JPH07103038A - Calibrating device for exhaust detection sensor of engine - Google Patents

Abstract

PURPOSE:To achieve desired control based on the actual detection signal from an exhaust detection sensor by facilitating calibration of the exhaust detection sensor even when the output characteristic of the sensor changes as time elapses as seen from the original output characteristic. CONSTITUTION:The calibrating device for the exhaust detection sensor of an engine is provided with an exhaust detection sensor 33 for detecting the condition of exhaust, driving condition detection sensors 34-36 for detecting the driving condition of the engine, and an output proper value calculation means 38 for calculating the output proper value of detection signal to be output by the exhaust detection sensor 33 at the time of idling based on the original output characteristic. A calibrating means 40 is also provided for bringing the output characteristic of the exhaust detection sensor 33 closer to the original output characteristic by means of the actual detection signal and output proper value of the exhaust detection sensor 33 at the time of idling.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust gas sensor calibrating device for an engine, which is provided with an exhaust gas sensor for detecting the properties of exhaust gas and which calibrates the change over time in the output characteristics of the exhaust gas sensor.

[0002]

2. Description of the Related Art Conventionally, an engine mounted on a motorcycle or the like is provided with an exhaust gas detection sensor and controls the air-fuel ratio based on the detection signal of the exhaust gas detection sensor to improve the driving performance of the engine or to reduce the fuel consumption. There is one that is designed to suppress the wasteful consumption of.

[0003]

By the way, when the exhaust gas detection sensor is used for a long period of time, the sensitive portion of the exhaust gas sensor may deteriorate over time, or foreign matter such as dust may adhere to the sensitive portion.

As described above, if the sensitive portion of the exhaust gas detection sensor is deteriorated or foreign matter is attached, the output characteristics of the exhaust gas detection sensor will change from the original output characteristics. In particular, when trying to perform highly accurate control based on the detection signal, there arises a problem that desired control cannot be performed.

Therefore, in order to perform the high-precision control as described above, it is required to calibrate the output characteristic of the exhaust gas detection sensor to the original output characteristic each time. The calibration work is complicated.

[0006]

SUMMARY OF THE INVENTION The present invention has been made by paying attention to the above circumstances. When an exhaust gas detection sensor for detecting the characteristics of engine exhaust gas is provided, the exhaust gas detection sensor is used to obtain the exhaust gas. Even if the output characteristics of the detection sensor change over time in view of the original output characteristics, it is possible to easily calibrate the output characteristics so that desired control can be performed based on the actual detection signal of the exhaust detection sensor. The purpose is to do.

[0007]

In order to achieve the above object, the present invention provides an exhaust gas detection sensor 33 for detecting the property of exhaust gas 25, and operating state detection sensors 34-36 for detecting the operating state of the engine 1. An appropriate output value for inputting the detection signals of the operating state detection sensors 34 to 36 at the time of idling and calculating an appropriate output value of the detection signal to be output by the exhaust detection sensor 33 based on the original output characteristic at the time of idling. Computation means 38 and calibration means 40 for calibrating the output characteristic of the exhaust detection sensor 33 so as to approximate the original output characteristic by the actual detection signal of the exhaust detection sensor 33 in idling and the appropriate output value. It is a thing.

[0008]

[Operation] The operation of the above configuration is as follows.

When the engine 1 is to be controlled on the basis of the actual detection signal of the exhaust detection sensor 33, first, the detection signal which the exhaust detection sensor 33 should output with its original output characteristic (hereinafter, Is referred to as an appropriate output value) by the appropriate output value calculation means 38 based on the detection signals of the operating state detection sensors 34 to 36.

In the above case, the idling time of the operating state of the engine 1 is selected. At this idling time, for example, the throttle opening is always the same, and what is the throttle opening? This is because there are few conditions for calculating the detection signal that should be output by the exhaust gas detection sensor 33, such as without considering the conditions of (1), that is, at the time of idling, it is easy to calculate the appropriate output value of the exhaust gas detection sensor 33. Because you can do it.

Then, by comparing the output proper value calculated by the output proper value calculating means 38 with the actual detection signal of the exhaust detection sensor 33 during idling, the output characteristic of the detection signal of the exhaust detection sensor 33 is determined. , It is determined how much the output characteristic is changing. Next, the changed amount is automatically calibrated by the calibrating means 40, and the changed output characteristic is brought close to the original output characteristic.

[0012]

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

In FIG. 2, reference numeral 1 is an engine mounted on a motorcycle. An intake pipe 2 is connected to an intake port of the engine 1, and a carburetor 3 is provided in the middle of the intake pipe 2. An exhaust pipe 4 is connected to the exhaust port of the engine 1, and a catalyst 5 is provided in the middle of the exhaust pipe 4.

