JP2004278348A - Control system of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control system of an internal combustion engine for excellently maintaining a combustion state by restraining influence of a supercharging effect adjusting means arranged in a turbocharger. <P>SOLUTION: This internal combustion engine 1 is provided with the turbocharger 10 including an electric motor 10d as the supercharging effect adjusting means for changing the corresponding relationship between an exhaust flow rate and the supercharging effect, and is provided with an EGR valve 23 as an EGR quantity adjusting means capable of adjusting EGR quantity separately from the turbocharger 10, and an ECU 17 as an EGR control means for controlling operation of the EGR valve 23 so as to offset a change in the EGR quantity generated according to an adjustment of the supercharging effect by the electric motor 10d. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an apparatus for controlling an EGR amount and a combustion state in an internal combustion engine.
[0002]
[Prior art]
In an internal combustion engine equipped with a turbocharger with a variable nozzle, when the EGR amount is insufficient even when the EGR valve is operated to the maximum opening, the variable nozzle of the turbocharger is throttled to increase the exhaust back pressure, thereby increasing the EGR amount. Is known (for example, see Patent Document 1). In addition, there is Patent Document 2 as a related art related to the present invention.
[0003]
[Patent Document 1]
JP 2001-152879 A [Patent Document 2]
Japanese Unexamined Patent Publication No. 2000-550544
[Problems to be solved by the invention]
Aside from the case where the opening of the variable nozzle is changed for the purpose of adjusting the EGR amount, the case where the nozzle opening is changed for the purpose of adjusting the supercharging effect, which is the original purpose of the variable nozzle, The exhaust back pressure changes in accordance with the adjustment of the pressure, and the amount of internal EGR, that is, the amount of combustion gas remaining in the cylinder changes due to the influence. If the operation state of the internal combustion engine is not controlled in consideration of such a change in the internal EGR amount, the combustion temperature, the combustion speed, and the like deviate from the optimal state, and the combustion state deteriorates, and the exhaust emission and the fuel consumption deteriorate. In a turbocharger with an electric motor, a similar problem occurs when the rotation of the turbine rotor is changed by the electric motor.
[0005]
SUMMARY OF THE INVENTION It is an object of the present invention to provide a control device for an internal combustion engine capable of suppressing the influence of a supercharging effect adjusting means provided in a turbocharger and maintaining a good combustion state.
[0006]
[Means for Solving the Problems]
The first control device of the present invention is applied to an internal combustion engine provided with a turbocharger including a supercharging effect adjusting means for changing a correspondence between an exhaust gas flow rate and a supercharging effect. And an EGR amount adjusting means provided separately from the turbocharger and capable of adjusting the EGR amount, and a change in the EGR amount caused by adjustment of the supercharging effect by the supercharging effect adjusting means. By providing EGR control means for controlling the operation of the EGR amount adjusting means, the above-mentioned problem is solved (claim 1).
[0007]
According to the present invention, even if the EGR amount changes due to the operation of the supercharging effect adjusting unit, the EGR amount adjusting unit operates so as to cancel the change, so that the optimal value of the EGR amount (target value of control). Deviation from the distance is suppressed. For this reason, a good combustion state is maintained, and deterioration of exhaust emission and fuel consumption is prevented.
[0008]
In the control device for an internal combustion engine of the present invention, an external EGR adjustment device for returning exhaust gas to the intake passage via an EGR passage connecting an exhaust passage and an intake passage of the internal combustion engine is provided as the EGR amount adjusting means. The EGR amount control means may control the EGR amount by the external EGR adjusting device so as to cancel the change in the EGR amount (claim 2). Alternatively, a variable valve mechanism that controls at least one of an intake valve and an exhaust valve of the internal combustion engine is provided as the EGR amount adjustment unit, and the EGR amount control unit is configured to change the EGR amount. May be controlled so that the variable valve actuation mechanism cancels out. According to these aspects, when the supercharging effect of the turbocharger is adjusted, the EGR amount by the external EGR adjusting device and the valve operating characteristics by the variable valve mechanism are adjusted so as to cancel the change in the EGR amount accompanying the adjustment. Is done. The variable valve mechanism includes a mechanism that changes, for example, the opening / closing timing or the operating angle as the valve operating characteristic. The internal EGR amount can be adjusted by changing the amount of overlap between the opening periods of the intake valve and the exhaust valve and the operating angle of the intake valve or the exhaust valve.
