JP2012097639A - Control device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control device for an internal combustion engine with a turbocharger actively controlling a WGV as well as an EGR device, in which the total EGR rate is adjusted to become a suitable value while misfires and torque decreases are suppressed even if a request for acceleration is demanded in a non-supercharging area.SOLUTION: The control device for an internal combustion engine includes: an EGR valve for opening/closing an external EGR passage; a turbocharger turbine disposed in an exhaust passage; and a bypass valve in a bypass passage between the upstream of the turbine and the downstream of the exhaust passage. The control device is configured to close the bypass valve when the operation area is a non-supercharging area where engine speed and load are lower than that of a supercharging range, and also when a request for a torque of more than a predetermined value has been input. The control device is configured to reduce, after closing the bypass valve, the opening degree of the EGR valve if the total of the external EGR rate and the internal EGR rate reaches more than a suitable value.

Description

  The present invention relates to a control device for an internal combustion engine, and more particularly to control of an internal combustion engine having a turbocharger that can actively control a waste gate valve (WGV) in addition to an EGR (Exhaust Gas Recirculation) device. Relates to the device.

  As a conventional technique, for example, as disclosed in Japanese Patent Application Laid-Open No. 2004-293392, a control device for an internal combustion engine that performs EGR is known. The EGR is realized by an internal EGR and an external EGR. In the external EGR, part of the exhaust gas is recirculated to the intake system through an external EGR passage that connects the exhaust system and the intake system. In the internal EGR, the valve overlap amount between the intake valve and the exhaust valve is adjusted by the variable valve means, and a part of the exhaust gas is re-inhaled into the cylinder.

  In the prior art, when the acceleration of the vehicle is greater than a predetermined acceleration, the internal EGR amount is decreased from that during normal control and the external EGR amount is increased from that during normal control. In the conventional technology, the total EGR rate for fresh air (the sum of the external EGR rate and the internal EGR rate) is controlled to be constant by such control.

JP 2004-293392A Japanese Patent Laid-Open No. 8-158854

  By the way, in an internal combustion engine having a turbocharger capable of actively controlling the WGV in addition to the EGR device, the WGV is normally controlled to be fully opened in a non-supercharged (natural intake) region having a lower rotation and a lower load than the supercharged region. To do. By fully opening the WGV, it is possible to reduce the back pressure and improve fuel efficiency. At this time, if there is an acceleration request, the WGV is controlled to be fully closed in order to improve the response.

  However, closing the WGV increases the back pressure, which increases the internal EGR rate. Furthermore, since the differential pressure (back pressure-intake pressure) increases, the external EGR rate also increases. In the above-described conventional technology, in order to keep the total EGR rate constant, control for decreasing the internal EGR rate is performed when there is an acceleration request. However, in an internal combustion engine equipped with a turbocharger, combustion resistance is low in a low rotation / low load non-supercharging region, pressure and temperature during the compression stroke are lowered, and there is a concern about misfire and torque reduction. Therefore, there is a problem that it cannot be applied in such a region.

  The present invention has been made to solve the above-described problems. In an internal combustion engine provided with a turbocharger capable of actively controlling the WGV in addition to the EGR device, there is a request for acceleration in a non-supercharging region. Even so, it is an object of the present invention to provide a control device for an internal combustion engine that can adjust the total EGR rate to an appropriate value while suppressing misfire and torque reduction.

In order to achieve the above object, a first invention is a control device for an internal combustion engine,
An external EGR passage connecting the exhaust passage and the intake passage of the internal combustion engine;
An EGR valve capable of opening and closing the external EGR passage;
A turbocharger turbine provided in the exhaust passage;
A bypass passage for bypassing the exhaust passage on the upstream side and the downstream side of the turbine;
A bypass valve capable of opening and closing the bypass passage;
When the operating region is a non-supercharging region where the engine speed and load are lower than the supercharging region, and when a required torque exceeding a predetermined value is input, an acceleration control means for closing the bypass valve;
After the bypass valve is closed by the acceleration control means, when the sum of the external EGR rate and the internal EGR rate of the internal combustion engine is equal to or greater than a conforming value, the external speed during acceleration that reduces the opening of the EGR valve EGR reduction means.

The second invention is the first invention, wherein
A variable valve timing device capable of changing a valve overlap amount between an intake valve and an exhaust valve of the internal combustion engine;
The acceleration control means closes the bypass valve when the operating region is a non-supercharging region where the engine speed and load are lower than the supercharging region, and when a required torque exceeding a predetermined value is input. The valve overlap amount is increased.