The carburetor 3 is of the air bleed type and has an intake passage 7 therein. A piston 8 is provided which extends and retracts toward the intake passage 7, and a venturi portion 9 is formed between the protruding portion of the piston 8 and the inner peripheral surface of the intake passage 7. A main nozzle 11 that opens toward the venturi portion 9 is provided. The main nozzle 11 communicates with the float chamber 13 storing the fuel 12, and also communicates with the intake pipe 2 on the upstream side of the carburetor 3 via the main air pipe 14. A taper needle 15 is provided on the piston 8 so as to project from the piston 8. The taper needle 15 is inserted into the main nozzle 11.

A butterfly type throttle valve 17 for adjusting the opening of the intake passage 7 on the downstream side of the venturi portion 9.
Is provided. A slow port 18 that opens toward the intake passage 7 is provided at a position corresponding to the throttle valve 17. The slow port 18 communicates with the float chamber 13 and also communicates with the inside of the intake pipe 2 upstream of the carburetor 3 via a slow air pipe 19.

Reference numeral 21 is an engine control device for electronically controlling the engine 1.

When the engine 1 is driven by the control of the engine control device 21, intake air 23 outside the machine is sucked into the engine 1 through the intake pipe 2. At this time, when the opening degree of the intake passage 7 is increased by operating the throttle valve 17, the venturi portion 9 and the intake passage 7 on the downstream side of the venturi portion 9 respond to the opening operation of the throttle valve 17. The negative pressure becomes high, and the negative pressure causes the fuel 12 to be sucked into the intake passage 7 through the main nozzle 11 and the slow port 18. And the fuel 12
Is mixed with the intake air 23, and the air-fuel mixture 24 generated thereby is sucked into the engine 1 and used for combustion.

Exhaust gas 25 generated by the combustion is discharged through the exhaust pipe 4 and the catalyst 5. At this time, the catalyst 5
Burns the unburned matter in the exhaust gas 25,
To purify.

In FIG. 3, the air-fuel ratio of the air-fuel mixture 24 is the theoretical air-fuel ratio (14.
Each part of the carburetor 3 is set so as to be always smaller than 7). That is, the operating performance is improved by sufficiently increasing the concentration of the fuel 12 in the air-fuel mixture 24.

1 and 2, a main system air valve 28 for adjusting the opening of the main system air pipe 14 is provided in the middle of the main system air pipe 14. Further, a main actuator 29 for opening and closing the main air valve 28 is provided. On the other hand, a slow air valve 30 for adjusting the opening degree of the slow air pipe 19 is provided. Further, a slow system actuator 31 for opening and closing the slow system air valve 30 is provided. Each of the actuators 29 and 31 is a servomotor or a solenoid.

Of the properties of the exhaust gas 25, an exhaust gas detection sensor 33, which is a CO sensor for detecting the CO concentration, is attached to the exhaust pipe 4. This exhaust gas detection sensor 33
Is, for example, a semiconductor made of a metal oxide made of SnO ₂ as a sensitizer, and as shown in FIG. To detect the CO concentration.

1 and 2, various operating state detection sensors for detecting the operating state of the engine 1 are provided. These operating state detection sensors include an engine rotation speed detection sensor 34 that detects the rotation speed of the engine 1, an intake negative pressure detection sensor 35 that detects the suction negative pressure of the intake passage 7 between the venturi portion 9 and the throttle valve 17, and the engine 1 The water temperature detection sensor 36 detects the temperature of the cooling water and indirectly detects the temperature of the engine 1.

In FIG. 1, the engine control unit 21
Is the intake air amount calculation means 32, the first air-fuel ratio calculation means 3
7, output proper value calculation means 38, comparison means 39, calibration means 40, actuator control means 41, and second air-fuel ratio calculation means 42.

Based on the detection signal of the suction negative pressure detection sensor 35, the amount of intake air 23 is calculated by the intake air amount calculation means 3 described above.
2 and the calculation result of the intake air amount calculation means 32 is input to the first air-fuel ratio calculation means 37. That is, the detection signal of the intake negative pressure detection sensor 35 is indirectly input to the first air-fuel ratio calculation means 37 via the intake air amount calculation means 32. Further, the detection signals of the engine speed detection sensor 34 and the water temperature detection sensor 36 are directly input to the first air-fuel ratio calculation means 37, respectively.

Based on the direct and indirect detection signals of the engine speed detection sensor 34, the suction negative pressure detection sensor 35, and the water temperature detection sensor 36 at the time of idling, the same as above is used to calculate the first air-fuel ratio at the time of idling. It is calculated by means 37.