[0009]
In the control device for an internal combustion engine of the present invention, the EGR amount control means may control an operation of the EGR amount adjustment means according to a change in the exhaust back pressure. The exhaust back pressure changes with the adjustment of the supercharging effect by the supercharging effect adjusting means. As a result, the EGR amount changes. Therefore, if the change in the exhaust back pressure is monitored, the change in the EGR amount can be grasped. The EGR amount adjusting means can be controlled so that the change in the amount is appropriately canceled.
[0010]
The EGR amount control means may specify the total EGR amount taken into the cylinder of the internal combustion engine, and control the operation of the EGR amount adjustment means based on the specified result. The total EGR amount is given as the sum of the internal EGR amount and the external EGR amount. If the total EGR amount is specified and the operation of the EGR amount adjusting means is controlled, the EGR amount can be more accurately controlled to the optimum value. .
[0011]
The second control device of the present invention is applied to an internal combustion engine provided with a turbocharger including a supercharging effect adjusting means for changing a correspondence between an exhaust flow rate and a supercharging effect. The above-mentioned problem is solved by providing combustion control means for controlling a value of a combustion control parameter that affects a combustion state in the internal combustion engine in accordance with a supercharge effect adjustment state by the supercharge effect adjustment means. (Claim 6).
[0012]
According to the present invention, even if the EGR amount changes due to the operation of the supercharging effect adjusting means, the value of the combustion control parameter is controlled so as to cancel the influence of the change on the combustion state, thereby reducing the combustion state. Can be favorably maintained.
[0013]
In the present invention, the concept of the specification and control of the EGR amount is not limited to the case where the EGR amount itself is a target, and the target value and the change amount regarding the EGR are specified by a physical quantity that can be converted into the EGR amount such as an EGR rate. This also includes the case where the EGR amount is controlled. In the present invention, the concept of “cancellation” is not limited to the case where the change in the EGR amount or the change thereof completely cancels the effect on combustion, and the effect of the change in the EGR amount or change thereof on combustion is partially or Includes cases where cancellation is incomplete.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
(1st Embodiment)
FIG. 1 shows an embodiment of an internal combustion engine to which the control device of the present invention is applied. The internal combustion engine 1 is an in-cylinder injection gasoline engine that takes in air from an intake passage 2 into a cylinder 3 and directly injects fuel from a fuel injection valve 4 into the cylinder 3 to form a fuel mixture in the cylinder 3. It is configured. The fuel mixture formed in the cylinder 3 is ignited by the ignition plug 5 and burns, and the piston 6 is reciprocated by the combustion energy. Although the internal combustion engine 1 is provided with a plurality of cylinders 3, FIG. 1 shows only a single cylinder 3 as a representative. The intake passage 2 and the exhaust passage 7 are opened and closed with respect to the cylinder 3 by an intake valve 8 and an exhaust valve 9, respectively. The internal combustion engine 1 may be a so-called port injection type gasoline engine that injects fuel from the fuel injection valve 4 into the intake passage 2 or a diesel engine using light oil as fuel.
[0015]
A turbocharger 10 is provided between the intake passage 2 and the exhaust passage 7. The turbocharger 10 includes a turbine rotor 10a housed in the exhaust passage 7, a compressor rotor 10b housed in the intake passage 2, and a spindle 10c coaxially connecting the rotors 10a and 10b. This is a well-known supercharging device that supercharges the intake air in the intake passage 2 to the cylinder 3 by integrally rotating the turbine rotor 10a, the spindle 10c, and the compressor rotor 10b using energy. However, the turbocharger 10 of the present embodiment is configured as a turbocharger with an electric motor including an electric motor 10d that drives a spindle 10c. The electric motor 10d can be configured by, for example, attaching a rotor to the spindle 10c and arranging a stator around the spindle 10c.
