JP2008019831A - Control device for internal combustion engine - Google Patents

Abstract

The present invention relates to a control device for an internal combustion engine, and an object thereof is to effectively suppress an increase in in-vehicle noise during transient operation and to obtain good drivability.
When it is determined that the vehicle is in an unsteady state, that is, in a transient operation state (step 100), it is next determined whether or not the vehicle is in a low gear (step 102). When the gear is in the low speed gear stage, it can be determined that an increase in combustion noise can be easily felt by the occupant, but the driving force margin is large. Therefore, in this case, transient correction (for example, increase in internal EGR) is performed in a direction in which combustion noise is suppressed (step 104). On the other hand, in the case of the high speed gear stage, it is possible to determine that the occupant is difficult to perceive even if the combustion noise slightly increases while the drive power margin is small. Therefore, in this case, transient correction (for example, an increase in swirl ratio) is performed in a direction that stabilizes combustion (step 106).
[Selection] Figure 6

Description

  The present invention relates to a control device for an internal combustion engine.

  2. Description of the Related Art An internal combustion engine having a variable valve mechanism that varies the valve timing of intake valves and exhaust valves is known. In such an internal combustion engine, parameters such as the internal EGR amount can be changed by changing the valve timing. Therefore, the valve timing is controlled so that the combustion state is optimized in accordance with the operating condition of the internal combustion engine, the traveling condition of the vehicle, and the like.

  For example, Japanese Patent Laid-Open No. 9-158749 discloses a reduction in drivability by increasing internal EGR during high speed gears to reduce fuel consumption and emissions, and reducing internal EGR during low speed gears and increasing combustion stability. A control device is disclosed which is intended to prevent.

JP-A-9-158749 Japanese Patent No. 2794213 Japanese Patent No. 2712544 JP-A-8-338272

  The above-described conventional control device is mainly intended for a gasoline engine. On the other hand, in recent years, diesel engines having a variable valve mechanism have been developed. In this diesel engine, the valve timing is adapted according to the engine load, the engine rotational speed, and the like so that optimum combustion can be obtained from the viewpoint of combustion noise, torque, emission, and the like. For this reason, at the time of steady operation, the optimum valve timing according to the engine load and the engine speed is realized, so that optimum combustion can be obtained.

  On the other hand, during transient operation (such as during rapid acceleration), it is necessary to change the combustion state greatly. For this reason, combustion noise, torque, emission, and the like are likely to deteriorate as compared to steady operation. For example, when a request to increase the fuel injection amount suddenly occurs, it is necessary to increase the amount of air in the cylinder rapidly. However, it takes time to increase the amount of air in the cylinder. It is easy to become a state with little. As a result, misfire is likely to occur. When misfire occurs, drivability is likely to deteriorate because sufficient torque cannot be obtained.

  In order to reliably prevent such misfire during transient operation, it is necessary to correct some control parameters so that the combustion is stabilized. However, when the combustion is stabilized, that is, when the fuel is more easily burned, generally, the combustion noise tends to increase. For this reason, if it is going to prevent misfire at the time of a transient operation, the new problem that the noise in a vehicle tends to become large will arise.

  The present invention has been made to solve the above-described problems, and is an internal combustion engine that can effectively suppress an increase in in-vehicle noise and obtain good drivability during transient operation. An object is to provide a control device.

In order to achieve the above object, a first invention is a control device for an internal combustion engine,
A discriminating means for discriminating whether a gear stage or a gear ratio of a transmission mounted on the vehicle is in a predetermined low speed range or a higher speed range;
When it is determined that the gear position or gear ratio is in a low speed state in the low speed range during transient operation, control parameters of the internal combustion engine mounted on the vehicle are set in a direction in which combustion noise is suppressed. First transient correction means for correcting;
It is characterized by providing.

The second invention is the first invention, wherein
A second transient that corrects the control parameter of the internal combustion engine in a direction in which combustion is stabilized when it is determined that the speed or speed ratio is in a high speed state in the high speed range during transient operation. It further comprises a correction means.

The third invention is a control device for an internal combustion engine,
A discriminating means for discriminating whether the vehicle speed is in a predetermined low speed range or a high speed range;
When it is determined that the vehicle speed is in the low speed range in the low speed range during the transient operation, the control parameter of the internal combustion engine mounted on the vehicle is corrected in a direction in which combustion noise is suppressed. First transient correction means;
It is characterized by providing.