The third invention is the first or second invention, wherein
A direct injection injector for injecting fuel into the cylinder of the internal combustion engine;
A port injector for injecting fuel into the intake port of the internal combustion engine;
Blowing ratio changing means for changing the fuel blowing ratio of the direct injector and the port injector;
Tip temperature calculating means for calculating the tip temperature of the direct injection injector;
In-cylinder temperature calculating means for calculating the in-cylinder temperature of the internal combustion engine;
After the opening degree of the EGR valve is reduced by the external EGR reducing means at the time of acceleration, an increase for correcting the blowing ratio of the direct injection injector is increased when the in-cylinder temperature is higher than the tip temperature of the direct injection injector And a correction unit.

Moreover, 4th invention is set in 3rd invention,
Storage means for storing in advance the relationship between the injection amount by the direct injection injector and the maximum advance value of the injection timing at which the smoke amount does not exceed the allowable value;
From the relationship, a maximum advance value calculation means for calculating a maximum advance value corresponding to the injection amount by the direct injection injector,
Injection timing setting means for setting the injection timing of the direct injection injector to the maximum advance value;
Is further provided.

According to a fifth invention, in any one of the first to fourth inventions,
When the operation region shifts from the supercharging region to the non-supercharging region by decelerating operation, the valve overlap amount is reduced and the deceleration time control means for opening the bypass valve;
After the bypass valve is opened by the deceleration-time control means, when the sum of the external EGR rate and the internal EGR rate of the internal combustion engine is equal to or greater than the conforming value, the deceleration-time external portion that reduces the opening degree of the EGR valve EGR reduction means is further provided.

  According to the first or second invention, when the operating region is the non-supercharging region where the engine speed and the load are lower than the supercharging region, and when the required torque exceeding the predetermined value is input, the bypass is performed. Close the valve. Thereafter, when the sum of the external EGR rate and the internal EGR rate of the internal combustion engine is equal to or greater than the conforming value, the opening degree of the EGR valve can be reduced. As a result, the internal EGR having a higher gas temperature than the external EGR can be positively used in the non-supercharging region where the combustion resistance is low, and the combustion can be stabilized. Therefore, according to the present invention, even if there is a request for acceleration in the non-supercharged region, the total EGR rate can be suitably adjusted to the appropriate value while suppressing misfire and torque reduction.

  According to the third invention, after the opening degree of the EGR valve is reduced at the time of acceleration, when the in-cylinder temperature is higher than the tip temperature of the direct injection injector, the blow ratio of the direct injection injector can be increased and corrected. it can. For this reason, according to this invention, the tip temperature can be lowered | hung by increasing the blowing ratio of the direct injection injector 12, and increasing the fuel injection quantity by a direct injection injector.

  According to the fourth aspect of the invention, the injection timing of the direct injection injector can be set to the maximum advance value at which the smoke amount does not exceed the allowable value. Therefore, according to the present invention, it is possible to reduce the tip temperature of the direct injection injector by suppressing the generation of smoke and making the injection timing as early as possible.

  According to the fifth aspect of the present invention, the operating region shifts from the supercharging region to the non-supercharging region due to the deceleration operation, and the sum of the external EGR rate and the internal EGR rate of the internal combustion engine is equal to or greater than the conforming value. In addition, the opening degree of the EGR valve can be reduced. For this reason, according to the present invention, even when the operation region shifts from the supercharging region to the non-supercharging region by the deceleration operation, the same effect as that of the first embodiment described above can be obtained.

It is a figure for demonstrating the system configuration | structure of Embodiment 1 of this invention. In Embodiment 1 of this invention, it is a flowchart of the control routine which ECU50 performs. It is a figure for demonstrating the calculation method of the internal EGR rate and the external EGR rate in Embodiment 1 of this invention. In Embodiment 2 of this invention, it is a flowchart of the control routine which ECU50 performs. It is a figure for demonstrating the relationship between the injection timing in Embodiment 3 of this invention, a smoke amount, or the front-end | tip temperature of the direct injection injector 12. FIG. It is a figure for demonstrating the driving | running area | region in Embodiment 4 of this invention. In Embodiment 4 of this invention, it is a flowchart of the control routine which ECU50 performs.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, the same code | symbol is attached | subjected to the element which is common in each figure, and the overlapping description is abbreviate | omitted.