[0016]
The electric motor 10d can rotate the spindle 10c in both forward and reverse directions with electric power supplied from the battery 12 via the inverter 11, and can also generate electric power by being driven by the spindle 10c. The electric power generated by the electric motor 10 d is charged into the battery 12 via the inverter 11. By changing the rotation of the spindle 10c by the electric motor 10d or by generating electric power by the electric motor 10d, the correspondence between the exhaust flow rate guided to the turbine rotor 10a and the supercharging effect of the intake air by the compressor rotor 10b changes. I do. Therefore, the electric motor 10d functions as a supercharging effect adjusting unit. The forward rotation of the electric motor 10d corresponds to the rotation direction when the turbine rotor 10a of the turbocharger 10 is rotated by the exhaust gas. On the turbine 10a side of the turbocharger 10, a variable nozzle may be provided in addition to the electric motor 10d as a supercharging effect adjusting means.
[0017]
An air filter 13 is arranged upstream of the compressor rotor 10b in the intake passage 2, and an intercooler 14 and a throttle valve 15 are arranged downstream of the compressor rotor 10b. An exhaust purification catalyst 16 is provided in the exhaust passage 7 downstream of the turbine rotor 10a.
[0018]
The throttle valve 15 is a so-called electronically controlled throttle valve whose opening is controlled by operating a throttle motor 18 by an engine control unit (ECU) 17. The ECU 17 is configured as a computer having a CPU, a RAM, a ROM, and an input / output interface as peripheral devices necessary for the operation of the internal combustion engine 1 and various programs attached to the internal combustion engine 1 according to various programs recorded in the ROM. Control the operation of the device. To control the opening of the throttle valve 15, information on the operation amount of the accelerator pedal 20 detected by the pedal position sensor 19 and information on the opening of the throttle valve 15 detected by the throttle opening sensor 21 are input to the ECU 17. You.
[0019]
In addition to the opening degree of the throttle valve 15, the ECU 17 also controls the fuel injection timing of the fuel injection valve 4, the ignition timing of the ignition plug 5, and the EGR valve (EGR valve 22 installed in the EGR passage 22 connecting the exhaust passage 7 and the intake passage 2 The opening degree of the external EGR adjusting device 23, the opening / closing operation of a bypass valve 25 installed in a bypass passage 24 bypassing the turbocharger 10, the operation of a variable valve mechanism 26 for changing the opening / closing timing of the intake valve 8, and the like are controlled. . The EGR valve 23 is an electronically controlled flow control valve whose opening is adjusted according to an instruction from the ECU 17.
[0020]
In order to appropriately control the operations of the various devices described above in accordance with the operating state of the internal combustion engine 1, the ECU 17 transmits the intake pressure in addition to the information detected by the pedal position sensor 19 and the throttle opening sensor 21 described above. Information corresponding to the pressure of the intake passage 2 (intake pipe pressure) detected by the sensor 27 and information corresponding to the crank angle detected by the crank angle sensor 28 are input. In addition, the temperature of the cooling water of the internal combustion engine 1, the air-fuel ratio in the exhaust passage 7, and the like are detected by sensors and input to the ECU 17, but these are not shown. The procedure of control of the fuel injection valve 4, the ignition plug 5, the EGR valve 23, and the bypass valve 25 by the ECU 17 may be the same as that for a known internal combustion engine, and is not the gist of the present invention, so that the description is omitted here.
[0021]
The ECU 17 controls the EGR amount toward a predetermined target value by adjusting the opening degree of the EGR valve 23 or the amount of overlap between the opening timings of the intake valve 8 and the exhaust valve 9 by the variable valve mechanism 26. Is done. The target value of the EGR amount here is a value necessary for optimally controlling the combustion state in the cylinder 3 in view of the operation state of the internal combustion engine 1. The target value of the EGR amount may be calculated by the ECU 17 based on detection signals from various sensors, or may be a potential value specified by a target value of a physical quantity other than the EGR amount representing the operating state of the internal combustion engine 1. May be. The EGR amount can be adjusted by operating the bypass valve 25 to adjust the supercharging pressure, or by adjusting the opening of the variable nozzle of the turbocharger 10. However, in the present embodiment, the EGR valve is particularly controlled. It is assumed that 23 and / or the variable valve mechanism 26 correspond to the EGR amount adjusting means.
