JP6536299B2 - Internal combustion engine control method and internal combustion engine control device - Google Patents

Description

  The present invention relates to a control method and control device for an internal combustion engine at the time of deceleration of a host vehicle.

  A technology called EGR (Exhaust Gas Recirculation) that re-inhales a part of exhaust gas after combustion in a small internal combustion engine for automobiles, mainly for the purpose of reducing nitrogen oxides (NOx) in exhaust gas and improving fuel consumption. It has been known. As a technique related to this EGR, Patent Document 1 discloses an internal combustion engine with an attached low pressure loop EGR device. This internal combustion engine prevents the misfire at the time of deceleration by performing control to thin the number of times of combustion in the cylinder while opening the throttle valve larger than the opening degree according to the deceleration request at the time of deceleration of the own vehicle.

JP 2012-82737 A

  However, at the time of deceleration of the host vehicle, there is a concern that the performance of the internal combustion engine may deteriorate due to various factors. For example, by thinning the number of times of combustion in order to prevent a misfire at the time of deceleration, there is a concern that the acoustic vibration performance may be deteriorated due to a change in the combustion interval. In addition, the exhaust gas is in the state of a mixed gas thinner than the theoretical air fuel ratio, and there is a concern that the nitrogen oxides discharged may be deteriorated. Furthermore, there is a concern that the operability may deteriorate due to a torque step when switching from normal combustion to thinning combustion or when switching from thinning combustion to normal combustion.

  An object of the present invention is to provide an internal combustion engine control method and an internal combustion engine control device which suppress the deterioration of the performance of the internal combustion engine at the time of deceleration of the host vehicle.

  In the internal combustion engine control method and the internal combustion engine control device according to one aspect of the present invention, in order to solve the above problems, a circulation passage for recirculating the exhaust gas flowing in the exhaust passage as EGR gas to the intake passage, and a circulation passage A control method for an internal combustion engine comprising an EGR valve for controlling the flow rate of exhaust gas, which measures an actual EGR rate based on an output from an intake oxygen sensor provided in an intake passage when the host vehicle decelerates. At the same time, the amount of air is controlled so that the amount of air in the intake passage increases as the actual EGR rate increases, and as a result of controlling the amount of air, when the amount of air increases, control to delay the ignition timing of the internal combustion engine Control to accelerate the opening timing of the exhaust valve, control to increase the load on accessories driven by the internal combustion engine, control to automatically increase the braking force of the brake, and stratified combustion of the internal combustion engine Of the control to be carried out at least one control.

  According to one aspect of the present invention, by controlling the amount of air according to the EGR rate, the combustion of the internal combustion engine at the time of deceleration of the host vehicle is stabilized. In addition, the combustion stability can be achieved by the increase of the air amount, and at the same time, it is possible to simultaneously achieve the deceleration torque required at the time of deceleration of the host vehicle. As a result, deterioration of the performance of the internal combustion engine at the time of deceleration of the host vehicle can be suppressed.

It is a figure showing an example of composition of an internal combustion engine control concerning one embodiment of the present invention. It is a figure for demonstrating the control flow of correction | amendment of the opening area of an EGR valve. It is a timing chart in the case of amendment of the opening area of an EGR valve. It is a figure showing an example of a target EGR rate map. It is a figure for demonstrating the criteria (reference value) in the case of correction | amendment of the opening area of an EGR valve. It is a flow chart which shows operation about air quantity control under deceleration of self-vehicles. It is a timing chart at the time of adjusting the amount of air based on an EGR rate while the own vehicle is decelerating. It is a timing chart at the time of performing control (retard) which retards the ignition timing of an internal-combustion engine while decelerating of the own vehicle. 5 is a timing chart when advancing the opening timing (EVO) of the exhaust valve of the internal combustion engine in order to suppress torque when the air amount increases at the time of deceleration of the host vehicle. It is a timing chart at the time of controlling the load of the auxiliary machine driven by an internal-combustion engine, in order to control torque at the time of air volume increase at the time of deceleration of self-vehicles. It is a timing chart at the time of controlling a brake in order to absorb torque generated at the time of air volume increase at the time of deceleration of self-vehicles. It is a timing chart at the time of carrying out stratified combustion at the time of air volume increase at the time of deceleration of self-vehicles.

