JP2022108481A - A/F sensor characteristic information generation system and engine control system - Google Patents

Abstract

To provide an A/F sensor characteristic information generation system for improving the responsiveness of an A/F sensor.SOLUTION: An A/F sensor characteristic information generation system W comprises: an A/F sensor 20 that is installed in an exhaust pipe 6 of an engine E installed in an engine testing device B; a high-response flowmeter 21 that is connected with an intake pipe 5; a manometer 22 and a thermometer 23 that are installed in the intake pipe 5; and a measuring device 110. The measuring device 110 acquires, while the engine testing device B actuates the engine E, a measured air-fuel ratio detected by the A/F sensor 20, an air flow rate measured by the high-response flowmeter 21, an intake pipe pressure measured by the manometer 22, and an intake pipe temperature measured by the thermometer 22, calculates a valve passage flow rate by using the acquired air flow rate, intake pipe pressure, and intake pipe temperature, calculates a value obtained by dividing the valve passage flow rate by a predetermined injection quantity as a reference air-fuel ratio, and calculates A/F sensor characteristic information by using the reference air-fuel ratio and the measured air-fuel ratio.SELECTED DRAWING: Figure 1

Description

The present invention relates to an A/F sensor characteristic information generation system and an engine control system.

Conventionally, an engine control unit (ECU (Electronic Control Unit)) installed in an automobile detects the air-fuel ratio sensor (A/F (Air/Fuel ratio) sensor) installed in the exhaust passage of the engine. Feedback control is performed to correct the fuel injection amount to the engine so that the actual air-fuel ratio converges to the target air-fuel ratio based on the fuel ratio. For example, Japanese Unexamined Patent Application Publication No. 2002-200001 discloses a technology related to engine control that corrects the amount of fuel injected into the engine using the detected value of an A/F sensor.

In addition, so-called zirconia type A/F sensors used for engine control of automobiles as described above are mainly used. This zirconia type A/F sensor is disclosed in Patent Document 2.
The zirconia A/F sensor described in Patent Document 2 includes a zirconia element, an atmosphere-side electrode provided on one surface (inner surface) of the zirconia element, and an air-side electrode provided on the other surface (outer surface) of the zirconia element. It has an exhaust-side electrode, a ceramic coating covering the exhaust-side electrode, and a heater for heating the zirconia element. Also, the A/F sensor has a cover that covers "the zirconia element, the atmosphere-side electrode, the exhaust-side electrode, and the ceramic coating."

JP 2018-145943 A JP 2007-315855 A

By the way, the above-described zirconia A/F sensor has a problem of poor responsiveness. Therefore, even if the engine control unit (ECU) of the automobile controls the fuel injection amount to the engine using the detection value of the zirconia type A / F sensor with poor response, it will operate optimally. There was a risk that the engine could not be controlled.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and its object is to provide an A/F sensor characteristic information generation system for improving the responsiveness of the A/F sensor. Another object of the present invention is to provide an engine control system that controls an engine using the A/F sensor characteristic information generated by the A/F sensor characteristic information generating system.

A first aspect of the present invention for solving the above problems is an A/F sensor installed in an exhaust pipe of an engine installed in an engine testing apparatus for detecting a measured air-fuel ratio of fluid discharged into the exhaust pipe, A high-response flowmeter that is connected to an intake pipe of the engine and measures the air flow rate of the fluid flowing into the intake pipe, a pressure gauge that is installed in the intake pipe and measures the intake pipe pressure, and a pressure gauge of the intake pipe. An A/F sensor characteristic information generation system equipped with a thermometer installed in a pipe for measuring intake pipe temperature and a measuring device for calculating A/F sensor characteristic information, wherein the engine testing device is A predetermined injection amount of fuel is injected, and the engine is operated so that the flow rate of air flowing into the engine changes sharply in each cycle. During operation, the measured air-fuel ratio detected by the A / F sensor, the flow rate of air flowing into the intake pipe measured by the high response flow meter, the intake pipe pressure measured by the pressure gauge, and the temperature a data acquisition unit that acquires the intake pipe temperature measured by the meter; and a valve passage flow rate of the fluid that passes through the intake valve of the engine is calculated using the acquired air flow rate, intake pipe pressure, and intake pipe temperature. a valve passage flow rate calculation unit that divides the calculated valve passage flow rate by the predetermined injection amount to calculate a reference air-fuel ratio, and using the reference air-fuel ratio and the acquired measured air-fuel ratio, the A/F sensor and an A/F sensor characteristic information calculation unit for calculating a regression transfer function of the A/F sensor as the characteristic information.

The reason for the above configuration is that if the inventor of the present application can accurately calculate the value of the valve passage flow rate of the fluid passing through the valve of the engine installed in the engine test apparatus and operating, the valve By calculating the value obtained by dividing the passing flow rate by the engine's "predetermined fuel injection amount", it was found that a value that approximates the true value of the air-fuel ratio of the fluid flowing through the engine's exhaust pipe can be obtained. It depends.

