ZrO ₂ .Y ₂ O ₃ ) to which 8 mol% of Y ₂ O ₃ is added, the cathode electrode 31a and the anode electrode 32b are platinum and bismuth oxide is 3 wt%. Mixed platinum electrode, glass as spiral type glass film 32 (coefficient of thermal expansion is the same as ZrO ₂ · Y ₂ O ₃ and contains a small amount of heat resistant particles having a predetermined particle size), seal plate 33 is forsterite, heating part 35 A platinum heater was used as.

The cathode electrode and the anode electrode are platinum electrodes in which platinum is mixed with 1 to 5 wt% of bismuth oxide. If bismuth oxide is 1 wt% or less, no characteristics can be obtained, and if it is 5 wt% or more, durability is improved. The composition was determined from the viewpoint of badness.

The manufacturing method will be described. First, the cathode electrode 31a and the anode electrode 31b are connected to the solid electrolyte plate 30.
It was formed by a process of thick film printing on the substrate and then firing. After that, the spiral glass film 32 was further formed by a process of thick film printing on the solid electrolyte plate 30 and then baking. On the other hand, the heating portion 35 was formed on the seal plate 33 by thick film printing and then firing. Next, the spiral glass film 32 on the solid electrolyte plate 30 and the seal plate 33 were laminated and heated and melted to form the oxygen diffusion holes 34. And the lead wire 36a
・ It is completed by attaching 36b using a fixing material. The dimensions of the device are 10 × 10 × 1.0 mm.

The device was wrapped with a heat insulating material from the surroundings, and this heat insulating material was further housed in a case made of stainless steel wire mesh. Then, a drive circuit using a resistance of 100Ω was connected as the current detection means 7, the voltage value at both ends of the resistance was measured, and the sensor output was obtained at that voltage value. The current was calculated by dividing the voltage across the resistor by 100Ω.

FIG. 4 shows the voltage-current characteristics of the limiting current type oxygen sensor in the atmosphere of 20.6% oxygen.

The initial use product had an ionic current characteristic in which the current increased as the voltage increased at a voltage of 0.6 V or less, but at a voltage of 0.6 V or more, the current showed a constant value regardless of the voltage. It was a current characteristic. When using the limiting current type oxygen sensor in combustion exhaust gas, it is necessary to set the applied voltage to 1.0 V or less in order to avoid the influence of moisture in the exhaust gas. Therefore, when the applied voltage is set to the combustion voltage value of 1.0 V and used in the combustion exhaust gas, the current (sensor output) of the initial use product becomes E in the atmosphere where the combustion is stopped and the atmosphere flows. Therefore, the value E is set as a threshold value stored in advance.

On the other hand, in the durability test product, the limiting current characteristic is obtained at a voltage of 1.2 V or more due to deterioration of the platinum electrode. Therefore, when the applied voltage is set to the combustion voltage value of 1.0 V and used in the combustion exhaust gas, the sensor output of the endurance test product becomes A and the limiting current characteristic becomes I can't get it. Therefore, the applied voltage must be set to 1.2 V or more in order to obtain the limiting current characteristic that the oxygen concentration can be accurately measured in the atmosphere. Therefore, when the applied voltage is changed and set to the correction voltage, the limiting current characteristic is obtained and the sensor output becomes B. This sensor output B is a constant value at any voltage value in the limit current region.

FIG. 5 shows the oxygen concentration-current characteristics of the limiting current type oxygen sensor. In the initial use product, the current (sensor output) at a combustion voltage of 1.0 V has a linear relationship with the oxygen concentration in all regions. The sensor output in the atmosphere (oxygen concentration 20.6%) is E, and when the oxygen concentration for air-fuel ratio control is 9.0%, the corresponding target value is X. Since the sensor output has a nearly linear relationship with the oxygen concentration in all regions, the target value X
Is 0.44 times E.

The endurance test product has a linear relationship with the sensor output at a combustion voltage of 1.0 V up to an oxygen concentration of about 17%, and does not change with the oxygen concentration thereafter and has a constant value. for that reason,
The oxygen concentration cannot be measured with the sensor output A in the atmosphere (oxygen concentration 20.6%). However, the sensor output at the correction voltage with a high voltage value has a linear relationship with the oxygen concentration in all regions, and the sensor output B is obtained in the atmosphere.

The sensor output in the atmosphere (oxygen concentration 20.6%) is B, and the oxygen concentration α for controlling the air-fuel ratio is 9.0%.
Then, the corresponding target value becomes Y. The target value Y is 0.44 times the sensor output B because the sensor output at the correction voltage value has a substantially linear relationship with the oxygen concentration in the entire region. This 0.44 times the value of 9.0% of the oxygen concentration α is 20.
It is 0.44 times the value divided by 6%. From this, it is understood that when the limiting current is obtained in the atmosphere, the air-fuel ratio control target value for achieving the oxygen concentration of 9.0% is obtained by multiplying the sensor output in the atmosphere by 0.44. This makes it possible to correct the air-fuel ratio control target value.

Now, comparing the sensor output A at the voltage of 1.0 V and the sensor output B at the correction voltage, the value A is the value B.
It is about 0.82 times. Value A is about 0.82 of value B
The reason why the value is doubled is that the value B is the limiting current. On the other hand, assuming that the value B is not the limiting current, the value should be much larger than the value B, and the ratio with the value A is much smaller than the above-mentioned value. From this, by comparing the sensor output A at the combustion voltage of 1.0 V and the sensor output B at the correction voltage, it can be determined whether the value B is the limit current.

The correction voltage may be any voltage value as long as it is 1.2 V or more, but if the voltage is too high, the limiting current cannot be obtained due to the influence of electron conduction, so the upper limit value is set to 1.
8V. Moreover, it was decided that this change of the applied voltage would be performed from time to time.

Therefore, the relationship between the sensor output value A of the durable product and the sensor output value (range value) E of the initial product at the combustion voltage value, the sensor correction voltage value determined by this relationship, and the combustion voltage The relationship between the sensor output A in terms of the value and the sensor output B in the case of the correction voltage value so that it can be determined that the current is the limiting current is summarized. This relationship is shown in (Table 1).

When A / E was +1.2 or more, it was determined that the sensor was faulty. This is because 1.2 times the value of E is set as the value E1 stored in advance, and when A is equal to or larger than the value E1, it means that the sensor has failed. Also, A
When / E is 0.6 or less, it is determined that the sensor has failed. This is because 0.6 times the value of E is set as the previously stored value E2, and when A becomes a value equal to or smaller than this value E2, it means that the sensor has failed.

