JP3680432B2 - Control device for internal combustion engine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a control device for an internal combustion engine mounted on an automobile or the like, and more particularly to a control device for an internal combustion engine capable of combustion at a lean air-fuel ratio by stratification of supplied fuel.
[0002]
[Prior art]
In an internal combustion engine equipped with a fuel injection valve that directly injects fuel into a cylinder, when torque down control is required during shifting of an automatic transmission, the thermal efficiency of the fuel injection timing from the direct injection type fuel injection valve is deteriorated. A control device for an internal combustion engine that realizes torque reduction by changing to is known (see Japanese Patent Laid-Open No. 4-301153).
[0003]
[Problems to be solved by the invention]
However, in the method of changing the torque according to the fuel injection timing as in the conventional control device for an internal combustion engine, only the fuel injection timing is corrected when aiming to improve fuel efficiency by realizing a lean air-fuel ratio by stratified combustion. Therefore, if the injection timing is changed greatly in order to greatly change the torque, the timing at which the combustible mixture comes near the spark plug may not match the ignition timing. Deterioration and eventually misfire may occur, resulting in deterioration of operability and exhaust.
[0004]
Further, in the method of changing the torque by the air-fuel ratio, the air-fuel ratio is normally set to a lean state near the stability limit when aiming to improve fuel efficiency by realizing a lean air-fuel mixture by stratified combustion. At this time, if the fuel supply amount is reduced to further reduce the torque in order to reduce the torque, the combustion stability limit will be exceeded, and as a result, combustion may worsen and eventually misfire may occur. Deterioration will occur.
[0005]
The present invention has been made in view of such conventional problems, and in an internal combustion engine that performs lean combustion by stratified combustion, it can satisfy the demand for quick torque change while suppressing deterioration of drivability and exhaust gas as much as possible. An object of the present invention is to provide a control device for an internal combustion engine.
[0006]
[Means for Solving the Problems]
  For this reason, the invention according to claim 1
  In an internal combustion engine that forms a combustible air-fuel mixture in a predetermined region in a combustion chamber and ignites the air-fuel mixture with a spark plug to perform stratified combustion,
  When torque reduction control of the engine is requested at the time of shifting of the automatic transmission connected to the internal combustion engine,
  Ignition is performed when the combustible air-fuel mixture comes near the spark plug, and when it is requested to change the engine torque below the limit value of torque change that can be ignited and burned reliably without causing misfire, the ignition timing or When the fuel injection timing is corrected and a change in the engine torque above the limit is requested, both the ignition timing and the fuel injection timing are corrected simultaneously to reduce the engine torque.It is characterized by being changed.
[0007]
(Action / Effect)
When performing lean combustion by stratified combustion, the air-fuel ratio is controlled near the lean limitBecause of this, torqueIf rapid reduction is required, reducing the amount of fuel supply and dealing with it will exceed the lean limit of the air-fuel ratio, and stable combustion will not be obtained.
Therefore, it is possible to change the torque quickly by correcting the ignition timing and the fuel injection timing by correcting the ignition timing and the fuel injection timing, but each independent correction ensures stable combustion. However, the amount of torque change possible is limited.
[0008]
Therefore, by correcting both the ignition timing and the fuel injection timing in synchronization, it is possible to satisfy a quick and large torque change request.
The invention according to claim 2
When a change in the engine torque less than the predetermined amount is requested, either the ignition timing or the fuel injection timing is corrected. When a change in the engine torque greater than the predetermined amount is requested, the ignition timing and the fuel injection timing are corrected. The engine torque is changed by correcting the timing at the same time.
[0009]
 (Action / Effect)
As described above, the torque can be changed within the respective limit ranges even at the ignition timing and the fuel injection timing alone. The torque is changed by correcting only one of the timing and the fuel injection timing, and the ignition timing and the fuel injection timing are corrected in synchronization only for a torque change request exceeding a predetermined amount that cannot be satisfied by a single correction. By doing so, this requirement can also be satisfied.
[0010]
Thus, within a possible range, a simple method can be achieved by performing only one correction, and the torque can be changed with high accuracy by synchronizing the two corrections only when necessary.
The invention according to claim 3
After correcting the engine torque by correcting at least one of the ignition timing and the fuel injection timing, while correcting the intake air amount and the fuel supply amount so that the changed engine torque is maintained in a desired combustion state, The ignition timing and the fuel injection timing are corrected again.
[0011]
 (Action / Effect)
Although it is possible to quickly change the torque by correcting the ignition timing and fuel injection timing, in general, the ignition timing and fuel injection timing are the efficiency and exhaust gas in the state of the intake air amount and fuel supply amount before the torque change. Since it is set to an optimum state in consideration of the purification performance, correcting the ignition timing and fuel injection timing without changing the intake air amount and the fuel supply amount will lower the efficiency and the exhaust purification performance. .
[0012]
  Therefore, after making a quick change of the torque according to the ignition timing and fuel injection timing, the ignition timing and fuel injection timing are re-adjusted while maintaining the changed torque and correcting the intake air amount and fuel supply amount. By correcting, the changed torque can be maintained while satisfying the efficiency (fuel consumption) and exhaust purification performance.
  Moreover, as shown in FIG.
  A combustible air-fuel mixture is formed in a predetermined area in the combustion chamber, and the air-fuel mixture is ignited by a spark plug to perform stratified combustion,
  Ignition timing control means for controlling the ignition timing by the spark plug;
  Fuel supply means for injecting and supplying fuel;
  Fuel supply amount control means for controlling the fuel supply amount from the fuel supply means;
  An internal combustion engine comprising: fuel injection timing detection means for controlling the fuel injection timing from the fuel supply means;
  Torque change instruction means for instructing quick change of the engine torque when engine torque down control is requested at the time of shifting of the automatic transmission coupled to the internal combustion engine;
  When a torque change is instructed from the torque change instruction means,Ignition is performed when the combustible air-fuel mixture comes near the spark plug, and when it is requested to change the engine torque below the limit value of torque change that can be ignited and burned reliably without causing misfire, the ignition timing or When the fuel injection timing is corrected and a change in the engine torque above the limit is requested, both the ignition timing and the fuel injection timing are corrected simultaneously to reduce the engine torque.Torque changing means to change;
  It is characterized by including.
