JP2022083229A - Vehicular control system and program - Google Patents

Abstract

To stabilize combustion of each cylinder of an internal combustion engine.SOLUTION: A vehicle includes: an EGR system 9 having an EGR passage 10 communicating an exhaust passage 3 and an intake passage 2 of an internal combustion engine 1 and an EGR valve 12 controlling a flow rate of exhaust gas to be returned from the exhaust passage 3 to the intake passage 2; and concentration sensors 13 each installed in each cylinder 1a of the internal combustion engine 1 and detecting an oxygen concentration or a carbon dioxide concentration on the intake side of each cylinder 1a. The control device 100 controls an opening of the EGR valve 12 in accordance with an EGR rate calculated on the basis of detection results from the concentration sensors 13. The control device 100 controls ignition timing of each cylinder 1a in accordance with the EGR rate of each cylinder 1a calculated on the basis of the detection result from the concentration sensor 13.SELECTED DRAWING: Figure 1

Description

The present invention relates to a vehicle control system and a program for controlling a vehicle equipped with an EGR (Exhaust Gas Recirculation) system.

Some vehicles equipped with an internal combustion engine are equipped with an EGR system. The EGR system has an EGR passage that connects the exhaust passage and the intake passage of the internal combustion engine, and an EGR valve that regulates the flow rate of the exhaust gas returned from the exhaust passage to the intake passage. With such an EGR system, it is possible to reduce nitrogen oxides and improve fuel efficiency.

For example, Patent Document 1 discloses a control device that controls an EGR device of an internal combustion engine. This control device includes an EGR calculation unit and an EGR correction unit. The EGR calculation unit calculates the EGR rate based on the detection result of the intake oxygen concentration sensor that detects the oxygen concentration contained in the intake air. The EGR correction unit corrects the EGR rate based on the detection result of the A / F sensor that detects the air-fuel ratio of the exhaust gas.

Patent Document 1 describes the following contents.
Oxygen contained in the exhaust gas generated when burning in a state where the air-fuel ratio is stoichiometric (theoretical air-fuel ratio) has a substantially constant concentration. Therefore, the control device calculates the EGR rate based on the intake oxygen concentration detected by using the intake oxygen concentration sensor provided in the intake pipe, and feedback-controls the opening degree of the EGR valve. As a result, the control device can improve fuel efficiency while suppressing deterioration of the operating condition.
However, when the air-fuel ratio shifts from stoichiometric to rich / lean, the oxygen concentration in the exhaust gas changes. Therefore, if the EGR rate is calculated based on the inspired oxygen concentration detected by the control device using the inspired oxygen concentration sensor, the calculated EGR rate and the actual EGR rate will be different.
Therefore, the EGR rate calculated by the control device is corrected based on the detection result of the A / F sensor that detects the air-fuel ratio of the exhaust gas. As a result, the control device can easily and accurately calculate the EGR rate.

Japanese Unexamined Patent Publication No. 2018-193979

In Patent Document 1, one intake oxygen concentration sensor provided in the intake pipe is used to detect the intake oxygen concentration, and the EGR rate is calculated based on the intake oxygen concentration.
However, in a multi-cylinder internal combustion engine, for example, due to the relationship between the connection position of the EGR passage with respect to the intake passage and the position of each cylinder, the shape of the branch pipe of the intake manifold connecting the intake passage to each cylinder, and the like, the cylinders There may be a difference in the actual EGR rate between them. In such a situation where the actual EGR rate may differ between cylinders, when calculating the EGR rate based on the intake oxygen concentration detected using one intake oxygen concentration sensor, depending on the cylinder, the calculated EGR rate may be used. There will be a difference from the actual EGR rate. Therefore, depending on the cylinder, combustion may not be stable, leading to deterioration of fuel efficiency and misfire.

The present invention has been made in view of such circumstances, and an object of the present invention is to stabilize the combustion of each cylinder of an internal combustion engine.

The vehicle control system of the present invention includes an EGR system having an EGR passage connecting an exhaust passage and an intake passage of an internal combustion engine and an EGR valve for adjusting the flow rate of exhaust gas returned from the exhaust passage to the intake passage. It is a vehicle control system that controls the vehicle, and is installed for each cylinder of the internal combustion engine, and is based on the concentration sensor that detects the oxygen concentration or carbon dioxide concentration on the intake side of each cylinder and the detection result of the concentration sensor. The EGR valve control means that controls the opening degree of the EGR valve according to the EGR rate, which is the ratio of the exhaust gas during intake, and each cylinder calculated based on the detection result of the concentration sensor. It is characterized by being provided with an ignition timing control means for controlling the ignition timing of each cylinder according to the EGR rate of the above.