[0022]
The electric motor 10d of the turbocharger 10 is operated by the ECU 17 via the inverter 11. For example, when a sufficient supercharging effect cannot be obtained only by the rotation of the turbine rotor 10a due to the exhaust energy, the electric motor is supplied from the battery 12 through the inverter 11 so that the supercharging effect according to the supercharging instruction from the ECU 17 is obtained. Electric power is supplied to 10d, and the electric motor 10d is driven forward. When the turbine rotor 10a is rotating in spite of not requiring a supercharging effect as in the case of deceleration of the internal combustion engine 1, that is, when the turbine rotor 10a has excess rotational energy, a power generation instruction from the ECU 17 is issued. , The operation state of the inverter 11 is switched, and electric power is generated by the electric motor 10 d, and the obtained power is charged into the battery 12 via the inverter 11. The operation of the electric motor 10d of the turbocharger 10 for the purpose of controlling the supercharging pressure may be performed in the same manner as the control of other turbochargers with electric motors.
[0023]
When the supercharging effect of the turbocharger 10 is changed by operating the electric motor 10d as described above, the exhaust back pressure of the exhaust passage 7 changes in accordance with the driving state of the turbine rotor 10a, and accordingly, the exhaust back pressure remains in the cylinder 3. The amount of combustion gas to be discharged, that is, the amount of internal EGR also changes. Therefore, the ECU 17 corrects the EGR amount according to the driving state of the electric motor 10d by repeatedly executing the EGR correction control routine shown in FIG. 2 at predetermined intervals. By executing the routine in FIG. 2, the ECU 17 functions as EGR control means.
[0024]
In the EGR correction control routine of FIG. 2, the ECU 17 first determines in step S11 whether or not an operation of a turbocharger with a motor (MAT, Motor Assist Turbo) 10 is required for controlling the supercharging effect. Monitoring conditions for driving the electric motor 10d in the control program of the electric motor 10d executed by the ECU 17 for adjusting the supercharging effect, and changing the state of the determination flag according to whether or not the condition is satisfied. Thus, it is possible to determine the presence or absence of the request in step S11.
[0025]
If the operation of the electric motor 10d is not requested in step S11, the current EGR correction control routine ends. On the other hand, when the operation is requested, the process proceeds to step S12, and the estimated value of the exhaust back pressure of the exhaust passage 7 is calculated. The estimated value of the exhaust back pressure can be calculated, for example, from the rotation speed (rotation speed) of the turbine rotor 10a. The exhaust back pressure may be calculated from another physical quantity correlated with the rotation speed of the turbine rotor 10a, for example, the power consumption or the power generation amount of the electric motor 10d. Instead of estimating the exhaust back pressure, a pressure sensor may be provided in the exhaust passage 7 to detect the exhaust back pressure.
[0026]
In the following step S13, a correction value of the EGR amount adjusting means necessary for canceling the change from the target value of the EGR amount caused by the change of the exhaust back pressure is determined. In this process, as shown in FIG. 3, for example, the load of the internal combustion engine 1 and the exhaust back pressure are set at the optimum opening degree of the EGR valve 23, that is, the change of the EGR amount due to the change of the exhaust back pressure is set to the target EGR amount. A map associated with the opening degree of the EGR valve 23 required to control the value is stored in the ROM of the ECU 17 in advance, and the exhaust back pressure acquired in step S12 and the load on the internal combustion engine 1 at the time of execution of step S13 are stored. It can be realized by acquiring the corresponding optimal EGR valve 23 opening degree from the map.
[0027]
In the map of FIG. 3, the optimal opening of the EGR valve 23 when the electric motor 10d is not operating is set as the base opening, and when the operation of the electric motor 10d reduces the exhaust back pressure, the EGR valve When the exhaust back pressure increases, the opening of the EGR valve 23 is set to be relatively smaller than the base opening. However, the map of FIG. 3 is an example, and the relationship among the load of the internal combustion engine 1, the exhaust back pressure, and the opening of the EGR valve 23 may be adjusted as appropriate. In FIG. 3, the EGR amount is corrected by the opening degree of the EGR valve 23. However, the EGR amount is changed according to the exhaust back pressure and the load by changing the advance amount related to the opening timing of the intake valve 8 by the variable valve mechanism 26. The amount may be corrected.
