DE10145974B4 - Control device and control method for internal combustion engines - Google Patents

Abstract

An engine control apparatus applied to an internal combustion engine (10) wherein an amount of EGR gas recirculated from an exhaust system to an intake system is adjusted by controlling a degree of opening of an EGR valve (20) that is in an EGR Passage (14) is provided, which connects the exhaust system and the intake system, and
which first switches the degree of opening of the EGR valve (20) to a desired opening degree set for switching from a stratified charge combustion mode to a uniform combustion mode when switching the combustion mode from a stratified charge combustion mode to a uniform combustion mode is required; Combustion mode therefore should be switched, and
a control mode of an injection system and an ignition system from a control mode set for the stratified charge combustion mode to a control mode set for the uniform combustion mode is switched after a predetermined delay time after switching the degree of opening of the EGR valve (20) has passed, and which performs a torque reduction control to a torque ...

Description

The The invention relates to a control device and a control method for an internal combustion engine, wherein the amount of EGR gas (exhaust gas reflux, exhaust gas recirculation) by controlling the degree of opening adapted to an EGR valve and the combustion mode between stratified charge combustion and more uniform Combustion is switched.

in the State of the art are internal combustion engines, such as an internal combustion engine with direct injection and spark ignition or similar, known by the Switching the combustion mode between stratified charge combustion and more uniform Combustion operated.

For example, the DE 197 43 248 A1 a control device for a direct injection internal combustion engine. The device detects misfires and gradually adjusts several parameters to return to stable combustion.

The DE 196 50 518 C1 discloses a method to control a direct injection internal combustion engine that can be run in stratified charge mode as well as in a homogeneous fuel / air mixture operation. According to the teaching of this document, switching to the stratified charge combustion mode is prevented when the temperature of the engine (more specifically, the cooling fluid) and the catalyst are not high enough to ensure the reduction of NOx.

If such an engine is in the stratified charge combustion mode, is the combustion by injecting the fuel in one later Reached section of the compression stroke of the internal combustion engine, around a layer of an ignitable dense one Fuel mixture just around a spark plug to form in a combustion chamber. During the uniform combustion mode The combustion is achieved by fuel during the intake stroke the engine is injected to a throughout the combustion chamber uniform To form a mixture layer. While The stratified charge combustion mode will determine the performance of the Motors essentially by controlling the amount of injected Fuel adapted. The control values for the injection system, the ignition system and similar, such as the values of the fuel injection, the ignition timing, etc., are in accordance with the amount of operation of a throttle lever or accelerator pedal set. In contrast, during the uniform one Burning mode, the engine power substantially through the control of the degree of opening adapted to a throttle. The above control values with respect to the injection system, the ignition system etc. will be in accordance with the amount of air delivered to the combustion chamber (amount of intake air) established.

In Internal combustion engines in which the combustion mode as above is switched, the amount of EGR gas, the returned from the exhaust system to the intake system by the controller adapted to an EGR valve, which is provided in an EGR passage, which is the exhaust system and the inlet system connects. A large amount of EGR gas will be released during the Stratified charge combustion mode for the purpose of improvement NOx emission, reduction of combustion noise, etc. returned to the intake system.

If however, EGR gas released during the stratified charge combustion mode was introduced while or after switching from the stratified charge combustion mode in the uniform Combustion mode in large quantity remains within the intake system or the combustion chamber can the combustion become unstable and misfires can occur, causing the Driving behavior is deteriorated.

In This type of internal combustion engine, therefore, the degree of opening of the EGR valve changed to a required degree of opening so that the amount of EGR gas returned to the intake system is sufficiently reduced, such as in Japanese Patent Application No. 11-287143 (JP 11-287143 A) when the Switching from the stratified charge combustion mode to the uniform Combustion mode is required. After the passage of one predetermined delay time after change the degree of opening of the EGR valve becomes the control mode of the ignition system or the injection system switched to a control mode designed for the uniform combustion is.

Therefore the combustion mode is switched after that in the intake system or completely removed in the combustion chamber remaining EGR gas is. Thus, the deterioration of drivability substantially be prevented.