[0042]

[Table 1]

FIG. 6 is a block diagram of a combustion device which is a second embodiment of the present invention. The second embodiment is different from the first embodiment in that the voltage changing means 12 always operates after measuring the sensor output A, and the voltage of the element driving DC power supply 6 is always set to the stored voltage value. It is a configuration to change.

FIG. 7 is a flow chart of the control flow of the combustion equipment according to the second embodiment of the present invention. The difference from the control flow of the first embodiment is that the applied voltage is increased in step 22, which is performed immediately after reading the sensor output A in step 21. The details will be described below.

The combustion is stopped, the atmosphere is introduced, and the limiting current type oxygen sensor in the state of being operated at the time of combustion is started when the oxygen sensor is exposed to the atmosphere. First, in step 20, the limiting current type oxygen sensor is exposed to the atmosphere for a predetermined time while operating at the combustion voltage value. When a predetermined time has passed, in step 21,
The sensor output A in the atmosphere of the limiting current type oxygen sensor is read. In step 22, the voltage applied to the limiting current type oxygen sensor is changed to a high voltage. In step 23, after the applied voltage is changed, it is exposed to the atmosphere for a predetermined time. In step 24, the sensor output B in the atmosphere of the limiting current type oxygen sensor in which the applied voltage is changed to high is read. In step 25, the sensor output A at the combustion voltage is compared with the sensor output B in which the applied voltage is changed to be high, and it is determined whether or not the current is the limit current. When it is determined that the current is the limit current, the routine proceeds to step 26, where the air-fuel ratio target value is corrected based on the sensor output B, and the new air-fuel ratio target value corrected at step 27 is set. On the other hand, when it is determined that the current is not the limit current, the process proceeds to step 28 and an alarm is issued.

The voltage-current characteristics of the limiting current type oxygen sensor in the atmosphere will be described with reference to FIG. The initial product has a voltage of 0.
It is a limiting current characteristic at 6 V or higher. When used in combustion exhaust gas, it is necessary to set the applied voltage to 1.0 V or less in order to avoid the influence of moisture in exhaust gas. When the applied voltage is set to 1.0 V and used in combustion exhaust gas, the current (sensor output) of the initial product used is E in an atmosphere in which combustion has stopped and the atmosphere has flowed in, and the value E was stored in advance. It is a threshold.

On the other hand, the durability test product has a limiting current characteristic at a voltage of 1.2 V or more. Therefore, combustion voltage 1.0V
When used in combustion exhaust gas after setting to, the sensor output of the endurance test product becomes A in the atmosphere where combustion is stopped and the air flows in, and the limiting current characteristic cannot be obtained. Therefore, in order to obtain the limiting current characteristic that oxygen concentration can be correctly measured in the atmosphere, the applied voltage needs to be set to a correction voltage of 1.2 V or more, and the sensor output B can be obtained.

The oxygen concentration-current characteristics of the limiting current type oxygen sensor will be described with reference to FIG. The initial product is a burning voltage of 1.0
The current (sensor output) at V has a linear relationship with the oxygen concentration in all regions. The sensor output in the atmosphere (oxygen concentration 20.6%) is E, and the oxygen concentration for air-fuel ratio control is 9.0.
%, The corresponding target value is X. Since the sensor output has a substantially linear relationship with the oxygen concentration in all regions, the target value X is 0.44 times E.

The endurance test product had a linear relationship until the sensor output at a combustion voltage of 1.0 V up to an oxygen concentration of about 17%, and does not change with the oxygen concentration thereafter and becomes a constant value. for that reason,
The oxygen concentration cannot be measured with the sensor output A in the atmosphere (oxygen concentration 20.6%). However, the sensor output at a correction voltage (for example, 1.6 V) with a high voltage value has a linear relationship with the oxygen concentration in all regions.

The sensor output in the atmosphere (oxygen concentration 20.6%) is B, and the corresponding target value is Y when the oxygen concentration for air-fuel ratio control is 9.0%. The target value Y is 0.44 times the value B because the sensor output at the correction voltage value has a substantially linear relationship with the oxygen concentration in all regions. This 0.
44 times is 0.44 times the value obtained by dividing 9.0% of the oxygen concentration by 20.6%. From this, it is understood that when the limiting current is obtained, the air-fuel ratio control target value for achieving the oxygen concentration of 9.0% can be obtained by multiplying the sensor output in the atmosphere by 0.44. This makes it possible to correct the air-fuel ratio control target value.

Now, comparing the sensor output A at the combustion voltage of 1.0 V and the sensor output B at the correction voltage (1.6 V), the value B is the limiting current, and therefore the value A is equal to the value B. It is about 0.82 times. The reason why the value A is about 0.82 times the value B is that the value B is the limiting current. on the other hand,
Assuming that the value B is not the limiting current, the value is the value B.
It should be a much larger value, and the ratio with the value A is a much smaller value than the above value. From this, by comparing the sensor output A at the combustion voltage of 1.0 V and the sensor output B at the correction voltage (1.6 V), it can be determined whether the value B is the limit current. The correction voltage is 1.
Any voltage value may be used as long as it is 2 V or more, but if the voltage is too high, the limit current cannot be obtained due to the influence of electron conduction, so the upper limit was set to 1.8 V.

The relationship between the sensor output A of the durable product and the sensor output E of the initial product at the combustion voltage value, the changed voltage value,
In the durability test product, the relationship between the sensor output A of 1.0 V and the sensor output B after the voltage change so that it can be determined that the current is the limiting current is arranged. It is shown in (Table 2).

When A / E was +1.2 or more, it was determined that the sensor was faulty. This is because 1.2 times the value of E is set as the value E1 stored in advance, and when A is equal to or larger than the value E1, it means that the sensor has failed. Also, A
When / E is 0.6 or less, it is determined that the sensor has failed. This is because 0.6 times the value of E is set as the previously stored value E2, and when A becomes a value equal to or smaller than this value E2, it means that the sensor has failed.

[0054]

[Table 2]

FIG. 8 is a block diagram of a combustion device which is a third embodiment of the present invention. The third embodiment differs from the first embodiment in that the limiting current characteristic determining means (II) determines the limiting current characteristic based on whether the sensor output overshoots during warm-up startup. Reference numeral 13 denotes a sensor correction output detecting means, which warms up the limiting current type oxygen sensor 5 in the atmosphere with the voltage value increased by the voltage changing means 12, and measures the sensor output B at that time. Reference numeral 19 is a limiting current characteristic judging means (II), which is a sensor correction output detecting means 13
The limiting current property is judged by the overshoot of the sensor output measured in step 2 at warm-up startup. Reference numeral 15 is an air-fuel ratio target value correcting means, which operates when the limiting current property determining means (II) 19 determines that the current is the limiting current, and outputs the stable sensor output B measured by the sensor correction output detecting means 13. Based on this, the air-fuel ratio target value set in the air-fuel ratio target value setting means 9 is corrected.