Next, an embodiment of the present invention will be described with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, it should be noted that the drawings are schematic and different from real ones. Therefore, specific components should be determined in consideration of the following description.
In addition, the embodiments described below illustrate apparatuses and methods for embodying the technical idea of the present invention, and the technical idea of the present invention includes the shape, structure, arrangement, and the like of components. It does not specify the following. The technical idea of the present invention can be variously modified within the technical scope defined by the claims described in the claims.
In the following detailed description, numerous specific details are set forth to provide a thorough understanding of an embodiment of the present invention. However, it will be apparent that one or more embodiments may be practiced without such specific details. Besides, well-known structures and devices are illustrated schematically in order to simplify the drawings.

Embodiment
Hereinafter, an internal combustion engine control system according to an embodiment of the present invention will be described.
(Internal combustion engine control device)
The internal combustion engine control system according to the present embodiment controls an exhaust gas recirculation system as shown in FIG. In this exhaust gas recirculation system, an intake passage 2 for passing intake gas is disposed upstream of an internal combustion engine 1 (engine) comprising, for example, a spark-ignition gasoline engine having a four-stroke cycle. Further, on the downstream side of the internal combustion engine 1, an exhaust passage 3 for passing the exhaust gas is disposed.

  The intake passage 2 is opened to the outside through an air intake (not shown) which is an intake port, and takes in external air as intake gas from the air intake. On the downstream side of this air intake, an intake valve 4 for adjusting the inflow of intake gas is disposed. On the downstream side of the intake valve 4, an intake-side compressor 5 a of the turbocharger 5 that raises the pressure of the intake gas to the atmospheric pressure or higher is disposed.

  An intake oxygen sensor 6 for measuring the concentration of oxygen in the intake gas is disposed downstream of the compressor 5a. On the downstream side of the intake oxygen sensor 6, a throttle chamber 7 containing an electronically controlled throttle valve for controlling the inflow of intake gas is disposed. On the downstream side of the throttle chamber 7, an intercooler 8 which is a cooling device for cooling intake gas whose temperature has risen by compression or the like is disposed.

  Here, the internal combustion engine 1 has, for example, a direct injection type configuration, and is provided with a fuel injection valve (not shown) for injecting fuel into the cylinder for each cylinder. The intake passage 2 branches between the intercooler 8 and the internal combustion engine 1 for each cylinder of the internal combustion engine 1 as an intake manifold for equalizing the intake distribution to the respective cylinders of the internal combustion engine 1. The fuel injection amount at the fuel injection valve is feedback-controlled based on the detection signal of the intake oxygen sensor 6. Further, in the internal combustion engine 1, a PCV valve (not shown) serving as a vent for releasing the pressure of the crankcase is disposed.

  The exhaust passage 3 combines a plurality of flow paths of the exhaust gas of the internal combustion engine 1 into one on the downstream side of the internal combustion engine 1 as an exhaust manifold. On the downstream side, the exhaust passage 3 is bifurcated, the turbine 5b on the exhaust side of the turbocharger 5 is disposed on one side, and the waste gate valve 9 is disposed on the other side. The waste gate valve 9 adjusts the inflow of the exhaust gas to the turbine 5 b of the turbocharger 5 by diverting a part of the exhaust gas by opening and closing. On the downstream side of the turbine 5 b and the waste gate valve 9, an exhaust purification device 10 such as a manifold catalyst or an underfloor catalyst is disposed. An exhaust silencer (not shown) is disposed downstream of the exhaust purification device 10. The exhaust passage 3 is opened to the outside through the exhaust silencer, and the exhaust gas passing through the exhaust passage 3 is discharged to the outside.

  Further, in the exhaust gas recirculation system, a circulation passage 11 connecting the intake passage 2 and the exhaust passage 3 is disposed. The circulation passage 11 branches from the exhaust passage 3 downstream of the exhaust gas purification device 10 and upstream of the exhaust silencer, and joins with the intake passage 2 at a stage upstream of the compressor 5 a on the intake side of the turbocharger 5. A portion of the exhaust gas is passed to the intake passage 2 as EGR gas. An EGR cooler 12 for cooling the EGR gas is disposed in the circulation passage 11. An EGR valve 13 is disposed downstream of the EGR cooler 12 to adjust the inflow of EGR gas from the exhaust side to the intake side. The circulation passage 11 merges with the intake passage 2 on the downstream side of the EGR valve 13. The intake gas passing through the intake passage 2 is mixed with the EGR gas passing through the circulation passage 11 to become a mixed gas. That is, when EGR is performed, the mixed gas flows into the compressor 5 a on the intake side of the turbocharger 5. Thereafter, on the downstream side of the compressor 5 a on the intake side of the turbocharger 5, mixed gas as intake gas passes through the intake passage 2. In this case, by using the intake oxygen sensor 6, it is possible to measure an EGR rate that indicates the ratio of the EGR gas in the mixed gas.