In addition, at the time of switching from the stratified charge combustion mode to the uniform combustion mode, the control value with respect to the intake system (degree of throttle opening) is also changed from a required value for the stratified charge combustion to a required value for the uniform combustion. The control is designed so that the required Value of the degree of throttle opening is set to a value closer to the closed side during the uniform combustion mode than during the stratified charge combustion mode when the amount of operation of the accelerator pedal remains the same. Therefore, the demanded value of the degree of the throttle opening is changed to a value closer to the closure of the throttle when the combustion mode is switched from the stratified charge combustion to the uniform combustion.

It However, in the intake system, there is a response delay, such as a delay Shut down of the throttle valve, a response delay of the air (the time of Moving the air from the throttle valve into the combustion chamber), etc. Immediately after the tax value with respect of the intake system from the required value for the stratified combustion the required value for the uniform one Changed combustion Therefore, due to the response delay in the intake system, the Amount of intake air is still greater than an actual required amount. Therefore, there is a danger that when the control mode the injection system and the ignition system in the for the uniform one Combustion is switched to the specified control mode, the control values of the injection system and the ignition system in accordance with the then occurring amount of intake air still greater than the needed Quantity is to be set, so that the torque of the engine is temporary can increase and a gradual torque change can occur.

In This type of internal combustion engine is therefore, immediately after the Control mode of the ignition system and the injection system into those for uniform combustion switched control mode is switched, an ignition timing delay correction carried out, For example, as disclosed in Japanese Patent Application Laid-Open Nos. 10-68375 and 11-107815. The ignition timing delay correction raises the increased torque due to the response delay of the intake system in essence, the occurrence of a stepwise torque change to prevent and reduce the deterioration of driving behavior.

Even though however, setting a delay time and the delay correction the ignition timing, As described above, the occurrence of torque fluctuation and the deterioration of driving behavior associated with switching the Combustion mode of the stratified charge combustion in the uniform Incineration are connected, can prevent the following Difficulties unmistakable.

If a delay time As described above, the stratified charge combustion mode proceeds while the delay time with a decreased amount of EGR, so that the NOx emission deteriorates and the combustion noise increases. Therefore, it is desirable that the delay time as far as possible is reduced. If, however, no sufficient delay time is ensured, the occurrence of a misfire is inevitable. Consequently, it is difficult to control the deterioration of NOx emission and the increase in combustion noise to suppress and at the same time to ensure a good driving behavior.

It It was suggested that the delay time in an operating state is reduced, in which the torque fluctuation of the engine is likely does not lead to a deterioration of driving behavior. For example is it during a strong acceleration less likely that the torque reduction due to a misfire leads to a deterioration of driving behavior, as if the vehicle is not greatly accelerated, because the strong acceleration itself causes a shock. Therefore, it is possible in such a state, the delay time reduce so that the deterioration of NOx emissions and reduces the increase in combustion noise will worsen without compromising drivability.

Even however, under the conditions mentioned above, there is an upper one Limit of permissible Magnitude of torque fluctuation, which does not worsen the driving behavior, and therefore exists as well a limit in reducing the delay time.

consequently It is an object of the invention, a control device and a Control procedure for to provide an internal combustion engine that allows NOx emission to continue improve and further reduce the combustion noise without the driving behavior during the time of switching the combustion mode from the stratified charge combustion to the uniform To worsen combustion.

These The object is achieved by the Device according to claim 1 and the method according to the claim 10 solved.

According to the invention, there is provided an engine control apparatus applied to an internal combustion engine in which an amount of an EGR gas recirculated from an exhaust system to an intake system is adjusted by controlling a degree of opening of an EGR valve that is in one EGR passage is provided, which connects the exhaust system and the intake system, and which, when a combustion mode of a stratified combustion mode is to be switched to a uniform combustion mode, after the lapse of a predetermined delay time after switching a degree of opening of the EGR valve to a required degree of opening set for switching from the stratified charge combustion mode to the uniform combustion mode, switches a control mode of an injection system and an ignition system from a control mode set for the stratified charge combustion mode to a control mode set for the uniform combustion mode and the torque reduction control of decreasing a torque of the internal combustion engine immediately after the switching of the control mode leads. The control device includes a changing means for changing the delay time in accordance with an operating condition, and adjusting means for setting a control value with respect to the torque-decreasing control in accordance with the delay time changed by the changing means.