FIG. 9 is a flow chart of the control flow of the combustion equipment according to the third embodiment of the present invention. The control flow of the first embodiment is different from that of the heating DC power supply and the element driving DC power supply. The details will be described below.

It starts when the combustion is stopped, the atmosphere flows in, and the limiting current type oxygen sensor is exposed to the atmosphere. First, in step 40, the operation of the heating DC power supply is stopped, and in step 41, the operation of the element driving DC power supply is stopped. After that, in step 42, the limiting current type oxygen sensor is exposed to the atmosphere for a predetermined time and its temperature is lowered to near room temperature. After a lapse of a predetermined time, in step 43, the element driving DC power supply is operated by increasing the applied voltage, and further in step 44, the heating DC power supply is operated and warmed up. Then step 4
At 5, the sensor output in the atmosphere of the limiting current type oxygen sensor is read periodically. In step 46, it is determined whether or not the sensor output overshoots during warm-up startup. When it is judged that the current is the limit current due to overshooting, step 47
Output, sensor output B when stable after being exposed to the atmosphere for a predetermined time
Read. After that, the routine proceeds to step 48, where the air-fuel ratio target value is corrected based on the sensor output B. Step 49
Then, the corrected new air-fuel ratio target value is set. On the other hand, if it is determined that the current does not overshoot and the current is not the limit current, the process proceeds to step 50 to issue an alarm.

FIG. 10 is a warm-up starting characteristic of the limiting current type oxygen sensor used in the combustion equipment according to the third embodiment of the present invention, which is obtained when the element driving DC power supply and the heating DC power supply are simultaneously operated. It is a transient change of the sensor output in the atmosphere. The non-defective product (durable product) shows a transient change in the case where the sensor output overshoots when the warm-up start is performed at the correction voltage value of 1.6 V and the limiting current characteristic is obtained. Then, the sensor output became stable after a lapse of a predetermined time, and the sensor output B when stable was read. The lifetime product (comparative product) is a transient change when the sensor output does not overshoot and the limiting current characteristic cannot be obtained.

The oxygen concentration-current characteristics of the limiting current type oxygen sensor will be described with reference to FIG. The sensor output in the atmosphere (oxygen concentration 20.6%) of a durable product capable of obtaining the limiting current characteristic is B, and when the oxygen concentration for air-fuel ratio control is 9.0%, the corresponding target value is Y. Since the sensor output at the correction voltage value has a substantially linear relationship with the oxygen concentration in all regions, the target value Y is 0.44 times B. This 0.44 times is 0.44 times the value obtained by dividing 9.0% of the oxygen concentration by 20.6%. When the limiting current is obtained from this, the sensor output B in the atmosphere is multiplied by 0.44 to obtain an oxygen concentration of 9.0.
It can be seen that the air-fuel ratio control target value for achieving the% can be obtained. This makes it possible to correct the air-fuel ratio control target value.

FIG. 11 is a block diagram of a combustion device according to a fourth embodiment of the present invention. The difference from the third embodiment is that the applied voltage value is determined from the sensor output A in the applied voltage determination means 11, and the limiting current characteristic is determined from the overshoot at the warm-up start at the determined voltage value. That is. Reference numeral 11 denotes an applied voltage determination means, which compares the sensor output A measured by the sensor output detection means 10 with a prestored threshold value E and determines the applied voltage value based on the comparison value. Reference numeral 12 is a voltage changing means, which changes the voltage applied by the element driving DC power supply 6 to a high value in order to make the applied voltage determined by the applied voltage determining means 11. Reference numeral 13 denotes a sensor correction output detecting means, which warms up the limiting current type oxygen sensor 5 in the atmosphere with the voltage value increased by the voltage changing means 12, and measures the sensor output B at that time. Reference numeral 19 denotes a limiting current characteristic determining means (II), which determines the limiting current characteristic by whether the sensor output measured by the sensor correction output detecting means 13 overshoots at the time of warm-up start. Reference numeral 15 is an air-fuel ratio target value correcting means, which is a limiting current characteristic judging means (II) 19
Is operated when it is determined to be the limit current in step S1, and the correction of the air-fuel ratio target value set in the air-fuel ratio target value setting means 9 is performed based on the stable sensor output B measured by the sensor correction output detection means 13. I do.

FIG. 12 is a flow chart of the control flow of the combustion equipment according to the fourth embodiment of the present invention. The difference from the control flow of the third embodiment is that the sensor output A in step 61.
Is read and the applied voltage is determined from the sensor output A in step 62, and then the operation of the heating DC power supply and the element driving DC power supply is stopped. It starts when the combustion stops and the atmosphere flows in, and the limiting current type oxygen sensor is exposed to the atmosphere. First step 60
Then, the limiting current type oxygen sensor is exposed to the atmosphere for a predetermined time in an operating state. When a predetermined time has elapsed, in step 61, the sensor output A of the limiting current type oxygen sensor in the atmosphere is read. In step 62, the sensor output A in the atmosphere is compared with the threshold value E stored in advance, and the applied voltage is determined according to the magnitude of the sensor output A and the threshold value E. Step 6
At step 3, the operation of the heating DC power supply is stopped, and at step 64, the operation of the element driving DC power supply is stopped. Then step 6
After a lapse of a predetermined time at 5, the limiting current type oxygen sensor is exposed to the atmosphere for a predetermined time and its temperature drops to around room temperature.
In step 66, the voltage value is increased to activate the element driving DC power supply, and in step 67, the heating DC power supply is activated to start warming up. Then, in step 68, the sensor output of the limiting current type oxygen sensor in the atmosphere is periodically read. In step 69, it is determined whether or not the sensor output overshoots during warm-up startup. When it is determined that the current is overshooting and the current is the limiting current, the routine proceeds to step 70, where the sensor output B is read when it is exposed to the atmosphere for a predetermined time and stable.
After that, the routine proceeds to step 71, where the air-fuel ratio target value is corrected based on the sensor output B. In step 72, the corrected new air-fuel ratio target value is set. On the other hand, when it is determined that the current does not overshoot and the current is not the limit current, the process proceeds to step 73 to issue an alarm.