[0013]
 (Action / Effect)
When a torque change is instructed by the torque changing means, both the ignition timing and the fuel injection timing are corrected synchronously through the ignition timing control means and the fuel injection timing control means at least under a predetermined condition. Thus, a quick torque change is performed, and a large torque change request can be satisfied by performing two corrections simultaneously.
[0014]
The invention according to claim 5
The torque change means corrects either the ignition timing or the fuel injection timing when the torque change instruction means instructs to change the engine torque less than a predetermined amount, and changes the engine torque greater than a predetermined amount. When the engine is required, the ignition timing and the fuel injection timing are corrected simultaneously to change the engine torque.
[0015]
 (Action / Effect)
The torque changing means corrects only the ignition timing control means or the fuel injection timing control means with respect to a torque change request less than a predetermined amount that can be achieved only by either the ignition timing or the fuel injection timing. The correction is performed in synchronism with the ignition timing and the fuel injection timing via both control means only for a torque change request exceeding a predetermined amount that cannot be satisfied by a single correction.
[0016]
Thus, within a possible range, a simple method can be achieved by performing only one correction, and the torque can be changed with high accuracy by synchronizing the two corrections only when necessary.
The invention according to claim 6
An intake air amount control means for controlling the intake air amount;
The torque changing means corrects at least one of the ignition timing and the fuel injection timing to change the engine torque, and then the intake air amount and the fuel supply so that the changed engine torque is maintained in a desired combustion state. The ignition timing and the fuel injection timing are corrected again while correcting the amounts.
[0017]
 (Action / Effect)
As described above, after a quick change of torque according to the ignition timing or fuel injection timing, while maintaining the torque after the change, correcting the intake air amount and fuel supply amount, It is desirable to recorrect the injection timing.
Therefore, the torque changing means corrects the ignition timing and the fuel injection timing by the ignition timing control means and the fuel injection timing control means, and after changing the torque quickly, the intake air amount control means and the fuel supply amount control means are changed. Thus, by correcting the ignition timing and the fuel injection timing while correcting the intake air amount and the fuel supply amount, it is possible to maintain the changed torque while satisfying the efficiency (fuel consumption) and the exhaust purification performance.
[0018]
The invention according to claim 7
The correction values for the ignition timing and the fuel injection timing were instructed from the current engine torque estimated from the engine operating state and the torque change instruction means.From the torque change value and the torque coefficient as the change rate of the current engine torque with respect to the correction amount of the ignition timing and fuel injection timingIt is characterized by calculating.
[0019]
 (Action / Effect)
Based on the estimated engine torque and the torque change value, for example, a torque coefficient (torque after change / current torque) is calculated, and the torque coefficient change amount, ignition timing, and fuel injection timing are calculated. If a method for obtaining the correction amount of the ignition timing and the fuel injection timing from the calculated torque coefficient in advance and obtaining the relationship with the correction amount, the correction amount can be obtained easily and quickly. Torque change control can be performed with good responsiveness.
[0020]
The invention according to claim 8 is
The predetermined value is a current value estimated from an operating state of the engine.From the engine torque and the torque coefficient as the change rate of the current engine torque with respect to the correction amount of the ignition timing and fuel injection timingIt is characterized by calculating.
(Action / Effect)
Independent from current engine torque and torque coefficientA limit is obtained for a correction amount that can maintain stable combustion by this correction, and by calculating this as a predetermined value, it is possible to perform simple correction alone as much as possible.
[0021]
The invention according to claim 9 is
The correction of the intake air amount by the torque changing means is based on the target air-fuel ratio determined from the current operating state and the fuel supply amount corresponding to the changed engine torque calculated based on the instruction of the torque changing instruction means. This is performed by calculating a target cylinder intake air amount and correcting the intake air amount control means so as to make the cylinder intake air amount the target cylinder intake air amount.
[0022]
 (Action / Effect)
By calculating the target cylinder intake air amount based on the target air-fuel ratio and the fuel supply amount corresponding to the changed engine torque, and controlling the intake air amount so as to obtain the target cylinder intake air amount, The amount of air can be controlled to a desired value with high accuracy.
[0023]
The invention according to claim 10 is
The correction of the fuel supply amount by the torque changing means calculates the target fuel supply amount from the target air-fuel ratio determined from the current operating state and the estimated value of the change in the cylinder intake air amount after the intake air amount correction, This is performed by correcting via the fuel supply amount control means so that the fuel supply amount becomes the target fuel supply amount in synchronization with a change in the cylinder intake air amount.
[0024]
 (Action / Effect)
After correcting the intake air amount, the change in the cylinder intake air amount is estimated in consideration of the delay, and the target fuel supply amount is calculated in synchronization with the change in the cylinder intake air amount while calculating the target fuel supply amount from the estimated value. By correcting to the value, the fuel supply amount can be controlled with high accuracy even while the intake air amount changes, and thus the torque after the change can be well maintained during this time.
[0025]
The invention according to claim 11 is
The torque changing means reduces the engine torque by controlling at least one of the ignition timing and the fuel injection timing to the retard side when the torque change instructing means is instructed to reduce the engine torque. Features.
 (Action / Effect)
The engine torque can be reduced with good responsiveness by controlling at least one of the ignition timing and the fuel injection timing to the retard side in response to the torque reduction instruction.