In accordance With this construction, the control mode of the injection system becomes and the ignition system after elapse of a predetermined delay time after changing the degree of opening of the EGR valve from the control mode used for stratified charge combustion is set in the control mode for the uniform combustion switched when the combustion mode of the stratified charge combustion to the uniform Combustion is switched. Therefore, the control mode becomes the injection system and the ignition system in the control mode for the uniform one Combustion switched after the effect of remaining EGR gas is significantly reduced. Thus, this is due to the occurrence of misfires caused drop in torque decreases. In addition, the Torque reduction control of torque reduction of the internal combustion engine immediately after switching the control mode the injection system and the ignition system carried out. Therefore is the torque increase, by the delay in the intake system is reduced.

moreover becomes in this construction the delay time in accordance changed with the operating state and the value related to the torque reduction control will be in accordance with the changed Delay time set. Therefore, it becomes possible to adjust the torque through the torque reduction control, because of misfires caused torque reduction by changing the delay time changed becomes. Thus, it becomes possible the by misfire better to suppress caused torque reduction. Thus, will it is possible a larger torque reduction to allow while a deterioration of driving behavior is prevented.

Therefore can further reduce the delay time by the by Misfire caused Torque reduction is attained, without that Deteriorate driving behavior. Consequently, it becomes possible to Deterioration of NOx emissions and the increase of combustion noise decrease while a good driving behavior is ensured.

In The device described above may use the torque reduction control the torque through a delay correction an ignition timing reduce the internal combustion engine, and the adjustment can an amount of the delay correction the ignition timing in terms of the torque reduction control in accordance with the delay time set by the modifier changed has been.

In accordance With this structure, the torque reduction control is performed by the delay correction the ignition timing carried out, and the value of the delay correction will be in accordance with the delay time established. Therefore, it becomes possible to control the torque easier and more suitable.

Further, the invention provides a method of controlling an internal combustion engine applied to an internal combustion engine, wherein an amount of an EGR gas recirculated from an exhaust system to an intake system is adjusted by controlling a degree of opening of an EGR valve is provided in an EGR passage that connects the exhaust system and the intake system, and that when a combustion mode is to be switched from a stratified charge combustion mode to a uniform combustion mode, a control mode of an injection system and an ignition system of a control mode set for the stratified charge combustion mode, is switched to a control mode set for the uniform combustion mode after a predetermined delay time after switching the degree of opening of the EGR valve to a required degree of opening, f r switching from the layer Charge combustion mode is set in the uniform combustion mode has passed, and performs a torque reduction control to reduce a torque of the internal combustion engine immediately after the control mode is switched.

The control method comprises the following steps:
Changing the delay time depending on an operating condition; and
Setting a control value with respect to the torque reduction control in dependence on the changed delay time.

The Invention will be described below with reference to the description of exemplary embodiments explained in more detail with reference to the drawing. Show it:

1 a schematic diagram of an overall construction of an embodiment of the invention;

2 a flowchart illustrating a procedure for switching the combustion mode;

3 a flowchart illustrating a procedure for switching the combustion mode;

4A to 4G Timing charts indicating control modes during the switching of the combustion mode; and

5A to 5C schematic diagrams showing the change of the torque during the switching of the combustion mode.

A preferred embodiment The invention will be described below with reference to the accompanying drawings described.

As in 1 is shown in an internal combustion engine 10 , which is designed as a built-in in a motor vehicle internal combustion engine with direct injection and spark ignition, a combustion chamber 11 with an inlet 12 and an outlet 13 connected. The inlet 12 for supplying air to the combustion chamber 11 has a throttle valve 15 to adjust the amount of fuel to the combustion chamber 11 delivered air (the amount of intake air GA). The degree of opening of the throttle valve 15 (Degree of throttle opening TA) is determined by the drive control of a throttle motor 15a adjusted by an electronic control unit (ECU) 16 is performed, the various controls of the engine 10 performs. An inlet pressure sensor 17 for detecting the pressure in the inlet 12 (Inlet pressure PM) is after the throttle valve 15 of the admission 12 intended. The ECU 16 determines the amount of the intake air GA due to a result of the detection of the intake pressure sensor 17 ,

In the combustion chamber 11 are an injection 18 , the fuel directly into the combustion chamber 11 injects, and a spark plug 19 , which ignites the injected fuel by spark discharge provided. The injection 18 and the spark plug 19 be from the ecu 16 driven and controlled. Therefore, the controls of an injection system and an ignition system of the engine 10 such as controls of timing of fuel injection and duration of fuel injection, control of ignition timing, etc., by the ECU 16 carried out.