  In the present embodiment, a configuration example in which the supercharger 5 is disposed in the exhaust gas recirculation system is described, but in practice, the supercharger 5 is not essential.

  Furthermore, in the internal combustion engine control device according to the present embodiment, an electronic control device 20 that controls various valve mechanisms by receiving output results from various sensors is disposed. For example, the electronic control unit 20 detects the oxygen concentration in the intake air based on the output from the intake oxygen sensor 6 installed in the intake passage 2, calculates the actual EGR rate from the detected oxygen concentration, and executes the internal combustion engine When there is a difference between the target EGR rate determined from the operating condition 1 and the calculated actual EGR rate, the EGR valve 13 is controlled to achieve the target EGR rate. Further, the electronic control unit 20 stores the difference between the target EGR rate and the actual EGR rate as a correction coefficient for each operating condition of the internal combustion engine 1, and corrects the target EGR rate.

  At this time, in response to a change in the operating condition of the internal combustion engine 1 due to the driver's operation, from the EGR gas outlet in the intake passage 2 to the installation position of the intake oxygen sensor 6 and the position of the intake oxygen sensor 6 It is necessary to consider the response delay of the intake volume until the mixed gas of EGR gas and fresh air flows into the inside. Controlling the EGR valve 13 based on the measurement results of the intake oxygen sensor 6 during transient operation where the operating condition changes as needed may lead to the introduction of excessive / insufficient EGR gas, and the drivability deterioration such as knocking or misfire, and It causes fuel efficiency deterioration. In addition, calculating the correction value as needed during transient operation may lead to erroneous learning in consideration of the response delay.

  In the exhaust gas recirculation system shown in FIG. 1, an exhaust gas outlet provided downstream of the turbine 5 b on the exhaust side of the turbocharger 5 in the exhaust passage 3 passes through the EGR valve 13 of the circulation passage 11 to the intake passage 2. The air is returned upstream of the compressor 5 a on the intake side of the turbocharger 5. Further, an intake oxygen sensor 6 for measuring the EGR rate is provided downstream of the compressor 5 a on the intake side of the turbocharger 5.

  However, the parts constituting the exhaust gas recirculation system naturally have initial variations in manufacture, and the variations also become large due to deterioration with time in the market. As a result, the EGR gas actually introduced may vary greatly from the design median value. That is, when the actual EGR is excessive, it leads to a misfire of the internal combustion engine 1, and when the actual EGR is too small, the fuel efficiency is lowered. Therefore, it is necessary to set a target EGR rate in consideration of these variations.

  However, since the EGR rate of the mixed gas actually flowing into the internal combustion engine 1 can be measured using the intake oxygen sensor 6, the opening area of the EGR valve 13 is corrected to reduce the deviation from the target EGR rate. The target EGR rate can be set high by reducing the initial component variation of the system that affects the introduction of EGR gas and the variation of the actual EGR rate with time-dependent changes in the market, leading to an improvement in fuel efficiency.

  As for correction of the opening area of the EGR valve 13, as shown in FIG. 2, in addition to the control for calculating the opening area of the EGR valve 13 at the base point in the designed central condition from the target EGR rate, Control is performed to correct the characteristic value on the trimming map under steady conditions determined from (at least one of the rotation speed and the load). Further, the opening area of the EGR valve 13 after the correction is calculated by multiplying the opening area of the EGR valve 13 at the base point by the correction coefficient.

  On the other hand, EGR gas is transported in the intake passage 2 with a response delay corresponding to the intake volume from the introduction portion to the intake passage 2 to the intake oxygen sensor 6 as shown in FIG. Therefore, the EGR rate measured by the intake oxygen sensor 6 is due to the opening area of the EGR valve 13 in a state prior to the time obtained by subtracting the response delay, and in the region where there is a response delay, the time including the response delay By correcting the opening area of the EGR valve 13 in consideration, erroneous learning can be prevented. Further, in the steady state condition where this response delay can be ignored, when it is determined that the operating condition of the internal combustion engine 1 matches the steady state condition (in the steady state), learning can be performed more accurately. The aperture area of 13 may be corrected.