[0027]
Claims 12 The invention according toThe correction of the ignition timing and the fuel injection timing is performed in a plurality of combustion batches.
[0028]
(Action / Effect)
Torque can be changed smoothly by correcting gradually in a plurality of combustion cycles.
Also,Claim 13The invention according to
The torque change instruction means instructs to change the engine torque when controlling behavior such as running stability of a vehicle equipped with the internal combustion engine.
[0029]
(Action / Effect)
For example, when controlling behavior such as running stability of the vehicle, it is possible to perform optimal engine control while satisfying running stability and the like by instructing to change the engine torque.
Also,Claim 14The invention according to
The torque change instructing means instructs to change the engine torque at the time of shifting of the automatic transmission connected to the internal combustion engine.
[0030]
(Action / Effect)
For example, a torque shock at the time of shifting can be alleviated by instructing to change the engine torque during shifting of the automatic transmission.
Also,Claim 15The invention according to claim is characterized in that the fuel supply means injects and supplies fuel directly into the cylinder of the engine.
[0031]
(Action / Effect)
The present invention can be applied to an engine that directly injects fuel into a cylinder that easily forms an air-fuel mixture for stratified combustion.
Also,Claim 16The fuel supply means injects and supplies fuel to the intake passage of the engine.
[0032]
 (Action / Effect)
Stratified combustion can also be performed by injecting fuel into the intake passage, and can be applied to such an engine.
[0033]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 shows a system configuration of one embodiment, and FIG. 3 shows a circuit configuration centering on the microcomputer of the same embodiment.
As means for detecting the operating state of the internal combustion engine 1, the intake air amount sensor 2 detects the intake air amount. The crank angle sensor 3, which is directly or indirectly connected to the crank angle shaft and the cam shaft rotating in conjunction with it, detects the crank angle position (crank angle) of the engine 1 and the rotational speed of the engine. To do.
[0034]
The fuel is directly injected into the combustion chamber by the fuel injection valve 4, and the air-fuel ratio of the air-fuel mixture is controlled by adjusting the fuel injection amount. The combustible air-fuel mixture stratified in the combustion chamber is ignited by the spark plug 5 so that lean combustion can be performed. In addition, a water temperature sensor 6 for detecting the engine coolant temperature (hereinafter referred to as water temperature) and an air-fuel ratio sensor 7 for detecting the air-fuel ratio by detecting the oxygen concentration in the exhaust gas are provided.
[0035]
Further, input / output of information with the outside and various operations are realized by the circuit shown in FIG. The CPU 301 executes calculations, and the ROM 302 stores a control program and various data described later in advance. The RAM 303 temporarily stores information during program execution. The input port 304 inputs information from an external sensor or the like, and the A / D converter 305 performs A / D conversion for handling an analog signal from the outside by a computer. The output port 306 outputs a signal for driving an external device.
[0036]
Next, the operation of the above system will be described.
As an advantage of stratified combustion, there is an improvement in fuel consumption due to a significant dilution of the air-fuel ratio. Here, in order to realize good combustion in an engine that performs stratified combustion, it is necessary to perform ignition when the combustible mixture reaches the vicinity of the spark plug. For this reason, the fuel injection timing and the ignition timing must be set with high precision, and as shown in FIG. 4, ignition is performed when the spark plug comes to the center of the combustible mixture or slightly closer to the traveling direction. This is desirable from the viewpoint of efficiency.
[0037]
By the way, when controlling the behavior of the vehicle, such as when ensuring the running stability of the vehicle, there is a case where a request for quickly changing the output torque of the engine may occur.
In a conventional engine that performs homogeneous mixing combustion, when the torque is increased, the fuel injection amount is increased to be rich, and when the torque is decreased, the fuel injection amount is decreased to be lean. However, when performing lean combustion by stratification, operation is performed at an ultra-lean air-fuel ratio close to the stability limit in order to achieve the maximum improvement in fuel consumption, so it is possible to enrich when torque is increased Even so, when the torque is reduced, further leaning is impossible. In order to reduce the torque while keeping the air-fuel ratio constant, it is conceivable to reduce the fuel injection amount while simultaneously reducing the air amount. However, this method has a large time delay in the air response. It is difficult to reduce the torque quickly.
[0038]
Therefore, as a method of quickly reducing the torque while maintaining an ultra-lean air-fuel ratio, a method of realizing a torque reduction by shifting the peak position of the in-cylinder pressure by changing the fuel injection timing or the ignition timing or both.
Normally, as shown in FIG. 4, ignition is performed when the spark plug comes to the center of the combustible mixture, and as shown in FIG. 5, the in-cylinder pressure peak position (θpmax) is a predetermined target value. The fuel injection timing and ignition timing are set so that (θtarg: MBT or knock limit point). Here, the indicated mean effective pressure (Pi), which is a parameter representing the magnitude of the generated torque, is obtained by summing the in-cylinder pressure and the volume change rate in FIG. 5 over one cycle, and dividing the result by the stroke volume. Since the generated torque decreases if the in-cylinder pressure peak position is shifted later and the in-cylinder pressure peak value decreases, in general, the in-cylinder pressure peak value (θpmax) and the indicated mean effective pressure (Pi) There is a relationship as shown in FIG.
[0039]
Therefore, if the in-cylinder pressure maximum timing (θpmax) is changed by controlling the fuel injection timing and ignition timing, the torque can be reduced without changing the air-fuel ratio. Since it is a parameter that can be changed for each combustion, a very fast response can be realized.
Here, when the fuel injection timing is delayed, as shown in FIG. 7, the end portion of the combustible air-fuel mixture is ignited, and the combustion takes time. Therefore, the combustion waveform is as shown in FIG. The internal pressure peak moves later, and the torque can be reduced from the relationship shown in FIG. Also, when the ignition timing is delayed, as shown in FIG. 9, the end portion of the combustible mixture is ignited, and similarly, it takes time to burn, so the combustion waveform is as shown in FIG. The in-cylinder pressure peak moves later, and the torque can be reduced from the relationship shown in FIG.