According to the present invention, it is possible to stabilize the combustion of each cylinder of the internal combustion engine.

It is a figure which shows the structure of the control system of the vehicle which concerns on embodiment. It is a figure which shows the functional structure of the control device of the vehicle control system which concerns on embodiment. It is a flowchart which shows the example of the control process in the control system of the vehicle which concerns on embodiment.

A vehicle control system according to an embodiment of the present invention includes an EGR passage that communicates an exhaust passage and an intake passage of an internal combustion engine, and an EGR valve that adjusts the flow rate of exhaust gas returned from the exhaust passage to the intake passage. A vehicle control system for controlling a vehicle equipped with an EGR system, which is installed for each cylinder of the internal combustion engine and has a concentration sensor for detecting the oxygen concentration or carbon dioxide concentration on the intake side of each cylinder, and the concentration. Calculated based on the EGR valve control means that controls the opening degree of the EGR valve according to the EGR rate, which is the ratio of exhaust gas during intake, and the detection result of the concentration sensor, which is calculated based on the detection result of the sensor. It is provided with an ignition timing control means for controlling the ignition timing of each cylinder according to the EGR rate of each cylinder.
As a result, it is possible to stabilize the combustion of each cylinder of the internal combustion engine, suppress the variation in combustion between the cylinders, and prevent deterioration of fuel efficiency performance, misfire, and the like.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.
FIG. 1 shows a configuration of a vehicle control system according to an embodiment. The vehicle is an automobile equipped with an internal combustion engine 1.
Although a detailed description thereof is omitted, the internal combustion engine 1 burns fuel in a cylinder and obtains a driving force of a vehicle by using the combustion gas generated thereby. The internal combustion engine 1 is connected to an intake passage 2 that introduces air into the internal combustion engine 1 and an exhaust passage 3 that exhausts the exhaust gas generated by the internal combustion engine 1. In addition, in FIG. 1, the flow of intake and exhaust is represented by an arrow. The internal combustion engine 1 is an engine having a plurality of cylinders 1a, and the intake passage 2 is connected to each cylinder 1a via an intake manifold 4 having a plurality of branch pipes 4a. An injector 5 for injecting fuel into each cylinder 1a is installed in each branch pipe 4a of the intake manifold 4. Further, a spark plug 6 for igniting fuel is installed in each cylinder 1a of the internal combustion engine 1.

A throttle valve 7 is installed in the intake passage 2. The throttle valve 7 adjusts the amount of intake air.

A purification device 8 is installed in the exhaust passage 3. The purification device 8 includes a catalyst for purifying harmful substances in the exhaust gas.

In addition, an EGR (Exhaust Gas Recirculation) system 9 is installed. The EGR system 9 has an EGR passage 10, an EGR cooler 11, and an EGR valve 12. The EGR passage 10 is connected to the downstream side of the exhaust passage 3 from the purification device 8 and the downstream side of the intake passage 2 from the throttle valve 7 to communicate the exhaust passage 3 and the intake passage 2. The EGR cooler 11 lowers the temperature of the exhaust gas returned from the exhaust passage 3 to the intake passage 2. The EGR valve 12 adjusts the flow rate of the exhaust gas returned from the exhaust passage 3 to the intake passage 2 by adjusting the opening degree thereof. In addition, in FIG. 1, the flow of the return of exhaust gas is represented by an arrow.

A concentration sensor 13 for detecting the oxygen concentration is installed in each branch pipe 4a of the intake manifold 4. In this way, the concentration sensor 13 installed for each cylinder 1a can detect the oxygen concentration on the intake side of each cylinder 1a. The concentration sensor 13 uses a highly responsive sensor to perform cycle-by-cycle control of the internal combustion engine 1. For example, when the value is output once per cycle, a responsiveness of about 10 ms is required to cope with an engine speed of up to 6000 rpm. In the present embodiment, the concentration sensor 13 corresponds to the concentration sensor referred to in the present invention.

