JPH0363559A - Method and device for evaluating characteristic of oxygen sensor - Google Patents

Abstract

PURPOSE:To obtain gas for measurement which is close to the composition of practical exhaust gas by an inexpensive method by burning the gases different in air/fuel ratio by two combustion equipments and utilizing the obtained gaseous mixture as the gas for measurement. CONSTITUTION:Main fuel is supplied to gas burners 20, 22 from the main gaseous fuel feeders 24, 26 and burned by supplying air to the gas burners 20, 22 form the main air feeders 28, 30. Excess air ratio is preset so that the excess air ratio in the gas burner 20 is regulated to - lambda and the excess air ratio in the gas burner 22 is regulated to lambda. Both gas-enriched exhaust gas obtained from the gas burner 20 and gas-lean exhaust gas obtained from the gas burner 22 are changed over by turning on/off the solenoid valves 32, 40, 34, 42. These exhaust gasses are introduced into an oxygen sensor 56. This oxygen sensor 56 is calibrated by performing measurement.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a method and apparatus for evaluating the characteristics of an oxygen sensor economically and with high reliability.

(Background Art) The characteristics of oxygen sensors used for detecting the oxygen concentration in automobile exhaust gas are generally measured individually during their development and manufacture.

By the way, the measurement or evaluation of the characteristics of such an oxygen sensor is
The most desirable method is to attach a sensor to an actual engine, and in the past, this method has been exclusively used, but measurements using an actual engine vary depending on the type of engine, control system, operating conditions, etc. Moreover, the equipment is expensive and it is economically disadvantageous.
In addition, it is difficult to say that it is practical because the measurement time is long and the number of man-hours is large.
In recent years, so-called gas substitution methods, such as the model gas method, combustion gas method, and additive gas method, have been exclusively employed.

However, conventional gas substitution methods such as the model gas method, combustion gas method, and additive gas method are not necessarily sufficient in terms of economic efficiency or reliability of measurement results, and there is still room for improvement. This is the reality.

In other words, the model gas method is a method in which a model gas with a composition similar to automobile exhaust gas is created using cylinder gas, etc., and the model gas is heated in an electric furnace or the like and then used as the measurement gas to measure oxygen sensor specificity. Although it is suitable for research fields because of its excellent accuracy and stability of measurement results, it consumes a large amount of expensive gas, so it is not suitable for characterizing mass-produced oxygen sensors at production sites. If used, there is a disadvantage that it would be economically disadvantageous.

In addition, the combustion gas method is a method that uses combustion exhaust gas obtained by burning fuel gas such as propane or city gas as the measurement gas, and is superior in terms of economy and equipment simplicity, so it is widely used at production sites. Although it is used to evaluate the characteristics of mass-produced oxygen sensors, the combustion gas is almost completely combusted.
Since the unburned gas component in the measured gas is significantly lower than that in the exhaust gas from an actual engine, there is a problem that the correlation with the measurement results from an actual engine is significantly poor, resulting in a lack of reliability. .

Furthermore, the additive gas method uses unburned gas components such as Co, H, and No added to the combustion exhaust gas obtained by the combustion gas method as a measurement gas, and has excellent correlation with actual engine equipment. However, the model gas method requires a relatively large amount of expensive gas, so like the model gas method, it is not economically viable when used to measure the characteristics of mass-produced oxygen sensors. This has the inherent problem of being significantly inferior.

(Problem to be solved) The present invention has been made against this background, and the problem to be solved is to economically advantageously increase the unburned gas component in the measured gas. By doing so, it is possible to economically advantageously generate a measurement gas with a composition close to the exhaust gas composition of the actual engine, thereby increasing the correlation with the actual engine and obtaining highly reliable evaluation results economically. An object of the present invention is to provide a method and device for evaluating an oxygen sensor.

(Solution Means) In order to solve this problem, in the method of the present invention, a measurement gas having a predetermined excess air ratio is supplied to an oxygen sensor, and a measurement gas is detected based on a signal output from the oxygen sensor. When evaluating the characteristics of an oxygen sensor, at least two combustion devices are used to combust a mixture of fuel gas and air at different air-fuel ratios, and the combustion exhaust gases emitted from these combustion devices are compared to each other. It was decided to mix them and use the mixed combustion exhaust gas as the measurement gas.