[0040]
In addition, in the case of correction only for the fuel injection timing or only for the ignition timing, both can be corrected in order to perform ignition when the combustible air-fuel mixture comes near the spark plug and reliably ignite and burn without causing misfire. Since the timing range is narrow, the range of torque correction is also narrow, but as shown in FIG. 11, if the fuel injection timing and the ignition timing are retarded in synchronization and ignited, as shown in FIG. Since the timing can be corrected in a larger range, as a result, torque correction can be performed in a larger range. Therefore, according to this method, since the combustible air-fuel mixture burns completely, the emission is not deteriorated, and a rapid torque reduction can be realized.
[0041]
The present invention pays attention to the above points and is based on correcting the fuel injection timing and the ignition timing in synchronization when a rapid torque change is required.
However, even after the torque is reduced by this method, if the ignition timing and the fuel injection timing are left retarded, the fuel supply amount for the required torque remains the same, and the efficiency is low due to the large amount. In addition, when the next request for torque reduction occurs, there is no delay angle and cannot be handled.
[0042]
Therefore, after realizing a rapid torque reduction as described above, the reduced torque is realized with a more efficient fuel supply amount, fuel injection timing and ignition timing (for example, MBT) as shown in FIG. As described above, the fuel injection timing and the ignition timing are reduced while reducing the fuel injection amount so as to maintain a constant torque according to the time constant of the change in the cylinder intake air amount while reducing the intake air amount by an electric throttle or the like. Corrections are made synchronously so as to obtain a predetermined value. As a result, the required torque can be realized by the highly efficient fuel injection amount, the fuel injection timing and the ignition timing, so that it is possible to cope with the next request for torque reduction.
[0043]
Hereinafter, specific control of the embodiment according to the present invention will be described according to a flowchart.
FIG. 14 shows a flow for calculating the correction amount of the fuel injection amount and the correction amount of the ignition timing, and is executed every predetermined time (for example, 10 ms).
In step 1401, the torque change is determined, and in step 1402, a fuel injection timing correction value and an ignition timing correction value for changing the torque are calculated.
[0044]
FIG. 15 shows a flow of fuel supply control, which is executed in synchronization with a reference signal output from the crank angle sensor 3 every constant crank angle period (180 ° in the case of a four-cylinder engine).
In step 1501, the hardware is set to actually execute fuel supply and ignition.
[0045]
Next, embodiments in which specific processes of the steps in FIGS. 14 and 15 are different will be described.
FIG. 16 shows a specific process of step 1401 (torque change determination) of FIG. 14 in the first embodiment.
In step 1601, the current operating state is detected.
[0046]
In step 1602, it is determined whether torque change is necessary in the current driving state based on the running stability of the vehicle.
If it is determined in step 1602 that the torque needs to be changed, the process proceeds to step 1603 and the value of the flag FLGTQR is set to 1.
Next, in step 1604, a necessary torque change value (dTrq) is calculated, and the process ends.
[0047]
Here, the torque change value (dTrq) may be obtained by searching from a map based on operating conditions, or may be obtained by calculation based on the current torque (Trq). Here, in general, when the fuel injection timing and the ignition timing are optimally set, the relationship shown in FIG. 24 is established between the output torque, the engine speed, and the fuel supply amount. The output torque can be obtained from the current fuel supply amount according to the characteristics shown in FIG.
[0048]
If it is determined in step 1602 that torque change is not necessary, the process proceeds to step 1605 to reset the value of the flag FLGTQR to 0.
Next, in step 1606, the torque change value (dTrq) is set to 0, and the process ends.
FIG. 17 shows a specific process of step 1402 (correction of fuel injection timing and ignition timing) in FIG. 14 in the first embodiment.
[0049]
In step 1701, it is determined whether or not the value of the flag FLGTQR is zero.
If it is determined in step 1701 that the value of the flag FLGTQR is 0, that is, if there is no torque change request, the routine proceeds to step 1702, where the fuel injection timing correction value (dTinj) is set to 0, and then in step 1703 the ignition timing is set. The correction value (dTign) is set to 0, and the process ends. That is, since there is no request for torque change, the current values are maintained without changing the fuel injection timing and ignition timing.
[0050]
If it is determined in step 1701 that the value of the flag FLGTQR is 1, that is, if a torque change is requested, the process proceeds to step 1704.
In step 1704, it is determined whether or not the absolute value (| dTrq |) of the torque change value is smaller than a predetermined value (dT1). Here, the predetermined value (dT1) is set to a limit value of the torque change that can be performed while maintaining the flammability only by correcting the ignition timing. Therefore, in step 1704, the torque change is requested only by the ignition timing. This is to determine whether or not it is possible. Generally, the relationship shown in Fig. 25 is established between the ignition timing correction value from the optimal ignition timing (here, MBT) and the ratio of torque to torque at the optimal ignition timing (torque coefficient). From the torque coefficient LTign at the limit dTign1 and the torque (Trq) obtained from FIG. 24, dT1 is obtained by the following equation.
[0051]
 dT1 = Trq × (1-LTign)
If it is determined in step 1704 that the absolute value of the torque change value is smaller than the predetermined value, it is possible to change the torque only by correcting the ignition timing, so in step 1705 the fuel injection timing correction value ( In step 1706, dTinj) is set to 0, and an ignition timing correction value (dTign) corresponding to the correction coefficient KTrq obtained from the torque change value (dTrq) by the following equation is calculated based on the table shown in FIG.