At the outlet 13 is an air-fuel ratio sensor 13a provided to the oxygen concentration in the exhaust gas, which comes from the combustion chamber 11 is ejected to capture. On the basis of a result of the detection by the air-fuel ratio sensor 13a detects the ECU 16 the air-fuel ratio of a mixture in the combustion chamber 11 (the weight ratio of fuel to air in the mixture).

An EGR passage 14 connects the outlet 13 of the motor 10 with a section of the inlet 12 after the throttle valve 15 , Part of the out of the combustion chamber 11 Exhaust gas emitted is via the EGR passage 14 in the inlet 12 recycled. The EGR passage 14 is with an EGR valve 20 Mistake. The degree of opening of the EGR valve 20 is through the ECU 16 so controlled that the amount of in the inlet 12 recirculated exhaust gas (EGR gas), ie the EGR quantity.

The ECU 16 receives the outputs of the inlet pressure sensor 17 and various other sensors and the like, for example, a NE sensor 21 for detecting the speed of the motor 10 (NE), an acceleration sensor 22 for detecting the value of the operation of an accelerator pedal (not shown), that is, the value of the operation of an accelerator ACCP, etc. Therefore, the ECU detects 16 the operating condition of the engine 10 and the motor vehicle. In accordance with the operating state of the combustion chamber 11 and the motor vehicle detected as described above drives and controls the ECU 16 the throttle valve 15 , the injection 18 , the spark plug 19 , the EGR valve 20 etc. and thus leads different controls of the engine 10 by.

As such, the ECU performs 16 a control of switching the combustion operating mode in the engine 10 between "stratified charge combustion" and "uniform combustion" in accordance with the operating condition of the engine 10 which is detected from the amount of the accelerator operation ACCP, the engine speed NE, and so on.

During the uniform combustion mode, combustion is performed with a mixture layer that is uniform in the combustion chamber 11 is distributed by the timing of the fuel injection is set to a timing in the intake stroke. During this mode, the ECU sets 16 a required value of the amount of fuel that comes from the injection 18 is injected, ie, a demanded value of the fuel injection Q in accordance with the amount of intake air GA flowing into the combustion chamber 11 is supplied, so that the air-fuel ratio becomes equal to a predetermined target air-fuel ratio. The amount of the intake air GA is in accordance with the degree of opening of the throttle valve 15 (Degree of throttle opening) TA adapted. Therefore, the power of the engine 10 during the uniform combustion mode by the control of the degree of opening of the throttle valve 15 customized.

During the stratified charge combustion mode, combustion is with a layer of a dense ignitable fuel mixture that is partially only around the spark plug 19 is performed by setting the fuel injection timing at a timing in a later period of the compression stroke immediately preceding the ignition. Therefore, during the stratified charge combustion mode, the combustion can be achieved at a very lean air-fuel ratio exceeding a limit value in the uniform combustion. During stratified charge combustion, the power of the engine becomes 10 adjusted by the control of the amount of fuel injection. The required value of the fuel injection Q is set in accordance with the required load KL set by the amount of the accelerator operation ACCP, the load of the air conditioner, the electric load, and so on.

in the Next, the switching of the combustion mode by the Stratified charge combustion into the uniform combustion in the above described designed embodiment described.

For switching the combustion mode from the stratified charge combustion to the uniform combustion in this embodiment, first, the degree of opening of the EGR valve becomes 20 as in the case of a conventional engine control apparatus described above, changed to a required opening degree required at the time of switching the combustion mode (in this case, "fully closed"). After elapse of a predetermined delay time after changing the opening degree of the EGR valve 20 For example, the control mode of the injection system and the ignition system is switched from the stratified charge combustion control mode to a control mode designed for the uniform combustion.

moreover is in this embodiment a torque reduction control of the reduction of the torque the internal combustion engine by a delay correction of the ignition timing carried out, after the control mode of the injection system and the ignition system of the control mode for the stratified charge combustion into the uniform combustion control mode is switched.

As described above, prevents the setting of a delay time essentially the torque reduction caused by a misfire, and the torque reduction control by the deceleration correction of ignition timing essentially prevents the caused by a delay in the intake system Torque increase. Therefore, you can Torque fluctuations during the switching of the combustion mode can be prevented.