Furthermore, in order to solve the above problems, the device of the present invention supplies gas with a predetermined excess air ratio to the oxygen sensor,
An oxygen sensor characteristic evaluation device that evaluates the characteristics of the oxygen sensor based on a signal output from the oxygen sensor,
(a) A plurality of combustion devices that combust a mixture of fuel gas and air mixed at different air-fuel ratios, and (b) Combustion exhaust gas that is produced by mixing the combustion exhaust gases discharged from these combustion devices. and an exhaust gas mixing section that supplies the oxygen sensor as a gas having the predetermined excess air ratio.

Here, the excess air ratio of the combustion exhaust gas discharged from each combustion device fluctuates due to drift when used for a long time, so in order to prevent fluctuations due to this drift, it is necessary to A detection means for detecting the excess air ratio of the combustion exhaust gas discharged from each corresponding combustion device to the exhaust gas mixing section is provided between each corresponding combustion device, and the excess air ratio detected by the detection means is detected by each corresponding combustion device. It is preferable to provide an air-fuel ratio adjusting means for adjusting the air-fuel ratio of the mixed gas combusted in each combustion device so as to match a preset excess air ratio for the combustion exhaust gas from the combustion apparatus.

Furthermore, when measuring sensor characteristics, for combustion equipment in which the air-fuel ratio of the combustion mixture gas is controlled to change in order to change and control the excess air ratio of the measurement gas, the air-fuel ratio is controlled to change based on a predetermined external signal. However, each of these combustion devices is provided with an air-fuel ratio control means that controls the air-fuel ratio of the combustion mixture gas based on the output signal of the oxygen sensor. The fuel ratio may be feedback-controlled based on the output signal of the oxygen sensor.

In this case, it is sufficient to have at least one combustion device in which the air-fuel ratio of the combustion mixture gas is controlled to change, but if the air-fuel ratio of the combustion mixture gas is controlled to change in all combustion devices, , air-fuel ratio control means will be provided for all combustion devices.

Furthermore, if the amount of unburned gas is insufficient just by mixing the combustion exhaust gases from each combustion device, oxidizing gas, reducing gas, or other gases such as oxidizing gas, reducing gas, or A gas supply means capable of supplying both of these may be connected to the exhaust gas mixing section.

(Function) When a single combustion device is used to obtain the measurement gas as in the conventional combustion gas method, it is necessary to obtain the measurement gas with the excess air ratio necessary for measuring the oxygen sensor characteristics. First, it is necessary to combust the mixed gas in the combustion device at an air-fuel ratio that is very close to the ideal air-fuel ratio, and therefore, as described above, the amount of unburned components in the combustion exhaust gas is significantly reduced.

However, like the method of the present invention, using multiple combustion devices,
When multiple combustion devices burn mixed gases with different air-fuel ratios, and the flue gases from those multiple combustion devices are mixed to produce a measurement gas, the amount of fuel gas produced by combustion in those combustion devices is The amount of fuel gas may be too low compared to the amount of air, or the amount of fuel gas may be too rich compared to the amount of air, resulting in the combustion exhaust gas from the combustion equipment performing lean combustion. There is a large amount of residual oxygen, and the amount of unburned gas remaining in the combustion exhaust gas from a combustion device where combustion is performed in a rich state is large, especially the amount of residual CO, which has a large effect on the measurement of oxygen sensor characteristics. The gas components of the measurement gas obtained by mixing them become closer to the actual engine exhaust gas components.

Incidentally, FIG. 1 shows the amount of OCO and 02 in the measurement gas obtained according to the measurement gas generation method according to the method of the present invention, and the amount of CO in the measurement gas obtained according to the measurement gas generation method according to the conventional combustion gas method. This is a graph showing the OCO amount and Ot amount in the measurement gas obtained by the measurement gas generation method according to the method of the present invention, and the O
The air-fuel ratio setting conditions for each combustion device are different, so in both of the two measurement results (■), the excess air ratio: λ is higher than that of the measurement gas obtained using the conventional combustion gas method. In a wide range of around 0.90 to 1.10, it is extremely close to that in the exhaust gas of an actual engine.