[0052]
 KTrq = 1-dTrq / Trq
If it is determined in step 1704 that the absolute value of the torque change value is equal to or greater than the predetermined value, the torque is changed using both the fuel injection timing and the ignition timing.
That is, in step 1707 and step 1708, as in step 1706, the fuel injection timing correction value (dTinj) and ignition timing correction value (dTign) for the torque change value (dTrq) are shown in the table shown in FIG. Calculate based on and finish.
[0053]
Here, FIG. 26 is a characteristic diagram showing the rate of change in torque when the optimal ignition timing and the optimal fuel injection timing set therewith are changed.
FIG. 18 shows a specific process of step 1501 (fuel supply, ignition) of FIG. 15 in the first embodiment.
In step 1801, the current operating state is read.
[0054]
In step 1802, the fuel injection amount is calculated based on the operating state.
In step 1803, the reference fuel injection timing (Tinj s) is calculated.
In step 1804, the reference ignition timing (Tign map) is calculated based on the map determined from the driving state.
[0055]
In step 1805, settings are made to actually output the fuel injection pulse.
In step 1806, the reference fuel injection timing (Tinj In s), the fuel injection timing (Tinj) corrected by the fuel injection timing correction value (dTinj) is set.
In step 1807, the reference ignition timing (Tign In map), the ignition timing (Tign) subjected to the ignition timing correction (dTign) is set, and the process ends.
[0056]
Based on these set values, the hardware performs fuel injection and ignition at the set fuel injection timing (dTinj) and ignition timing (Tign).
In this embodiment, the characteristics of the torque coefficient shown in FIG. 25 and FIG. 26 are constant regardless of the operating conditions, but this may be configured with a plurality of these tables for each operating condition, and the accuracy is high. improves.
[0057]
Next, a second embodiment will be described.
In the above embodiment, when the required torque change value is small, the correction is made only by the ignition timing. However, in this embodiment, when the torque change value is small, the correction is made only by the fuel injection timing. Is.
14, 15, 16, and 18 can be used in the same manner as in the first embodiment, but in the second embodiment, step 1402 in FIG. 14 (correction of fuel injection timing and ignition timing) is performed. FIG. 19 is used in place of FIG. 17 as a diagram showing the specific processing.
[0058]
In Step 1901, it is determined whether or not the value of the flag FLGTQR is 0. If it is determined in Step 1901 that the value of the flag FLGTQR is 0, that is, if there is no torque change request, the process proceeds to Step 1902. Similarly, the fuel injection timing correction value (dTinj) is set to 0, the ignition timing correction value (dTign) is set to 0 in step 1903, and the fuel injection timing and the ignition timing are not corrected.
[0059]
On the other hand, if it is determined in step 1901 that the value of the flag FLGTQR is 1, that is, if there is a request for torque change, the process proceeds to step 1904.
In Step 1904, it is determined whether or not the absolute value (| dTrq |) of the torque change value is smaller than a predetermined value (dT2). Here, the predetermined value (dT2) is set to a limit value of a torque change that can be performed while maintaining the combustibility only by correcting the fuel injection timing, and therefore, step 1904 is a torque only by correcting the fuel injection timing. It is determined whether a change request is possible. Here, the fuel injection timing correction value from the optimal fuel injection timing (for example, the fuel injection timing that can realize FIG. 4 when the ignition timing is MBT) and the ratio of the torque to the torque at the optimal fuel injection timing (torque coefficient) Since the relationship shown in FIG. 27 is generally established between them, dT2 is obtained by the following equation from the torque coefficient LTinj at the retard limit dTinj1 and the torque (Trq) obtained from FIG.
[0060]
 dT2 = Trq × (1-LTinj)
If it is determined in step 1904 that the absolute value of the torque change value is smaller than the predetermined value, the torque change value (dTrq) can be changed in step 1905 because the torque can be changed only at the fuel injection timing. Based on the table shown in FIG. 27, the fuel injection timing correction value (dTinj) corresponding to the correction coefficient KTrq obtained from the following equation is calculated.
[0061]
 KTrq = 1-dTrq / Trq
Next, at step 1906, the ignition timing correction value (dTinj) is set to 0, and the process ends.
If it is determined in step 1904 that the absolute value of the torque change value is equal to or greater than the predetermined value, the torque is changed using both the fuel injection timing and the ignition timing.
That is, in step 1907 and step 1908, the fuel injection timing correction value (dTinj) and the ignition timing correction value (dTign) for the torque change value (dTrq) are the same as in steps 1707 and 1708. An operation is performed based on the indicated table, and the process ends.
[0062]
Next, a third embodiment will be described.
In the present embodiment, after realizing a rapid torque decrease by the fuel injection timing or ignition timing, the intake air amount is corrected by an electric throttle or the like, and the torque is made constant in synchronization with the change of the cylinder intake air amount. By changing the fuel supply amount, fuel injection timing, and ignition timing to recover to a highly efficient operating state (ignition timing is MBT or knock limit), it will be possible to cope with the next demand for torque reduction. It is a thing.
[0063]
14, FIG. 15, and FIG. 16 can be used similarly to the first embodiment. FIG. 20 specifically shows the processing of step 1402 (correction of fuel injection timing and ignition timing) in FIG. 14 in the third embodiment.
In step 2001, it is determined whether the flag ADJUST is 0 or not. Here, this flag ADJUST is set in FIG. 22 described later, and is a flag indicating whether or not the fuel injection timing or the ignition timing is currently corrected. The flag ADJUST is 0. If it is determined that no correction has been performed, the process proceeds to step 2002 to determine whether the flag FLGTRQ is 0 or not.
[0064]
If it is determined in step 2002 that the value of the flag FLGTQR is 0, the fuel injection timing correction value (dTinj) is set to 0 in step 2003, the ignition timing correction value (dTinj) is set to 0 in step 2004, and the fuel injection timing is set. The ignition timing is not corrected, the flag FLGADJ is set to 0 in step 2005, and in step 2006, 1 is assigned to the fuel supply amount correction coefficient αf, and the process ends.