In the above case, the idling time of the operating state of the engine 1 is selected because, for example, the throttle opening is always the same when the engine is idling, and how much the throttle opening is. This is because there are few conditions for calculating the detection signal that should be output by the exhaust gas detection sensor 33, such as without considering the conditions of (1), that is, at the time of idling, it is easy to calculate the appropriate output value of the exhaust gas detection sensor 33. Because you can do it. In addition,
Immediately after the engine 1 is started during the idling, the temperature of the engine 1 is low and has not reached a stable operating state. Therefore, after the engine 1 reaches a predetermined temperature, the sensors 33 to 35 detect the temperature. It is designed to output a signal.

In FIGS. 1 and 4, based on the air-fuel ratio at idling calculated by the first air-fuel ratio calculating means 37, the appropriate output value calculating means 38 causes the CO concentration in the exhaust gas 25 (A in FIG. 4). Points) are calculated. Also, this CO
The appropriate output value of the exhaust gas detection sensor 33 at the concentration (B in FIG. 4)
Point) is calculated by the original output characteristic (a) which is a map.

By the way, assuming that the exhaust detection sensor 33 has the original output characteristics, such as when no foreign matter is attached to the sensor of the exhaust detection sensor 33, the same as the actual exhaust detection sensor 33 during idling. The detection signal is also
It should be the same as or close to the appropriate output value (point B in FIG. 4).

However, if the output characteristic of the exhaust gas detection sensor 33 changes due to the use of the exhaust gas detection sensor 33, such as when foreign matter adheres to the sensitive body of the exhaust gas detection sensor 33, the actual characteristics of the exhaust gas detection sensor 33 will change. The detection signal of
For example, it will decrease to point C in FIG. Therefore, when the CO concentration is calculated using the original output characteristic (a) based on this actual detection signal, this value (point F in FIG. 4) is the CO calculated by the output appropriate value calculation means 38. A large error occurs in terms of the density (point A in FIG. 4).

Then, next, the same as above, the actual detection signal of the exhaust gas detection sensor 33 during idling (point C in FIG. 4).
And the appropriate output value (point B in FIG. 4) are compared by the comparison means 39, and the comparison result is input to the calibration means 40.

In FIG. 4, the calibration means 40 has, as a map, a first output characteristic (b) and a second output characteristic (c).
Is set. Each of these output characteristics (b) and (c) is obtained by substantially translating the basic characteristic (a).

In the calibration means 40, an output characteristic passing near the intersection of the points A and C in FIG. 4 (point D in FIG. 4) is selected. That is, in FIG. 4, the first output characteristic (b) is selected, and the CO concentration is calculated as the calibration concentration based on the first output characteristic (b) (point E in FIG. 4).

That is, even when the actual detection signal of the exhaust gas detection sensor 33 is at point C in FIG. 4, the calibration means 40 calculates the CO concentration as the calibration concentration by the first output characteristic (b) ( (Point E in FIG. 4). Then, the calibration concentration becomes the same as or close to the calculated CO concentration (point A in FIG. 4) by selecting the first output characteristic (b).

Therefore, even if the output characteristic of the exhaust gas detection sensor 33 is changed from the original output characteristic, the calibration unit 40 determines the original output characteristic or the original output characteristic based on the actual detection signal of the exhaust gas detection sensor 33. Is calibrated to an output characteristic close to, and a CO concentration that is almost the same as the original output characteristic is calculated as the calibration concentration.

1 and 2, the calibration concentration calculated by the calibration means 40 is input, and the second air-fuel ratio calculation means 42 calculates the air-fuel ratio again. Based on this calculation result, the main system actuator 29 and the slow system actuator 31 are driven via the actuator control means 41, and the main system air valve 28 and the slow system air valve 30 are opened and closed.

By the opening / closing valve operation, the amount of the fuel 12 sucked through the main nozzle 11 and the slow port 18 to the intake passage 7 side is adjusted, and the air-fuel ratio of the air-fuel mixture 24 is adjusted. As a result, the driving performance of the engine 1 is improved, and the wasteful consumption of the fuel 12 is suppressed.

In FIG. 2, the catalyst 5 is an oxidation catalyst,
CO and HC in the exhaust gas 25 react with the catalyst 5 to be burned, whereby the exhaust gas 25 is purified and discharged.

1 and 2, an exhaust gas purification device 43 for purifying the exhaust gas 25 is provided.

The exhaust gas purification device 43 is provided with a secondary air pipe 44 which connects the inside of the intake pipe 2 upstream of the carburetor 3 to the inside of the exhaust pipe 4. A secondary air valve 45 for adjusting the opening degree of the secondary air pipe 44 in the middle of the secondary air pipe 44.
Is installed. Further, a secondary air actuator 46 for opening and closing the secondary air valve 45 is provided. This secondary air actuator 46 is a servo motor,
Alternatively, it is a solenoid or the like.