[0028]
In the following step S14, the correction value determined in step S13 is reflected on the operation of the EGR amount adjusting means. For example, when the correction value of the opening degree of the EGR valve 23 is obtained from the map of FIG. 3, the EGR amount is corrected by changing the EGR valve 23 to the opening degree. Thereafter, the current EGR amount control routine ends.
[0029]
(Second embodiment)
Next, a second embodiment of the present invention will be described. In this embodiment, instead of the EGR correction control of FIG. 2, the ECU 17 functions as an EGR control means by repeating the EGR correction control routine of FIG. 4 at a predetermined cycle. The configuration of the internal combustion engine 1 and its attachments is the same as in FIG.
[0030]
In the EGR correction control routine of FIG. 4, the ECU 17 first determines in step S21 whether or not the operation of the turbocharger 10 with an electric motor is required for controlling the supercharging effect. If the operation is not requested, the current EGR correction control routine ends. On the other hand, when the operation is requested, the process proceeds to step S22, and the target EGR rate corresponding to the rotation speed and the load of the internal combustion engine 1 is acquired with reference to the map stored in the ROM. Note that the EGR rate means the ratio of the amount of combustion gas (EGR gas) to the amount of intake gas in the cylinder 3.
[0031]
In a succeeding step S23, an EGR rate is calculated from the intake gas amount and the intake air amount. The intake gas amount is the amount of intake gas to the cylinder 3 calculated from the intake pipe pressure detected by the intake pressure sensor 27, and the intake air amount is the amount of air taken into the intake passage 2 detected by an air flow meter (not shown). is there. The air flow meter is installed relatively upstream of the intake passage 2, for example, immediately after the air filter 13, and detects the flow rate of air taken into the intake passage 2 from the outside. On the other hand, the intake pressure sensor 27 is installed near a surge tank 29 (see FIG. 1) to which the EGR passage 22 is connected, and the detected pressure is the amount of all the gas taken into the cylinder 3, that is, the intake pressure. It corresponds to the total value of the amount of air taken into the passage 2, the amount of external EGR gas taken through the EGR passage 22, and the amount of internal EGR gas remaining in the cylinder 3. Therefore, by subtracting the intake air amount from the intake gas amount, the total EGR amount (sum of the external EGR gas amount and the internal EGR gas amount) taken into the cylinder 3 can be obtained. Then, the EGR rate is calculated by dividing the obtained total EGR amount by the intake gas amount.
[0032]
In the next step S24, it is determined whether or not the calculated EGR rate matches the target EGR rate acquired in step S22. If they match, the current EGR correction control routine ends. On the other hand, if the EGR rate does not match the target EGR rate, the process proceeds to step S25, the EGR amount adjusting means is operated according to the deviation of the EGR rate, and the current routine ends. For example, when the EGR rate is smaller than the target EGR rate, the opening degree of the EGR valve 23 is increased or the opening timing of the intake valve 8 is advanced so that the EGR amount increases. When the EGR rate is larger than the target EGR rate, the opening degree of the EGR valve 23 is reduced or the opening timing of the intake valve 8 is retarded so that the EGR amount decreases. The degree of adjustment of the opening degree of the EGR valve 23 or the opening timing of the intake valve 8 increases as the deviation from the target value of the EGR rate increases from the viewpoint of offsetting the deviation of the EGR amount due to the operation of the electric motor 10d. Is set.
[0033]
In this embodiment, since the EGR rate is estimated from the intake air amount and the intake pipe pressure, there is no need to estimate or detect the exhaust back pressure.
[0034]
(Third embodiment)
Next, a third embodiment of the present invention will be described. In this embodiment, instead of the EGR correction control of FIGS. 2 and 4, the ECU 17 functions as a combustion control means by repeating the combustion control value correction control routine of FIG. 5 at a predetermined cycle. The configuration of the internal combustion engine 1 and its attachments is the same as in FIG.
[0035]
In the combustion control value correction control routine of FIG. 5, the ECU 17 first determines in step S31 whether the operation of the turbocharger with electric motor 10 is required for controlling the supercharging effect. If the operation is requested, the process proceeds to step S32, and an estimated value of the exhaust back pressure of the exhaust passage 7 is obtained. The estimated value of the exhaust back pressure can be calculated from the rotation speed of the turbine rotor 10a, the power consumption of the electric motor 10d, or the power generation amount, as in the first embodiment. Instead of estimating the exhaust back pressure, a pressure sensor may be provided in the exhaust passage 7 to detect the exhaust back pressure.