[0065]
If it is determined in step 2002 that the flag FLGTRQ is 1 and there is a request for torque change, the process proceeds to step 2007.
In step 2007, it is determined whether or not the absolute value (| dTrq |) of the torque change value is smaller than a predetermined value (dT1). Here, the calculation of the predetermined value (dT1) is the same as in the first embodiment.
[0066]
In Step 2007, when it is determined that the absolute value of the torque change value is smaller than the predetermined value, the torque is changed only by the ignition timing.
In step 2008, the fuel injection timing correction value (dTinj) is set to zero.
In step 2009, the ignition timing correction value (dTign) corresponding to the torque change value (dTrq) is calculated based on the table shown in FIG. 25 as in the first embodiment.
[0067]
In step 2010, the flag FLGADJ is set to 1 indicating whether or not the fuel injection timing or ignition timing is corrected immediately after the torque change request is made (1 if present).
In step 2011, the initial value N is set in the counter C, step 2006 is executed, and the process ends.
If it is determined in step 2007 that the absolute value of the torque change value is equal to or greater than the predetermined value, the torque is changed using both the fuel injection timing and the ignition timing.
[0068]
That is, in step 2012 and step 2013, the fuel injection timing correction value (dTinj) and the ignition timing correction value (dTign) for the torque change value (dTrq) are shown in the table shown in FIG. 26 as in the first embodiment. After that, the process proceeds to step 2010, step 2011, and step 2006 to perform the above-described processing, and ends.
If it is determined in step 2001 that the flag ADJUST is not 0, the ignition timing or the fuel injection timing is corrected to change the torque. In step 2014, the intake air amount, the fuel supply amount, the fuel injection timing, and the ignition timing are corrected and the process ends.
[0069]
FIG. 21 specifically shows the processing of step 2014 in FIG.
In step 2101, it is determined whether or not the flag FLGAIR is zero. Here, the flag FLGAIR is a flag indicating whether or not the intake air amount has been corrected after the torque change. The flag FLGAIR is set to 1 when the intake air amount is corrected and is set to 0 when the intake air amount is not corrected. If the flag FLGAIR is determined to be 0 in step 2101, that is, if the intake air amount is not corrected, the process proceeds to step 2102, and the current torque that has been corrected according to the ignition timing and fuel injection timing. Trq 'is calculated by the following formula.
[0070]
 Trq ’= Trq −dTrq
In Step 2103, the fuel supply amount is calculated from the characteristics shown in FIG. 24 based on the current torque Trq ', and the target cylinder intake air amount is calculated from the current target air-fuel ratio and the fuel supply amount.
In step 2104, it is determined whether or not the value of the counter C set in step 2011 of FIG. 20 has become 0 or less, that is, whether or not a predetermined time has elapsed since the correction of the fuel injection timing and ignition timing. If it is 0 or less, the process proceeds to step 2105; otherwise, the value of the counter C is decremented by 1 in step 2112 and the process ends.
[0071]
If it is determined in step 2104 that the value of the counter C is 0 or less, that is, if a predetermined time has elapsed, in step 2105, the current cylinder intake air amount is set to the target cylinder intake air amount calculated in step 2013. Correct the throttle opening.
In step 2106, since the intake air amount correction is performed, a flag FLGAIR indicating that is set to 1.
[0072]
In step 2107, T0 corresponding to a time constant representing a time delay until the cylinder intake air amount reaches the target value is substituted into the counter T as an initial value. The counter initial value T0 corresponding to this time constant is obtained by searching or the like from a map created with data examined in advance for each operating condition.
In step 2108, in order to estimate the current cylinder intake air amount after correcting the throttle, calculate the target fuel supply amount from the estimated value and the target air-fuel ratio, and use the current fuel supply amount as the target fuel supply amount The correction coefficient αf (T0) is calculated.
[0073]
In Step 2109 and Step 2110, a fuel supply amount correction value dTinj (T0) and an ignition timing correction value dTign (T0) for realizing the torque Trq ′ with the fuel supply amount corrected by the correction coefficient αf (T0) are calculated. .
In step 2111, the value of the counter T is decremented by 1, and the process ends.
If the flag FLAGAIR is not 0 in step 2101, that is, if the intake air amount has already been corrected, the routine proceeds to step 2113, where it is determined whether the value of the counter T is 0 or less.
[0074]
If the value of the counter T is not less than 0, that is, if the time constant T0 has not elapsed and it is determined that the intake air amount is changing, the cylinder intake air amount corresponding to the current counter T is determined in step 2114. The target fuel supply amount is calculated from the estimated value and the target air-fuel ratio, and a correction coefficient αf (T) for setting the current fuel supply amount as the target fuel supply amount is calculated.
[0075]
In Step 2115 and Step 2116, a fuel supply amount correction value dTinj (T) and an ignition timing correction value dTign (T) for realizing the torque Trq ′ with the fuel supply amount corrected by the correction coefficient αf (T) are calculated. .
In Step 2117, the value of the counter T is decremented by 1, and the process ends.
On the other hand, if it is determined in step 2113 that the value of the counter T is 0 or less and the time constant T0 after the throttle correction has elapsed, the cylinder intake air amount reaches the target value, and the fuel supply amount, fuel injection timing, Since it is determined that the ignition timing is also corrected to the optimum value, the flag FLAGAIR is set to 0 in step 2118, the flag ADJUST is set to 0 in step 2119, and the process is terminated.
[0076]
FIG. 22 specifically shows the processing of step 1501 (fuel supply, ignition correction) of FIG. 15 in the third embodiment.