Embodiment 1 FIG.
[System configuration]
FIG. 1 is a diagram for explaining a system configuration according to the first embodiment of the present invention. The system shown in FIG. 1 includes an internal combustion engine 10. The internal combustion engine 10 is a four-cycle engine mounted on a vehicle or the like and used as a power source. Although the internal combustion engine 10 shown in FIG. 1 is an in-line four-cylinder type, in the present invention, the number of cylinders and the cylinder arrangement are not limited thereto.

  Each cylinder of the internal combustion engine 10 is provided with a direct injection injector 12 that directly injects fuel into the cylinder. The present invention is not limited to such an in-cylinder injection type internal combustion engine, but a port injection type internal combustion engine including a port injector 13 for port-injecting fuel into an intake port, a direct injection injector 12 and a port injector. The present invention can be similarly applied to an internal combustion engine that is used together with No. 13. Each cylinder of the internal combustion engine 10 is provided with an in-cylinder pressure sensor 14 for detecting the in-cylinder pressure.

  An intake passage 16 and an exhaust passage 18 are connected to each cylinder of the internal combustion engine 10. An intake valve 20 that opens and closes between the cylinder and the intake passage 16 is provided at the downstream end of the intake passage 16. Similarly, an exhaust valve 22 that opens and closes between the cylinder and the exhaust passage 18 is provided at the upstream end of the exhaust passage 18.

  Exhaust gas discharged from each cylinder of the internal combustion engine 10 flows into the exhaust passage 18. The internal combustion engine 10 includes a turbocharger 24 that performs supercharging with the energy of exhaust gas. The turbocharger 24 includes a turbine 24a that is rotated by the energy of the exhaust gas, and a compressor 24b that is rotated by being driven by the turbine 24a. The turbine 24 a is arranged in the middle of the exhaust passage 18, and the compressor 24 b is arranged in the middle of the intake passage 16.

  The exhaust passage 18 upstream of the turbine 24 a is connected to the intake passage 16 by an external EGR passage 26. The external EGR passage 26 is provided with an EGR cooler 28 and an EGR valve 30. The EGR valve 30 is a valve that opens and closes the external EGR passage 26 by, for example, a motor-driven actuator.

  A bypass passage 32 that connects the exhaust passage 18 near the inlet of the turbine 24a and the exhaust passage 18 near the outlet of the turbine 24a is provided in the vicinity of the turbine 24a. In the bypass passage 32, a WGV (Waste Gate Valve) 34 is provided. The WGV 34 is, for example, a valve that opens and closes the bypass passage 32 by a pressure control type actuator.

  A catalyst 36 for purifying harmful components in the exhaust gas is provided in the exhaust passage 18 downstream of the turbine 24a. As the catalyst 36, for example, a three-way catalyst, an oxidation catalyst, an NOx storage reduction catalyst, or the like can be used.

  An air cleaner 38 is provided near the inlet of the intake passage 16. An air flow meter 40 for detecting the intake air amount is provided in the vicinity of the downstream side of the air cleaner 38. A compressor 24 b is provided downstream of the air flow meter 40. An intercooler 42 is provided downstream of the compressor 24b.

  The fresh air sucked through the air cleaner 38 is compressed by the compressor 24 b of the turbocharger 24 and then cooled by the intercooler 42. An electronically controlled throttle valve 44 is provided downstream of the intercooler 42. The fresh air that has passed through the throttle valve 44 flows into a surge tank 46 formed in the downstream portion of the intake passage 16. The fresh air flowing into the surge tank 46 is distributed and flows into each cylinder. The surge tank 46 is provided with an intake pipe pressure sensor 48 for detecting the internal pressure.

  The system of this embodiment further includes an ECU (Electronic Control Unit) 50. In addition to the in-cylinder pressure sensor 14 and the air flow meter 40 described above, an input unit of the ECU 50 detects a crank angle sensor 52 for detecting the crank angle, and a value corresponding to the amount of depression of the accelerator operated by the driver. Various sensors for detecting the operating state of the internal combustion engine 10 such as the accelerator opening sensor 54 are connected.

  In addition, the output portion of the ECU 50 includes a variable valve timing device capable of changing the cam phase (valve timing) in addition to the direct injection injector 12, the EGR valve 30, the WGV 34, the throttle valve 44, and the intake pipe pressure sensor 48 described above. (VVT) 56, various actuators for controlling the operating state of the internal combustion engine 10 such as a spark plug (not shown) are connected. As the variable valve timing device 56, for example, a conventional mechanism for advancing / retarding the phase of the cam by hydraulic pressure can be used. The ECU 50 controls the operating state of the internal combustion engine 10 by operating various actuators according to a predetermined program based on the outputs of the various sensors described above.