Therefore, the inventor of the present application provided a configuration (high-response flow meter, pressure gauge, thermometer, data acquisition unit, valve passage flow calculation unit) for calculating the valve passage flow rate as described above, and calculated "valve passage flow rate A value obtained by dividing the "flow rate" by the "predetermined injection amount of fuel" is calculated as the reference air-fuel ratio, and using the calculated reference air-fuel ratio and the measured air-fuel ratio detected by the A/F sensor, A configuration having an A/F sensor characteristic information calculation unit that calculates a regression transfer function of the A/F sensor as characteristic information is adopted.
Then, by correcting the measured value (measured air-fuel ratio) detected by the "A/F sensor" using the "A/F sensor characteristic information (regression transfer function)" obtained by one aspect of the present invention, air-fuel ratio can be calculated. That is, according to one aspect of the present invention, a "zirconia type A/F sensor" with poor responsiveness, which is generally used for automobile engine control, is replaced with an "A/F sensor" with high responsiveness. can function as

Further, the A/F sensor characteristic information calculation unit uses the reference air-fuel ratio as an input value and the measured air-fuel ratio detected by the A/F sensor corresponding to the reference air-fuel ratio as an output value, and performs Fourier analysis calculation. Preferably, the transfer characteristic of the A/F sensor is calculated, the transfer function is calculated from the calculated transfer characteristic, and the regression transfer function is calculated from the transfer function.
Also, the high-response flowmeter is preferably an ultrasonic flowmeter or a lamina flowmeter.

A second aspect of the present invention includes an engine control device that stores the regression transfer function generated by the A/F sensor characteristic information generation system, and an engine that includes the A/F sensor. wherein the A/F sensor is installed in an exhaust pipe of the engine to measure the air-fuel ratio of fluid discharged to the exhaust pipe, and transmits the measured air-fuel ratio to the engine control device The engine control device acquires the air-fuel ratio measured by the A/F sensor, and corrects the acquired air-fuel ratio using the stored regression transfer function to obtain a corrected air-fuel ratio is calculated, and the fuel injection amount of the engine is controlled using the corrected air-fuel ratio.

According to the second aspect of the present invention, in an engine control system that controls an engine equipped with a zirconia type A/F sensor with poor response, the air-fuel ratio of the fluid flowing through the exhaust pipe measured by the A/F sensor is is corrected to an accurate value, the fuel injection amount of the engine can be controlled. Therefore, according to the engine control device of the present invention, highly accurate engine control is realized.

According to the present invention, it is possible to provide an A/F sensor characteristic information generation system for improving the responsiveness of the A/F sensor. Further, according to the present invention, it is possible to provide an engine control system that controls an engine using the A/F sensor characteristic information generated by the A/F sensor characteristic information generating system.

1 is a schematic diagram showing the configuration of an A/F sensor characteristic information generation system according to an embodiment of the present invention; FIG. FIG. 5 is a schematic diagram for explaining valve passage flow rate calculation processing performed by the A/F sensor characteristic information generation system according to the embodiment of the present invention; 4 is a schematic diagram showing the relationship between the air flow rate measured by the high-response flowmeter of the A/F sensor characteristic information generating system of the embodiment of the present invention and the valve passage flow rate calculated by the A/F sensor characteristic information generating system; FIG. 4 is a flow chart showing the procedure of A/F sensor characteristic information generation processing performed by the A/F sensor characteristic information generation system according to the embodiment of the present invention; 4 is a schematic diagram showing the input/output relationship of the transfer characteristics of the A/F sensor calculated by the A/F sensor characteristics information generating system according to the embodiment of the present invention; FIG. FIG. 5 is a schematic diagram for explaining a process of fitting a transfer function to the transfer characteristic of the A/F sensor calculated by the A/F sensor characteristic information generating system according to the embodiment of the present invention and identifying the A/F sensor; FIG. 5 is a schematic diagram for explaining an example of utilization of A/F sensor characteristic information generated by the A/F sensor characteristic information generating system according to the embodiment of the present invention; 1 shows an engine control system with a device; Using the A / F sensor characteristic information calculated by the A / F sensor characteristic information generation system of the embodiment of the present invention, the regressed air-fuel ratio obtained by regressing the detection value of the A / F sensor and the measured air detected by the A / F sensor 4 is a graph showing the relationship between the fuel ratio and the target air-fuel ratio; Using the A / F sensor characteristic information calculated by the A / F sensor characteristic information generation system of the embodiment of the present invention, the regressed air-fuel ratio obtained by regressing the detection value of the A / F sensor and the measured air detected by the A / F sensor 4 is a graph showing the relationship between the fuel ratio and the target air-fuel ratio;

An A/F sensor characteristic information generation system according to an embodiment of the present invention will be described below with reference to the drawings.

First, the configuration of the A/F sensor characteristic information generating system according to the embodiment of the present invention will be described with reference to FIG.

Here, FIG. 1 is a schematic diagram showing the configuration of the A/F sensor characteristic information generating system of this embodiment.

As illustrated, the A/F sensor characteristic information generating system W of the present embodiment is installed in an exhaust pipe 6 of an engine E installed on an engine bench (engine test equipment) B, and detects fluid discharged to the exhaust pipe 6. A/F sensor 20 for detecting air-fuel ratio (measured air-fuel ratio); and a measuring device 110 for calculating A/F sensor characteristic information (transfer function, regression transfer function).
In addition, the A/F sensor characteristic information generation system W includes a fuel supply device 31 that supplies fuel to the fuel injection device (injector) 9 of the engine E installed on the engine bench B, and a fuel supply device 31 that supplies fuel to the fuel injection device 9. and a fuel flow meter 32 for measuring the fuel flow rate.
In the illustrated example, the fuel injection device 9 is configured to inject fuel into the intake pipe 5, but this is just an example. This embodiment is also applied to a direct injection engine in which the fuel injection device 9 directly injects fuel into the cylinder 11 .