Moreover, 4th invention is set in 3rd invention,
Second transient correction means for correcting the control parameter of the internal combustion engine in a direction in which combustion is stabilized when it is determined that the vehicle speed is in a high speed state in the high speed range during transient operation. Is further provided.

According to a fifth invention, in any one of the first to fourth inventions,
When it is determined that the vehicle is in the low speed state during transient operation, the first transient correction unit performs correction in a direction in which the internal EGR amount increases.

The sixth invention is the second or fourth invention, wherein
When it is determined that the vehicle is in the high speed state during transient operation, the second transient correction unit performs correction in a direction in which the swirl ratio increases.

According to a seventh invention, in any one of the first to sixth inventions,
A variable valve mechanism for varying at least the valve timing of the intake valve among the valve timings of the intake valve and the exhaust valve of the internal combustion engine;
The first transient correction means performs correction by changing a valve timing of the variable valve mechanism.

The eighth invention is the second or fourth invention, wherein
A variable valve mechanism that varies at least the valve timing of the intake valve among the valve timings of the intake valve and the exhaust valve of the internal combustion engine;
The second transient correction means performs correction by changing a valve timing of the variable valve mechanism.

  According to the first aspect of the present invention, when the shift stage or gear ratio of the transmission is in the low speed range during the transient operation of the internal combustion engine, the control parameter of the internal combustion engine is corrected in a direction in which the combustion noise is suppressed. be able to. When the gear stage or the gear ratio is in the low speed range, it can be determined that the vehicle speed is relatively low. In this case, since other noises such as wind noise and road noise are small, if the combustion noise increases, the vehicle interior noise tends to increase. According to the first invention, since combustion noise can be suppressed in such a case, an increase in in-vehicle noise can be effectively suppressed, and comfort in the vehicle can be achieved. In addition, when transient correction is performed in such a direction as to suppress combustion noise, a torque decrease due to misfire or the like is somewhat likely to occur. However, when the gear position or the gear ratio is in the low speed range, the driving force margin is large, so the driver hardly feels that the acceleration force is insufficient. For this reason, a decrease in drivability can be effectively prevented.

  According to the second invention, during the transient operation of the internal combustion engine, if the gear stage or gear ratio of the transmission is in the high speed range, the control parameter of the internal combustion engine is corrected in a direction that stabilizes combustion. Can do. When the gear stage or the gear ratio is in the high speed range, it can be determined that the vehicle speed is relatively high. In this case, since there is little driving force margin, if a sufficient torque cannot be generated due to misfire or the like during transient operation, the driver may feel lack of acceleration force. According to 2nd invention, in such a case, combustion can be stabilized and a misfire etc. can be prevented reliably. For this reason, it is possible to generate sufficient torque without causing a decrease in torque at the time of sudden acceleration or the like. Therefore, the driver does not feel lack of acceleration force, and good drivability can be ensured. In addition, when the transient correction in the direction of stabilizing the combustion is performed in this way, the combustion noise is likely to increase somewhat. However, in this case, since the vehicle speed is relatively high, other noise such as wind noise and road noise is large, and combustion noise is relatively small. Therefore, even if the combustion noise increases somewhat, the in-vehicle noise hardly increases and does not cause a problem.

  According to the third invention, when the vehicle speed is in the low speed range during the transient operation of the internal combustion engine, the control parameter of the internal combustion engine can be corrected in a direction in which the combustion noise is suppressed. When the vehicle speed is relatively low, other noises such as wind noise and road noise are small. Therefore, if combustion noise increases, vehicle interior noise tends to increase. According to the third invention, since combustion noise can be suppressed in such a case, an increase in in-vehicle noise can be effectively suppressed, and comfort in the vehicle can be achieved. In addition, when transient correction is performed in such a direction as to suppress combustion noise, a torque decrease due to misfire or the like is somewhat likely to occur. However, when the vehicle speed is in the low speed range, the driving force margin is large, so the driver hardly feels that the acceleration force is insufficient. For this reason, a decrease in drivability can be effectively prevented.