  In the system including the turbocharger 24 that can actively control the WGV 34 described above, the operating range (for example, determined by the engine speed NE and the load KL) is lower than the supercharging range where the turbocharger 24 can be used. When the ECU 50 is in the non-supercharging region (natural intake region), the ECU 50 normally controls the WGV 34 to be fully opened, and controls the opening timing and closing timing of the intake valve 20 to the retard side by the variable valve timing device 56. .

  Thus, in the non-supercharging region, the back pressure can be lowered by opening the WGV 34 to improve fuel efficiency. At this time, when detecting the acceleration request from the driver, the ECU 50 closes the WGV 34 and improves the opening timing and closing timing of the intake valve 20 to improve the response.

  As a result of this control, when the WGV 34 is closed, the back pressure rises and the internal EGR gas increases. Further, the differential pressure (back pressure-intake pressure) increases, and the external EGR gas also increases. Further, since the opening timing of the intake valve 20 is advanced, the valve overlap amount is increased and the internal EGR gas is increased.

  For this reason, the total EGR rate for fresh air (the sum of the external EGR rate and the internal EGR rate) increases more than at the time of adaptation (during normal control), and there is a concern that the ignition timing may deviate from MBT. For this reason, it is desirable to control the total EGR rate to a value that is predetermined according to the operation region.

[Characteristic control]
In the present system equipped with the turbocharger 24, the non-supercharging region of low load and low rotation is an operating region with low combustion resistance. In view of this point, the present invention controls the total EGR rate to an appropriate value by lowering the external EGR rate so as to stabilize combustion by actively using the internal EGR having a higher gas temperature than the external EGR. It was decided.

  FIG. 2 is a flowchart of a control routine executed by the ECU 50 in order to realize the above-described operation. This routine is executed at regular time intervals (for example, several cycles). In the routine shown in FIG. 3, first, in step S100, it is determined whether or not the engine speed NE and the load KL are lower than each set value. The engine speed NE is calculated from a signal detected by the crank angle sensor 52. The load KL is calculated based on, for example, the intake air amount detected by the air flow meter 40 and the intake pipe pressure detected by the intake pipe pressure sensor 48. Each set value is a value that defines the boundary between the supercharging region and the non-supercharging region. If the determination condition in step S100 is not satisfied, this routine is terminated.

  When the determination condition of step S100 is satisfied, the operation region is in the non-supercharging region where the load and the engine speed are lower than in the supercharging region. In this case, the ECU 50 opens the WGV 34 and retards the opening timing and closing timing of the intake valve 20 by the variable valve timing device 56. This retardation value is a value determined so that the valve overlap amount between the intake valve 20 and the exhaust valve 22 is smaller than the reference in the supercharging region.

  Thereafter, it is determined whether or not the required torque exceeds a predetermined value during operation in the non-supercharging region (step S110). The request torque is calculated based on, for example, the driver request torque and the vehicle control request torque. The driver request torque is calculated based on the accelerator opening detected by the accelerator opening sensor 54. The vehicle control request torque is calculated based on a request from the vehicle side required for vehicle control. The predetermined value is a value indicating rapid acceleration, and is set in advance by experiments or the like according to the vehicle. If the determination condition in step S110 is not satisfied, this routine is terminated, and the determination is made again in the next routine.

  If the determination condition of step S110 is satisfied, the opening timing of the intake valve 20 is then advanced by the variable valve timing device 56 (step S120). As a result, the valve overlap amount in the intake stroke increases and the internal EGR rate increases.

  Subsequently, the WGV 34 is closed (step S130). Closing the WGV 34 improves the response during sudden acceleration. On the other hand, since the back pressure increases, the internal EGR rate increases. Further, the differential pressure (back pressure-intake pipe pressure) increases, so that the external EGR rate also increases. Therefore, the total EGR rate in the cylinder for fresh air increases.

  Thereafter, it is determined whether or not the sum of the external EGR rate and the internal EGR rate (total EGR rate) exceeds a conforming value (step S140). Here, FIG. 3 is a diagram for explaining a method of calculating the internal EGR rate and the external EGR rate. FIG. 3A shows the relationship between the valve lift amount and the crank angle of the intake valve 20 (solid line) and the exhaust valve 22 (broken line). FIG. 3B shows the relationship between the in-cylinder pressure and the crank angle.