Of the Degree of impact of torque fluctuations on drivability varies depending on the operating conditions. Under certain conditions, a certain amount of torque reduction be allowed due to misfires. Therefore, in this embodiment, the Delay Time in accordance changed with the operating state. If the operating condition is such that it is unlikely that by misfires caused torque fluctuation leads to a ver deteriorated driving behavior is the delay time shorter held as if other operating conditions prevail. Therefore be shortened the delay time, to switch the combustion mode without deterioration Driving behavior earlier too quit, the deterioration of NOx emissions and the increase in combustion noise reduced.

In addition, in addition to the above-described manner of switching the combustion mode from the stratified charge combustion to the uniform combustion, a value A of the time delay correction with respect to the ignition timing retard correction is in agreement determined with the delay time, which is changed in accordance with the operating state. Therefore, the switching of the combustion mode can be achieved in a more preferable manner.

Specific controls related to the switching of the combustion mode from the stratified charge combustion to the uniform combustion and performed by the control apparatus of the internal combustion engine in this embodiment will be described with reference to FIGS 2 to 5 described.

The 2 and 3 illustrate a control process of the ECU 16 with respect to switching the combustion mode from the stratified charge combustion to the uniform combustion. The 4A to 4G show types of control performed at the time of switching the combustion mode.

As in 4A shown, the ECU calculates 16 First, at a time t0, when a request for switching from the stratified charge combustion to the uniform combustion occurs, first reference delay times Tdn1, Tdn2 based on the current engine speed NE and the currently requested load KL of the engine 10 (Step 10 in 2 ).

The reference delay times Tdn1, Tdn2 are, as mentioned above, delay times set under conditions in which the torque fluctuation is unlikely to result in deteriorated drivability. The so-defined reference delay times Tdn1, Tdn2 are sufficiently long times, so that the remaining EGR gas decreases so much that the risk of misfiring after the change of the degree of opening of the EGR valve 20 no longer exists. The thus-established reference delay time Tdn1 is a delay time from the variation of the degree of opening of the EGR valve 20 until the switching of the control mode of the intake system to a control mode designed for the uniform combustion. The reference delay time Tdn2 is a delay time from the change of the control mode of the intake system for changing the control mode of the ignition system and the injection system to the uniform combustion control mode.

The ECU 16 determined afterwards in the step 20 whether the operating state with respect to. the shortening of the delay time is present. That is, the ECU 16 determines whether the present operating conditions are conditions in which torque fluctuations are unlikely to result in degraded drivability and therefore a certain torque reduction due to a shortened delay time is allowed. The following are examples of operating conditions that satisfy the above-mentioned conditions.

During high acceleration, torque fluctuations are unlikely to result in degraded ride because, as mentioned above, there is an acceleration shock. Even during high-load operation, the torque fluctuation is unlikely to cause deteriorated drivability as long as the torque fluctuation is moderate because of the engine 10 generates strong noises and vibrations.

In a vehicle in which an automatic transmission is equipped with a lock-up clutch, the above-mentioned conditions are satisfied when the lock-up clutch is not in a fully-closed state. In such a vehicle, the input and output sides of the automatic transmission are mechanically connected when the lock-up clutch is fully engaged, so that power can be transmitted directly between the crankshaft and the drive shaft without interposing the oil of the torque converter. Therefore, in the fully-closed state, the torque fluctuation of the engine becomes 10 transmitted directly to the drive shaft and therefore it is likely that the torque fluctuation leads to deteriorated driving performance. On the other hand, when the lock-up clutch is not in the fully-closed state, that is, when the lock-up clutch is fully released or when the lock-up clutch is only partially connected (in a slip state), the rotation of the engine becomes 10 transmitted via the torque converter oil to the drive shaft. Therefore, the torque fluctuation is less likely to result in deteriorated drivability when the lockup clutch is not fully closed than when the lockup clutch is fully closed.

The ECU 16 changes the subsequent procedure in accordance with the result of the determination. First, a procedure performed when the above operating conditions are not achieved ("NO" in step) will be described 20 ), that is, when the operating state is not a state in which the torque fluctuation is unlikely to result in deteriorated drivability.

In this case, the ECU puts down 16 the reference delay times Tdn1, Tdn2 as delay times Td1, Td2, which are actually used (Step 36 ), and performs an operation related to the switching of the combustion mode.