Also, the engine bench B collects measured values used for calculating A/F sensor characteristic information (transfer function, regression transfer function) from each sensor (A/F sensor 20, high-response flowmeter 21, pressure gauge 22, temperature In the data measurement processing step (see S1 in FIG. 4) that is measured by the meter 233 and the fuel flow meter 32), the engine E injects a predetermined injection amount of fuel, and the air flow rate that flows into the engine E rises steeply in each cycle. The engine E is operated so as to change to .

The A/F sensor 20 is installed in the exhaust pipe 6 that discharges fluid from the engine cylinder 11 and detects the air-fuel ratio (measured air-fuel ratio) of the fluid flowing through the exhaust pipe 6 . Further, the A/F sensor 20 is electrically connected to the measuring device 110, and when detecting the air-fuel ratio (measured air-fuel ratio) of the fluid discharged from the engine E, the measuring device 110 outputs the detected air-fuel ratio (measured air-fuel ratio) is sent.
In this embodiment, as an example of the A/F sensor 20, a conventional "zirconia A/F sensor" is used.

The high-response flow meter 21 is connected to one end of the intake pipe 5 that feeds air into the engine cylinder 11 and measures the air flow rate (air flow rate) of the fluid (air) that flows into the engine E. The high-response flow meter 21 is electrically connected to the measuring device 110 , and when measuring the air flow rate of the fluid flowing into the engine E, transmits the measured air flow rate to the measuring device 110 .
The high-response flowmeter 21 is an airflowmeter that has a higher (faster) response to fluctuations in the airflow rate than the "hot wire type airflow sensor" that is generally installed in the engine E of an automobile. Say. For example, the high-response flowmeter 21 can be an ultrasonic flowmeter or a lamina flowmeter (laminar flowmeter). The illustrated example shows the case where the high-response flow meter 21 is a lamina flow meter.

A pressure gauge 22 is installed in the intake pipe 5 and measures the intake pipe pressure. Moreover, the pressure gauge 22 is electrically connected to the measuring device 110 , and transmits the measured intake pipe pressure to the measuring device 110 when measuring the intake pipe pressure.
A thermometer 23 is installed in the intake pipe 5 and measures the intake pipe temperature. The thermometer 23 is also electrically connected to the measuring device 110 , and upon measuring the intake pipe temperature, transmits the measured intake pipe temperature to the measuring device 110 .

A fuel flow meter 32 is provided in a fuel supply pipe that connects the fuel supply device 31 and the fuel injection device 9 . The fuel flow meter 32 is electrically connected to the measuring device 110 and measures the flow rate of fuel supplied to the fuel injection device 9 (injection amount of fuel injected by the fuel injection device 9). After measuring the “fuel injection amount”, the fuel flow meter 32 transmits the measured “fuel injection amount” to the measuring device 110 .
In this embodiment, the fuel injection device 9 is set to inject a predetermined injection amount (predetermined injection amount) of fuel, and the fuel supply device 31 supplies the fuel injection device 9 with a predetermined amount of fuel. An injection amount of fuel is supplied.

The measuring device 110 measures the measured values (measured air-fuel ratio, air flow rate, intake pipe pressure, intake pipe temperature, fuel injection amount). Further, the control device 110 calculates the "valve flow rate" of the fluid passing through the valves of the engine E using the "air flow rate, intake pipe pressure, intake pipe temperature" among the received measurement values.

The measuring device 110 also calculates a reference air-fuel ratio by dividing the calculated "valve flow rate" by the fuel injection amount (predetermined injection amount) injected by the fuel injection device 9 of the engine E. In addition, the measurement device 110 uses the calculated reference air-fuel ratio and the measured value (measured air-fuel ratio) acquired from the A/F sensor 20 to calculate the transfer function (Gx(s)) of the A/F sensor 20. Then, a regression transfer function (Gy(s)) is generated from the transfer function (Gx(s)) and stored.

The engine bench B also controls the dynamometer 50 that applies a load to the engine E to be tested, the shaft 53 that connects the rotating shaft of the dynamometer 50 and the rotating shaft of the engine E, and the operation of the dynamometer 50. A dynamo control device 51 and an engine control device 60 for controlling the operation of the engine E are provided. The engine control device 60 provides control parameters such as valve timing, throttle opening and ignition advance to the engine E, and controls the operation of the engine E by controlling the opening/closing state of the throttle valve 7 and the valve angle of the intake valve. do.
Since the engine bench B uses a well-known technology, detailed description thereof will be omitted. Also, since the engine E to be tested has a well-known configuration, only the parts directly related to the A/F sensor characteristic information generating system W of this embodiment are shown in the drawing.