  According to the fourth aspect of the invention, when the vehicle speed is in the high speed range during the transient operation of the internal combustion engine, the control parameter of the internal combustion engine can be corrected in a direction that stabilizes the combustion. When the vehicle speed is relatively high, there is little margin for driving force, so if a sufficient torque cannot be generated due to misfire or the like during transient operation, the driver tends to feel insufficient acceleration force. According to the fourth aspect of the invention, in such a case, it is possible to stabilize combustion and prevent misfire and the like reliably. For this reason, it is possible to generate sufficient torque without causing a decrease in torque at the time of sudden acceleration or the like. Therefore, the driver does not feel lack of acceleration force, and good drivability can be ensured. In addition, when the transient correction in the direction of stabilizing the combustion is performed in this way, the combustion noise is likely to increase somewhat. However, in this case, since the vehicle speed is relatively high, other noise such as wind noise and road noise is large, and combustion noise is relatively small. Therefore, even if the combustion noise increases somewhat, the in-vehicle noise hardly increases and does not cause a problem.

  According to the fifth aspect of the present invention, during the transient operation, when the gear position, the gear ratio, or the vehicle speed is in the low speed range, the combustion is slowed by correcting the internal EGR amount in the increasing direction. Can be made. Thereby, the increase in combustion noise can be suppressed effectively. Therefore, an increase in in-vehicle noise during transient operation can be more reliably suppressed.

  According to the sixth aspect of the present invention, during the transient operation, when the gear stage, the gear ratio, or the vehicle speed is in the high speed state in the high speed range, the transient correction is performed in the direction in which the swirl ratio increases, Mixing with air can be effectively promoted. For this reason, it can suppress more reliably that misfire etc. generate | occur | produce. Therefore, a decrease in torque during transient operation can be avoided more reliably, and better drivability can be obtained.

  According to the seventh aspect, the transient correction of the first transient correction means can be performed by changing the valve timing of the variable valve mechanism. For this reason, transient correction can be performed easily and effectively.

  According to the eighth aspect, the transient correction of the second transient correction means can be performed by changing the valve timing of the variable valve mechanism. For this reason, transient correction can be performed easily and effectively.

  Embodiments of the present invention will be described below 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.
[Description of 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 a four-cycle diesel engine 10. It is assumed that the diesel engine 10 is mounted on a vehicle and used as a power source. Although the diesel engine 10 of the present embodiment is an in-line four-cylinder type, the number of cylinders and the cylinder arrangement of the diesel engine in the present invention are not limited to this.

  Hereinafter, although this embodiment demonstrates the case where this invention is applied to control of a diesel engine (compression ignition internal combustion engine), this invention is not limited to control of a diesel engine, A gasoline engine (spark ignition) Internal combustion engine) It can be applied to control of various other internal combustion engines.

  Each cylinder of the diesel engine 10 is provided with an injector 12 that injects fuel directly into the cylinder. The injectors 12 of each cylinder are connected to a common common rail 14. In the common rail 14, high-pressure fuel pressurized by the supply pump 16 is stored. Then, fuel is supplied from the common rail 14 to each injector 12.

  The injector 12 can inject the fuel into the cylinder at an arbitrary timing a plurality of times during one cycle. That is, the injector 12 can perform, in addition to the main injection, pilot injection performed prior to the main injection, after injection, post injection, etc. performed after the main injection, during one cycle.

  An exhaust passage 18 of the diesel engine 10 is branched by an exhaust manifold 20 and connected to an exhaust port 22 (see FIG. 2) of each cylinder. The diesel engine 10 of this embodiment includes a turbocharger 24. The exhaust passage 18 is connected to the exhaust turbine of the turbocharger 24.

  An exhaust purification device 26 that purifies exhaust gas is provided in the exhaust passage 18 downstream of the turbocharger 24. As the exhaust gas purification device 26, for example, one of an oxidation catalyst, a storage reduction type or selective reduction type NOx catalyst, a DPF (Diesel Particulate Filter), a DPNR (Diesel Particulate-NOx-Reduction system), or a combination thereof Etc. can be used.

  An air cleaner 30 is provided near the inlet of the intake passage 28 of the diesel engine 10. The air drawn through the air cleaner 30 is compressed by the intake compressor of the turbocharger 24 and then cooled by the intercooler 32. The intake air that has passed through the intercooler 32 is distributed by the intake manifold 34 to the intake ports 35 (see FIG. 2) of the respective cylinders.

  An intake throttle valve 36 is installed between the intercooler 32 and the intake manifold 34 in the intake passage 28. An air flow meter 38 for detecting the amount of intake air is installed in the vicinity of the intake passage 28 downstream of the air cleaner 30.