  The steady state condition referred to here is a range in which the target EGR rate is constant (EGR) while the rotational speed and load of the internal combustion engine 1 are transiently changed, in addition to the condition that the rotational speed and load of the internal combustion engine 1 are constant. Also included are conditions moving within the region). FIG. 4 shows an example of a target EGR rate map for the EGR region. If the rotational speed and load of the internal combustion engine 1 move in the EGR region, the target EGR rate becomes constant, and the actual EGR rate by the intake oxygen sensor 6 becomes constant, so the EGR condition is a steady condition. It can be said.

  Further, while the measurement accuracy of intake air oxygen sensor 6 at the steady state of internal combustion engine 1 is affected by component characteristics and manufacturing variations, it is further increased with electronic control device 20 at the transient time (non-steady state) of internal combustion engine 1. The measurement accuracy of the intake oxygen sensor 6 at the time of transition of the internal combustion engine 1 becomes worse because it is affected by the delay of communication and calculation. Therefore, as shown in FIG. 5, there is a difference between the measurement accuracy of the intake oxygen sensor 6 between the steady state and the transition time of the internal combustion engine 1, so that the steady state and the transition time of the internal combustion engine 1 By setting the criteria (reference value) individually according to the measurement accuracy and making the steady state criteria of the internal combustion engine 1 smaller than the transient condition of the internal combustion engine 1, the operating conditions of the internal combustion engine 1 are determined as steady conditions. When it can be determined that they fit, the opening area of the EGR valve 13 can be corrected accurately. At this time, the measurement accuracy of the intake oxygen sensor 6 may be set as a criterion.

  In the above correction of the opening area of the EGR valve 13, in the case of a system provided with an intake throttle valve (ADM valve) (not shown) on the upstream side of the merging portion of EGR gas in the intake passage 2, the intake throttle valve is opened. Because the EGR rate also affects the EGR rate depending on the degree, the correction is performed only when the intake throttle valve is fully open or is equivalent to the condition that the intake throttle valve does not affect the EGR rate. Corrections can be made. Here, "equivalent to full opening" means that the opening degree of the intake throttle valve has an opening degree that hardly affects the EGR rate. The intake throttle valve as the intake throttle valve hardly affects the flow rate of the working gas flowing even if it is opened beyond a certain opening degree, and thus the opening degree of the intake throttle valve having such a predetermined threshold value By grasping in advance, it is possible to define the full opening degree.

  If the target negative pressure is not generated correctly by the intake air throttle valve, the relationship between the target EGR rate and the opening degree of the EGR valve 13 deviates due to the influence of exhaust pulsation. Therefore, the target negative pressure is correctly generated by correcting the intake throttle valve first. In practice, the intake throttle valve may be a throttle valve or a flow control valve.

(Control of air amount)
The internal combustion engine control device according to the present embodiment may estimate or measure the EGR concentration contained in the intake air at the time of deceleration of the host vehicle, and control the air amount based on the EGR concentration. For example, when the host vehicle decelerates, the electronic control unit 20 adjusts the amount of air in the intake passage 2 based on the EGR rate measured by the intake oxygen sensor 6 so as not to cause a misfire. By controlling the air amount with the EGR concentration, the combustion of the internal combustion engine at the time of deceleration of the host vehicle is stabilized.

An example of the operation relating to air amount control during deceleration of the host vehicle will be described with reference to FIG.
First, the electronic control unit 20 determines whether the host vehicle is decelerating (step S101). For example, whether the electronic control unit 20 is decelerating based on a sensor provided around the pedal such as an accelerator pedal or a brake pedal, or an output result from a vehicle speed sensor or an acceleration sensor or the like of the own vehicle It is determined whether or not.
Here, when it is determined that the host vehicle is not decelerating (in the case of No at step S101), the electronic control unit 20 ends the series of processes. Further, the electronic control unit 20 also determines that the host vehicle is not decelerating even when the host vehicle stops or restarts acceleration.

  When it is determined that the host vehicle is decelerating (in the case of Yes in step S101), the electronic control unit 20 reads the output result from the intake oxygen sensor 6 (step S102). Here, the electronic control unit 20 reads the ratio of oxygen in the mixed gas measured by the intake oxygen sensor 6 as the output result from the intake oxygen sensor 6.