[0036]
In a succeeding step S33, a correction value of the combustion control value corresponding to the change amount of the exhaust back pressure accompanying the operation of the electric motor 10d is determined. The combustion control value is a set value of a combustion control parameter operated by the ECU 17 to control the combustion state in the internal combustion engine 1 to a predetermined state. The combustion control parameters include the ignition timing of the ignition plug 5, the combustion injection timing from the fuel injection valve 4, the opening of the throttle valve 15, the air-fuel ratio (A / F), and the like. The ECU 17 determines the optimum value of the combustion control parameter based on the state of various parameters such as the cooling water temperature, the vehicle speed, the depression amount of the accelerator pedal 20, the temperature of the catalyst 16 and the like without considering the influence of the operation of the electric motor 10d. Is repeatedly calculated at a predetermined cycle. The correction value determined in step S33 corresponds to a correction amount of the base value required to offset the influence of the operation of the electric motor 10d on the combustion state. The determination of such a correction value is performed by, for example, as shown in FIG. 6, a map in which the amount of change in the exhaust back pressure and the load of the internal combustion engine 1 are associated with a combustion control correction value, in this example, a correction value of the ignition timing. This can be realized by storing in advance in the ROM and acquiring the optimum combustion control correction value corresponding to the change amount of the exhaust back pressure and the load of the internal combustion engine 1 from the map. The calculation of the base value may be executed in the same procedure as that of other known internal combustion engine control devices.
[0037]
The load 1 is smaller than the load 2 in the map of FIG. The intersection of the vertical axis and the horizontal axis indicated by the dashed line in the figure is the origin of the change amount = 0 and the correction value = 0, and when the load is small, the ignition timing increases as the change amount of the exhaust back pressure increases in the positive direction. The correction value changes so that the ignition timing is advanced as the change amount of the exhaust back pressure increases in the negative direction. When the electric motor 10d is driven to hinder the rotation of the turbine rotor 10a, the exhaust back pressure increases in the positive direction. When the electric motor 10d is driven to rotate the turbine rotor 10a in the positive direction, the exhaust back pressure becomes negative. To increase.
[0038]
On the other hand, when the load is large in the map of FIG. 6, the ignition timing is slightly retarded when the change in the exhaust back pressure increases in the negative direction, and the ignition timing increases as the change in the exhaust back pressure increases in the positive direction. Is changed so that is advanced. However, the map of FIG. 6 is merely an example, and the correspondence relationship between the change amount of the exhaust back pressure, the load of the internal combustion engine 1 and the correction value of the combustion control value is appropriately changed according to the characteristics of the internal combustion engine 1 and the like. Good. Further, the combustion control value is not limited to the ignition timing, and may be controlled based on the above-described injection timing, throttle opening, air-fuel ratio, and the like.
[0039]
Returning to FIG. 5, after determining the correction value in step S33, the process proceeds to step S34, in which the correction value is added to the base value of the combustion control parameter to obtain a combustion control value corresponding to the current driving state of the electric motor 10d. . In this way, by correcting the base value of the combustion control parameter according to the amount of change in the exhaust back pressure by the electric motor 10d, it is possible to offset the effect of the change in the exhaust back pressure due to the operation of the electric motor 10d on the combustion state. .
[0040]
After the combustion control value is corrected in step S34, the current combustion control value correction control routine ends. The combustion control value corrected in step S34 is reflected in the subsequent combustion control by the ECU 17. For example, when the ignition timing is corrected, the ECU 17 controls the ignition timing of the ignition plug 5 with the corrected ignition timing as a target value.
[0041]
On the other hand, if it is determined in step S31 that the operation of the turbocharger with an electric motor 10 is not requested, the process proceeds to step S35, where the correction value relating to the combustion control value is set to 0, and the current combustion control value correction routine ends.