  In the present embodiment, the internal EGR rate is calculated from, for example, the in-cylinder pressure or the internal pressure of the surge tank 46 during the period from the opening timing (IVO) of the intake valve 20 during the intake stroke to the closing timing (EVC) of the exhaust valve 22. . The external EGR rate is calculated from, for example, the in-cylinder pressure and the internal pressure of the surge tank 46 during the period from the closing timing (EVC) of the exhaust valve 22 in the intake stroke to the bottom dead center (BDC) of the intake stroke. The in-cylinder pressure is detected by the in-cylinder pressure sensor 14, and the internal pressure of the surge tank 46 is detected by the intake pipe pressure sensor 48.

  If the determination condition of step S140 is not satisfied, this routine is terminated and the determination is again made in the next routine. On the other hand, when the determination condition of step S140 is satisfied, the EGR valve 30 is closed by a predetermined opening (step S150). Specifically, the ECU 50 stores a correction map in which the relationship between the amount by which the total EGR rate exceeds the conforming value (upper limit value) and the closing amount of the EGR valve 30 is determined by experiments or the like. From this map, the closing amount of the EGR valve 30 corresponding to the amount exceeding the upper limit value is determined. The EGR valve 30 is corrected and controlled according to the closing amount.

  As described above, according to the routine shown in FIG. 2, when the total EGR rate exceeds the conforming value, the opening degree of the EGR valve 30 can be lowered to reduce the external EGR rate. According to this control, in the present system equipped with the turbocharger 24, the internal EGR having a higher gas temperature than the external EGR can be positively used in the non-supercharging region where the combustion resistance is low, thereby stabilizing the combustion. Can be planned. In general, since the motor-driven EGR valve 30 is controlled at a higher operating speed than the hydraulic variable valve timing device 56 or the pressure-controlled WGV 34, highly responsive EGR control is realized. It is possible.

  According to such control, in the present system including the variable valve timing device 56, the external EGR passage 26, the EGR valve 30 and the turbocharger 24 that can actively control the WGV 34, an acceleration request is issued from the non-supercharging region. Even in such a case, it is possible to realize a control that suitably adjusts the total EGR rate to the appropriate value while suppressing misfire and torque reduction.

  By the way, in the system of the first embodiment described above, in step S100 and step S120, the control for advancing / retarding the intake valve 20 is performed. However, the present invention does not execute this control. Can also be adapted. This point is the same in the following embodiments.

  In the first embodiment described above, the intake passage 16 is the “intake passage” in the first invention, the exhaust passage 18 is the “exhaust passage” in the first invention, and the external EGR passage 26 is the first. In the “external EGR passage” in the first invention, the EGR valve 30 is in the “EGR valve” in the first invention, the turbocharger 24 is in the “turbocharger” in the first invention, and the turbine 24a is in the first In the “turbine” in the invention, the bypass passage 32 is in the “bypass passage” in the first invention, the WGV 34 is in the “bypass valve” in the first invention, and the variable valve timing device 56 is “in the second invention”. It corresponds to “variable valve timing device”.

  Further, here, the ECU 50 executes the processing of the above steps S100 to S130, so that the “acceleration control means” in the first and second inventions executes the processing of the above steps S140 to S150. Thus, the “acceleration-time external EGR reduction means” according to the first aspect of the present invention is realized.

Embodiment 2. FIG.
[System configuration]
Next, a second embodiment of the present invention will be described with reference to FIG. The system of this embodiment is based on FIG. 1 described above, and further includes a port injector 13 for injecting fuel into the intake port of each cylinder in addition to the direct injection injector 12 for directly injecting fuel into each cylinder. I have. Each injector is connected to the output section of the ECU 50. The ECU 50 calculates the total injection amount based on the above-described engine speed NE, load KL, and the like, and causes each injector to inject fuel at a predetermined blowing ratio. The ECU 50 stores in advance a map that defines the total injection amount according to the operation region. In addition, a map that defines a reference value for the blowing ratio according to the operation region is stored in advance.

[Characteristic control]
In the system of this embodiment, the application of the control routine of FIG. In the system of the present embodiment that performs blow control by the direct injection injector 12 and the port injector 13, the tip temperature of the direct injection injector 12 rises in a low load / low rotation non-supercharging region with a small total injection amount, There is a risk of promoting deposit deposition on the injector.

  Further, in the process of step S120 in FIG. 2, the front end temperature of the direct injection injector 12 rises by advancing the opening timing of the intake valve 20 even at the equal engine speed NE and the equal load KL. There is a risk of promoting deposit deposition on the surface.