The warm-up starting characteristic of the limiting current type oxygen sensor used in the combustion equipment according to the fourth embodiment of the present invention will be described with reference to FIG. This is a transient change in the sensor output in the atmosphere when the element driving DC power supply and the heating DC power supply operate simultaneously. The non-defective product (durable product) shows a transient change when the sensor output overshoots when the warm-up start is performed with the correction voltage value and the limiting current characteristic is obtained. Then, the sensor output became stable after a lapse of a predetermined time, and the sensor output B when stable was read. The lifetime product (comparative product) is a transient change when the sensor output does not overshoot and the limiting current characteristic cannot be obtained.

The oxygen concentration-current characteristics of the limiting current type oxygen sensor will be described with reference to FIG. The sensor output in the atmosphere (oxygen concentration 20.6%) of a durable product capable of obtaining the limiting current characteristic is B, and when the oxygen concentration for air-fuel ratio control is 9.0%, the corresponding target value is Y. The target value Y is 0.44 times the sensor output B because the sensor output at the correction voltage value has a substantially linear relationship with the oxygen concentration in the entire region. This 0.44
Double is the value obtained by dividing 9.0% of the oxygen concentration by 20.6%. When the limiting current is obtained from this, the sensor output B in the atmosphere is multiplied by 0.44 to obtain an oxygen concentration of 9.0%.
It can be seen that the air-fuel ratio control target value for achieving

The relationship between the sensor output value A of the durable product and the sensor output value (zone value) E of the initial product in the voltage value for combustion and the sensor correction voltage value determined by this relationship were summarized. This relationship is shown in (Table 3).

The upper limit of the correction voltage is set to 1.8 V because if the voltage is too high, the limiting current cannot be obtained due to the influence of electron conduction.

When A / E was +1.2 or more, it was determined that the sensor was faulty. This is because 1.2 times the value of E is set as the value E1 stored in advance, and when A is equal to or larger than the value E1, it means that the sensor has failed. Also, A
When / E is 0.6 or less, it is determined that the sensor has failed. This is because 0.6 times the value of E is set as the previously stored value E2, and when A becomes a value equal to or smaller than this value E2, it means that the sensor has failed.

[0067]

[Table 3]

FIG. 13 is a block diagram of a combustion device which is a fifth embodiment of the present invention. The difference from the first to fourth embodiments is that the configuration determines whether the air-fuel ratio control is possible from the value of the sensor output A in the atmosphere. Reference numeral 18 denotes a sensor output quality checking means, which compares whether the sensor output A is less than a prestored value E1 and is equal to or more than a value E2. The pre-stored value E1 is larger than the pre-stored threshold value E, and the pre-stored value E2 is smaller than the pre-stored threshold value E. Sensor output verification means 10
If it is determined that the sensor output A is less than the pre-stored value E1 and is equal to or more than the value E2, the air-fuel ratio control means 8 performs the air-fuel ratio control. On the other hand, when the sensor output verification unit determines that the sensor output A is greater than or equal to the value E1 stored in advance or less than the value E2, the alarm generation unit 17 issues an alarm.

FIG. 14 is a flowchart showing the control flow of the combustion equipment according to the fifth embodiment of the present invention. It starts from the time when the combustion is stopped, the atmosphere flows in, and the limiting current type oxygen sensor in the state of being operated at the voltage value for combustion is exposed to the atmosphere. First, at step 80, the limiting current type oxygen sensor is exposed to the atmosphere for a predetermined time in an operating state. When a predetermined time has passed, in step 81, the sensor output A of the limiting current type oxygen sensor in the atmosphere is read. In step 82, the sensor output A in the atmosphere is compared with the value E1 stored in advance. If the sensor output A is less than the value E1, the process proceeds to step 83, and if the sensor output A is the value E1 or more, the process proceeds to step 85. . In step 83, the sensor output A in the atmosphere is compared with the value E2 stored in advance. If the sensor output A is the value E2 or more, the process proceeds to step 84, and the sensor output A is the value E2.
If it is 2 or less, the process proceeds to step 85. In step 84, it is judged that the air-fuel ratio control is possible, and in step 85, an alarm is issued.

FIG. 15 is an effect characteristic diagram of the combustion equipment according to the fifth embodiment of the present invention. In the initial use product, a limiting current is obtained at a voltage of 0.6 V or higher in the atmosphere. When used in combustion exhaust gas, it is necessary to set the applied voltage to 1.0 V or less in order to avoid the influence of moisture in exhaust gas. Therefore, when the applied voltage is set to 1.0 V, the current (sensor output) becomes E in the atmosphere. Therefore, the value E is set as a threshold value stored in advance. Further, the limiting current is obtained even when oxygen is 9% in the combustion atmosphere, and the current (sensor output) at the applied voltage of 1.0 V becomes X.

On the other hand, in the durability test product, the current decreases and the limiting current characteristic is obtained at a voltage of 1.2 V or more in the atmosphere. Therefore, when the applied voltage is set to 1.0 V, the sensor output becomes A in the atmosphere and the limiting current characteristic cannot be obtained. However, a limiting current is obtained when oxygen is 9% in a combustion atmosphere, and the sensor output is X at an applied voltage of 1.0V.

From the characteristics of the limiting current, the applied voltage 1.0V
With the setting, when the sensor output in the atmosphere is X or more, the limiting current at oxygen 9% is obtained. From this,
The sensor output A in the atmosphere is a value larger than X, E2
With the above, the limiting current at 9% oxygen can be obtained. On the other hand, when the size of the oxygen diffusion hole formed to obtain the limiting current is greatly expanded, the sensor output increases, and in the worst case, the limiting current cannot be obtained. Therefore,
If the sensor output in the atmosphere is set to E1 which is a value larger than the threshold value E stored in advance, the worst case test in which the limiting current cannot be obtained can be performed.

FIG. 16 is a block diagram of a combustion device which is a sixth embodiment of the present invention. The difference from the first to fifth embodiments is that the air-fuel ratio control is canceled to temporarily deteriorate the combustion, and the quality of the combustion equipment is judged from the obtained sensor output Z.