That is, as in 4B shown that the target opening degree of the EGR valve 20 at time t0, when the request for the mode switching comes to a required opening degree (in this case, a fully closed state) is changed (step 40 ). Then, at a time point t2, when the reference delay time Tdn1 set to the delay time Td1 has elapsed ("YES" in step) 50 ), the control mode of the intake system is switched to the control mode designed for the uniform combustion, such as a dot-dash line in FIG 4C displayed. Therefore, the degree of opening TA of the throttle valve becomes 15 at time t2 is changed to a polled uniform combustion opening degree (step 60 ), as indicated by a dot-dash line in 4D shown. After the opening degree of the throttle valve 15 As described above, the amount of intake air GA changes with retardation and remains above the required value for the uniform combustion, that is, remains in an excess amount as indicated by a dot-dash line in FIG 4E displayed.

Thereafter, at a time point t4, when the reference delay time Tdn2 set to the delay time Td2 elapses after the time t2 ("YES" in the step) 70 ), the control mode of the ignition system and the injection system are switched to the control mode designed for the uniform combustion (step 80 ), as indicated by a dot-dash line in 4F shown. Simultaneously with the mode switching, a time delay correction value A is set as indicated by a dot-and-dash line in FIG 4G is shown, and a torque reduction control is performed by the Zündzeitpunktverzögerungskorrektur (step 110 ).

The value of the time delay correction A in this case is based on the engine speed NE and the requested load KL of the engine 10 determined (step 105 ). The value of the time delay correction A is set so that the torque is reduced by a value related to the excess of the amount of the intake air GA. More specifically, the value of the time delay correction A is set as described above for a predetermined period after the time t4. Thereafter, the value of the time delay correction A is gradually changed to "zero" irrespective of changes in the amount of the intake air GA.

After the torque reduction control ends by the ignition timing delay correction, the opening degree of the EGR valve becomes 20 changed to the required opening degree for the uniform combustion (step 120 ), thereby completing the switching of the combustion mode.

Thus, the delay time is set to a time sufficient for the remaining EGR gas to decrease to a value that causes no misfires when the operating condition is not a condition in which the torque fluctuation is unlikely to become one worsened driving behavior leads. In this case, the value of the time delay correction A is set so that the torque is reduced by a value related to the excess of the amount of intake air GA caused by the delay in the intake system. Thus, the ignition timing is corrected in the deceleration direction. Therefore, during the switching of the combustion mode, the torque fluctuation is substantially suppressed, as in FIG 5A shown.

On the other hand, if the above-mentioned predetermined operating conditions exist ("YES" in step 20 ), that is, when the operating state is a state in which the torque fluctuation is unlikely to result in deteriorated drivability, the following operation is performed.

That is, the ECU 16 determines the reference delay times Tdn1, Tdn2 (step 10 in 2 ) and further determines the delay times Tds1, Tds2 (step 30 ). Then put the ECU 16 the thus determined delay times Tds1, Tds2 as delay times Td1, Td2, which are actually used for the process (step 33 ), and performs the subsequent operation.

The times Tds1, Tds2 are determined by the improbability that torque fluctuations result in degraded drivability, in addition to the engine speed NE and the polled load KL of the engine 10 is included. The thus determined times Tds1, Tds2 are set shorter than the reference delay times Tdn1, Tdn2. Therefore, in this case, the switching of the combustion mode is performed without waiting for elapse of a delay time during which the effect of the remaining EGR gas is sufficiently reduced. As a result, a slight torque drop due to misfire occurs.

Therefore, in this case, at the time t0 when the request for the mode switching comes, the target opening degree of the EGR valve becomes 20 set to the fully closed state, which corresponds to the required opening degree, which is set for switching the operating modes corresponds (Step 40 ). As indicated by a solid line in 4C 11, at the time point t1, when the time Tds1 has elapsed, the control mode of the intake system is switched to the uniform combustion control mode. In addition, at the time t0, the degree of the throttle opening TA becomes the required degree of the uniform combustion opening (step 60 ), as indicated by a solid line in FIG 4E shown.

At the time t3, when the time Tds2 set as the delay time Td2 has elapsed after the time t1, the control mode of the ignition system and the injection system is switched to the uniform combustion control mode (step S3) 80 ), as indicated by a solid line in 4F shown. At the same time, the torque reduction control is performed by the ignition timing delay correction by using the set value of the time delay correction A (step 110 ), as indicated by a solid line in 4G shown.