  One end of an external EGR passage 40 is connected to the intake passage 28 in the vicinity of the intake manifold 34. The other end of the external EGR passage 40 is connected to the vicinity of the exhaust manifold 20 of the exhaust passage 18. In this system, a part of the exhaust gas (burned gas) can be recirculated to the intake passage 28 through the external EGR passage 40, that is, external EGR (Exhaust Gas Recirculation) can be performed.

  In the middle of the external EGR passage 40, an EGR cooler 42 for cooling the external EGR gas is provided. An EGR valve 44 is provided downstream of the EGR cooler 42 in the external EGR passage 40. By changing the opening degree of the EGR valve 44, the amount of exhaust gas passing through the external EGR passage 40, that is, the amount of external EGR can be adjusted.

  In this system, the external EGR amount can be adjusted not only by the opening degree of the EGR valve 44 but also by the opening degree of the intake throttle valve 36. When the opening of the intake throttle valve 36 is reduced to throttle the intake air, the intake pressure decreases, so the differential pressure from the back pressure (exhaust pressure) increases. That is, the differential pressure before and after the external EGR passage 40 increases. For this reason, the amount of external EGR can be increased.

  The system of this embodiment further includes an accelerator opening sensor 48 that detects the amount of depression of the accelerator pedal (accelerator opening) and an ECU (Electronic Control Unit) 50. The ECU 50 is connected to the various sensors and actuators described above. The ECU 50 controls the operating state of the diesel engine 10 by operating each actuator according to a predetermined program based on the output of each sensor.

  It is assumed that the vehicle on which the diesel engine 10 is mounted is equipped with a transmission (not shown) that shifts the power output from the diesel engine 10 and transmits it to the drive shaft of the vehicle. The system of the present embodiment further includes a shift speed sensor 66 that detects the current shift speed of the transmission, and a vehicle speed sensor 68 that detects the speed of the vehicle. Both these sensors are also connected to the ECU 50. The transmission may be any of a manual transmission, an automatic transmission, and a semi-automatic transmission.

  FIG. 2 is a view showing a cross section of one cylinder of the diesel engine 10 in the system shown in FIG. Hereinafter, the diesel engine 10 will be further described. As shown in FIG. 2, a crank angle sensor 62 that detects the rotation angle of the crankshaft 60 is attached in the vicinity of the crankshaft 60 of the diesel engine 10. The crank angle sensor 62 is connected to the ECU 50. The crank angle sensor 62 can detect the engine speed.

  The diesel engine 10 includes an intake variable valve mechanism 54 that continuously varies the valve timing (opening / closing timing) of the intake valve 52, and an exhaust variable valve that continuously varies the valve timing of the exhaust valve 56. Mechanism 58 is provided. The intake variable valve mechanism 54 and the exhaust variable valve mechanism 58 are each connected to the ECU 50.

  The specific structures of the intake variable valve mechanism 54 and the exhaust variable valve mechanism 58 are not particularly limited, and may be any structure as long as the valve timing can be changed as described later. In addition, the intake variable valve mechanism 54 and the exhaust variable valve mechanism 58 may be an electromagnetically driven valve or a hydraulically driven valve that can be opened and closed at any time, even if a mechanical mechanism such as a cam mechanism is used. It may be used.

[Features of Embodiment 1]
(Control of internal EGR amount)
In the diesel engine 10 of the present embodiment, the magnitude of the negative valve overlap between the intake valve 52 and the exhaust valve 56 can be continuously changed by the intake variable valve mechanism 54 and the exhaust variable valve mechanism 58. . FIG. 3 is a diagram for explaining negative valve overlap. As shown in FIG. 3, the negative valve overlap is a period during which both the intake valve 52 and the exhaust valve 56 are closed after the exhaust valve 56 is closed until the intake valve 52 is opened.

  3 is a valve lift diagram of the intake valve 52 and the exhaust valve 56 when no negative valve overlap is provided. From this state, the closing timing of the exhaust valve 56 is advanced and the opening timing of the intake valve 52 is delayed, so that a negative valve overlap can be caused. A thick curve in FIG. 3 is a valve lift diagram of the intake valve 52 and the exhaust valve 56 when a negative valve overlap is generated. The magnitude of the negative valve overlap can be changed according to the degree to which the closing timing of the exhaust valve 56 and the opening timing of the intake valve 52 are changed.