  From the above, when the acceleration from the non-supercharging region of low load and low rotation is advanced, when the opening timing of the intake valve 20 is advanced and the WGV 34 is controlled to be fully closed, the control that gives priority to the internal EGR is The internal temperature rises, the tip temperature of the direct injection injector 12 rises, and there is a risk of promoting deposit deposition on the injector.

  Therefore, in the system of the present embodiment, when the in-cylinder temperature exceeds the estimated value of the tip temperature of the direct injection injector 12, the blowing ratio of the direct injection injector 12 is increased to lower the tip temperature. did.

  FIG. 4 is a flowchart of a control routine executed by the ECU 50 in order to realize the above function. This routine is the same as the routine shown in FIG. 2 except that steps S160 and S170 are added after step S150. Hereinafter, in FIG. 4, the same steps as those shown in FIG. 2 are denoted by the same reference numerals, and the description thereof is omitted.

  In the routine shown in FIG. 4, after step S150, it is determined in step S160 whether or not the in-cylinder temperature exceeds the estimated value of the tip temperature of the direct injection injector 12. The in-cylinder temperature is estimated from the in-cylinder pressure during combustion detected by the in-cylinder pressure sensor 14. The ECU 50 stores in advance a map that defines the relationship between the in-cylinder pressure and the in-cylinder temperature. Further, the tip temperature of the direct injection injector 12 is estimated from the area exposed by the flame, the in-cylinder temperature, and the fuel injection amount. The ECU 50 stores in advance a map that defines the relationship between the exposed area determined by design, the in-cylinder temperature, the fuel injection amount, and the tip temperature.

  When the in-cylinder temperature is equal to or lower than the estimated value of the tip temperature, this routine is thereafter terminated. On the other hand, when the in-cylinder temperature exceeds the estimated value of the tip temperature, the blowing ratio by the direct injection injector 12 is then increased (step S170). Specifically, the ECU 50 stores in advance a correction map that defines a relationship for increasing and correcting the injection ratio of the direct injection injector as the difference between the in-cylinder temperature and the estimated value increases. By adding the injection ratio calculated from the correction map to the reference value of the blowing ratio corresponding to the above-described operation region, the blowing ratio by the direct injection injector 12 is increased.

  As described above, according to the routine shown in FIG. 4, in the above-described system, when the in-cylinder temperature exceeds the estimated value of the tip temperature of the direct injection injector 12, the blowing ratio of the direct injection injector 12 is increased. Thus, by increasing the fuel injection amount by the direct injection injector 12, the tip temperature can be lowered.

  In the second embodiment described above, the direct injector 12 is the “direct injector” in the third invention, the port injector 13 is the “port injector” in the third invention, and the ECU 50 is the third injector. This corresponds to the “blowing ratio changing means” in the present invention.

  Further, here, the ECU 50 executes the process of step S160, so that the “tip temperature estimating means” in the third aspect of the invention executes the processes of step S160 to step S170. The “increase correction means” in FIG.

Embodiment 3 FIG.
[System configuration]
Next, Embodiment 3 of the present invention will be described with reference to FIG. The system of the present embodiment can be realized by causing the ECU 50 to perform injection timing control, which will be described later, in the same configuration as that of the second embodiment.

  In the second embodiment described above, in the system configuration including the direct injection injector 12 and the port injector 13, the blowing ratio by the direct injection injector 12 is increased when certain conditions are satisfied, and the tip of the direct injection injector 12 is The temperature was lowered.

  By the way, in order to lower the temperature of the direct injection injector 12, it is also conceivable to advance the injection timing of the direct injection injector 12. However, excessive early injection causes the spray from the direct injection injector 12 to collide with the top surface of the piston, which causes an increase in smoke.

[Controlling injection timing]
FIG. 5 is a diagram for explaining the relationship between the injection timing and the amount of smoke or the tip temperature of the direct injection injector 12. FIG. 5A is a diagram showing the relationship between the injection timing and the smoke amount. FIG. 5B is a diagram showing the relationship between the injection timing and the tip temperature of the direct injection injector 12. As shown in FIG. 5B, the tip temperature can be reduced by advancing the injection timing to the top dead center (TDC) side of the intake stroke rather than the bottom dead center (BDC) side of the intake stroke. . On the other hand, as shown in FIG. 5A, when the advance value of the injection timing exceeds a predetermined value, there is a problem that the spray collides with the top surface of the piston and the smoke amount increases rapidly.