In addition, Fig. 2 shows the equipment used for the above measurement (2), where 2 and 4 are the gas burners as combustion devices, and 6 is the combustion exhaust gas from the gas burners 2 and 4. The exhaust gas mixing section that mixes and generates the measurement gas,
Furthermore, 8 and 10 indicate a gas analyzer and an oxygen concentration detector for measuring the amount of CO and the amount of 02. Here, using such a device, fuel gas and air are supplied from the fuel gas supply device 12 and the air supply device 14 to the gas burner 2 so that the excess air ratio of the combustion exhaust gas from the gas burner 2 becomes A. , from the fuel gas supply device 16 and the air supply device 18 to the gas burner 4 so that the excess air ratio of the combustion exhaust gas from the gas burner 4 becomes B.
The difference in the excess air ratio; A-B was set to 0.08. Difference: A
The above measurement (2) was carried out under the condition that -B was set to 0.12.

As described above, the method of the present invention is an extremely simple and inexpensive means of obtaining a measurement gas from the flue gas obtained by burning fuel gas, and can produce a composition that is closer to the actual engine exhaust gas composition, which has a large amount of unburned gas components. Therefore, as the output signal of the oxygen sensor, a signal that is closer to the measurement result in the actual engine can be obtained, and the evaluation results based on that output signal also match the actual engine. This results in higher reliability, with a higher correlation with engine measurements.

Furthermore, according to the present invention, as is clear from the measurement results in FIG. 1, the unburned gas components can be adjusted by setting the air-fuel ratio in each combustion device, so that the present invention can accommodate various engine conditions. It is also possible.

According to the device of the present invention, such a method can be carried out advantageously, and if the device of the present invention that implements such a method is provided with the above-mentioned detection means and air-fuel ratio adjustment means, errors caused by drift can be avoided. by suppressing the
This makes it possible to obtain more reliable measurement results.

Furthermore, if the apparatus of the present invention is provided with the air-fuel ratio control means as described above, it is possible to evaluate the characteristics of the oxygen sensor in a state closer to the control state in the actual engine.
Furthermore, by connecting a gas supply means as described above to the exhaust gas mixing section, the unburned gas component in the measured gas can be increased as necessary, making it possible to evaluate the characteristics of the engine under more diverse conditions. . In addition, since such gas supply means is used only to compensate for the lack of unburned gas components, it is less likely to produce oxidizing or reducing gases than the conventional model gas method, as well as compared to the additive gas method. As a result, the consumption amount is kept extremely small, and the cost required for it is also kept very small.

(Example) Hereinafter, in order to clarify the present invention more specifically,
Some embodiments thereof will be described in detail based on the drawings.

First, FIG. 3 shows an example of an oxygen sensor characteristic evaluation device according to the present invention. There, 20.22 is a gas burner as a combustion device, and fuel gas such as propane is continuously supplied to these gas burners 20, 22 from a main fuel gas supply device 24.26 at a constant flow rate. and the main air supply device 28.30
Air is continuously supplied at a constant flow rate. Further, auxiliary fuel gas supply devices 36 and 38 are connected to the gas burners 20 and 22 through electromagnetic valves 32 and 34 that are driven to open and close by a solenoid valve drive device 31, respectively. A sub-air supply device 44.46 is connected via a solenoid valve 40.42 which is driven to open and close by the auxiliary fuel gas supply device 36.38 when the solenoid valve 32.34 is opened. Gas and, when the solenoid valves 40, 42 are open, air is supplied from the auxiliary air supply device 44, 46 to the gas burners 20, 22 at predetermined flow rates, respectively.

Here, a mass flow controller having a flow rate control function is used in each of the fuel gas supply devices and air supply devices.

On the other hand, each of the gas burners 20 and 22 is connected to an exhaust gas mixing section 48 provided in common to them via exhaust pipes 50 and 52 for discharging the combustion exhaust gas burned therein. The combustion exhaust gas discharged from each gas burner 20, 22 is mixed in the exhaust gas mixing section 48 to generate a measurement gas, and the measurement gas is mixed with the combustion exhaust gas discharged from each gas burner 20, 22 in the exhaust gas mixing section 48. The oxygen sensor 56 is supplied to the cylindrical boat 54, that is, to the oxygen sensor 56 attached to the mounting portion of the cylindrical boat 54.