In step 2201, the current operating state is read, and in step 2202, the basic fuel supply amount (Qfuel is calculated based on the operating state. s), and in step 2203, the reference fuel injection timing (Tinj s), and in step 2204, the reference ignition timing (Tign map) is calculated based on the map determined from the driving state.
[0077]
In step 2205, the basic fuel supply amount (Qfuel) s) is set to actually output the fuel injection pulse corrected by αf.In step 2206, the reference fuel injection timing (Tinj s) is set to the fuel injection timing (Tinj) corrected by dTinj.In step 2207, the reference ignition timing (Tign Set ignition timing (Tign) corrected by dTign in map).
[0078]
In step 2208, it is determined whether or not the flag FLGADJ is 0. If it is 0, the flag ADJUSTU is set to 0 in step 2209. If it is not 0, the flag ADJUSTU is set to 1 in step 2210, and the process ends.
Based on the set values from step 2205 to step 2207, the hardware performs actual fuel injection and ignition.
[0079]
Next, a fourth embodiment will be described.
The third embodiment is configured to correct only by the ignition timing when the torque change value is small, whereas the present embodiment performs correction only by the fuel injection timing when the torque change value is small. FIG. 23 is used instead of FIG. Since changes to the third embodiment are the same as the changes of the first embodiment to the second embodiment, description thereof will be omitted.
[0080]
Next, a fifth embodiment will be described.
In the first to fourth embodiments, when the torque change amount is small, the torque reduction is realized by correcting only the fuel injection timing or only the ignition timing. Regardless of the amount, the fuel injection timing and the ignition timing may always be corrected. In this case, the processing shown in FIG. 28 is performed instead of FIG. 28, FIG. Since the processing contents are clear from the figure, the description is omitted.
[0081]
In the embodiment described above, the quick change of the torque is realized by one correction of the fuel injection timing and the ignition timing. However, this may be realized by several corrections. For example, when correcting the ignition timing by dTign, it may be corrected by dividing it into N combustions by dTign / N. From the characteristics shown in FIGS. 25 to 27, dTign is set so that the torque change amount becomes equal each time. May be corrected by dividing it into N combustions.
[0082]
Further, in the above embodiment, an in-cylinder direct injection engine that directly injects fuel into a cylinder has been described as an example. An engine that performs injection can be applied to any engine that can perform stratified combustion.
In the above embodiment, the case where the torque is all reduced is described. However, the ignition timing and the fuel injection timing are set to the retard side rather than the MBT ignition timing and the fuel injection timing corresponding thereto, If the torque increase allowance is secured (a point where the correction value is 0 is set on the retard side from FIGS. 25 to 27), the present invention can also be applied to increase the torque.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration / function of an invention according to claim 4;
FIG. 2 is a diagram showing a system configuration of an embodiment of the present invention.
FIG. 3 is a diagram showing a circuit configuration centering on a microcomputer according to the embodiment;
FIG. 4 is a cross-sectional view showing a combustion state during normal control of ignition timing and fuel injection timing.
FIG. 5 is a time chart showing the state change of in-cylinder pressure and volume change amount during normal control.
FIG. 6 is a diagram showing a relationship between an in-cylinder pressure peak position and an indicated mean effective pressure.
FIG. 7 is a sectional view showing a combustion state when the ignition timing is normally controlled and the fuel injection timing is retarded.
FIG. 8 is a time chart showing a state change of an in-cylinder pressure and a volume change amount during the same control.
FIG. 9 is a cross-sectional view showing a combustion state when fuel injection timing is normally controlled and ignition timing is retarded.
FIG. 10 is a time chart showing a state change of an in-cylinder pressure and a volume change amount during the same control.
FIG. 11 is a cross-sectional view showing a combustion state when both ignition timing and fuel injection timing are retarded.
FIG. 12 is a time chart showing the state change of the in-cylinder pressure and the volume change amount during the retard angle control.
FIG. 13 is a time chart showing changes in various state quantities when the control according to the present invention is performed.
FIG. 14 is a flowchart for calculating a fuel injection amount correction amount and an ignition timing correction amount.
FIG. 15 is a flowchart of fuel supply control.
FIG. 16 is a flowchart showing specific processing for torque change determination according to the first embodiment;
FIG. 17 is a flowchart showing specific processing of fuel injection timing and ignition timing correction according to the first embodiment.
FIG. 18 is a flowchart showing specific processing of fuel supply and ignition according to the first embodiment.
FIG. 19 is a flowchart showing specific processing for torque change determination according to the second embodiment;
FIG. 20 is a flowchart showing specific processing of fuel injection timing and ignition timing correction according to the second embodiment.
FIG. 21 is a flowchart showing a specific process for re-correcting the fuel injection timing and the ignition timing during the process.
FIG. 22 is a flowchart showing a specific process of fuel supply and ignition according to the second embodiment.
FIG. 23 is a flowchart showing a specific process of fuel injection timing and ignition timing correction according to the third embodiment.
FIG. 24 is a diagram showing a relationship among engine rotation speed, fuel supply amount, and output torque.
FIG. 25 is a diagram showing a relationship between an ignition timing correction value and a torque coefficient.
FIG. 26 is a diagram showing a relationship between a correction value of fuel injection timing and ignition timing and a torque coefficient.
FIG. 27 is a diagram showing a relationship between a fuel supply amount correction value and a torque coefficient.
FIG. 28 is a flowchart showing specific processing of fuel injection timing and ignition timing correction according to the fourth embodiment.
FIG. 29 is a flowchart showing specific processing of fuel injection timing and ignition timing correction according to the fifth embodiment.