An A / F sensor 14 is installed on the upstream side of the exhaust passage 3 with respect to the purification device 8. The A / F sensor 14 can detect the air-fuel ratio from the oxygen concentration contained in the exhaust gas. The A / F sensor 14 uses a sensor having high responsiveness that can measure the A / F sensor value for each cylinder. For example, in a 4-cylinder engine, when measuring with one A / F sensor, a responsiveness of about 1 ms is required. In the present embodiment, the A / F sensor 14 corresponds to the air-fuel ratio sensor referred to in the present invention.

As described in detail below, the control device 100 controls the opening degree of the EGR valve 12 according to the EGR rate calculated based on the detection result of the concentration sensor 13. Further, as described in detail below, the control device 100 controls the ignition timing of each cylinder 1a according to the EGR rate of each cylinder 1a calculated based on the detection result of the concentration sensor 13. The EGR ratio is the ratio of exhaust gas during intake.

FIG. 2 shows the functional configuration of the control device 100. The control device 100 includes an EGR rate calculation unit 101, a correction unit 102, an EGR valve control unit 103, and an ignition timing control unit 104. In the present embodiment, the EGR rate calculation unit 101, the correction unit 102, the EGR valve control unit 103, and the ignition timing control unit 104 are used as the EGR rate calculation means, the correction means, the EGR valve control means, and the ignition timing control means in the present invention, respectively. Equivalent to.

The EGR rate calculation unit 101 calculates the EGR rate of each cylinder 1a based on the detection result of the concentration sensor 13 installed for each cylinder 1a. As described in Patent Document 1, since the oxygen contained in the exhaust gas generated when burning in a state where the air-fuel ratio is stoichiometric is almost constant, the ratio of the oxygen concentration contained in the intake air in each cylinder 1a. The EGR rate can be calculated based on.

The correction unit 102 includes a correction amount acquisition unit 102a that acquires a correction amount of the EGR rate based on the detection result of the A / F sensor 14, and calculates the EGR rate using the correction amount acquired by the correction amount acquisition unit 102a. The EGR rate of each cylinder 1a calculated by the unit 101 is corrected.
Here, when the air-fuel ratio changes from stoichiometric to rich, the oxygen concentration contained in the exhaust gas becomes lower than that at the time of stoichibatic gas, so that the EGR rate calculated by the EGR rate calculation unit 101 tends to be larger than the actual EGR rate. On the other hand, when the air-fuel ratio changes from stoichiometric to lean, the oxygen concentration contained in the exhaust gas becomes higher than that at the time of stoichibatic gas, so that the EGR rate calculated by the EGR rate calculation unit 101 tends to be smaller than the actual EGR rate.
Therefore, the correction amount acquisition unit 102a acquires the correction amount of the EGR rate based on the air-fuel ratio detected by the A / F sensor 14. For example, as described in Patent Document 1, a graph showing the relationship between the A / F sensor value and the correction amount is prepared by an experiment or the like, and the correction amount acquisition unit 102a uses this graph to perform the A / F. The correction amount according to the sensor value is acquired. The correction amount represented by the graph is corrected so that the EGR rate calculated by the EGR rate calculation unit 101 is small on the rich side, and the EGR rate calculated by the EGR rate calculation unit 101 is large on the lean side. Become a thing. The correction amount may be a value to be multiplied by the EGR rate calculated by the EGR rate calculation unit 101, or may be a value to be added or subtracted.
Here, an example showing the relationship between the A / F sensor value and the correction amount in a graph has been described, but the present invention is not limited to this. For example, a map or table showing the relationship between the A / F sensor value and the correction amount may be used. Further, a calculation formula expressing the relationship between the A / F sensor value and the correction amount is prepared, and the correction amount acquisition unit 102a calculates the correction amount according to the A / F sensor value using this calculation formula. You may do so.

The EGR valve control unit 103 controls the opening degree of the EGR valve 12 based on the EGR ratio of each cylinder 1a corrected by the correction unit 102.
The EGR valve control unit 103 calculates, for example, an average value of the EGR rate of each cylinder 1a corrected by the correction unit 102. Further, the EGR valve control unit 103 determines the target EGR rate based on the operating state of the internal combustion engine 1. Then, the EGR valve control unit 103 feedback-controls the opening degree of the EGR valve 12 so that the average value of each cylinder 1a corrected by the correction unit 102 becomes the target EGR rate.