[0042]
(Fourth embodiment)
Next, a fourth embodiment of the present invention will be described. In this embodiment, the ECU 17 functions as a combustion control means by repeating the combustion control value correction control routine of FIG. 7 at a predetermined cycle instead of the combustion control value correction control of FIG. The configuration of the internal combustion engine 1 and its attachments is the same as in FIG.
[0043]
In the combustion control value correction control routine of FIG. 7, the ECU 17 first determines in step S41 whether or not the operation of the turbocharger with electric motor 10 is required for controlling the supercharging effect. If the operation has not been requested, the current combustion control value correction control routine ends. On the other hand, when the operation is requested, the process proceeds to step S42, and the target EGR rate corresponding to the rotation speed and the load of the internal combustion engine 1 is acquired with reference to the map stored in the ROM. In a succeeding step S43, an EGR rate is calculated from the intake gas amount and the intake air amount. The calculation method may be the same as in the case of step S23 in FIG.
[0044]
In the next step S44, the amount of change in the EGR rate calculated in step S43 based on the target EGR rate obtained in step S42 is obtained, and a correction value of the combustion control value corresponding to the amount of change is determined. As in the third embodiment, the combustion control value is set to a combustion control parameter such as the ignition timing of the ignition plug 5, the combustion injection timing from the fuel injection valve 4, the opening of the throttle valve 15, and the air-fuel ratio (A / F). The ECU 17 repeatedly calculates the base value of the combustion control parameter as in the case of FIG. The correction value determined in step S44 corresponds to a correction amount of the base value required to offset the influence of the operation of the electric motor 10d on the combustion state. The determination of such a correction value is performed by, for example, as shown in FIG. 8, a map in which the amount of change in the EGR rate and the load of the internal combustion engine 1 are associated with a combustion control correction value, in this example, a correction value of the ignition timing. The optimum combustion control correction value corresponding to the difference between the target EGR rate acquired in step S42 and the EGR rate calculated in step S43, and the load of the internal combustion engine 1 at the time of executing step S44. 8 can be realized.
[0045]
The load 1 is smaller than the load 2 in the map of FIG. The intersection of the vertical axis and the horizontal axis indicated by the one-dot chain line in the figure is the origin of the change amount = 0 and the correction value = 0. When the load is small, the ignition timing increases as the change amount of the EGR rate increases in the positive direction. The correction value changes so that the ignition timing is advanced as the amount of retard is retarded and the amount of change in the EGR rate increases in the negative direction. On the other hand, when the load is large, the ignition timing is slightly retarded when the change in the EGR rate increases in the negative direction, and the ignition timing is advanced as the change in the EGR rate increases in the positive direction. The correction value has changed. However, the map in FIG. 8 is merely an example, and the correspondence between the amount of change in the EGR rate, the load, and the correction value of the combustion control value may be appropriately changed according to the characteristics of the internal combustion engine 1 and the like. Further, the combustion control value is not limited to the ignition timing, and may be controlled based on the above-described injection timing, throttle opening, air-fuel ratio, and the like.
[0046]
Returning to FIG. 7, after determining the correction value in step S44, the process proceeds to step S45, in which the correction value is added to the base value of the combustion control parameter to obtain a combustion control value corresponding to the current driving state of the electric motor 10d. . In this way, by correcting the base value of the combustion control parameter according to the amount of change in the EGR rate by the electric motor 10d, it is possible to offset the effect of the change in the EGR rate accompanying the operation of the electric motor 10d on the combustion state.
[0047]
After correcting the combustion control value in step S45, the current combustion control value correction control routine ends. The combustion control value corrected in step S45 is reflected in the subsequent combustion control by the ECU 17. For example, when the ignition timing is corrected, the ECU 17 controls the ignition timing of the ignition plug 5 with the corrected ignition timing as a target value.
[0048]
On the other hand, if it is determined in step S41 that the operation of the turbocharger with an electric motor 10 has not been requested, the process proceeds to step S46, in which the correction value relating to the combustion control value is set to 0, and the current combustion control value correction routine ends.
[0049]
The present invention is not limited to the above embodiments, and may be implemented in various forms. For example, the amount of overlap between the opening period of the EGR valve and the opening period of the intake valve and the opening period of the exhaust valve by the variable valve mechanism is set so as to offset the change in the EGR amount when the opening of the variable nozzle is changed. It may be controlled. The EGR amount may be changed by changing the operating angle of the intake valve or the exhaust valve. Alternatively, the combustion control value may be controlled so as to offset the influence of the change in the opening of the variable nozzle on the combustion state.