A catalyst temperature detecting sensor 47 is attached to the catalyst 5. The catalyst temperature detection sensor 47 directly detects the temperature of the catalyst 5, or indirectly detects the temperature of the catalyst 5 by the temperature of the exhaust gas 25 passing through the catalyst 5. Further, the engine control device 21 is provided with a secondary air supply amount determination means 49 and an actuator control means 50.

The air-fuel ratio calculated by the second air-fuel ratio calculating means 42 and the detection signal of the catalyst temperature detecting sensor 47 are input to the secondary air supply amount determining means 49, and based on this, the secondary air supply amount is determined. The air supply amount determining means 49 determines the amount of the secondary air 23a to be supplied from the inside of the intake pipe 2 through the secondary air pipe 44 into the exhaust pipe 4. Then, as much as the supply amount of the secondary air 23a thus determined is obtained,
The secondary air actuator 46 is opened / closed by the actuator control means 50.

The secondary air 23a is the exhaust gas 2 in the exhaust pipe 4.
CO, H contained in the exhaust gas 25 when supplied to
C is burned by the oxygen in the secondary air 23a and is sufficiently purified.

Although the above is based on the illustrated example, there may be three or more maps of the output characteristics in the calibration means 40. Further, the calibration means 40 may be one that does not include the map of FIG. 4 described above and calibrates the actual detection signal of the exhaust gas detection sensor 33 by calculation.

Further, the catalyst 5 and the exhaust gas purification device 43 are not essential to the present invention. Further, when the engine 1 has a large number of cylinders, the above-mentioned calibration device may be provided for each cylinder, which prevents variations in the output between the cylinders.

[0045]

According to the present invention, the exhaust detection sensor for detecting the property of exhaust gas, the operation state detection sensor for detecting the operation state of the engine, and the detection signals of the operation state detection sensor during idling are input. Same as above, output proper value calculating means for calculating the output proper value of the detection signal that the exhaust detection sensor should output based on the original output characteristics at the time of idling, and the same as above, the actual detection signal of the exhaust detection sensor at idling and the above output properness. And a calibration means for calibrating the output characteristic of the exhaust gas detection sensor so as to approach the original output characteristic.

Therefore, when the engine is to be controlled on the basis of the actual detection signal of the exhaust gas detection sensor, first, the detection signal (the appropriate output value) which the exhaust gas detection sensor should output with its original output characteristic is It is calculated by the output appropriate value calculation means based on the detection signal of the operating state detection sensor at idling.

Then, by comparing the output proper value calculated by the output proper value calculating means with the actual detection signal of the exhaust gas detection sensor at the time of idling, the output characteristic of the detection signal of the exhaust gas detection sensor is the original. It is determined how much the output characteristic changes. Next, the changed amount is automatically calibrated by the calibrating means, and the changed output characteristic is brought close to the original output characteristic.

Therefore, when the exhaust gas detection sensor for detecting the property of the exhaust gas of the engine is provided, it is assumed that the output characteristic of the exhaust gas detection sensor changes with time from the original output characteristic by using the exhaust gas detection sensor. However, this can be easily calibrated, and desired control can be performed based on the actual detection signal of the exhaust gas detection sensor.

[Brief description of drawings]

FIG. 1 is an electric block diagram showing an engine control device.

FIG. 2 is an overall diagram.

FIG. 3 is a graph showing the relationship between engine output and air-fuel ratio.

FIG. 4 is a diagram showing output characteristics of an exhaust gas detection sensor.

[Explanation of symbols]

1 engine 25 exhaust gas 33 exhaust gas detection sensor 34 engine speed detection sensor (operating state detection sensor) 35 intake negative pressure detection sensor (operating state detection sensor) 36 water temperature detection sensor (operating state detection sensor) 38 output proper value calculation means 39 comparison Means 40 Calibration means 43 Exhaust gas purification device (a) Original output characteristics B point output proper value

Claims (1)

[Claims] 1. An exhaust gas detection sensor for detecting a property of exhaust gas, an operating state detection sensor for detecting an operating state of an engine, and a detection signal of the operating state detection sensor during idling, which are the same as above when idling. An appropriate output value calculation means for calculating an appropriate output value of the detection signal that the exhaust gas detection sensor should output based on the original output characteristics,
Same as above, an exhaust gas detection sensor calibration device for an engine, comprising an actual detection signal of the exhaust gas detection sensor in idling and the output proper value, and a calibration means for calibrating the output characteristics of the exhaust gas detection sensor so as to approximate the original output characteristics. .