Numeral 20 is an abnormality detecting setting means, which makes the combustion worse by the control of either the fuel supply means 1 or the air supply means 2 when the control by the air-fuel ratio control means 8 is released. . Reference numeral 21 denotes an abnormal output detection means, which measures the sensor output Z obtained from the limiting current type oxygen sensor 5 in the combustion state in the abnormality detection setting means 20. Reference numeral 22 denotes an abnormal output verification means, which is a sensor output Z measured by the abnormal output detection means 21 and a value H stored in advance.
1 and the value H2 are compared. Reference numeral 17 denotes an alarm generating means, which issues an alarm when the sensor output Z obtained by the abnormal output detecting means 21 is not less than the value H1 or less than the value H2. When the abnormality detection setting means 20 is driven for a short time immediately after combustion or immediately before combustion is stopped, there is an advantage that the combustion equipment operates effectively.

FIG. 17 is a flowchart showing the control flow of the combustion equipment according to the sixth embodiment of the present invention. It starts when the limiting current type oxygen sensor in the state of being burned and operated at the voltage value for combustion is exposed to the combustion exhaust gas. First, at step 100, the air-fuel ratio control is released. Then, in step 101, the combustion is changed to the abnormality detecting setting means, and the combustion is performed at an oxygen concentration higher than the oxygen concentration α corresponding to the target value X by the control of either the fuel supply means or the air supply means. After a predetermined time has elapsed in step 102, the sensor output Z of the limiting current type oxygen sensor in the exhaust gas is read in step 103. In step 104, the sensor output Z in the exhaust gas and the previously stored value H1
If the sensor output Z is less than the value H1, the process proceeds to step 105, and if the sensor output Z is more than the value H1, the process proceeds to step 107. In step 105, the sensor output Z
Is compared with a previously stored value H2. If the sensor output Z is equal to or more than the value H2, the process proceeds to step 106, and if the sensor output Z is less than or equal to the value H2, the process proceeds to step 107. Step 1
In step 106, it is determined that the air-fuel ratio control is possible, and in step 107, an alarm is issued.

FIG. 18 is an effect characteristic diagram of the combustion device according to the sixth embodiment of the present invention. (a) is the relationship between the oxygen concentration in the combustion exhaust gas and the sensor output, and (b) is the relationship between the oxygen concentration in the combustion exhaust gas and the carbon monoxide concentration in the exhaust gas.

In the initial product, when the air-fuel ratio control target value is X, the corresponding oxygen concentration is α. When the combustion is performed at an oxygen concentration higher than the oxygen concentration α corresponding to the air-fuel ratio control target value X for detecting an abnormality, the obtained sensor output Z becomes a value larger than the target value X. Therefore, if a lower limit value H2 that is larger than the target value X is set, the sensor output Z will have a lower limit value H
It becomes a value larger than 2. On the other hand, the sensor output Z is the upper limit value H
When it is 1, the oxygen concentration becomes η, and incomplete combustion occurs when the oxygen concentration is η or more, and a large amount of carbon monoxide is generated. Therefore, when the sensor output Z exceeds the upper limit value H1, an alarm is issued to notify the abnormality.

When the air-fuel ratio control target value is X, the corresponding oxygen concentration of the durability test product (characteristic deterioration product) is β, and the product burns at a concentration different from the original oxygen concentration α, causing a slight incomplete combustion. . When the combustion is carried out at an oxygen concentration higher than the oxygen concentration α corresponding to the target value X for detecting an abnormality, this concentration is lower than the oxygen concentration ε corresponding to the lower limit value H2, so the obtained sensor output Z is The value is smaller than the lower limit value H2. Therefore, an alarm is issued and the abnormality is found. In particular, if the lower limit value H2 is set to the same value as the target value X, the abnormality becomes apparent.

The endurance test product (characteristic-enhanced product) has a corresponding oxygen concentration of γ when the air-fuel ratio control target value is X, and burns at a lower concentration than the original oxygen concentration α, but is normal combustion.
However, when the combustion is performed at an oxygen concentration higher than the oxygen concentration α corresponding to the target value X for detecting an abnormality, this concentration is higher than the oxygen concentration ζ corresponding to the lower limit value H2.
The obtained sensor output Z becomes a value larger than the lower limit value H2. However, since the concentration is higher than the oxygen concentration ι corresponding to the upper limit value H1, the obtained sensor output Z becomes a value larger than the upper limit value H1. Therefore, an alarm is issued and the abnormality is found.

As described above, when the abnormality detecting setting means 20 is used to release the air-fuel ratio control and to burn at an oxygen concentration higher than the oxygen concentration α corresponding to the air-fuel ratio control target value X, a durability test product is obtained. It is possible to discriminate the characteristic deterioration or characteristic increase. Therefore, due to changes in the characteristics of the limiting current type oxygen sensor,
It is possible to prevent combustion from occurring at an oxygen concentration different from the oxygen concentration α corresponding to the air-fuel ratio control target value X. Further, when the sensor output Z becomes a value smaller than the lower limit value H2, if the target value of the air-fuel ratio control is changed to a value smaller than X, even if the characteristics of the endurance test product are deteriorated, the original oxygen concentration α is approximated. It can burn at oxygen concentrations. Further, when the sensor output Z becomes a value larger than the upper limit value H1, if the air-fuel ratio control target value is changed to a value larger than X, even if the characteristics of the endurance test product increase, the oxygen concentration will be close to the original oxygen concentration α. It can burn at oxygen concentrations. Target value setting means 23 having this function
Was added.

In the combustion equipment of the present invention, the sensor output detection means 10 for measuring the sensor output A when the limiting current type oxygen sensor 5 is activated and exposed to the atmosphere after the combustion is stopped, and the sensor output A are stored in advance. A configuration is further provided in which a sensor output quality detecting means 18 for comparing the upper limit value E1 and the lower limit value E2 with each other and an alarm generating means 17 for issuing an alarm when the sensor output A is equal to or more than the upper limit value E1 or less than the lower limit value E2 are provided. Is also possible. As a result, the life of the limiting current type oxygen sensor can be determined, and a combustion device that does not cause incomplete combustion can be obtained. In particular, when the oxygen sensor is operated at the combustion voltage value immediately after the combustion is stopped and the sensor output A when exposed to the atmosphere is measured, there is an advantage that the combustion device operates effectively. In addition,
The value E1 stored in advance is a value larger than the sensor output E of the initial product in use when the combustion voltage value is applied and exposed to the atmosphere. The value E2 stored in advance is the sensor output E
It is smaller and larger than the air-fuel ratio target value.