A data processing device 58 is connected to the oxygen sensor 56 attached to the mounting portion of the cylindrical boat 54, and as in the conventional case, the data processing device 58 processes the output signal from the oxygen sensor 56 based on the output signal from the oxygen sensor 56. , characteristics of the oxygen sensor 56 such as response characteristics and control points are measured.

Note that the data processing operation in the data processing device 58 is performed in accordance with the cycle set by the programmer 60 and in synchronization with the alternative opening/closing operation of the solenoid valves 32.34 and 40.42 by the solenoid valve driving device 31. It will be done.

In order to evaluate the characteristics of the oxygen sensor 56 using such an evaluation device, the main fuel gas supply device! The amount of fuel gas supplied from the main air supply device 24 to the gas burner 20 is set to be a certain amount larger than that from the main fuel gas supply device 26 to the gas burner 22, while the amount of air supplied from the main air supply device 28 to the gas burner 20 is set to be larger than that from the main fuel gas supply device 26 to the gas burner 20. 30 to the gas burner 22 by a certain amount. As a result, the fuel gas from the main fuel gas supply device 24 and the main air supply device 2
During the combustion of the mixed gas (base gas) with air from the gas burner 20, the excess air ratio of the combustion exhaust gas discharged from the gas burner 20 is made to be smaller than the stoichiometric ratio by a certain amount: Δλ, while the main fuel When the mixed gas (base gas) of the fuel gas from the gas supply device 26 and the air from the main air supply device 30 is combusted, the excess air ratio of the combustion exhaust gas discharged from the gas burner 22 is constant compared to the stoichiometric ratio. i
E: In the exhaust gas mixing section 48 where the combustion exhaust gases of the base gases are mixed,
The excess air ratio: λ of the mixed gas (measured gas) is made to be the stoichiometric ratio (λ=1).

Then, with the fuel gas outflow amount from the main fuel gas supply device 24.26 and the air outflow amount from the main air supply device 28.30 set in this manner, the solenoid valve 32 is operated at a predetermined cycle set by the programmer 60. .34 and 40.42 are selectively opened and closed, and fuel gas and air are alternately flowed into the corresponding gas burners 20 and 22 from the auxiliary fuel gas supply device 36.38 and the auxiliary air supply device 44.46. Then, the excess air ratio of the measurement gas mixed and generated in the exhaust gas mixing section for 4 days: λ is in the rich state (λ<1) and in the rich state (λ>1).
Based on the output signal from the oxygen sensor 56 obtained under such switching operation, the characteristics of the oxygen sensor 56 such as response characteristics and control points are measured in the same way as in the conventional method.

That is, the response characteristic of the oxygen sensor 56 is, for example,
As shown in (a) and middle) of the figure, the solenoid valve is activated when the measurement gas is in a rich state, with the threshold level being 0°45V, which is the center of the level fluctuation of the output signal of the oxygen sensor 56. Since being switched, oxygen sensor 5
Rich/lean response time until the output signal level of 6 falls below its threshold level: TR3 and
The lean/rich response time: 'r'Ls from when the solenoid valve is switched until the output signal level of the oxygen sensor 56 exceeds the threshold level is measured under the condition that the measurement gas is in a lean state. , the reciprocal of their sum: 1/(T*s+TLs) is determined and used as an index.

In addition, the control points of the oxygen sensor 56 are the rich/lean response time: T”*s and the lean/rich response time: T
Find the ratio T, ls/T, and use it as an index.

In this way, according to the device of this embodiment, the characteristics of the oxygen sensor 56, such as response characteristics and control points, can be measured in the same way as the conventional device. In the device of this embodiment, when measuring these characteristics, two gas burners 20 and 22 are used as described above, and in one gas burner 20, the amount of fuel gas is in excess of the ideal air-fuel ratio. The mixed gas is combusted and the other gas burner 22
, the mixed gas in which the fuel gas is less than the ideal air-fuel ratio is combusted, and the combustion exhaust gases are mixed in the exhaust gas mixing section 48 to generate the measurement gas. Although it is a simple and inexpensive method to generate the measurement gas by combustion, it significantly increases the unburned gas component in the measurement gas compared to the conventional combustion gas method, making it possible to produce a measurement gas close to the composition of the exhaust gas from an actual engine. Therefore, as a result of measuring the characteristics of the oxygen sensor 56 such as the response characteristics and control points, it is possible to obtain highly reliable evaluation results that have a high correlation with the measured values in the actual engine. It is.