  When a negative valve overlap is generated, the exhaust valve 56 is closed before the burned gas in the cylinder completely flows out to the exhaust port 22. The burned gas that has not been discharged to the exhaust port 22 remains in the cylinder as it is, or once exits to the intake port 35 when the intake valve 52 is opened, and then the piston 64 descends together with fresh air. Inhaled. When a negative valve overlap occurs, internal EGR can be performed in this way. As the negative valve overlap is increased, the internal EGR amount can be increased.

  The amount of internal EGR greatly affects the state of combustion. The optimum internal EGR amount varies depending on the rotational speed and load of the diesel engine 10. In the system of the present embodiment, the relationship between the valve timing of the intake valve 52 and the exhaust valve 56 (or the magnitude of the negative valve overlap) for obtaining the optimum internal EGR amount, the engine speed and the engine load is mapped. And stored in advance in the ECU 50. When the diesel engine 10 is in steady operation, the internal variable EGR amount is controlled by controlling the intake variable valve mechanism 54 and the exhaust variable valve mechanism 58 according to the map.

  In the present invention, internal EGR is performed by generating a normal valve overlap (positive valve overlap) in which both the intake valve 52 and the exhaust valve 56 are open, and the magnitude of the positive valve overlap is large. The internal EGR amount may be adjusted by changing the length.

(Control of swirl ratio)
FIG. 4 is a schematic plan view of one cylinder of the diesel engine 10. As shown in the figure, the diesel engine 10 is provided with two intake ports 35 of a helical port 35a and a tangential port 35b per cylinder. The helical port 35 a and the tangential port 35 b are opened and closed by separate intake valves 52. The helical port 35a allows air to flow into the cylinder while swirling in a spiral. That is, the helical port 35a is the intake port 35 having a large swirl ratio. On the other hand, the tangential port 35b allows air to flow toward the tangential direction of the cylinder bore. The tangential port 35b is an intake port 35 that allows a larger amount of air to flow into the cylinder, although the swirl ratio is smaller than that of the helical port 35a.

  FIG. 5 is a graph showing the lift characteristics of the intake valve 52 on the tangential port 35b side. The intake variable valve mechanism 54 can perform an operation of closing the intake valve 52 on the tangential port 35b side earlier than the intake valve 52 on the helical port 35a side (hereinafter referred to as “one-valve early closing”). It has become. The solid line in FIG. 5 is the lift characteristic of the intake valve 52 on the tangential port 35b side at the normal time, and the broken line in FIG. 5 is the lift characteristic of the intake valve 52 on the tangential port 35b side at the time of the one-valve early closing execution. It is a characteristic.

  When the intake valve 52 on the helical port 35a side and the intake valve 52 on the tangential port 35b side are both open, the strong swirl created by the air flowing in from the helical port 35a is canceled out by the flow from the tangential port 35b. Will be weakened. On the other hand, when only the intake valve 52 on the helical port 35a side is open, the strong swirl created by the air flowing from the helical port 35a remains without being canceled. For this reason, the swirl ratio can be increased as the closing timing of the intake valve 52 on the tangential port 35b side is earlier. In the diesel engine 10, when the intake valve 52 on the tangential port 35b side is quickly closed by the intake variable valve mechanism 54, the swirl ratio can be freely adjusted by continuously changing the closing timing. it can.

  The swirl ratio greatly affects the state of combustion. The optimum swirl ratio varies depending on the rotational speed and load of the diesel engine 10. In the system of the present embodiment, the relationship between the valve timing (closing timing) of the intake valve 52 on the helical port 35a side and the tangential port 35b side for obtaining the optimum swirl ratio, the engine rotation speed and the engine load is mapped. It is assumed that it is stored in the ECU 50 in advance. In the steady operation of the diesel engine 10, the swirl ratio is controlled by controlling the intake variable valve mechanism 54 according to the map.

  In the present invention, the method of changing the valve timing of the intake valve 52 when changing the swirl ratio is not limited to the above-described method, and any other method may be used.

  In the diesel engine 10 during steady operation, the optimal internal EGR amount and swirl ratio that are preliminarily adapted are realized by controlling the valve timing to be optimal according to the rotational speed and load. For this reason, optimal combustion can be obtained, combustion noise can be kept low, and sufficient torque can be generated.

  On the other hand, during the transient operation in which the engine speed and the engine load change suddenly, the combustion state changes greatly. For example, at the time of rapid acceleration, there is a demand for rapidly increasing the fuel injection amount, while it takes time to increase the amount of air in the cylinder. For this reason, the amount of air becomes excessive with respect to the fuel injection amount, and as a result, misfire is likely to occur. When misfire occurs, drivability is likely to deteriorate because sufficient torque cannot be obtained.