Further, in the combustion apparatus of the present invention, when the limiting current property judging means 14 or the limiting current property judging means (II) 19 judges that the limiting current cannot be obtained, the combustor is activated to generate an alarm. A configuration provided with the means 17 is also possible. As a result, the life of the limiting current type oxygen sensor can be determined, and a combustion device that does not cause incomplete combustion can be obtained. When an alarm is issued by the alarm generating means 17,
If the combustion stopping means 25 for stopping the combustion and the air-fuel ratio control releasing means 24 for canceling the air-fuel ratio control are further used as required, a more reliable combustion device can be obtained. In particular, if the combustion stopping means 25 is activated by a plurality of alarms, the reliability of the combustion equipment will be further improved.

[0083]

【The invention's effect】

(1) The present invention operates the limiting current type oxygen sensor in the atmosphere at a voltage value that is higher than the combustion voltage value by an optimum value, and determines whether the obtained sensor output B has the limiting current property or not. The combustion device is provided with means for correcting the air-fuel ratio target value based on the output B. Therefore, a sensor output B can be obtained in a short time, and a highly accurate correct oxygen concentration can always be obtained, and a long-life combustion device that does not cause incomplete combustion can be obtained.

(2) In the present invention, the limiting current type oxygen sensor is operated in the atmosphere at a voltage value higher than the combustion voltage value, and it is judged whether the obtained sensor output B has the limiting current property or not. The combustion device is provided with a means for correcting the air-fuel ratio target value based on B. Therefore, a highly accurate correct oxygen concentration can always be obtained, and a long-life combustion device that does not cause incomplete combustion can be obtained.

(3) In the present invention, the limiting current type oxygen sensor is operated in the atmosphere at a voltage value higher than the combustion voltage value, and whether or not the obtained sensor output B has the limiting current property is over-shut. The combustion device is provided with a means for correcting the air-fuel ratio target value based on the sensor output B after the judgment. Therefore, a highly accurate correct oxygen concentration can always be obtained, and a long-life combustion device that does not cause incomplete combustion can be obtained.

(4) In the present invention, the limiting current type oxygen sensor is operated in the atmosphere at a voltage value which is higher than the combustion voltage value by an optimum value, and whether the obtained sensor output B has the limiting current characteristic is determined. The combustion device is provided with a means for correcting the target value of the air-fuel ratio based on the sensor output B after the judgment of the overshoot. Therefore, the sensor output B can be obtained in a short time, and the correct oxygen concentration with high accuracy can always be obtained,
A long-life combustion device that does not cause incomplete combustion can be obtained.

(5) According to the present invention, it is judged whether the sensor output A when the limiting current type oxygen sensor is operated at the combustion voltage value in the atmosphere is larger or smaller than the upper limit value E1 and the lower limit value E2 stored in advance. It is a combustion device provided with means. Therefore, the life of the limiting current type oxygen sensor can be determined, and a combustion device that does not cause incomplete combustion can be obtained.

(6) The present invention provides means for judging whether the sensor output Z of the limiting current type oxygen sensor in the combustion state in which the oxygen concentration in the exhaust gas is increased is larger than the upper limit value H1 and the lower limit value H2 stored in advance. It is a burning equipment. Therefore, the life of the limiting current type oxygen sensor can be determined, and a combustion device that does not cause incomplete combustion can be obtained.

[Brief description of drawings]

FIG. 1 is a block diagram of a combustion device that is a first embodiment of the present invention.

FIG. 2 is a flow chart of a control flow of the combustion device according to the first embodiment of the present invention.

FIG. 3 is a partially cutaway perspective view of an element of a limiting current type oxygen sensor used in a combustion device according to an embodiment of the present invention.

FIG. 4 is a characteristic characteristic diagram of a limiting current type oxygen sensor used in a combustion device according to an embodiment of the present invention.

FIG. 5 is a characteristic diagram of a limiting current type oxygen sensor used in a combustion device according to an embodiment of the present invention.

FIG. 6 is a block diagram of a combustion device according to a second embodiment of the present invention.

FIG. 7 is a flow chart of a control flow of the combustion device according to the second embodiment of the present invention.

FIG. 8 is a block diagram of a combustion device that is a third embodiment of the present invention.

FIG. 9 is a flow chart of the control flow of the combustion device according to the third embodiment of the present invention.

FIG. 10 is a characteristic diagram of a limiting current type oxygen sensor used in a combustion device according to a third embodiment and a fourth embodiment of the present invention.

FIG. 11 is a block diagram of a combustion device according to a fourth embodiment of the present invention.

FIG. 12 is a flow chart of the control flow of the combustion device according to the fourth embodiment of the present invention.

FIG. 13 is a block diagram of a combustion device according to a fifth embodiment of the present invention.

FIG. 14 is a flowchart of a control flow of a combustion device that is a fifth embodiment of the present invention.

FIG. 15 is a characteristic diagram of a limiting current type oxygen sensor used in a combustion device according to a fifth embodiment of the present invention.

FIG. 16 is a block diagram of a combustion device according to a sixth embodiment of the present invention.

FIG. 17 is a flowchart of the control flow of the combustion device according to the sixth embodiment of the present invention.

FIG. 18 (a) is a characteristic diagram of a limiting current type oxygen sensor used in a combustion device according to a sixth embodiment of the present invention. (B) Oxygen concentration-monoxide of the combustion device according to the sixth embodiment of the present invention. Carbon generation characteristic diagram

FIG. 19 is a block diagram of a conventional combustion device.

[Explanation of symbols]

 1 Fuel Supply Means 2 Air Supply Means 3 Combustion Section 4 Exhaust Gas Flow Path 5 Limiting Current Type Oxygen Sensor 6 Element Driving DC Power Supply 7 Current Detection Means 8 Air-Fuel Ratio Control Means 9 Air-Fuel Ratio Target Value Setting Means 10 Sensor Output Detection Means 11 Application Voltage determining means 12 Voltage changing means 13 Sensor correction output detecting means 14 Limiting current characteristic judging means 15 Air-fuel ratio target value correcting means 16 Heating DC power supply 17 Alarm generating means 18 Sensor output quality checking means 19 Limiting current characteristic judging means (II) 20 Abnormality Detection Setting Means 21 Abnormal Output Detection Means 22 Abnormal Output Quality Checking Means 23 Target Setting Means 24 Air-Fuel Ratio Control Releasing Means 25 Combustion Stopping Means 30 Oxygen Ion Conductive Solid Electrolytes 31a Cathode Electrodes 32 Helical Glass Membrane 33 Seal Plates 34 Oxygen diffusion hole 35 Heating part

Claims (20)