Next, the functional configuration of the measuring device 110 that constitutes the A/F sensor characteristic information generating system W of this embodiment will be described with reference to FIGS. 1, 2 and 3 described above.
Here, FIG. 2 is a schematic diagram for explaining the valve passage flow rate calculation processing performed by the A/F sensor characteristic information generation system of the present embodiment. FIG. 3 is a schematic diagram showing the relationship between the air flow rate measured by the high-response flowmeter of the A/F sensor characteristic information generation system of this embodiment and the valve passage flow rate calculated by the A/F sensor characteristic information generation system. be.

As shown in FIG. 1 , the measurement device 110 has a control section 111 , a data acquisition section 112 , a valve passage flow rate calculation section 113 , and an A/F sensor characteristic information calculation section 114 .

Although the hardware configuration of the measuring device 110 is not particularly limited, the measuring device 110 may be, for example, a computer ( (one or more computers). In this case, "A/F sensor 20, high response flow meter 21, pressure gauge 22, thermometer 23, fuel flow meter 32" are connected to the input/output interface. The auxiliary storage device also stores a program for realizing the functions of the "control section 111, data acquisition section 112, valve passage flow rate calculation section 113, and A/F sensor characteristic information calculation section 114." The functions of the "control unit 111, data acquisition unit 112, valve passing flow rate calculation unit 113, and A/F sensor characteristic information calculation unit 114" are executed by the CPU loading the program into the main storage device. It is realized by

The control unit 111 controls the overall operation of the measuring device 110, receives various settings and inputs from the user, and receives operation requests to the A/F sensor characteristic information generation system W. .
The data acquisition unit 112 obtains measured values (measured air-fuel ratio, air flow rate, intake pipe pressure, intake pipe temperature, fuel injection amount).

As shown in FIG. 2, the valve passage flow rate calculation unit 113 calculates the "air flow rate m _l flowing into the intake pipe 5" measured by the high-response flow meter 21 and the "intake pipe pressure P _in ”, “Intake pipe temperature T _in ” measured by the thermometer 23 , “Volume V _in of the intake pipe 5 ”, and the following “(Formula 1) and (Formula 2)” are used to calculate the “Valve flow rate m _iv ".
Here, the “volume V _in of the intake pipe 5 ” is preset in the valve passage flow rate calculation unit 113 . For example, as a preparatory process before performing the A/F sensor characteristic information generation process, "the volume V _in of the intake pipe 5" is stored in the storage unit of the measurement device 110 (auxiliary storage device and main storage device of the measurement device 110). let me When calculating the “valve flow rate m _iv ”, the valve flow rate calculation unit 113 reads out the “volume V _in of the intake pipe 5 ” from the storage unit and uses it for the “valve flow rate m _iv ” calculation process.

The “air flow rate m ₁ ” measured by the high-response flowmeter 21 is approximately the same value as the “air flow rate m _th ” passing through the throttle valve 7 . Therefore, in the present embodiment, the valve passage flow rate calculator 113 sets the value of the "air flow rate m _l " measured by the high-response flowmeter 21 to be the same value as the "air flow rate m _th passing through the throttle valve 7". (See (Formula 1) below).
Then, the valve passage flow rate calculation unit 113 adds the “intake pipe pressure P _in ” measured by the pressure gauge 22 and the “intake pipe temperature T _in ” and “the volume V _in of the intake pipe 5 ” are substituted. Further, the valve passage flow rate calculation unit 113 substitutes the value of the "air flow rate m _l " measured by the high-response flowmeter 21 into the "air flow rate m _th " of the pressure differential equation shown in (Equation 2) below. As a result, the "valve passing flow rate m _iv " is calculated.

Here, FIG. 3 shows the relationship between the “valve passage flow rate m _iv ” calculated by the valve passage flow rate calculator 113 and the “air flow rate m ₁ ” measured by the high-response flowmeter 21 .
As shown in the figure, the "air flow rate m _l " measured by the high-response flowmeter 21 has a delayed response due to the influence of the intake pipe volume. does not become 0. On the other hand, the "valve flow rate m _iv " calculated using the above equations (1) and (2) becomes 0 at the point where the lift amount is closed, and the flow rate that flows into the cylinder is calculated appropriately. It shows that it is done.

Further, the A/F sensor meter characteristic information calculation unit 114 acquires the fuel injection amount (predetermined injection amount) from the data acquisition unit 112 . Then, the A/F sensor meter characteristic information calculation unit 114 calculates the reference air-fuel ratio by dividing the calculated "valve passage flow rate m _iv " by the obtained "fuel injection amount (predetermined injection amount)". do.
Further, the A/F sensor meter characteristic information calculation unit 114 uses the calculated reference air-fuel ratio and the measured value (measured air-fuel ratio) acquired from the A/F sensor 20 to calculate the transfer function of the A/F sensor 20 ( Gx(s)) is calculated, and a regression transfer function (Gy(s)) is generated from the transfer function (Gx(s)) and stored.

Next, the procedure of the A/F sensor characteristic information generating process performed by the A/F sensor characteristic information generating system W of this embodiment will be described with reference to FIGS. 1 and 2 and FIGS.
Here, FIG. 4 is a flow chart showing the procedure of A/F sensor characteristic information generation processing performed by the A/F sensor characteristic information generation system of this embodiment. FIG. 5 is a schematic diagram showing the input/output relationship of the transfer characteristics of the A/F sensor calculated by the A/F sensor characteristics information generating system of the present embodiment. FIG. 6 is a schematic diagram for explaining a process of fitting a transfer function to the transfer characteristic of the A/F sensor calculated by the A/F sensor characteristic information generating system of the present embodiment and identifying the A/F sensor.