The ignition timing control unit 104 controls the ignition timing of each cylinder 1a based on the EGR rate of each cylinder 1a corrected by the correction unit 102.
The ignition timing control unit 104 advances the ignition timing in a cylinder in which the EGR rate corrected by the correction unit 102 is larger than the target EGR rate. In a cylinder whose EGR rate is larger than the target EGR rate, combustion becomes unstable, and there is a possibility that combustion misfire is likely to occur. Therefore, by advancing the ignition timing, misfire of combustion is prevented and combustion is stabilized.
Further, the ignition timing control unit 104 delays the ignition timing in a cylinder in which the EGR rate corrected by the correction unit 102 is smaller than the target EGR rate. In a cylinder whose EGR rate is smaller than the target EGR rate, the combustion temperature rises, which may cause excessive knocking. Therefore, by retarding the ignition timing, excessive knocking is prevented and combustion is stabilized.
For example, a graph showing the relationship between the difference from the target EGR rate and the amount of advance and retard suitable for stabilizing combustion is prepared by an experiment or the like, and the ignition timing is used using this graph. The control unit 104 acquires the advance angle amount or the retard angle amount according to the difference between the EGR rate corrected by the correction unit 102 and the target EGR rate.

The control device 100 as described above is composed of a computer device including, for example, a CPU, a ROM, a RAM, and the like, and the CPU executes a predetermined program stored in the ROM, for example, to realize the functions of the respective units 101 to 104. Will be done. For example, the control device 100 may be realized as a function of the engine control module mounted on the vehicle.

Next, with reference to FIG. 3, the control process by the control device 100 will be described in detail.
FIG. 3 is a flowchart showing an example of control processing in the vehicle control system according to the embodiment. The control device 100 repeatedly executes the control process shown in FIG. 3 while the EGR system 9 is operating. In the flowchart of FIG. 3, the processing by the EGR rate calculation unit 101, the correction unit 102, and the ignition timing control unit 104 is shown, and the processing by the EGR valve control unit 103 is omitted.

In step S1, the EGR rate calculation unit 101 acquires the oxygen concentration which is the detection result of the concentration sensor 13 installed for each cylinder 1a, and calculates the EGR rate of each cylinder 1a based on the oxygen concentration.

In step S2, the correction amount acquisition unit 102a of the correction unit 102 acquires the A / F sensor value which is the detection result of the A / F sensor 14, and based on this, acquires the correction amount of the EGR rate.

In step S3, the correction unit 102 corrects the EGR rate of each cylinder 1a calculated in step S1 by using the correction amount of the EGR rate acquired in step S2. As described in Patent Document 1, it corresponds to the time for the exhaust gas to recirculate from the time when the A / F sensor 14 detects the change in the air-fuel ratio to the time when the oxygen concentration on the intake side detected by the concentration sensor 13 changes. There will be a delay time. Therefore, the delay time corresponding to the response difference between the A / F sensor 14 and the concentration sensor 13 may be obtained, and the EGR rate may be corrected after the lapse of the delay time.

Although not shown in the flowchart of FIG. 3, the EGR valve control unit 103 calculates the average value of the EGR rate of each cylinder 1a corrected in step S3. Further, the EGR valve control unit 103 determines the target EGR rate based on the operating state of the internal combustion engine 1. Then, the EGR valve control unit 103 feedback-controls the opening degree of the EGR valve 12 so that the average value of each cylinder 1a corrected in step S3 becomes the target EGR rate.

In step S4, the ignition timing control unit 104 compares the EGR rate of each cylinder 1a corrected in step S3 with the target EGR rate. As a result, in the case where the EGR rate corrected in step S3 is larger than the target EGR rate, the process proceeds to step S5 to advance the ignition timing. Further, in the case where the EGR rate corrected in step S3 is smaller than the target EGR rate, the process proceeds to step S6 and the ignition timing is retarded.

As described above, the control device 100 controls the ignition timing of each cylinder 1a according to the EGR rate of each cylinder 1a calculated based on the detection result of the concentration sensor 13. Specifically, in a cylinder having an EGR rate larger than the target EGR rate, by advancing the ignition timing, it is possible to prevent combustion misfire and stabilize combustion. Further, in a cylinder whose EGR rate is smaller than the target EGR rate, by retarding the ignition timing, excessive knocking can be prevented and combustion can be stabilized. In this way, it is possible to stabilize the combustion of each cylinder 1a of the internal combustion engine 1, suppress the variation in combustion between the cylinders 1a, and prevent deterioration of fuel efficiency performance, misfire, and the like.