[0050]
【The invention's effect】
As described above, according to the present invention, even if the EGR amount changes due to the operation of the supercharging effect adjusting unit provided in the turbocharger, the EGR amount adjusting unit is operated so as to cancel the change, and the EGR amount is adjusted. Since the value of the combustion control parameter can be controlled so as to suppress the deviation of the amount from the optimal value or to offset the influence of the change in the EGR amount on the combustion state, the combustion state of the internal combustion engine can be maintained well, Exhaust emission and deterioration of fuel efficiency can be prevented.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of an internal combustion engine to which a control device according to an embodiment of the present invention is applied and an accessory device thereof.
FIG. 2 is a flowchart illustrating an example of an EGR correction control routine executed by the ECU of FIG. 1;
FIG. 3 is a diagram showing an example of a map in which a load of an internal combustion engine and an exhaust back pressure are associated with an optimal opening of an EGR valve.
FIG. 4 is a flowchart showing another example of an EGR correction control routine executed by the ECU of FIG. 1;
FIG. 5 is a flowchart illustrating an example of a combustion control value correction control routine executed by the ECU of FIG. 1;
FIG. 6 is a diagram showing an example of a map in which a change amount of an exhaust back pressure and a load of an internal combustion engine are associated with a correction value of an ignition timing.
FIG. 7 is a flowchart illustrating another example of a combustion control value correction control routine executed by the ECU of FIG. 1;
FIG. 8 is a diagram showing an example of a map in which a change amount of an EGR rate and a load of an internal combustion engine are associated with a correction value of an ignition timing.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Internal combustion engine 2 Intake passage 3 Cylinder 4 Fuel injection valve 10 Turbocharger 10a Turbine rotor 10b Compressor rotor 10c Spindle 10d Electric motor (supercharging effect adjusting means)
11 Inverter 15 Throttle valve 17 Engine control unit (control device, EGR control means, combustion control means)
22 EGR passage 23 EGR valve (external EGR adjusting device, EGR amount adjusting means)
26 Variable valve mechanism (EGR amount adjusting means)

Claims (6)

In a control device applied to an internal combustion engine provided with a turbocharger including a supercharging effect adjusting unit that changes a correspondence relationship between an exhaust flow rate and a supercharging effect,
EGR amount adjusting means provided separately from the turbocharger and capable of adjusting the EGR amount;
EGR control means for controlling the operation of the EGR amount adjustment means so as to offset a change in the EGR amount caused by the adjustment of the supercharge effect by the supercharge effect adjustment means,
A control device for an internal combustion engine, comprising: As the EGR amount adjusting means, an external EGR adjusting device for returning exhaust gas to the intake passage via an EGR passage connecting an exhaust passage and an intake passage of the internal combustion engine is provided. The control device according to claim 1, wherein an EGR amount by the external EGR adjusting device is controlled so as to cancel the change of the EGR. As the EGR amount adjustment means, a variable valve mechanism for controlling at least one of the intake valve and the exhaust valve characteristics of the internal combustion engine is provided, and the EGR amount control means controls the change in the EGR amount. 2. The control device according to claim 1, wherein the valve operating characteristics of the variable valve operating mechanism are controlled so as to cancel each other. The control device according to claim 1, wherein the EGR amount control unit controls an operation of the EGR amount adjustment unit according to a change in exhaust back pressure. 2. The control device according to claim 1, wherein the EGR amount control means specifies the total EGR amount taken into a cylinder of the internal combustion engine, and controls the operation of the EGR amount adjustment means based on a result of the specification. 3. In a control device applied to an internal combustion engine provided with a turbocharger including a supercharging effect adjusting unit that changes a correspondence relationship between an exhaust flow rate and a supercharging effect,
A control apparatus for an internal combustion engine, comprising: combustion control means for controlling a value of a combustion control parameter that affects a combustion state of the internal combustion engine in accordance with a supercharge effect adjustment state by the supercharge effect adjustment means. .

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