It should be noted here that the value of the time delay correction A is determined by a degree of reduction P of the delay time in addition to the engine speed NE and the requested load KL of the engine 10 is included (step 100 ). The degree of reduction P is determined as a ratio of the sum of the times Tds1, Tds2 set as delay times to the sum of the reference delay times Tdn1, Tdn2. The value of the time delay correction A set by taking in the degree of reduction P as indicated by the solid line in FIG 4G is smaller than the normal value of the time delay correction A, which is determined only by the engine speed NE and the requested load KL, as indicated by the broken line in FIG 4G shown. That is, in this case, by the torque reduction control by the ignition timing retard correction, sufficient torque reduction in accordance with the excess of the amount of intake air GA is not achieved, but the torque is increased.

Then the degree of opening of the EGR valve 20 to the requested degree of uniform combustion opening (step 120 ) after the torque reduction control ends by the ignition timing delay correction, thereby completing the switching of the combustion mode.

As As described above, the delay times Td1, Td2 in this embodiment in accordance changed with the operating conditions. When the delay times Td1, Td2 changed be changed the amount of EGR that occurs during switching of the combustion mode remains, and the type and the manner caused by the effect of the remaining EGR gas Torque reduction is changing as well. In this embodiment becomes the value of the time delay correction A in accordance fixed with the degree P of the reduction of the delay time, the through the delay times Td1, Td2, which are changed as described above. Therefore, the delay correction can the ignition timing so performed be that torque in line with the torque reduction caused by misfires suitable customized becomes.

When torque reduction occurs due to misfires caused by the variation of the delay times Td1, Td2, it is also possible to prevent the torque reduction due to the misfires from leading to deteriorated drivability, for example by setting the value of the time delay correction A so is that a torque increase of an appropriate magnitude occurs immediately after the aforementioned torque reduction, as in 5B shown. This measure is effective because the torque fluctuations in positive and negative directions are different during the path from the engine 10 lift to the drive shaft. Thus, deterioration of drivability can be prevented by setting a value of the time lag correction A so that a larger torque increase associated with the torque reduction occurs even if, as in FIG 5C shown a greater torque reduction occurs.

Consequently will it be possible a suitable torque control in accordance with the torque reduction perform, which varies based on the definition of delay times, though the value of the time delay correction A in accordance with the delay times Td1, Td2 (in this case the degree of reduction P passing through the delay times is determined) is determined. Through this torque control is it is possible the occurrence of larger torque reductions to enable while simultaneously prevents the deterioration of driving behavior becomes. Therefore, it becomes possible the delay time continue to decrease.

The embodiment described above achieves the following advantages.

In this embodiment, when the combustion mode is switched from the stratified charge combustion to the uniform combustion, the delay times Td1, Td2 of the change in the degree of opening of the EGR valve 20 changed to the switching of the control mode of the ignition system and the injection system in accordance with the operating state. Then, the value of the time delay correction A is set in accordance with the delay times Td1, Td2 changed as described above, and the torque reduction control by the ignition timing correction is performed immediately after the switching of the control mode of the injection system and the ignition system. Therefore, it becomes possible to suitably adjust the torque because the manner of torque reduction caused by misfire is changed by changing the delay times Td1, Td2. As a result, it becomes possible to better suppress the torque reduction caused by misfire. Thus, it becomes possible to allow greater torque reduction while preventing deterioration of drivability. Therefore, further reduction of the delay times Td1, Td2 accompanied by torque reduction due to misfire can be achieved without deteriorating the driveability. As a result, it becomes possible to reduce the NOx emission deterioration and the increase of the combustion noise while ensuring a good drivability.

The above embodiment can be changed as follows become.

Even though in the above embodiment the value of the time delay correction A using the degree of reduction P of the delay time is set, the value of the time delay correction A may also be be set on the basis of the values of the delay times. In addition, the value of the time delay correction A be set on the basis of each parameter, as long as the value of the parameter changes in direct relation to the delay time. Similar to the above embodiment enable it these changes, a suitable torque control in accordance with the type and Way of reducing torque, with the delay time changed is going to perform. Thus, the changes reach Essentially the same advantages as those given by the above embodiment be achieved.

Even though in the above embodiment the torque reduction control by the deceleration correction the ignition timing is performed, can be a similar one Torque control by using other parameters, for example by correcting the amount of fuel injection. Such a change allows it also, a suitable torque control in accordance with the torque reduction when the control value with respect to the torque reduction control in accordance with the delay time is determined. Thus, this change also substantially achieves the same advantages as the above embodiment.