As shown in FIG. 4, first, the A/F sensor characteristic information generation system W performs data measurement processing (S1).

In this data measurement process (S1), the engine bench B is driven, the engine E installed on the engine bench B injects a predetermined injection amount of fuel, and the air flow rate flowing into the engine changes sharply in each cycle. Run the engine E as follows.
In this embodiment, the engine bench B provides, for example, a control parameter for controlling the valve timing to the engine E, and controls the valve angle of the intake valve so that the air flow rate flowing into the engine changes sharply in each cycle. to operate the engine E. Alternatively, the engine bench B provides, for example, a control parameter for controlling the throttle opening to the engine E, controls the throttle opening, and controls the engine E so that the flow rate of air flowing into the engine changes sharply in each cycle. make it work.
It should be noted that the engine bench B fixes the fuel injection amount that the engine E injects. That is, the engine bench B operates the engine E so that the engine E injects a predetermined amount of fuel in each cycle.

Then, in the data measurement process (S1), while the data acquisition unit 112 of the measurement device 110 is operating the engine E as described above, the measured air-fuel ratio detected by the A / F sensor 20 and the high response The “air flow rate m _l ” flowing into the intake pipe 5 measured by the flow meter 21, the “intake pipe pressure P _in ” of the intake pipe 5 measured by the pressure gauge 22, and the “intake pipe temperature T _in ” and the fuel injection amount (predetermined injection amount) measured by the fuel flow meter 32 are acquired.
In addition, the data acquisition unit 112 associates the acquired measurement values (measured air-fuel ratio, air flow rate m _l , intake pipe pressure P _in , intake pipe temperature T _{in ,} injection amount (predetermined injection amount)) with each measurement time. (for example, stored in a storage unit not shown (auxiliary storage device and main storage device of the measuring device 110)).

Next, the A/F sensor characteristic information generating system W uses the measured value obtained in S1 to calculate the valve passage flow rate (S2).
Specifically, in S2, first, the valve passage flow rate calculation unit 113 of the measuring device 110 acquires “air flow rate m _l , intake pipe pressure P _in , and intake pipe temperature T _in ” from the data acquisition unit 112 . Further, the valve passage flow rate calculation unit 113 reads out the “volume V _in of the intake pipe 5 ” from the storage unit (auxiliary storage device and main storage device of the measuring device 110 ).
Further, in S2, the valve passage flow rate calculation unit 113 calculates the "air flow rate m _l flowing into the intake pipe 5" measured by the high-response flow meter 21, the "intake pipe pressure P _in " measured by the pressure gauge 22, Using the “intake pipe temperature T _in ” measured by the thermometer 23, the “volume V _in of the intake pipe 5 ”, and the above-mentioned “(Formula 1) and (Formula 2)”, the valve passage flow rate _miv is calculated. calculate.

Next, the A/F sensor characteristic information generation system W performs a reference air-fuel ratio calculation process (S3).
Specifically, in S3, the A/F sensor characteristic information calculation unit 114 of the measurement device 110 acquires the “fuel injection amount (predetermined injection amount)” from the data acquisition unit 112, and the valve passage flow rate calculation unit From 113, the above-calculated "valve passing flow rate m _iv " is acquired. Then, the A/F sensor meter characteristic information calculation unit 114 calculates a value obtained by dividing the above-mentioned "valve passage flow rate m _iv " by the above-mentioned "fuel injection amount (predetermined injection amount)" as a "reference air-fuel ratio". do.
In this embodiment, the fuel injection amount (predetermined injection amount) measured by the fuel flow meter 32 is used to calculate the "reference air-fuel ratio", but the present invention is not particularly limited to this. In this embodiment, since the fuel injection amount to be injected into the engine E is fixed, the fixed fuel injection amount (predetermined injection amount) is stored in advance in the storage unit of the measuring device 110. Also good. In this case, the "reference air-fuel ratio" may be calculated using the "fuel injection amount (predetermined injection amount)" read by the A/F sensor characteristic information calculation unit 114 from the storage unit.

Next, the A/F sensor characteristic information generation system W performs transfer function calculation processing (S4).
In this transfer function calculation process (S4), first, as shown in FIG. Then, Fourier analysis is performed using the air-fuel ratio (measured air-fuel ratio (A/F')) measured by the A/F sensor 20 at the measurement time corresponding to the reference air-fuel ratio (A/F) as an output value. Calculate the transfer characteristic (Gx'(s)) of the F sensor.
The gain diagram of FIG. 6 shows an example of the transfer characteristic (Gx'(s)) obtained by the above Fourier analysis calculation.
Further, in S4, the A/F sensor characteristic information calculation unit 114 fits an arbitrary transfer function (Gx(s)) to the calculated transfer characteristic (Gx'(s)) to obtain "Gx'(s) =Gx(s)” (see FIG. 6).

