JPH1061476A - Control device for internal combustion engine - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To quickly satisfy a demand for torque change of a stratified combustion internal combustion engine. A fuel injection timing and an ignition timing are synchronously retarded when a torque reduction request is made, so that the torque is quickly reduced in accordance with the request, and after a predetermined time elapses, a throttle opening degree is reduced. To reduce the cylinder intake air amount with a first-order lag, and while gradually reducing the fuel supply amount so as to maintain a constant air-fuel ratio, the difference between the cylinder intake air amount and the fuel supply amount. Depending on the change,
The fuel injection timing and ignition timing are re-corrected so as to keep the torque constant.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field 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 performing combustion at a lean air-fuel ratio by stratifying supply fuel.

[0002]

2. Description of the Related Art In an internal combustion engine provided with a fuel injection valve for directly injecting fuel into a cylinder, when torque reduction control is required at the time of shifting of an automatic transmission, the fuel injection timing from a direct injection type fuel injection valve is changed. 2. Description of the Related Art A control device for an internal combustion engine that realizes torque reduction by changing the thermal efficiency so as to deteriorate is known (Japanese Patent Laid-Open No. 4-301153).
Reference).

[0003]

However, in such a method of changing the torque according to the fuel injection timing as in such a conventional control device for an internal combustion engine, it is necessary to improve the fuel efficiency by realizing a lean air-fuel ratio by stratified combustion. However, since only the fuel injection timing is corrected and the ignition timing is not corrected, if the injection timing is greatly changed to greatly change the torque, the timing at which the combustible mixture comes near the spark plug does not match the ignition timing. And as a result,
Combustion may worsen, and misfire may occur, resulting in deterioration of drivability and exhaust.

In the method of changing the torque by the air-fuel ratio, the air-fuel ratio is usually set to a lean state near the stability limit in order to improve fuel efficiency by realizing a lean 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. As a result, the combustion may worsen, and eventually misfire may occur. It will worsen.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems. In an internal combustion engine that performs lean combustion by stratified combustion, a demand for a rapid torque change while minimizing deterioration of operability and exhaust gas is minimized. It is an object of the present invention to provide a control device for an internal combustion engine that can satisfy the following.

[0006]

SUMMARY OF THE INVENTION Accordingly, the present invention provides 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 lean combustion. Wherein the engine torque is changed by synchronizing and correcting both the ignition timing and the fuel injection timing at least under a predetermined condition when a change in the engine torque is requested.

(Operation / Effect) When performing lean combustion by stratified combustion, since the air-fuel ratio is controlled near the lean limit, when a rapid decrease in torque is required, the fuel supply amount is reduced to cope with this. This means that stable combustion cannot be obtained beyond the lean limit of the air-fuel ratio. So, ignition timing,
In the correction that synchronizes the fuel injection timing, it is possible to change the torque quickly by correcting the ignition timing and the fuel injection timing. The amount of change is limited.

[0008] Therefore, by synchronizing and correcting both the ignition timing and the fuel injection timing, a quick and large torque change request can be satisfied. Further, in the invention according to claim 2, when a change of the engine torque less than the predetermined amount is requested, one of the ignition timing and the fuel injection timing is corrected, and the change of the engine torque of the predetermined amount or more is requested. In this case, the ignition timing and the fuel injection timing are simultaneously corrected to change the engine torque.

(Operation / Effect) As described above, the ignition timing,
Since the torque can be changed within the respective limit ranges even with the fuel injection timing alone, any request that is less than the predetermined amount for which the torque can be changed by the single correction can be selected from either the ignition timing or the fuel injection timing. Change the torque by correcting only one side,
The request can be satisfied by synchronizing and correcting the ignition timing and the fuel injection timing only for a torque change request of a predetermined amount or more that cannot be satisfied by a single correction.

As a result, in a possible range, a simple system can be realized by performing only one correction, and the torque can be changed with high accuracy by synchronizing the two corrections only when necessary. Further, the invention according to claim 3 is characterized in that after at least one of the ignition timing and the fuel injection timing is corrected to change the engine torque, the intake air is maintained in a desired combustion state so that the changed engine torque is maintained. The ignition timing and the fuel injection timing are re-corrected while correcting the amount and the fuel supply amount.