  The electronic control unit 20 calculates an EGR rate that indicates the ratio of the EGR gas in the mixed gas based on the output result from the intake oxygen sensor 6 (step S103).

The electronic control unit 20 controls the amount of air in the intake passage 2 based on the EGR rate (step S104). For example, the electronic control unit 20 controls the intake valve 4 and the EGR valve 13 to adjust the ratio of the intake gas to the EGR gas contained in the mixed gas passing through the intake passage 2.
Thereafter, the electronic control unit 20 determines again whether or not the host vehicle is decelerating (return to step S101).

  Here, when the driver decelerates the accelerator pedal (OFF) or depresses the brake pedal (ON) and the own vehicle is decelerating and the accelerator opening degree becomes minimum, the intake of the conventional vehicle is as follows: It is usual to close the valve 4 to reduce the amount of air in the intake passage 2. However, in the conventional control, even if the intake valve 4 is closed, the EGR gas remaining in the circulation passage 11 flows into the intake passage 2 by inertia. At this time, the EGR rate increases because the EGR gas flows in while the amount of air decreases. If the EGR gas flows into the internal combustion engine 1 in this state, it may cause a misfire.

  Therefore, the internal combustion engine control device according to the present embodiment controls the intake valve 4 so that the amount of air in the intake passage 2 increases as the EGR rate increases in setting the amount of air while the host vehicle is decelerating. For example, as shown in (a) and (b) of FIGS. 7 to 12, the electronic control unit 20 decelerates according to the increase in the EGR rate when the host vehicle is decelerating and the accelerator opening becomes minimum. Increase the air volume when. As described above, when the host vehicle is decelerating, the misfire can be prevented by opening the intake valve 4 and increasing the air amount when the EGR rate is high. On the other hand, when the EGR rate is low, closing the intake valve 4 to reduce the amount of air makes it possible to obtain deceleration torque necessary at the time of deceleration as in conventional control.

  Thereby, as shown in (c) to (e) of FIG. 7, scavenging of exhaust gas (external EGR) which is directly pulled back from the exhaust passage 3 via the circulation passage 11 outside the internal combustion engine 1 is promoted. External EGR is scavenged earlier than conventional control. In addition, the exhaust gas recirculated inside the internal combustion engine 1 (internal EGR) is lower than that in the conventional control. As a result, with respect to the total EGR rate, the peak EGR rate is lower than that in the conventional control.

  Further, the internal combustion engine control device according to the present embodiment may perform control (retard) to delay the ignition timing of the internal combustion engine 1 in order to suppress the torque when the air amount increases when the host vehicle is decelerating. For example, as shown in (c) and (d) of FIG. 8, the electronic control unit 20 performs control (retard) to delay the ignition timing of the internal combustion engine 1 to suppress generation of torque. As a result, the combustion stability can be achieved by the increase of the air amount, and the decelerating torque necessary for the deceleration of the host vehicle can be compatible.

  Further, the internal combustion engine control device according to the present embodiment performs control to accelerate the opening timing (EVO) of the exhaust valve of the internal combustion engine 1 in order to suppress the torque when the air amount increases at the time of deceleration of the own vehicle. It is good. For example, as shown in (c) and (d) of FIG. 9, generation of torque is suppressed by advancing the opening timing (EVO) of the exhaust valve of the internal combustion engine 1. As a result, the combustion stability can be achieved by the increase of the air amount, and the decelerating torque necessary for the deceleration of the host vehicle can be compatible.

  Further, the internal combustion engine control device according to the present embodiment may control the load of the accessory driven by the internal combustion engine 1 in order to absorb the torque when the air amount increases when the host vehicle is decelerating. For example, as shown in (c) and (d) of FIG. 10, the generated torque is absorbed by increasing the load of the accessory. Examples of such auxiliary equipment include an AC generator (alternator), an oil pump, a water pump, an injection pump, a cooling fan, a compressor of an air conditioner, a power steering pump, and the like. By increasing the load of the auxiliary machine, it is possible to achieve combustion stability by increasing the amount of air, and make it possible to simultaneously achieve the deceleration torque required at the time of deceleration of the host vehicle.