なお、Ａ/Ｆセンサ特性情報算出部１１４は、図示しない記憶部（計測装置１１０の補助記憶装置及び主記憶装置）に、Ｓ４で算出した「伝達特性（Ｇｘ’（ｓ））、伝達関数（Ｇｘ（ｓ））」と、Ｓ５で算出した回帰伝達関数（Ｇｙ（ｓ））に記憶させる。 Next, the A/F sensor characteristic information generation system W performs a regression transfer function calculation process (S5).
In this regression transfer function calculation process (S5), the A/F sensor characteristic information calculation unit 114 of the measurement device 110 uses the transfer function (Gx(s)) calculated in S4 to obtain the following (Equation 3): Calculate the regression transfer function (Gy(s)) shown.
"Lowpassfilter" is a characteristic that does not interfere with Gx(s) by using a filter whose cutoff is set to a higher frequency than the band of Gx(s).

Note that the A/F sensor characteristic information calculation unit 114 stores the "transfer characteristic (Gx'(s)), transfer function ( Gx(s))" and stored in the regression transfer function (Gy(s)) calculated in S5.

Thus, the reason why the configuration of the A/F sensor characteristic information generation system W of the present embodiment is adopted is that the inventor of the present application can accurately calculate the value of the valve passage flow rate of the fluid passing through the valve of the engine E. If possible, the true value of the air-fuel ratio of the fluid discharged to the exhaust pipe 6 is calculated by dividing the valve passage flow rate by the "fuel injection amount" of the engine E installed on the engine bench B. It is due to finding that a value approximating to is obtained.
In addition, the inventor of the present application calculated a value obtained by dividing the "valve passage flow rate" by the "predetermined fuel injection amount" as a reference air-fuel ratio, and calculated the reference air-fuel ratio and the measurement detected by the A / F sensor 20. The air-fuel ratio is used to calculate the regression transfer function of the A/F sensor as the A/F sensor characteristic information.
As a result, by correcting the measured value (measured air-fuel ratio) detected by the "A/F sensor" using the "A/F sensor characteristic information (regression transfer function)" obtained by this embodiment, an accurate Air-fuel ratio can be calculated. That is, according to the present embodiment, the "zirconia type A/F sensor", which is generally used for controlling the engine E of an automobile, is replaced with the "A/F sensor" with high response. can function.

Specifically, the inventor of the present application paid attention to the fact that the flow rate of fluid passing through the intake valve of the engine E is substantially the same as the flow rate of the fluid passing through the exhaust valve of the engine E. A high-response flowmeter 21 composed of a lamina flowmeter or the like is connected to the intake pipe 5 of the engine, and the high-response flowmeter 21 measures the "air flow rate of air (fluid) flowing into the intake pipe 5". adopted the configuration. With this configuration, it is possible to measure with a high response a transient air flow rate in which the air flow rate of the air flowing into the intake pipe 5 of the engine E changes sharply, and a highly accurate value of the air flow rate can be obtained.

In addition, the inventors of the present application have found that the "valve flow rate of fluid passing through the intake valve m _iv ," which is substantially the same as the "valve flow rate of fluid passing through the exhaust valve," is equal to the "air flow rate m _l flowing into the intake pipe 5." , “intake pipe pressure P _in ”, “intake pipe temperature T _in ”, “volume V _in of intake pipe 5 ”, and “pressure differential equation” shown in (Equation 2) above, I paid attention to the fact that it can be calculated.
Therefore, the inventors of the present application have adopted a configuration in which "the pressure gauge 22 and the temperature gauge 23" are provided in the intake pipe 5 and the "intake pipe pressure P _in and the intake pipe temperature T _in " are measured. In addition, the measuring device 110 is provided with an “air flow rate m _l ” measured by the high-response flow meter 21 , an “intake pipe pressure P _in ” measured by the pressure gauge 22 , and an “intake pipe temperature T _in ”, “the volume V _in of the intake pipe 5 ”, and the pressure differential equation of (Equation 2) described above, the valve passage flow rate calculation unit 113 that calculates the valve passage flow rate of the fluid that passes through the valve of the engine E. The configuration of This gives an accurate value for engine E "flow through valve".

In addition, in the present embodiment, since an accurate value of the "valve flow rate" can be calculated, the value obtained by dividing the calculated "valve flow rate" by the "predetermined injection amount of fuel" is displayed in the measuring device 110 as a "reference empty space". A/ A configuration in which the F sensor characteristic information calculation unit 114 is provided is adopted. By correcting the measured value (measured air-fuel ratio) detected by the "A/F sensor" using this "A/F sensor characteristic information (regression transfer function)", an accurate air-fuel ratio can be calculated.

<<Engine control system of application example of the present embodiment>>
Next, an example of utilization of the A/F sensor characteristic information generated by the A/F sensor characteristic information generating system W of this embodiment will be described with reference to FIG.
Here, FIG. 7 is a schematic diagram for explaining an example of utilization of the A/F sensor characteristic information generated by the A/F sensor characteristic information generating system of this embodiment. 1 shows an engine control system having an engine control unit with a

The illustrated engine control system has an engine E with an A/F sensor 20 and an engine control unit (hereinafter referred to as "ECU") 200 for controlling the operation of the engine E. Used.

The ECU 200 controls the operation of the engine E mounted on the vehicle, and includes an engine control unit 201 that controls the operation of the engine E, and the "A /F sensor characteristic information (regression transfer function (Gy(s)))”.