(Operation / Effect) It is possible to quickly change the torque by correcting the ignition timing and the fuel injection timing.
Generally, the ignition timing and the fuel injection timing are set to optimal conditions in consideration of the efficiency and the exhaust purification performance in the state of the intake air amount and the fuel supply amount before the torque change.
Correcting the ignition timing and the fuel injection timing without changing the fuel supply amount will lower the efficiency and the exhaust purification performance.

Therefore, after the torque is rapidly changed in accordance with the ignition timing and the fuel injection timing, the intake air amount and the fuel supply amount are corrected while maintaining the changed torque.
Efficiency is improved by re-correcting the ignition timing and fuel injection timing.
It is possible to maintain the changed torque while satisfying (fuel efficiency) and exhaust purification performance. The invention according to claim 4 is
As shown in FIG. 1, a flammable air-fuel mixture is formed in a predetermined region in a combustion chamber, and this air-fuel mixture is ignited by an ignition plug to perform lean combustion and to control ignition timing by the ignition 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, and fuel injection timing detection means for controlling the fuel injection timing from the fuel supply means A torque change instructing means for instructing a rapid change in engine torque; and when the torque change instructing means instructs a change in torque, the ignition timing control means is provided at least under a predetermined condition. A torque changing means for changing the engine torque by synchronizing and correcting both the ignition timing and the fuel injection timing via the fuel injection timing control means. It is characterized in.

(Operation / Effect) When a torque change is instructed by the torque changing means, the torque changing means controls the ignition timing and the fuel injection timing through the ignition timing control means and the fuel injection timing control means at least under predetermined conditions. By performing the correction in synchronization with each other, the torque can be changed quickly, and by simultaneously performing the two corrections, a large torque change request can be satisfied.

According to a fifth aspect of the present invention, when the torque change instructing means instructs to change the engine torque to be less than a predetermined amount, the torque changing means may select one of the ignition timing and the fuel injection timing. When one of them is corrected and the change of the engine torque by a predetermined amount or more is requested, the ignition timing and the fuel injection timing are simultaneously corrected to change the engine torque.

(Operation / Effect) The torque changing means is provided with an ignition timing control means or a fuel injection timing control means in response to a request to change the torque less than a predetermined amount which is possible only in one of the ignition timing and the fuel injection timing. The ignition timing and the fuel injection timing are synchronously corrected via both control means only for a torque change request of a predetermined amount or more that cannot be satisfied by a single correction. .

Thus, as far as possible, a simple system can be realized 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 is configured to include intake air amount control means for controlling an intake air amount, wherein the torque changing means corrects at least one of the ignition timing and the fuel injection timing to reduce the engine torque. After the change, the ignition timing and the fuel injection timing are re-corrected while correcting the intake air amount and the fuel supply amount so that the changed engine torque is maintained in a desired combustion state.

(Operation / Effect) As described above, after the torque is rapidly changed by the ignition timing and the fuel injection timing, the intake air amount and the fuel supply amount are reduced while maintaining the changed torque. It is desirable to re-correct the ignition timing and the fuel injection timing while making corrections. 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 the torque is rapidly changed, the intake air amount control means and the fuel supply amount control means are changed. By re-correcting the ignition timing and the fuel injection timing while correcting the intake air amount and the fuel supply amount, the changed torque can be maintained while satisfying the efficiency (fuel efficiency) and the exhaust purification performance.

According to a seventh aspect of the present invention, the correction values of the ignition timing and the fuel injection timing are the current engine torque estimated from the operating state of the engine and the torque change value indicated by the torque change instruction means. And the relationship between the amount of change in torque and the correction amounts of the ignition timing and the fuel injection timing.

(Operation / Effect) For example, a torque coefficient (torque after change / current torque) is calculated from the estimated engine torque and the torque change value, and the change amount of the torque coefficient is calculated as the torque change amount. If the relationship between the ignition timing and the correction amount of the fuel injection timing is determined in advance, and the correction amount of the ignition timing and the fuel injection timing is determined from the calculated torque coefficient, the method can be performed easily and quickly. The correction amount can be obtained, and the torque change control can be performed with good responsiveness.