Incidentally, FIG. 5 shows the reciprocal of the sum of the rich/lean response time (TR3) and the lean/rich response time (TLs) as an index of the response characteristics of the oxygen sensor 56 measured using the device of this embodiment: 1/ (T113+TL!+) and the engine feedback control frequency as an index of response characteristics measured by mounting these oxygen sensors 56 on an actual engine. A significantly higher correlation is observed than in the case of law.

Further, FIG. 6 shows the ratio of the lean/lean response time: T"ms to the lean/rich response time: Ttg as an index of the control point of the oxygen sensor 56 measured using the device of this embodiment: T□/ This shows the relationship between TL- and the excess air ratio at the engine control point measured by installing the oxygen sensor 56 on an actual engine. A high correlation has been recognized.

In other words, from these facts, it is recognized that the present embodiment has higher reliability as an engine alternative method than the conventional combustion gas method.

In the measurements shown in FIGS. 5 and 6, propane was used as the fuel gas, and in one gas burner 20, the excess air ratio of the combustion exhaust gas during base gas combustion was set to 0.9.
On the other hand, in the other gas burner 22, the excess air ratio of the combustion exhaust gas during base gas combustion was set to 1.06.

Next, another embodiment of the present invention will be described in detail based on FIG. Note that only the points different from the previous embodiment will be described in detail here.

That is, in this embodiment, each gas burner 20.2
first and second A/F meters 62 for measuring the excess air ratio of the combustion exhaust gas from each gas burner 20, 22 with respect to the exhaust pipe 50.
64 are provided, and signals representing the excess air ratio of each combustion exhaust gas are sent from the A/F meters 62 and 64 to the flow rate control circuit 6.
6.68 respectively. The flow control circuits 66 and 68 then compare the preset target excess air ratio with the actual excess air ratio represented by the signals from the A/F meters 62 and 64, and find that they match. In this way, the amount of fuel gas supplied from the main fuel gas supply device 24, 26 to each gas burner 20, 22 is adjusted. The excess air ratio of the combustion exhaust gas to be discharged is kept unchanged. In other words, this makes it possible to effectively prevent the occurrence of measurement errors due to drift.As is clear from this, here, the A/F
A total of 62 and 64 constitute the detection means, and the flow rate control circuits 66 and 68 constitute the air-fuel ratio adjustment means.

Note that the excess air ratio correction operation by the flow rate control circuits 66 and 68 is performed with each electromagnetic valve set in a closed state and only the base gas flowing into each gas burner 20, 22.

The excess air ratio correction operation by the flow control circuit 66.68 can also be performed by adjusting the air outflow from the main air supply device 28.30.

On the other hand, in the device of this embodiment, the output signal of the oxygen sensor 56 is compared with the threshold level of 0.45 V at the center of the level fluctuation of the output signal, and the output signal of the oxygen sensor 56 is determined. A feedback control circuit 70 is connected that outputs a solenoid valve switching signal when the signal level exceeds and falls below the threshold level. Here, the solenoid valve drive device 31 is controlled by the solenoid valve switching signal from the feedback control circuit 70, and the auxiliary fuel gas supply device 36.3
8 compatible solenoid valves 32, 34 and sub air supply device 44
．． The solenoid valves 40 and 42 corresponding to the oxygen sensor 56 are driven to open and close alternately.
The output of the oxygen sensor 56 is increased or decreased at a cycle according to the response characteristics of the oxygen sensor 56. In other words, by measuring the vibration frequency of the oxygen sensor output, in other words, the feedback frequency of the device of this embodiment, the response characteristics of the oxygen sensor 56 can be determined using the measurement results as an index. Feedback control circuit 70
The feedback frequency is measured by a measuring device 72 connected to.