  As a method of preventing misfire during transient operation, a method of correcting the valve timing or some other parameter so as to stabilize the combustion can be considered. However, stabilizing combustion, that is, making the fuel more combustible generally tends to increase combustion noise. For this reason, when it is going to prevent misfire at the time of a transient operation reliably, the case where the in-vehicle noise becomes large by the increase in combustion noise is also considered.

  By the way, even if the diesel engine 10 generates the same combustion noise, the in-vehicle noise, that is, the feeling actually felt by the occupant in the vehicle, varies greatly depending on the traveling conditions of the vehicle. That is, when the vehicle speed is low, other noises such as wind noise and road noise are small, so the combustion noise ratio is relatively large. For this reason, when combustion noise increases, vehicle interior noise tends to increase. On the other hand, when the vehicle speed is high, other noises such as wind noise and road noise are large, so the ratio of combustion noise is relatively small. For this reason, even if the combustion noise increases, the in-vehicle noise hardly increases.

  Even when the torque of the diesel engine 10 is reduced due to deterioration of the combustion state such as misfire, the driver's feeling is greatly different depending on the traveling condition of the vehicle. That is, in the relationship between the transmission gear ratio and the driving force of the vehicle, there is a large margin of driving force when the gear is in the low speed gear stage. For this reason, when the accelerator pedal is depressed, even if the generated torque of the diesel engine 10 is somewhat lower than the original torque (requested torque), the vehicle speed and the engine speed increase sufficiently quickly. Therefore, the driver does not feel dissatisfied with drivability.

  On the other hand, when it is in the high speed gear stage, there is little margin of driving force. That is, when the gear is in the high speed gear stage, the vehicle speed and the engine speed increase when the accelerator pedal is depressed are originally slow. Therefore, if the diesel engine 10 cannot generate the original torque at that time, the increase in the vehicle speed and the engine rotation speed is further slowed down, and the driver tends to feel drivability unsatisfactory.

  Therefore, in the present embodiment, when correcting the parameters related to combustion during the transient operation of the diesel engine 10, depending on whether the shift stage of the transmission is in the low speed gear stage or the high speed gear stage, The direction of correction was changed. That is, when the gear is in the low speed gear stage, correction is performed in a direction in which combustion noise is suppressed. As correction for suppressing combustion noise, in this embodiment, increase correction of internal EGR is performed. When the amount of internal EGR is increased, combustion is slowed down, so that combustion noise can be reduced. On the other hand, misfire is somewhat likely to occur. However, when the gear is in a low-speed gear stage with a large margin of driving force, as described above, even if the torque is somewhat reduced due to misfire, the driver hardly feels that the acceleration force is insufficient, which causes a harmful effect. There is no.

  On the other hand, in the case of the high speed gear stage during the transient operation, the correction is made in the direction in which the combustion is stabilized. In this embodiment, the swirl ratio is increased as correction for stabilizing the combustion. When the swirl ratio is increased, mixing of air and fuel is promoted, and the fuel becomes easy to burn. Therefore, combustion is stabilized, combustion fluctuation is reduced, and occurrence of misfire can be surely prevented. For this reason, since the diesel engine 10 can generate | occur | produce sufficient torque, favorable drivability (acceleration force) can be obtained. On the other hand, the combustion noise tends to be slightly increased. However, since the vehicle speed is relatively high when the gear is in the high speed gear stage, the combustion noise ratio is relatively small as compared with other noises such as wind noise and road noise as described above. . For this reason, even if the combustion noise increases to some extent, the increase in in-vehicle noise is small, and no harmful effects occur.

[Specific Processing in Embodiment 1]
FIG. 6 is a flowchart of a routine executed by the ECU 50 in the present embodiment in order to realize the above function. According to the routine shown in FIG. 6, first, it is determined whether or not the operating state of the diesel engine 10 is in an unsteady state (step 100). Specifically, if the accelerator pedal depression speed detected by the accelerator opening sensor 48 exceeds a predetermined value, it is determined that the vehicle is in an unsteady state, that is, a transient state, and otherwise, it is in a steady state. Is determined. If it is determined that the current state is a steady state, it is not necessary to execute the following transient correction, and thus the processing of this routine is terminated as it is.