  Therefore, in the system of the present embodiment, the maximum advance value of the injection timing at which the spray does not collide with the piston top surface is calculated and used as the use injection timing.

  The ECU 50 stores in advance a relationship map that defines the relationship between the engine speed NE, the required injection amount, the fuel pressure, and the smoke amount according to the injection timing. This relationship map can be obtained experimentally by simulating the piston collision state of the spray according to the engine speed NE, the required injection amount, the fuel pressure, and the injection timing.

  The ECU 50 determines the use injection timing corresponding to the engine speed NE, the required injection amount, and the fuel pressure from this relationship map. Here, the engine speed NE is calculated from a signal detected by the crank angle sensor 52. The required injection amount is calculated from the total injection amount and the blowing ratio of the direct injector 12 in the second embodiment. The fuel pressure may be a design value or may be detected by further providing a fuel pressure sensor. The determined use injection timing is the maximum advance value of the injection timing at which the smoke amount shown in FIG. 5 does not exceed the allowable amount.

  The system of the present embodiment can be realized by advancing the injection timing in the control routine similar to that in FIG. Specifically, in the process of step S170 of FIG. 4, the injection amount of the direct injection injector 12 is increased and the injection timing is set as the use injection timing.

  As described above, according to the system of the present embodiment, it is possible to reduce the tip temperature of the direct injection injector 12 by suppressing the generation of smoke and making the injection timing as early as possible.

  In Embodiment 3 described above, the ECU 50 corresponds to the “storage means”, “maximum advance value calculation means”, and “injection timing setting means” in the fourth aspect of the invention.

Embodiment 4 FIG.
[System configuration]
Next, a fourth embodiment of the present invention will be described with reference to FIGS. The system of the present embodiment can be realized by causing the ECU 50 to execute the routine of FIG. 7 described later in the configuration shown in FIG.

[Characteristic control]
FIG. 6 illustrates changes in the operation region in the present embodiment. FIG. 6 shows an operation region defined by the engine speed NE and the load KL. Region A is a supercharge region with low load and high rotation. In the region A, the ECU 50 advances the opening / closing timing of the intake valve 20 to fully close the WGV 34. Region B is a non-supercharging region with low load and low rotation. In the region B, as described in the first embodiment, the ECU 50 delays the opening / closing timing of the intake valve 20 and fully opens the WGV 34.

  In the above-described first and second embodiments, the control routine in the case of accelerating from the non-supercharging region of low load and low rotation has been described. In the present embodiment, on the contrary, a control routine in the case of decelerating from a supercharging region of low rotation and high load will be described.

  FIG. 7 is a flowchart of a control routine executed by the ECU 50 in order to realize the above-described operation. This routine is executed at regular time intervals (for example, several cycles). In the routine shown in FIG. 7, first, in step S200, it is determined whether or not the engine speed NE and the load KL are lower than each set value. The engine speed NE is calculated from a signal detected by the crank angle sensor 52. The load KL is calculated based on, for example, the intake air amount detected by the air flow meter 40 and the intake pipe pressure detected by the intake pipe pressure sensor 48. If the determination condition in step S200 is not satisfied, this routine is terminated.

  If the determination condition in step S200 is satisfied, it is next determined whether or not the opening timing of the intake valve 20 is advanced from a predetermined value (step S210). This predetermined value is a value suitable for the region B in FIG. When the determination condition of step S210 is satisfied, it can be determined that the opening timing of the intake valve 20 is a value advanced from the conforming value in the region B, that is, a value corresponding to the region A. Therefore, next, the ECU 50 retards the opening timing of the intake valve 20 by the variable valve timing device 56 (step S220).

  Subsequently, it is determined whether or not the opening degree of the WGV 34 is closed below a predetermined value (step S230). This predetermined value is a value suitable for the region B in FIG. When the determination condition of step S220 is satisfied, it can be determined that the opening degree of the WGV 34 is closed from the appropriate value, that is, the region A equivalent value. Therefore, next, the ECU 50 opens the WGV 34 (step S240). In addition, it can be judged that it is the deceleration driving | operation from the area | region A when the determination conditions of step S210 and step S230 are satisfied.

  Thereafter, it is determined whether or not the sum of the external EGR rate and the internal EGR rate (total EGR rate) exceeds a conforming value (step S250). Since the process of step S250 is the same as that of step S140 of FIG. 2 described above, the description thereof is omitted.