As is clear from the above description, here, the feedback control circuit 70, the solenoid valve drive device 31 controlled by the feedback control circuit 70, and the gas burner 20 controlled to open and close by the solenoid valve drive device 31 are used. , 22;
Air-fuel ratio control means is configured.

In addition, in the device of this embodiment, a third A/F meter 74 is provided on the cylindrical boat 54 in which the oxygen sensor 56 is arranged, and this A/F meter 74 supplies the oxygen to the oxygen sensor 56. The excess air ratio: λ of the measurement gas is measured, and the measurement signal is supplied to the measuring device 72. In the measuring device 72, the average value of the excess air ratio: λ measured by the A/F meter 74 is determined as the control point of the oxygen sensor 56.

In addition, FIG. 8 shows the output signal (electromotive force) of the oxygen sensor 56.
and the open/closed states of solenoid valves 32, 34 and 40, 42,
It shows the temporal fluctuation relationship with the output signal of the A/F meter 74.

Even in such an evaluation device, since the method of generating the measurement gas is the same as that of the above-mentioned embodiment, it is possible to obtain the same effect as that of the above-mentioned embodiment.

Incidentally, FIG. 9 shows the feedback control frequency as an index of the response characteristics of the oxygen sensor 56 measured using the device of this embodiment, and the feedback control frequency as an index of the response characteristic measured with the oxygen sensor 56 mounted on an actual engine. FIG. 10 shows the relationship between the oxygen sensor 5 and the engine feedback control frequency, and FIG.
This figure shows the relationship between the excess air ratio at the control point 6 and the excess air ratio at the control point measured by installing the oxygen sensor 56 on an actual engine. A significantly higher correlation is observed compared to the above, and this shows that, like the previous example, this example has higher reliability as an engine alternative method than the conventional combustion gas method. It is recognized that they have it.

In the measurements shown in FIGS. 9 and 10 above, propane is used as the fuel gas in the same manner as in the measurements shown in FIGS. 5 and 6 above. Reduce excess air ratio of combustion exhaust gas to 0
．． 94, and in the other gas burner 22, the excess air ratio of the combustion exhaust gas during base gas combustion is set to 1.94.
It was set to 06.

Although several embodiments of the present invention have been described in detail above, the present invention is not limited to these specific examples, and various changes, modifications, improvements, etc. can be made without departing from the spirit thereof. Of course, it can be implemented in the same manner as described above.

For example, in the second embodiment, when measuring the characteristics of the oxygen sensor 56, the excess air ratio of the combustion exhaust gas of both the two gas burners 20 and 22 is changed and controlled at the same time. are those gas burners 2
However, if only the excess air ratio of the combustion exhaust gas of one gas burner is to be changed and controlled, an air-fuel ratio control means must be provided for only that one gas burner. Bye.

Further, in the above embodiments, only two gas burners were used as combustion devices, but it is also possible to configure the apparatus of the present invention using three or more combustion devices.

Furthermore, as shown by the broken line in FIG. 7, a gas supply device 76 for supplying at least one of an oxidizing gas such as air or a reducing gas such as C○ or H2 is connected to the exhaust gas mixing section 48. These oxidizing gases and reducing gases may be mixed into the measurement gas as necessary. Even with this method, the amount of oxidizing gas or reducing gas supplied from the gas supply device 76 to the exhaust gas mixing section 48 can be extremely small, compared to the conventional model gas method, additive gas method, etc. And the cost required for this is extremely low. The flow of gas from the gas supply device 76 to the exhaust gas mixing section 48 is controlled by controlling the opening and closing of a solenoid valve (not shown) by the solenoid valve control device 31.

(Effect of the invention) As is clear from the above explanation, according to the method of the present invention,
It is a simple and inexpensive method similar to the conventional combustion gas method in which fuel gas is combusted, and it is possible to obtain a measurement gas with a composition more similar to that of the engine exhaust gas, making it significantly more reliable than the conventional combustion gas method. High evaluation results can be obtained economically and economically compared to conventional model gas methods and additive gas methods. According to the apparatus of the present invention, the method of the present invention can be suitably implemented.