In summary, it does the invention:

If the combustion mode of an internal combustion engine of stratified charge combustion to more uniform Combustion is switched, an ECU switches the control mode an injection system and an ignition system in a control mode, the for the uniform one Combustion is provided after a predetermined delay time after changing the opening degree an EGR valve has elapsed. After switching the control mode, the ECU, a torque reduction control by a delay correction the ignition timing by. The ECU changed the delay time in accordance with the operating condition and sets in accordance with the changed Delay Time a value of the delay correction fixed, which is related to the torque reduction control.

Claims (10)

Internal combustion engine control device, which is based on an internal combustion engine ( 10 ), wherein an amount of an EGR gas recirculated from an exhaust system to an intake system is controlled by controlling a degree of opening of an EGR valve ( 20 ) stored in an EGR passage ( 14 ) which connects the exhaust system and the intake system and which first determines the degree of opening of the EGR valve ( 20 ) to a requested opening degree set to switch from a stratified charge combustion mode to a uniform combustion mode, when the switching of the combustion mode from a stratified charge combustion mode to a uniform combustion mode is required and the combustion mode is therefore to be switched, and a control mode of an injection system and of an ignition system from a control mode set for the stratified charge combustion mode to a control mode set for the uniform combustion mode, switches after a predetermined delay time after switching the degree of opening of the EGR valve (FIG. 20 ) has elapsed, and that performs a torque reduction control to control a torque of the internal combustion engine ( 10 ), immediately after the Control mode is switched, characterized by a changing means ( 16 ) which changes the delay time depending on an operating condition; and an adjustment device ( 16 ) which sets a control value with respect to the torque-reduction control in accordance with the delay time changed by the changing means. Control device according to claim 1, characterized in that the torque reduction control detects the torque by a delay correction of an ignition timing of the internal combustion engine ( 10 ) decreased. Control device according to claim 2, characterized in that the adjusting device ( 16 ) adjusts a value of the retard correction of the ignition timing with respect to the torque reduction control depending on the delay time changed by the changing means. Control device according to claim 3, characterized in that the adjusting device ( 16 ) adjusts the value of the deceleration correction to cause a torque fluctuation substantially canceling a torque fluctuation caused by the variation of the delay time. Control device according to Claim 3 or 4, characterized in that the adjusting device ( 16 ) the value of the delay correction depending on a degree of reduction of the delay time, a demanded load and a rotational speed of the internal combustion engine ( 10 ). Control device according to one of Claims 1 to 5, characterized in that the altering device ( 16 ) reduces the delay time when the internal combustion engine ( 10 ) is in an operating condition in which torque fluctuation caused by misfire is unlikely to result in deteriorated drivability. Control device according to claim 6, characterized in that the adjusting device ( 16 ) adjusts the value of the delay correction so as to cause a torque increase when the delay time is reduced. Control device according to Claim 6 or 7, characterized in that the operating state is either a state in which a vehicle is greatly accelerating, or a state in which a load of the internal combustion engine ( 10 ), or a condition in which a lock-up clutch is not fully engaged. Control device according to one of Claims 1 to 8, characterized in that the internal combustion engine ( 10 ) is a direct injection and spark ignition internal combustion engine. Method for controlling an internal combustion engine that is based on an internal combustion engine ( 10 ), wherein an amount of an EGR gas recirculated from an exhaust system to an intake system is controlled by controlling a degree of opening of an EGR valve ( 20 ) stored in an EGR passage ( 14 ), which connects the exhaust system and the intake system, and which first determines the degree of opening of the EGR valve ( 20 ) to a requested opening degree set to switch from a stratified charge combustion mode to a uniform combustion mode, when the switching of the combustion mode from a stratified charge combustion mode to a uniform combustion mode is required and the combustion mode is therefore to be switched, and a control mode of an injection system and of an ignition system from a control mode set for the stratified charge combustion mode to a control mode set for the uniform combustion mode, switches after a predetermined delay time after switching the degree of opening of the EGR valve (FIG. 20 ) has elapsed, and that performs a torque reduction control to control a torque of the internal combustion engine ( 10 ) immediately after the control mode is switched, characterized by: changing the delay time depending on an operating condition; and setting a control value with respect to the torque reduction control depending on the changed delay time.