  On the other hand, if it is determined in step 100 that the current state is an unsteady state, it is next determined whether or not the current gear position of the transmission matches any of the predetermined low speed gear steps. (Step 102). For example, if the first gear and the second gear are determined as the low gear, it is determined whether the current gear detected by the gear sensor 66 is the first gear or the second gear.

  If it is determined in step 102 that the gear is in the low speed gear stage, transient correction is performed in a direction in which combustion noise is suppressed (step 104). Specifically, correction for increasing the internal EGR is performed by increasing the negative valve overlap between the exhaust valve 56 and the intake valve 52. More specifically, the target internal EGR amount is set to a larger value than during steady operation, and the operations of the intake variable valve mechanism 54 and the exhaust variable valve mechanism 58 are controlled based on the target internal EGR amount. Thereby, internal EGR increases, combustion becomes slow, and combustion noise can be suppressed. When in the low gear, the vehicle speed is relatively low and other noises such as wind noise and road noise are low. For this reason, if the combustion noise increases, the in-vehicle noise tends to increase. However, according to the processing in step 102, an increase in the combustion noise can be effectively suppressed. For this reason, it can suppress effectively that a passenger | crew senses the increase in a vehicle interior noise.

  If transient correction is performed in the above-described step 104 to suppress combustion noise, misfire is likely to occur. However, in this case, since there is a large margin of driving force due to the low speed gear stage, even if the torque slightly decreases due to misfire, the driver hardly feels that the acceleration force is insufficient. There will be no reduction in performance.

  On the other hand, if it is determined in step 102 that the gear is in the high speed gear stage, transient correction is performed in a direction that stabilizes combustion (step 106). Specifically, the swirl ratio is corrected by increasing the closing timing of the intake valve 52 on the tangential port 35b side. More specifically, the target swirl ratio is set to a larger value than that during steady operation, and the operation of the intake variable valve mechanism 54 is controlled based on the target swirl ratio. This increases the swirl ratio, promotes mixing of air and fuel, and stabilizes combustion. For this reason, combustion fluctuations are reduced and the occurrence of misfire is effectively prevented. As a result, a decrease in torque due to misfire can be avoided and sufficient torque can be generated. When the gear is in a high speed gear stage, there is little margin for driving force, so if the diesel engine 10 cannot generate sufficient torque during rapid acceleration or the like, the driver is likely to be dissatisfied with drivability (acceleration force). According to the processing of step 106, misfire can be reliably prevented and the diesel engine 10 can generate sufficient torque, so that good drivability (acceleration force) can be ensured.

  Further, when the transient correction in the direction to stabilize the combustion is performed in step 106, the combustion noise tends to be slightly increased. However, in this case, it can be determined that the vehicle speed is also relatively high because of the high gear position. If the vehicle speed is high, other noises such as wind noise and road noise are large, so the combustion noise is relatively small. Therefore, even if the combustion noise increases somewhat, there is little problem for the occupant to feel the increase in in-vehicle noise, and there is no problem.

  The transient correction performed in step 104 or 106 is canceled when it is determined that the diesel engine 10 is in a steady operation state. After the cancellation of the transient correction, the internal EGR amount and the swirl ratio are controlled so as to become normal target values, respectively. Note that whether or not the diesel engine 10 is in a steady operation state can be determined based on, for example, whether or not the engine rotational speed or the intake air amount is in a constant state.

  As described above, according to the present embodiment, during transient operation, it is possible to reliably suppress the passenger from feeling an increase in in-vehicle noise, and the factors that cause a decrease in drivability such as misfire are effective. Can be removed.

  In the first embodiment described above, whether to perform the transient correction in the direction to suppress the combustion noise or to stabilize the combustion is determined according to the gear position (step 102). In the case of a vehicle equipped with a continuously variable transmission, the determination may be made according to whether the current gear ratio is on the low speed side or the high speed side compared to a predetermined boundary value.

  Further, instead of the processing in step 102, the directionality of the transient correction may be determined according to the vehicle speed detected by the vehicle speed sensor 68. That is, when the vehicle speed is less than or equal to a predetermined value, transient correction is performed in a direction that suppresses combustion noise, and when the vehicle speed exceeds the predetermined value, transient correction may be performed in a direction that stabilizes combustion. Good.

  In the present invention, the transient correction for suppressing combustion noise is not limited to increasing the internal EGR amount. For example, combustion noise can be suppressed by correcting the delay of the fuel injection timing or increasing the pilot injection amount. Therefore, in step 104 described above, these corrections may be performed instead of increasing the internal EGR amount.