  Further, the internal combustion engine control device according to the present embodiment controls, for example, the driving force of the vehicle when the air amount increases at the time of deceleration of the own vehicle, for example, VDC (Vehicle Dynamics) which is a type of side slip prevention mechanism (stability control system). Control of the driver's operation or the speed of the vehicle may be performed by a driving support system such as a Control) system to automatically control the output of the brake or the internal combustion engine. For example, as shown in (c) and (d) of FIG. 11, the generated torque is absorbed as a vehicle by automatically controlling the brake and raising the braking force. As a result, the combustion stability can be achieved by the increase of the air amount, and the vehicle driving force meeting the driver's request can be made compatible at the time of deceleration of the own vehicle.

  Further, the internal combustion engine control device according to the present embodiment may perform stratified combustion (for example, lean combustion) of the internal combustion engine 1 when the amount of air increases when the host vehicle is decelerating. For example, as shown in (c) and (d) of FIG. 12, the same torque as conventional control can be obtained by performing stratified combustion of the internal combustion engine 1. As described above, by making stratified combustion possible without increasing the amount of fuel when the amount of air is increased, it is possible to achieve stable combustion and to simultaneously achieve the decelerating torque necessary for decelerating the own vehicle.

  The processes relating to (a) and (b) in FIGS. 8 to 12 described above are the same as the processes relating to (a) and (b) in FIG. 7. That is, the processes related to (c) and (d) in FIGS. 8 to 12 can be performed at the same time as the processes related to (c) to (e) in FIG. 7.

(Effect of this embodiment)
According to the present embodiment, the following effects can be obtained.
(1) The internal combustion engine control method according to the present embodiment includes a circulation passage for recirculating the exhaust gas flowing in the exhaust passage as EGR gas to the intake passage, and an EGR valve for controlling the flow rate of the exhaust gas flowing in the circulation passage. In the method of controlling an internal combustion engine, the actual EGR rate is measured based on the output from the intake oxygen sensor provided in the intake passage at the time of deceleration of the host vehicle, and the air amount in the intake passage is higher as the actual EGR rate is higher. When the amount of air increases as a result of controlling the amount of air so as to increase the amount of air, the control to delay the ignition timing of the internal combustion engine, the control to accelerate the opening timing of the exhaust valve of the internal combustion engine, the internal combustion engine At least one control is performed among the control for increasing the load of the accessory driven by the engine, the control for automatically raising the braking force of the brake, and the control for stratified combustion of the internal combustion engine .
Thus, by controlling the amount of air according to the EGR rate, the combustion of the internal combustion engine at the time of deceleration of the host vehicle is stabilized. In addition, the combustion stability can be achieved by the increase of the air amount, and at the same time, it is possible to simultaneously achieve the deceleration torque required at the time of deceleration of the host vehicle. As a result, deterioration of the performance of the internal combustion engine at the time of deceleration of the host vehicle can be suppressed.

(2) Further, in the internal combustion engine control method according to the present embodiment, the opening area of the EGR valve is corrected so that the target EGR rate determined from the operating conditions of the internal combustion engine matches the actual EGR rate. When correcting the opening area, correct the characteristic value on the trimming map under steady conditions determined by at least one of the rotational speed and the load of the internal combustion engine, and correct the actual EGR rate and the target EGR rate with respect to the opening area of the EGR valve. By multiplying the correction coefficient which is the difference between the above and the above, the opening area of the EGR valve after correction is calculated.
As described above, the target EGR rate can be set high by reducing the initial part variation of the system affecting EGR gas introduction and the variation of the actual EGR rate due to the time-dependent change in the market, which leads to the improvement of fuel efficiency.

(3) Further, in the internal combustion engine control method according to the present embodiment, when it is determined that the operating conditions of the internal combustion engine conform to the steady conditions, the response delay for the intake volume from the EGR valve to the intake oxygen sensor is considered. The measurement result is used to correct the opening area of the EGR valve.
As described above, by performing the correction in consideration of the response delay time determined by the intake volume and the flow velocity, the correction can be performed even under the transitional operating condition of the internal combustion engine, and the correction value can be corrected without erroneous learning. It can be asked. In addition, when it is determined that the operating condition of the internal combustion engine matches the steady condition, the EGR gas response delay is not affected. Therefore, the correction may be performed more accurately under such conditions.