The A/F sensor 20 is installed in the exhaust pipe 6 of the engine cylinder E, detects the air-fuel ratio of fluid discharged from the engine E, and transmits the detected air-fuel ratio to the ECU 200 .

Further, when the engine control unit 201 of the ECU 200 receives the "air-fuel ratio" transmitted from the A/F sensor 20, the "regression transfer function (Gy(s))" stored in the storage unit 203 is read out and received. By applying the read "regression transfer function (Gy(s))" to the obtained "air-fuel ratio", the "air-fuel ratio" measured by the A/F sensor 20 is corrected to the "corrected air-fuel ratio".
After that, the engine control unit 201 controls the fuel injection amount that the engine E injects using the "correction air-fuel ratio".

The illustrated ECU 200 uses the A/F sensor characteristic information (regression transfer function (Gy(s))) of the A/F sensor 20 generated by the A/F sensor characteristic information generation system W of the above-described embodiment. , the air-fuel ratio measured by the A/F sensor 20 is corrected, and the operation of the engine E is controlled using the corrected air-fuel ratio. detailed description is omitted.

In this way, the A/F sensor characteristic information generation system W of the present embodiment generates A/F sensor characteristic information indicating the characteristics of the A/F sensor 20 and stores it in the ECU 200, thereby improving the responsiveness. The engine E can be controlled based on the improved measured value (corrected air-fuel ratio) of the A/F sensor 20 .
Therefore, for example, even in an automobile equipped with an engine E having a zirconia type A/F sensor, which is a main component of automobiles, by configuring like the above ECU 200 (for example, existing By changing the ECU program), the engine E can be controlled to operate optimally.

Note that FIG. 7 described above exemplifies an engine control system that controls the engine E mounted on a vehicle, but the present invention is not particularly limited to this. For example, the above A/F sensor characteristic information (regression transfer function (Gy(s))) may be used in an engine testing apparatus for testing an engine E having a zirconia A/F sensor 20. . In this case, the "regression transfer function (Gy(s))" is stored in the engine control device that controls the driving of the engine E, and the engine control device uses the regression transfer function (Gy(s)) to obtain the A The air flow rate measured by the /F sensor 20 may be corrected, and the corrected air flow rate obtained may be used to control the operation of the engine E and perform various tests of the engine.

Further, in the above-described embodiment, an ultrasonic flowmeter or a lamina flowmeter was shown as an example of the high-response flowmeter 21, but the responsiveness to fluctuations in the air flow rate is higher (faster) than that of the hot-wire airflow sensor. is applied to the present invention.

For example, the high-response flow meter 21 may use the flow measurement system described in the document (Japanese Patent Application Laid-Open No. 2020-1134243 (Patent Document 3)) filed by the applicant of the present application. In this flow measurement system, the characteristics of the differential pressure sensor (differential pressure sensor characteristic information) installed in the lamina flow meter (laminar flow meter) are calculated in advance, and the measured value ( The air flow rate (differential pressure measured by the differential pressure sensor) is corrected with the differential pressure sensor characteristic information, and the corrected value is used as the air flow rate.

Specifically, the lamina flowmeter of the flow measurement system described in Patent Document 3 includes a main body provided with a laminar flow element, a static pressure upstream of the laminar flow element, and a static pressure downstream of the laminar flow element. A differential pressure sensor is provided for measuring and outputting the differential pressure from the static pressure of the part.
In addition, the differential pressure sensor includes a first connecting pipe that acquires the static pressure of the upstream portion of the laminar flow element, a second connecting pipe that acquires the static pressure of the downstream portion of the laminar flow element, and the first and second connecting pipes. It has a sensor unit that is connected to each of them and measures the differential pressure between the static pressure at the upstream portion and the static pressure at the downstream portion.

The above differential pressure sensor characteristic information is obtained by removing the differential pressure sensor from the lamina flowmeter and connecting the air inflow path to the first connection pipe of the removed differential pressure sensor in the stage prior to the process of calculating the intake air flow rate of the engine. One end of the second connecting pipe of the connected and removed differential pressure sensor is opened to the atmosphere. Further, in the above state, air is caused to flow into the differential pressure sensor through the air inflow path, and the pressure in the air inflow path near the first connection pipe is measured as the first pressure, and the differential pressure sensor unit Measuring the differential pressure between the pressure of the connecting pipe and the pressure of the second connecting pipe as the second pressure, converting the relationship between the first pressure and the second pressure into frequency characteristic information indicated by gain and phase for each frequency, The frequency characteristic information is indicated by a transfer function.

Then, when the high-response flow meter 21 of the A/F sensor characteristic information generation system W of the present embodiment is applied to the flow measurement system described in Patent Document 3, the measuring device 110 has a pre-calculated differential pressure Store the sensor characteristic information. Also, a lamina flow meter is used for the high response device 21 of the A/F sensor characteristic information generating system W. FIG. Then, when the data acquisition unit 112 acquires the measured value measured by the lamina flow meter (for convenience of explanation, it will be referred to as a “lamina air flow rate”), the data acquisition unit 112 uses the stored differential pressure sensor characteristic information to obtain the “lamina air flow rate”. The corrected air flow rate obtained by correcting and correcting is defined as "the air flow rate m _l flowing into the intake pipe 5" in the above-described embodiment.
Also in this case, the same effect as the embodiment described above can be obtained.