[Brief explanation of drawings]

Figure 1 shows the amount of 02N and CO in the measurement gas generated according to the generation method according to the present invention and the amount of 02N and CO in the measurement gas generated according to the generation method according to the conventional combustion gas method.
FIG. 2 is a graph showing the amount of CO and the amount of CO in comparison with those in the exhaust gas of an actual engine. FIG. It is a figure showing the apparatus which measured the amount of CO. FIG. 3 is a diagram showing an example of an oxygen sensor evaluation device according to the present invention, and (a) and (b) of FIG. / lean response time: TR8 and lean/rich response time: Tts. FIG. 5 is a diagram for explaining 1/( FIG. 6 is a graph showing the relationship between T□+T0.) and the engine feedback control frequency as an index of the response characteristics of an actual engine.
4 is a graph showing the relationship between TR3/TL as an index of the control point of the oxygen sensor measured using the apparatus of FIG. 3 and the excess air ratio of the control point of an actual engine. FIG. 7 is a diagram showing another example of the oxygen sensor evaluation device according to the present invention, and FIG. 8 shows the oxygen sensor output in the device of FIG. 7, the opening/closing control state of each electromagnetic valve, and the third A/
FIG. 9 is a waveform diagram showing the relationship with the output of the F meter, and FIG. 9 shows the device feedback control frequency as an index of the response characteristics of the oxygen sensor measured using the device shown in FIG. 7, and the response characteristics of the actual engine. 10 is a graph showing the relationship between the engine feedback control frequency as an index, and FIG. 10 shows the excess air ratio at the control point of the oxygen sensor measured using the device shown in FIG. 7 and the excess air ratio at the control point of the actual engine. It is a graph showing the relationship between 20.22: Gas burner (combustion device) 24.26i Main fuel gas supply device 28.30: Main air supply device 31: Solenoid valve drive device 32.34, 40.42: Solenoid valve 36.38: Sub-fuel gas supply device 44.46: Sub-air supply device 4th: Exhaust gas mixing section 50, 52: Discharge pipe 56: Oxygen sensor 58: Data processing device 62.64: A/F
Meter (detection means) 66.68: Flow rate control circuit (air-fuel ratio adjustment means) 7 (l Feedback control circuit 72: Measuring device 74: A/F meter 6: Gas supply device

Claims (5)

[Claims] (1) When supplying a measurement gas with a predetermined excess air ratio to an oxygen sensor and evaluating the characteristics of the oxygen sensor based on the signal output from the oxygen sensor, at least two combustion devices are used to mutually Burns a mixture of fuel gas and air mixed at different air-fuel ratios,
An oxygen sensor characteristic evaluation method characterized in that combustion exhaust gases discharged from these combustion devices are mixed with each other and the mixed combustion exhaust gas is used as the measurement gas. (2) An oxygen sensor characteristic evaluation device that supplies a measurement gas with a predetermined excess air ratio to an oxygen sensor and evaluates the characteristics of the oxygen sensor based on a signal output from the oxygen sensor, which A plurality of combustion devices that burn a mixed gas of fuel gas and air mixed at a fuel ratio, and combustion exhaust gas discharged from these combustion devices are mixed, and the mixed combustion exhaust gas is sent to the oxygen sensor as the measurement gas. An oxygen sensor characteristic evaluation device comprising: an exhaust gas mixing section for supplying exhaust gas. (3) A detection means for detecting the excess air ratio of the combustion exhaust gas discharged from each corresponding combustion device to the exhaust gas mixing section is provided between the plurality of combustion devices and the exhaust gas mixing section; an air-fuel ratio adjustment for adjusting the air-fuel ratio of the mixed gas combusted in each combustion device such that the excess air ratio detected by the means matches a preset air excess ratio for the flue gas from each corresponding combustion device; The oxygen sensor characteristic evaluation device according to claim 2, further comprising means. (4) Corresponding to at least one of the plurality of combustion devices, air-fuel ratio control means is provided for controlling the air-fuel ratio of the mixed gas combusted in the combustion device based on the output signal of the oxygen sensor. The oxygen sensor characteristic evaluation device according to claim 2 or 3, characterized in that: (5) The gas supply means according to any one of claims (2) to (4), characterized in that a gas supply means capable of supplying at least one of an oxidizing gas and a reducing gas is connected to the exhaust gas mixing section. Oxygen sensor characteristic evaluation device.