(4) Further, in the internal combustion engine control method according to the present embodiment, when correcting the opening area of the EGR valve, a reference value corresponding to the measurement accuracy of the intake oxygen sensor is set, and the difference between the actual EGR rate and the target EGR rate When it exceeds the reference value, it is judged that the correction is necessary, and the opening area of the EGR valve is corrected.
Since the measurement result by the intake oxygen sensor includes the accuracy variation of each part, when there is a difference between the target EGR rate and the actual EGR rate, it may lead to erroneous learning if it is attempted to carry out all the corrections. Therefore, false learning can be prevented by setting the time when the accuracy variation of the intake oxygen sensor is exceeded as the reference value.

(5) Further, in the internal combustion engine control method according to the present embodiment, individual values are set as the above-mentioned reference value at steady state and transient time of the internal combustion engine, and the reference value at steady state of the internal combustion engine Make it smaller than the transitional reference value.
When the internal combustion engine is in steady state, the reference value can be set small, so that the correction can be performed with high accuracy.

(6) Further, in the internal combustion engine control method according to the present embodiment, when correcting the opening area of the EGR valve, the intake throttle valve (ADM valve) is provided upstream of the merging portion of EGR gas in the intake passage. If the intake throttle valve is fully open or in a state corresponding to full open, the opening area of the EGR valve is corrected.
When the intake throttle valve is provided, the intake throttle valve opening also affects the EGR rate, so when there is a difference between the target EGR rate and the actual EGR rate when the intake throttle valve is at the intermediate opening degree. It can not be determined which of the intake throttle valve and the EGR valve is the cause. Therefore, the correction of the opening area of the EGR valve can be accurately performed by performing the correction only when the intake throttle valve is fully open or in a state equivalent to the full open (conditions in which the intake throttle valve does not affect the EGR rate).

  While the invention has been described with reference to particular embodiments, it is not intended that the invention be limited by these descriptions. Various modifications of the disclosed embodiments, as well as alternative embodiments of the present invention, will be apparent to persons skilled in the art upon reference to the description of the invention. Therefore, it is to be understood that the claims cover these modifications or embodiments which fall within the scope and spirit of the present invention.

1 internal combustion engine 2 intake passage 3 exhaust passage 4 intake valve 5 supercharger 5a compressor 5b turbine 6 intake oxygen sensor 8 intercooler 9 waste gate valve 10 exhaust purification device 11 circulation passage 12 cooler 13 valve 20 electronic control device

Claims (7)