Although the embodiments of the present invention have been described in detail with reference to the drawings, each embodiment merely shows a specific example in carrying out the present invention. The technical scope of the present invention is not limited to each embodiment. The present invention can be modified in various ways without departing from the spirit of the present invention, and these are also included in the technical scope of the present invention.
For example, the concentration sensor 13 installed for each cylinder 1a detects the oxygen concentration on the intake side of each cylinder 1a, but may also detect the carbon dioxide concentration on the intake side of each cylinder 1a. When the air-fuel ratio changes from stoichiometric to rich, the oxygen concentration in the exhaust gas is lower than that at the time of stoichiometric, and the fuel is higher than that at the time of stoichiometric. Therefore, the concentration of carbon dioxide in the exhaust gas increases, and the EGR rate calculated by the EGR rate calculation unit 101 tends to be larger than the actual EGR rate. On the other hand, when the air-fuel ratio changes from stoichiometric to lean, the oxygen concentration in the exhaust gas is higher than that at the time of stoichiometric, and the fuel is less than that at the time of stoichiometric. Therefore, the concentration of carbon dioxide in the exhaust gas decreases, and the EGR rate calculated by the EGR rate calculation unit 101 tends to be smaller than the actual EGR rate.
The present invention can also be realized by supplying software (program) to a system or device via a network or various storage media, and the computer of the system or device reads and executes the program.

1: Internal combustion engine, 1a: Cylinder, 2: Intake passage, 3: Exhaust passage, 4: Intake manifold, 4a: Branch pipe, 5: Injector, 6: Ignition plug, 7: Throttle valve, 8: Purification device, 9: EGR system, 10: EGR passage, 11: EGR cooler, 12: EGR valve, 13: concentration sensor, 14: A / F sensor, 100: control device, 101: EGR rate calculation unit, 102: correction unit, 102a: correction Quantity acquisition unit, 103: EGR valve control unit, 104: ignition timing control unit

Claims (4)

A vehicle control system that controls a vehicle equipped with an EGR system having an EGR passage connecting an exhaust passage and an intake passage of an internal combustion engine and an EGR valve for adjusting the flow rate of exhaust gas returned from the exhaust passage to the intake passage. And,
A concentration sensor installed for each cylinder of the internal combustion engine and detecting the oxygen concentration or carbon dioxide concentration on the intake side of each cylinder,
An EGR valve control means that controls the opening degree of the EGR valve according to the EGR rate, which is the ratio of exhaust gas during intake, calculated based on the detection result of the concentration sensor.
A vehicle control system including an ignition timing control means for controlling the ignition timing of each cylinder according to the EGR rate of each cylinder calculated based on the detection result of the concentration sensor. The EGR valve control means determines the opening degree of the EGR valve based on the EGR rate calculated based on the detection result of the concentration sensor and the target EGR rate determined based on the operating state of the internal combustion engine. Control and
The ignition timing control means advances the ignition timing in a cylinder whose EGR rate calculated based on the detection result of the concentration sensor is larger than the target EGR rate, and is calculated based on the detection result of the concentration sensor. The vehicle control system according to claim 1, wherein the EGR rate is smaller than the target EGR rate, and the ignition timing is retarded. An air-fuel ratio sensor provided in the exhaust passage to detect the air-fuel ratio from the exhaust gas,
An EGR rate calculating means for calculating the EGR rate of each cylinder based on the detection result of the concentration sensor, and an EGR rate calculating means.
A correction means for correcting the EGR rate of each cylinder calculated by the EGR rate calculation means based on the detection result of the air-fuel ratio sensor is provided.
The EGR valve control means controls the opening degree of the EGR valve based on the EGR rate of each cylinder corrected by the correction means.
The vehicle control system according to claim 1 or 2, wherein the ignition timing control means controls the ignition timing of each cylinder based on the EGR rate of each cylinder corrected by the correction means. An EGR system having an EGR passage connecting an exhaust passage and an intake passage of an internal combustion engine and an EGR valve for adjusting the flow rate of exhaust gas returned from the exhaust passage to the intake passage, and an EGR system installed for each cylinder of the internal combustion engine. , A program for controlling a vehicle equipped with a concentration sensor for detecting an oxygen concentration or a carbon dioxide concentration on the intake side of each cylinder.
An EGR valve control means that controls the opening degree of the EGR valve according to the EGR rate, which is the ratio of exhaust gas during intake, calculated based on the detection result of the concentration sensor.
A program for operating a computer as an ignition timing control means for controlling the ignition timing of each cylinder according to the EGR rate of each cylinder calculated based on the detection result of the concentration sensor.

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