[Explanation of symbols]
1 Internal combustion engine
2 Intake air volume sensor
3 Crank angle sensor
4 Fuel injection valve
5 Spark plug

Claims (16)

In an internal combustion engine that forms a combustible air-fuel mixture in a predetermined region in a combustion chamber and ignites the air-fuel mixture with a spark plug to perform stratified combustion,
When torque reduction control of the engine is requested at the time of shifting of the automatic transmission connected to the internal combustion engine,
Ignition is performed when the combustible air-fuel mixture comes near the spark plug, and when it is requested to change the engine torque below the limit value of torque change that can be reliably ignited and burned without causing misfire, The fuel injection timing is corrected, and when a change in the engine torque exceeding the limit value is requested, both the ignition timing and the fuel injection timing are corrected simultaneously to change the engine torque. Control device for internal combustion engine. When a change in engine torque less than a predetermined value is requested when the torque down control is requested , either one of the ignition timing and the fuel injection timing is corrected, and a change in engine torque greater than a predetermined value is requested 2. The control apparatus for an internal combustion engine according to claim 1, wherein the engine torque is changed by simultaneously correcting the ignition timing and the fuel injection timing. At the time of the torque down control request, the engine torque is changed by correcting at least one of the ignition timing and the fuel injection timing, and then the intake air amount and the engine torque are maintained so that the changed engine torque is maintained in a desired combustion state. 3. The control apparatus for an internal combustion engine according to claim 1, wherein the ignition timing and the fuel injection timing are corrected again while correcting the fuel supply amount. A combustible air-fuel mixture is formed in a predetermined region in the combustion chamber, and the air-fuel mixture is ignited by a spark plug for stratified combustion,
Ignition timing control means for controlling the ignition timing by the spark plug;
Fuel supply means for injecting and supplying fuel;
Fuel supply amount control means for controlling the fuel supply amount from the fuel supply means;
An internal combustion engine comprising: fuel injection timing detection means for controlling the fuel injection timing from the fuel supply means;
Torque change instruction means for instructing quick change of the engine torque when engine torque down control is requested at the time of shifting of the automatic transmission coupled to the internal combustion engine;
When a torque change is instructed from the torque change instructing means , the limit value of the torque change that can be ignited and reliably ignited and burned without causing misfiring when the combustible mixture comes near the spark plug. When a change in engine torque of less than is requested, the ignition timing or fuel injection timing is corrected. When a change in engine torque greater than the limit value is requested, both the ignition timing and fuel injection timing are corrected simultaneously. And torque changing means for changing the engine torque ,
A control apparatus for an internal combustion engine, comprising: The torque changing means corrects either the ignition timing or the fuel injection timing when the torque change instruction means instructs to change the engine torque less than the predetermined value, and changes the engine torque greater than or equal to the predetermined value. 5. The control apparatus for an internal combustion engine according to claim 4, wherein the engine torque is changed by simultaneously correcting the ignition timing and the fuel injection timing when the engine is required. An intake air amount control means for controlling the intake air amount is included, and the torque changing means corrects at least one of the ignition timing and the fuel injection timing to change the engine torque, and then changes the engine torque in a desired combustion state. 6. The internal combustion engine according to claim 4, wherein the ignition timing and the fuel injection timing are corrected again while correcting the intake air amount and the fuel supply amount so that the engine torque after the change is maintained. Engine control device. The correction values for the ignition timing and the fuel injection timing are the current engine torque estimated from the engine operating state, the torque change value instructed by the torque change instruction means, and the current correction amount for the ignition timing and the fuel injection timing correction amount. The control device for an internal combustion engine according to any one of claims 4 to 6, wherein the controller is calculated from a torque coefficient as a change rate of the engine torque . The predetermined value is calculated from a current engine torque estimated from an engine operating state and a torque coefficient as a change rate of the current engine torque with respect to a correction amount of an ignition timing and a fuel injection timing. The control device for an internal combustion engine according to any one of claims 5 to 7. The correction of the intake air amount by the torque changing means is based on the target air-fuel ratio determined from the current operating state and the fuel supply amount corresponding to the changed engine torque calculated based on the instruction of the torque changing instruction means. 5. The calculation is performed by calculating a target cylinder intake air amount and performing correction via the intake air amount control means so that the cylinder intake air amount becomes the target cylinder intake air amount. Item 9. The control device for an internal combustion engine according to any one of Items 8 to 9. The correction of the fuel supply amount by the torque changing means calculates the target fuel supply amount from the target air-fuel ratio determined from the current operating state and the estimated value of the change in the cylinder intake air amount after the intake air amount correction, The fuel supply amount is corrected by the fuel supply amount control means so that the fuel supply amount becomes the target fuel supply amount in synchronization with a change in the cylinder intake air amount. The control device for an internal combustion engine according to any one of 9. The torque changing means reduces the engine torque by controlling at least one of the ignition timing and the fuel injection timing to the retard side when the torque change instructing means is instructed to reduce the engine torque. 11. The control device for an internal combustion engine according to any one of claims 4 to 10, wherein the control device is an internal combustion engine. The ignition timing, correction of the fuel injection timing control device for an internal combustion engine according to any one of claims 4 to claim 11, characterized in that it is performed in a plurality of combustion times. The torque change instructing means, in controlling the behavior of the running stability of the vehicle equipped with the internal combustion engine, one of claims 4 to claim 12, characterized in that instructing a change of the engine torque 1 A control apparatus for an internal combustion engine according to claim 1. The internal combustion engine according to any one of claims 4 to 13 , wherein the torque change instruction means instructs to change the engine torque at the time of shifting of an automatic transmission connected to the internal combustion engine. Control device. The fuel supply means, the control device for an internal combustion engine according to any one of claims 4 to claim 14, characterized in that inject and supply fuel directly into the cylinders of the engine. The fuel supply means, the control device for an internal combustion engine according to any one of claims 4 to claim 15, characterized in that inject and supply fuel into the intake passage of the engine.

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