Next, using the A/F sensor characteristic information (regression transfer function (Gy(s))) calculated by the A/F sensor characteristic information generation system W of the present embodiment, the actual measured value of the A/F sensor 20 is The relationship between the corrected regression result (A/F sensor regression value), the measured value of the A/F sensor 20, and the target air-fuel ratio will be described with reference to FIGS.

Here, FIGS. 8 and 9 show regression values (regressed air-fuel ratio) obtained by regressing the detected value of the A/F sensor using the A/F sensor characteristic information calculated by the A/F sensor characteristic information generation system of the present embodiment. , and the relationship between the measured value (measured air-fuel ratio) detected by the A/F sensor and the target air-fuel ratio (true value of the air-fuel ratio).

Note that FIG. 8 shows a graph in which the air flow rate is stepped by 1 cycle and the A/F is changed sharply. As shown in the graph of FIG. 8, the measured value of the A/F sensor 20 has poor responsiveness to the target air-fuel ratio (true value of the air-fuel ratio), and an instantaneous value cannot be obtained. On the other hand, from Fig. 8, the A/F sensor regression value (regression result) captures the instantaneous value appropriately. It shows the results of the investigation. As shown in FIG. 9, it can be seen that the regression result appropriately captures the target air-fuel ratio (true value) for points other than those shown in FIG.
Thus, according to the present embodiment, by calculating the A/F sensor characteristic information (regression transfer function (Gy(s))) of the A/F sensor 20, the "A/F sensor 20" with poor responsiveness can can function as an "A/F sensor" with high responsiveness, and the responsiveness of the A/F sensor 20 can be improved.

W... A/F sensor characteristic information generation system 20... A/F sensor 21... High response flow meter 22... Pressure gauge 23... Thermometer 31... Fuel supply device 32... Fuel gauge 110... Measurement device 111... Control unit 112... Data Acquisition unit 113 ... valve passage flow rate calculation unit 114 ... A/F sensor characteristic information calculation unit

B... Engine bench 50... Dynamometer 51... Dynamo controller 53... Shaft 60... Engine controller

E... Engine 5... Intake pipe 6... Exhaust pipe 7... Throttle valve 9... Fuel injection device 11... Engine cylinder

Claims (4)

An A/F sensor installed in an exhaust pipe of an engine installed in an engine testing apparatus for detecting the measured air-fuel ratio of fluid discharged into the exhaust pipe, and an A/F sensor connected to an intake pipe of the engine and flowing into the intake pipe. A high-response flow meter that measures the air flow rate of the fluid, a pressure gauge that is installed inside the intake pipe and measures the intake pipe pressure, and a thermometer that is installed inside the intake pipe and measures the intake pipe temperature; An A/F sensor characteristic information generation system comprising a measuring device for calculating /F sensor characteristic information,
The engine testing device operates the engine such that the engine injects a predetermined injection amount of fuel and the flow rate of air flowing into the engine changes sharply in each cycle,
The measuring device is
While the engine test equipment is operating the engine, the measured air-fuel ratio detected by the A / F sensor, the air flow rate measured by the high response flow meter and flowing into the intake pipe, and the pressure gauge a data acquisition unit that acquires the measured intake pipe pressure and the intake pipe temperature measured by the thermometer;
a valve passage flow rate calculation unit that calculates a valve passage flow rate of fluid passing through an intake valve of the engine using the acquired air flow rate, intake pipe pressure, and intake pipe temperature;
A value obtained by dividing the calculated valve passage flow rate by the predetermined injection amount is calculated as a reference air-fuel ratio, and the A/F sensor is used as the A/F sensor characteristic information using the reference air-fuel ratio and the acquired measured air-fuel ratio. and an A/F sensor characteristic information calculation unit for calculating a regression transfer function of A/F sensor characteristic information generation system. The A/F sensor characteristic information calculation unit uses the reference air-fuel ratio as an input value and the measured air-fuel ratio detected by the A/F sensor corresponding to the reference air-fuel ratio as an output value, performs Fourier analysis calculation, and performs the A A according to claim 1, wherein the transfer characteristic of the /F sensor is calculated, the transfer function is calculated from the calculated transfer characteristic, and the regression transfer function is calculated from the transfer function. /F sensor characteristic information generation system. 3. The A/F sensor meter characteristic information generating system according to claim 1, wherein said high response flowmeter is an ultrasonic flowmeter or a lamina flowmeter. An engine control device storing the regression transfer function generated by the A/F sensor characteristic information generation system according to any one of claims 1 to 3, and an engine provided with the A/F sensor. an engine control system with
The A/F sensor is installed in an exhaust pipe of the engine to measure the air-fuel ratio of fluid discharged to the exhaust pipe, and transmits the measured air-fuel ratio to the engine control device,
The engine control device acquires the air-fuel ratio measured by the A/F sensor, calculates a corrected air-fuel ratio by correcting the acquired air-fuel ratio using the stored regression transfer function, and calculates the corrected air-fuel ratio. An engine control system, characterized in that it controls a fuel injection amount of an engine using a fuel ratio.

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