[Claims] 1. A fuel supply unit, an air supply unit, a combustion unit, an exhaust gas flow passage, a limiting current type oxygen sensor arranged in the exhaust gas flow passage, and a voltage applied to an electrode arranged in the oxygen sensor. An element driving DC power source to be applied, a current detecting means arranged in a closed circuit of the electrode and the element driving DC power source to obtain a sensor output, and an air source for setting an air-fuel ratio target value and issuing a signal thereof. One of the fuel supply means or the air supply means so that the air-fuel ratio target value set by the air-fuel ratio target value setting means based on the sensor output from the fuel ratio target value setting means and the oxygen sensor is reached. In a combustion device having an air-fuel ratio control means for controlling the above, a sensor output detection means for measuring the sensor output A when the oxygen sensor is applied at a combustion voltage value during non-combustion and exposed to the atmosphere, And applying a voltage determining means for determining the applied voltage compared to the basis of the comparison value with the measured sensor output A previously and stored frequency values E by capacitors output detecting unit,
Voltage changing means for changing the voltage applied by the element driving DC power supply to the applied voltage determined by the applied voltage determining means, and the oxygen sensor for the atmosphere with the voltage value increased by the voltage changing means. The sensor correction output detecting means for measuring the sensor output B when the voltage is applied inside, and the sensor output B measured by the sensor correction output detecting means and the sensor output A measured by the sensor output detecting means are compared to the limit. The limiting current characteristic determining means for determining the current characteristic, and the air-fuel ratio target value based on the sensor output B measured by the sensor correction output detecting means, which operates when the limiting current characteristic is determined to be the limiting current. Combustion equipment provided with air-fuel ratio target value correction means for correcting the air-fuel ratio target value set by the setting means. 2. A voltage is supplied to a fuel supply means, an air supply means, a combustion section, an exhaust gas flow path, a limiting current type oxygen sensor arranged in the exhaust gas flow path, and an electrode arranged in the oxygen sensor. An element driving DC power source to be applied, a current detecting means for obtaining a sensor output by being arranged in a closed circuit of the electrode and the element driving DC power source, and an air source for setting a target value of the air-fuel ratio and issuing a signal thereof. Fuel ratio target value setting means and control of one of the fuel supply means or the air supply means so that the air-fuel ratio target value of the air-fuel ratio target value setting means becomes the air-fuel ratio target value based on the sensor output from the oxygen sensor. In a combustion device having an air-fuel ratio control means, a sensor output detection means for measuring the sensor output A when the oxygen sensor is applied at a combustion voltage value and exposed to the atmosphere during non-combustion, and the element driving DC power supply And voltage changing means but to increase a voltage to be applied, the sensor output when the oxygen sensor was exposed to air is applied at high change voltage value at the voltage changing means B
The sensor correction output detecting means for measuring the sensor current, the sensor output B measured by the sensor correction output detecting means and the sensor output A measured by the sensor output detecting means are compared to judge the limiting current characteristic. And an air-fuel ratio target value set by the air-fuel ratio target value setting means on the basis of the sensor output B measured by the sensor correction output detection means which operates when the limit current is judged to be the limit current. A combustion device provided with an air-fuel ratio target value correction means for correcting 3. A fuel supply means, an air supply means, a combustion section, an exhaust gas passage, a limiting current type oxygen sensor arranged in the exhaust gas passage, and a voltage applied to an electrode arranged in the oxygen sensor. An element driving DC power source to be applied, a current detecting means for obtaining a sensor output by being arranged in a closed circuit of the electrode and the element driving DC power source, and an air source for setting a target value of the air-fuel ratio and issuing a signal thereof. Fuel ratio target value setting means and control of one of the fuel supply means or the air supply means so that the air-fuel ratio target value of the air-fuel ratio target value setting means becomes the air-fuel ratio target value based on the sensor output from the oxygen sensor. In a combustion device having an air-fuel ratio control means for performing, a voltage changing means for increasing the voltage applied by the element driving DC power source,
The sensor correction output detecting means for measuring the sensor output B when the oxygen sensor is warmed up to a voltage value higher than the combustion voltage value by the voltage changing means and exposed to the atmosphere during non-combustion, and the sensor correction output detecting means. Limiting current property judging means (II) for judging the limiting current property depending on whether the measured sensor output B overshoots at the time of starting, and it operates when it is judged as the limiting current by the limiting current property judgment (II). Combustion equipment provided with air-fuel ratio target value correction means for correcting the air-fuel ratio target value set by the air-fuel ratio target value setting means based on the sensor output B measured by the sensor correction output detection means. 4. A voltage is applied to a fuel supply unit, an air supply unit, a combustion unit, an exhaust gas passage, a limiting current type oxygen sensor arranged in the exhaust gas passage, and an electrode arranged in the oxygen sensor. An element driving DC power source to be applied, a current detecting means for obtaining a sensor output by being arranged in a closed circuit of the electrode and the element driving DC power source, and an air source for setting a target value of the air-fuel ratio and issuing a signal thereof. Fuel ratio target value setting means and control of one of the fuel supply means or the air supply means so that the air-fuel ratio target value of the air-fuel ratio target value setting means becomes the air-fuel ratio target value based on the sensor output from the oxygen sensor. In a combustion device having an air-fuel ratio control means, a sensor output detection means for measuring a sensor output A when a limiting current type oxygen sensor is applied at a combustion voltage value at the time of non-combustion and exposed to the atmosphere; Measured by the detecting means sensor output A