  In the present invention, the transient correction for stabilizing the combustion noise is not limited to increasing the swirl ratio. For example, combustion can be stabilized by correcting the advance angle of the fuel injection timing or reducing the pilot injection amount. Therefore, in step 106 described above, these corrections may be performed instead of increasing the swirl ratio.

  Further, in the first embodiment described above, the diesel engine 10 has been described as including both the intake variable valve mechanism 54 and the exhaust variable valve mechanism 58, but the internal combustion engine to be controlled in the present invention. May not include the exhaust variable valve mechanism 58.

  In the first embodiment described above, the internal EGR amount and the swirl ratio correspond to the “control parameter” in the first and second inventions. Further, when the ECU 50 executes the process of step 102, the “discriminating means” in the first aspect of the invention executes the process of step 104 of the “first step” in the first to third aspects of the invention. The “transient correction means” implements the “second transient correction means” in the first to third inventions by executing the processing of step 106 described above. The intake variable valve mechanism 54 and the exhaust variable valve mechanism 58 correspond to the “variable valve mechanism” in the fifth aspect of the invention.

It is a figure for demonstrating the system configuration | structure of Embodiment 1 of this invention. It is a figure which shows the cross section of one cylinder of the diesel engine in the system shown in FIG. It is a figure for demonstrating a negative valve overlap. FIG. 2 is a schematic plan view of one cylinder of a diesel engine in the system shown in FIG. 1. It is a figure which shows the lift characteristic of the intake valve by the side of a tangential port. It is a flowchart of the routine performed in Embodiment 1 of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Diesel engine 12 Injector 14 Common rail 18 Exhaust passage 20 Exhaust manifold 22 Exhaust port 24 Turbocharger 26 Exhaust gas purification device 28 Intake passage 34 Intake manifold 35 Intake port 35a Helical port 35b Tangential port 36 Inlet throttle valve 38 Air flow meter 40 External EGR passage 44 EGR valve 48 Accelerator opening sensor 50 ECU
52 Intake valve 54 Intake variable valve mechanism 56 Exhaust valve 58 Exhaust variable valve mechanism 62 Crank angle sensor 64 Piston

Claims (8)

A discriminating means for discriminating whether a gear stage or a gear ratio of a transmission mounted on the vehicle is in a predetermined low speed range or a higher speed range;
When it is determined that the gear position or gear ratio is in a low speed state in the low speed range during transient operation, control parameters of the internal combustion engine mounted on the vehicle are set in a direction in which combustion noise is suppressed. First transient correction means for correcting;
A control device for an internal combustion engine, comprising:   A second transient that corrects the control parameter of the internal combustion engine in a direction in which combustion is stabilized when it is determined that the speed or speed ratio is in a high speed state in the high speed range during transient operation. 2. The control apparatus for an internal combustion engine according to claim 1, further comprising a correcting means. A discriminating means for discriminating whether the vehicle speed is in a predetermined low speed range or a high speed range;
When it is determined that the vehicle speed is in the low speed range in the low speed range during the transient operation, the control parameter of the internal combustion engine mounted on the vehicle is corrected in a direction in which combustion noise is suppressed. First transient correction means;
A control device for an internal combustion engine, comprising:   Second transient correction means for correcting the control parameter of the internal combustion engine in a direction in which combustion is stabilized when it is determined that the vehicle speed is in a high speed state in the high speed range during transient operation. The control apparatus for an internal combustion engine according to claim 3, further comprising:   5. The method according to claim 1, wherein when the low-speed state is determined during transient operation, the first transient correction unit performs correction in a direction in which the internal EGR amount increases. A control device for an internal combustion engine according to claim.   5. The internal combustion engine according to claim 2, wherein the second transient correction unit performs correction in a direction in which a swirl ratio increases when it is determined that the high-speed state is present during transient operation. Engine control device. A variable valve mechanism that varies at least the valve timing of the intake valve among the valve timings of the intake valve and the exhaust valve of the internal combustion engine;
7. The control apparatus for an internal combustion engine according to claim 1, wherein the first transient correction means performs correction by changing a valve timing of the variable valve mechanism. . A variable valve mechanism that varies at least the valve timing of the intake valve among the valve timings of the intake valve and the exhaust valve of the internal combustion engine;
The control apparatus for an internal combustion engine according to claim 2 or 4, wherein the second transient correction means performs correction by changing a valve timing of the variable valve mechanism.

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