A control method of an internal combustion engine, comprising: a circulation passage for returning exhaust gas flowing in an exhaust passage to an intake passage as EGR gas; and an EGR valve for controlling the flow rate of exhaust gas flowing in the circulation passage.
The actual EGR rate is measured based on the output from the intake oxygen sensor provided in the intake passage at the time of deceleration of the host vehicle, and the air amount of the intake passage increases as the actual EGR rate increases. Control
Correct the opening area of the EGR valve under steady conditions determined by at least one of the number of revolutions and the load of the internal combustion engine so that the target EGR rate determined from the operating conditions of the internal combustion engine matches the actual EGR rate And
When correcting the opening area of the EGR valve, the correction coefficient, which is the difference between the actual EGR rate and the target EGR rate, is stored for each operating condition determined from the at least one of the rotational speed and the load of the internal combustion engine. By multiplying the opening area of the EGR valve, the opening area of the EGR valve after correction is calculated;
As a result of controlling the amount of air, when the amount of air increases, a control for delaying the ignition timing of the internal combustion engine, a control for advancing the opening timing of the exhaust valve of the internal combustion engine, a control driven by the internal combustion engine An internal combustion engine control method comprising at least one of control for increasing a machine load, control for automatically increasing a braking force of a brake, and control for stratified combustion of the internal combustion engine.   When it is determined that the operating condition is compatible with the steady condition, the opening area of the EGR valve is corrected using a measurement result taking into account the response delay for the intake volume from the EGR valve to the intake oxygen sensor An internal combustion engine control method according to claim 1.   When correcting the opening area of the EGR valve, a reference value according to the measurement accuracy of the intake oxygen sensor is set, and correction is required when the difference between the actual EGR rate and the target EGR rate exceeds the reference value. The internal combustion engine control method according to claim 1 or 2, wherein the opening area of the EGR valve is corrected. The reference value is set as an individual value in steady state and transient state of the internal combustion engine, and the reference value in steady state of the internal combustion engine is smaller than the reference value in transient state of the internal combustion engine. The internal combustion engine control method according to A control method of an internal combustion engine, comprising: a circulation passage for returning exhaust gas flowing in an exhaust passage to an intake passage as EGR gas; and an EGR valve for controlling the flow rate of exhaust gas flowing in the circulation passage.
The actual EGR rate is measured based on the output from the intake oxygen sensor provided in the intake passage at the time of deceleration of the host vehicle, and the air amount of the intake passage increases as the actual EGR rate increases. Control
A target determined from the operating conditions of the internal combustion engine when an intake throttle valve is provided on the upstream side of the merging portion of the EGR gas in the intake passage and the intake throttle valve is in a fully open or fully open state The opening area of the EGR valve is corrected under steady-state conditions determined by at least one of the rotational speed and the load of the internal combustion engine such that the EGR rate matches the actual EGR rate.
When correcting the opening area of the EGR valve, the correction coefficient, which is the difference between the actual EGR rate and the target EGR rate, is stored for each operating condition determined from the at least one of the rotational speed and the load of the internal combustion engine. By multiplying the opening area of the EGR valve, the opening area of the EGR valve after correction is calculated;
As a result of controlling the amount of air, when the amount of air increases, a control for delaying the ignition timing of the internal combustion engine, a control for advancing the opening timing of the exhaust valve of the internal combustion engine, a control driven by the internal combustion engine An internal combustion engine control method comprising at least one of control for increasing a machine load, control for automatically increasing a braking force of a brake, and control for stratified combustion of the internal combustion engine. An internal combustion engine comprising: a circulation passage for returning exhaust gas flowing in the exhaust passage as EGR gas to the intake passage; and an EGR valve for controlling the flow rate of the exhaust gas flowing in the circulation passage;
An intake oxygen sensor that detects the concentration of oxygen in the air of the intake passage;
The actual EGR rate is measured based on the output from the intake oxygen sensor at the time of deceleration of the host vehicle, and the amount of air is controlled so that the amount of air in the intake passage increases as the actual EGR rate increases. As a result of controlling the amount, when the amount of air increases, the control for delaying the ignition timing of the internal combustion engine, the control for advancing the opening timing of the exhaust valve of the internal combustion engine, the accessory driven by the internal combustion engine And an electronic control unit for performing at least one of the control for increasing the load, the control for automatically raising the braking force of the brake, and the control for performing the stratified combustion of the internal combustion engine,
The electronic control unit
Correct the opening area of the EGR valve under steady conditions determined by at least one of the number of revolutions and the load of the internal combustion engine so that the target EGR rate determined from the operating conditions of the internal combustion engine matches the actual EGR rate And
When correcting the opening area of the EGR valve, the correction coefficient, which is the difference between the actual EGR rate and the target EGR rate, is stored for each operating condition determined from the at least one of the rotational speed and the load of the internal combustion engine. The opening area of the EGR valve after correction is calculated by multiplying the opening area of the EGR valve.
An internal combustion engine control device characterized in that. An internal combustion engine comprising: a circulation passage for returning exhaust gas flowing in the exhaust passage as EGR gas to the intake passage; and an EGR valve for controlling the flow rate of the exhaust gas flowing in the circulation passage;
An intake oxygen sensor that detects the concentration of oxygen in the air of the intake passage;
The actual EGR rate is measured based on the output from the intake oxygen sensor at the time of deceleration of the host vehicle, and the amount of air is controlled so that the amount of air in the intake passage increases as the actual EGR rate increases. As a result of controlling the amount, when the amount of air increases, the control for delaying the ignition timing of the internal combustion engine, the control for advancing the opening timing of the exhaust valve of the internal combustion engine, the accessory driven by the internal combustion engine And an electronic control unit for performing at least one of the control for increasing the load, the control for automatically raising the braking force of the brake, and the control for performing the stratified combustion of the internal combustion engine,
The electronic control unit
A target determined from the operating conditions of the internal combustion engine when an intake throttle valve is provided on the upstream side of the merging portion of the EGR gas in the intake passage and the intake throttle valve is in a fully open or fully open state The opening area of the EGR valve is corrected under steady-state conditions determined by at least one of the rotational speed and the load of the internal combustion engine such that the EGR rate matches the actual EGR rate.
When correcting the opening area of the EGR valve, the correction coefficient, which is the difference between the actual EGR rate and the target EGR rate, is stored for each operating condition determined from the at least one of the rotational speed and the load of the internal combustion engine. The opening area of the EGR valve after correction is calculated by multiplying the opening area of the EGR valve.
An internal combustion engine control device characterized in that.

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