And an applied voltage determining means for determining an applied voltage value based on the comparison value with a prestored threshold value E, and the element driving DC power supply for making the applied voltage determined by the applied voltage determining means. And a sensor correction for measuring the sensor output B when the oxygen sensor is exposed to the atmosphere by warming up the oxygen sensor at a voltage value higher than the combustion voltage value by the voltage changing means during non-combustion. Output detection means, limit current characteristic determination means (II) for determining the limit current characteristic depending on whether the sensor output B measured by the sensor correction output detection means overshoots at startup, and the limit current characteristic determination (II). The air-fuel ratio target value set by the air-fuel ratio target value setting means is corrected based on the sensor output B measured by the sensor correction output detection means when the air-fuel ratio target value is determined to be the limit current. A combustion device provided with a fuel ratio target value correction means. 5. A voltage is supplied to the fuel supply means, the air supply means, the combustion section, the exhaust gas passage, the limiting current type oxygen sensor arranged in the exhaust gas passage, and the electrode arranged in the oxygen sensor. An element driving DC power source to be applied, a current detecting means for obtaining a sensor output by being arranged in a closed circuit of the electrode and the element driving DC power source, and an air source for setting a target value of the air-fuel ratio and issuing a signal thereof. Fuel ratio target value setting means and control of one of the fuel supply means or the air supply means so that the air-fuel ratio target value of the air-fuel ratio target value setting means becomes the air-fuel ratio target value based on the sensor output from the oxygen sensor. In a combustion device having an air-fuel ratio control means, a sensor output detection means for measuring the sensor output A when the oxygen sensor is applied at a combustion voltage value and exposed to the atmosphere during non-combustion, and an upper limit value stored in advance 1 is set to a value larger than the threshold value E which is the sensor output of the initial use product when a combustion voltage value is applied and exposed to the atmosphere, and the lower limit value E2 stored in advance is smaller than the threshold value E and more than the air-fuel ratio target value. A sensor output pass / fail test means for comparing the upper limit value E1 and the lower limit value E2 in the case of a large value with the sensor output A measured by the sensor output detection means, and an upper limit value E for the sensor output pass / fail detection means.
Combustion equipment provided with an alarm generating means for issuing an alarm when it is 1 or more or less than the lower limit value E2. 6. A fuel supply means, an air supply means, a combustion section, an exhaust gas passage, a limiting current type oxygen sensor arranged in the exhaust gas passage, and a voltage applied to an electrode arranged in the oxygen sensor. An element driving DC power supply to be applied and operated, a current detecting means arranged in a closed circuit of the electrode and the element driving DC power supply to obtain a sensor output, and an air-fuel ratio target value X are set. Air-fuel ratio target value setting means for issuing a signal,
It has an air-fuel ratio control means for controlling either one of the fuel supply means or the air supply means so as to reach the air-fuel ratio target value of the air-fuel ratio target value setting means based on the sensor output from the oxygen sensor. In combustion equipment,
The control by the air-fuel ratio control means is released, and the combustion state is made at an oxygen concentration value larger than the oxygen concentration value corresponding to the air-fuel ratio target value X by the control of either the fuel supply means or the air supply means. Abnormality detection setting means, abnormal output detection means for measuring the sensor output Z from the oxygen sensor in the combustion state in the abnormality detection setting means, and sensor output Z measured by the abnormal output detection means are stored in advance. Upper limit value H1 and lower limit value H that are values equal to or greater than the set target value X
The output abnormality detecting means for comparing the magnitude with 2 and the alarm generating means for issuing an alarm when the sensor output Z from the oxygen sensor in the output abnormality detecting means is equal to or more than the upper limit value H1 or less than the lower limit value H2 are provided. Combustion equipment. 7. A sensor output detecting means for measuring a sensor output A when a limiting current type oxygen sensor is applied at a combustion voltage value at the time of non-combustion and exposed to the atmosphere, and an upper limit value E stored in advance.
1 is set to a value larger than the threshold value E which is the sensor output of the initial use product when a combustion voltage value is applied and exposed to the atmosphere, and the lower limit value E2 stored in advance is smaller than the threshold value E and more than the air-fuel ratio target value. A sensor output pass / fail test means for comparing the upper limit value E1 and the lower limit value E2 in the case of a large value with the sensor output A measured by the sensor output detection means, and an upper limit value E1 or more for the sensor output pass / fail test means. Alternatively, an alarm generating means for issuing an alarm when the value is less than the lower limit value E2 is provided, claim 1 or claim 2 or claim 3 or claim 4.
Alternatively, the combustion device according to claim 6. 8. The combustion apparatus according to claim 1, 2, 3 or 4, wherein the applied voltage is changed from time to time by the voltage changing means. 9. The combustion apparatus according to claim 1, wherein an upper limit value is provided for the change of the applied voltage performed by the voltage changing means, and an alarm generating means for giving an alarm when the upper limit value is reached is provided. 10. A method according to claim 1, further comprising alarm generating means for operating and issuing an alarm when the limiting current characteristic determining means or the limiting current characteristic determining means (II) determines that the limiting current cannot be obtained. The combustion device according to claim 2 or claim 3 or claim 4. 11. A combustion stopping means for stopping combustion according to an alarm issued by the alarm generating means is provided, or claim 5, 6, or 7 or 9 or 10.
The combustion device as described. 12. A combustion stopping means for stopping combustion by a plurality of warnings issued by the warning generating means is provided.
Alternatively, the combustion device according to claim 6 or claim 7 or claim 9 or claim 10. 13. The combustion according to claim 5, wherein the air-fuel ratio control releasing means for releasing the air-fuel ratio control by an alarm issued by the alarm generating means is provided. machine. 14. The combustion apparatus according to claim 6, wherein the abnormality detection setting means is driven for a short time immediately after combustion or immediately before combustion is stopped. 15. A sensor output A when a limiting current type oxygen sensor is operated at a combustion voltage value immediately after combustion is stopped and exposed to the atmosphere.
The combustion device according to claim 1, 2 or 4, or 5 or 7, which measures 16. A limiting current type oxygen sensor, an oxygen ion conductive solid electrolyte sintered substrate having platinum electrodes formed on both surfaces, and a spiral arranged on one side of the solid electrolyte substrate so as to surround the electrode. 7. A glass-type glass film, and a sinterable seal plate disposed on the upper part of the spiral-shaped glass film, claim 1 or claim 2, claim 3 or claim 4, claim 5 or claim 6. Combustion equipment described. 17. A limiting current type oxygen sensor, a platinum electrode mixed with 1 to 15 wt% of bismuth oxide, a zirconia-based oxygen ion conductive solid electrolyte sintered substrate having platinum electrode films formed on both surfaces, and the solid substance. A spiral glass film having the same coefficient of thermal expansion as the solid electrolyte within ± 10%, which is arranged on one side of the electrolyte substrate and surrounds the electrode, and made of forsterite arranged on the spiral glass film. The combustion device according to claim 1, 2 or 3, 3 or 4 or 5 or 6, which is configured to include a sinterable seal plate. 18. The combustion apparatus according to claim 1, 2 or 3, 4 or 5 or 6, wherein a limiting current type oxygen sensor is provided with a heating section. 19. The combustion apparatus according to claim 6, wherein the air-fuel ratio target value X is set so as to obtain combustion on the high oxygen concentration side in the exhaust gas oxygen concentration range where good combustion is obtained. 20. When the sensor output Z is a value larger than the upper limit H1, the air-fuel ratio target value is changed to a prestored value larger than X, and when the sensor output Z is a value smaller than the lower limit H2, the air-fuel ratio is changed. 7. The combustion device according to claim 6, further comprising target value setting means for changing the target value to a prestored value smaller than X.