  If the determination condition in step S250 is satisfied, the EGR valve 30 is closed by a predetermined opening (step S260). Specifically, the ECU 50 stores a correction map in which the relationship between the amount by which the total EGR rate exceeds the conforming value (upper limit value) and the closing amount of the EGR valve 30 is determined by experiments or the like. From this map, the closing amount of the EGR valve 30 corresponding to the amount exceeding the upper limit value is determined. The EGR valve 30 is corrected and controlled according to the closing amount.

  As described above, according to the routine shown in FIG. 7, the opening degree of the EGR valve 30 is determined when the operation shifts from the region A to the region B by the deceleration operation and the total EGR rate exceeds the conforming value. Can be reduced to reduce the external EGR rate. Therefore, the same effect as in the first embodiment described above can be obtained.

  In the fourth embodiment described above, the ECU 50 executes the processing of step S200 to step S240 so that the “deceleration control means” in the fifth aspect of the invention executes the processing of step S240. Thus, the “deceleration external EGR reducing means” according to the fifth aspect of the present invention is realized.

DESCRIPTION OF SYMBOLS 10 Internal combustion engine 12 Direct injection injector 13 Port injector 14 In-cylinder pressure sensor 16 Intake passage 18 Exhaust passage 20 Intake valve 22 Exhaust valves 24, 24a, 24b Turbocharger, turbine, compressor 26 External EGR passage 30 EGR valve 32 Bypass passage 34 WGV ( Waste Gate Valve)
40 Air Flow Meter 46 Surge Tank 48 Intake Pipe Pressure Sensor 50 ECU (Electronic Control Unit)
52 Crank angle sensor 54 Accelerator opening sensor 56 Variable valve timing device (VVT)
KL Load NE Engine speed

Claims (5)

An external EGR passage connecting the exhaust passage and the intake passage of the internal combustion engine;
An EGR valve capable of opening and closing the external EGR passage;
A turbocharger turbine provided in the exhaust passage;
A bypass passage for bypassing the exhaust passage on the upstream side and the downstream side of the turbine;
A bypass valve capable of opening and closing the bypass passage;
When the operating region is a non-supercharging region where the engine speed and load are lower than the supercharging region, and when a required torque exceeding a predetermined value is input, an acceleration control means for closing the bypass valve;
After the bypass valve is closed by the acceleration control means, when the sum of the external EGR rate and the internal EGR rate of the internal combustion engine is equal to or greater than a conforming value, the external speed during acceleration that reduces the opening of the EGR valve EGR reduction means;
A control device for an internal combustion engine, comprising: A variable valve timing device capable of changing a valve overlap amount between an intake valve and an exhaust valve of the internal combustion engine;
The acceleration control means closes the bypass valve when the operating region is a non-supercharging region where the engine speed and load are lower than the supercharging region, and when a required torque exceeding a predetermined value is input. Increasing the valve overlap amount;
The control device for an internal combustion engine according to claim 1. A direct injection injector for injecting fuel into the cylinder of the internal combustion engine;
A port injector for injecting fuel into the intake port of the internal combustion engine;
Blowing ratio changing means for changing the fuel blowing ratio of the direct injector and the port injector;
Tip temperature calculating means for calculating the tip temperature of the direct injection injector;
In-cylinder temperature calculating means for calculating the in-cylinder temperature of the internal combustion engine;
After the opening degree of the EGR valve is reduced by the external EGR reducing means at the time of acceleration, an increase for correcting the blowing ratio of the direct injection injector is increased when the in-cylinder temperature is higher than the tip temperature of the direct injection injector Correction means;
The control device for an internal combustion engine according to claim 1, further comprising: Storage means for storing in advance the relationship between the injection amount by the direct injection injector and the maximum advance value of the injection timing at which the smoke amount does not exceed the allowable value;
From the relationship, a maximum advance value calculation means for calculating a maximum advance value corresponding to the injection amount by the direct injection injector,
Injection timing setting means for setting the injection timing of the direct injection injector to the maximum advance value;
The control apparatus for an internal combustion engine according to claim 3, further comprising: When the operation region shifts from the supercharging region to the non-supercharging region by decelerating operation, the deceleration time control means for opening the bypass valve;
After the bypass valve is opened by the deceleration-time control means, when the sum of the external EGR rate and the internal EGR rate of the internal combustion engine is equal to or greater than the conforming value, the deceleration-time external portion that reduces the opening degree of the EGR valve EGR reduction means;
The control device for an internal combustion engine according to any one of claims 1 to 4, further comprising:

Images