According to an eighth aspect of the present invention, the predetermined value is calculated from a current engine torque estimated from an operating state of the engine, and a relationship between a torque change amount and a correction amount of an ignition timing and a fuel injection timing. It is characterized by doing. (Operation / Effect) From the relationship between the amount of change in torque and the amount of correction of the ignition timing or fuel injection timing, a limit is determined for a correction amount that can maintain stable combustion by a single correction, and this is calculated as a predetermined value. In addition, simple correction can be performed independently as much as possible.

According to a ninth aspect of the present invention, the correction of the intake air amount by the torque changing means is calculated based on a target air-fuel ratio determined from a current operating state and an instruction of the torque changing instruction means. By calculating a target cylinder intake air amount from the fuel supply amount corresponding to the changed engine torque and correcting the target cylinder intake air amount via the intake air amount control means so that the cylinder intake air amount becomes the target cylinder intake air amount. Is performed.

(Operation / Effect) The target cylinder intake air amount is calculated based on the target air-fuel ratio and the fuel supply amount corresponding to the changed engine torque, and the intake air amount is calculated so that the target cylinder intake air amount is obtained. By controlling the amount, the amount of intake air can be controlled to a desired value with high accuracy.

According to a tenth aspect of the present invention, the correction of the fuel supply amount by the torque changing means includes a change in the target air-fuel ratio determined from a current operation state and a change in the cylinder intake air amount after the correction of the intake air amount. From the estimated value of the above, the target fuel supply amount is calculated, and the fuel supply amount is corrected through the fuel supply amount control means so as to be the target fuel supply amount in synchronization with a change in the cylinder intake air amount. It is characterized by being performed.

(Operation / Effect) After correcting the intake air amount, a change in the cylinder intake air amount is estimated in consideration of the delay, and the target fuel supply amount is calculated from the estimated value. By synchronizing and correcting the fuel supply amount to the target value, the fuel supply amount can be controlled with high accuracy even when the intake air amount changes, so that the torque after the change can be maintained well during this time. it can.

According to an eleventh aspect of the present invention, when the torque change instructing means instructs a decrease in engine torque, at least one of the ignition timing and the fuel injection timing is retarded. It is characterized in that the engine torque is reduced by controlling to the side. (Operation / Effect) By controlling at least one of the ignition timing and the fuel injection timing to the retard side in response to the instruction to decrease the torque, the engine torque can be reduced with good responsiveness.

According to a twelfth aspect of the present invention, the ignition timing control means and the fuel injection timing control means pre-ignite so as to secure a torque increase allowance for an engine torque increase instruction from the torque change instruction means. The timing and the fuel injection timing are controlled to the retard side, and the torque changing means, when the increase of the engine torque is instructed by the torque change instructing means, advances at least one of the ignition timing and the fuel injection timing. It is characterized in that the engine torque is increased by controlling to the side.

(Operation / Effect) In response to the instruction to increase the torque,
By controlling at least one of the ignition timing and the fuel injection timing to the advanced side, the engine torque can be increased with good responsiveness. The invention according to claim 13 is characterized in that the correction of the ignition timing and the fuel injection timing is executed separately for a plurality of combustion times.

(Operation / Effect) The torque can be smoothly changed by gradually correcting the torque for each of a plurality of combustions. The invention according to claim 14 is characterized in that the torque change instructing means instructs a change in engine torque when controlling behavior such as running stability of a vehicle equipped with the internal combustion engine.

(Operation / Effect) For example, when controlling behavior such as running stability of a vehicle, by instructing to change the engine torque, it is possible to perform optimum engine control while satisfying running stability and the like. it can. The invention according to claim 15 is characterized in that the torque change instructing means instructs a change in engine torque at the time of a shift of an automatic transmission connected to the internal combustion engine.

(Operation / Effect) For example, by instructing to change the engine torque at the time of shifting of the automatic transmission, torque shock at the time of shifting can be reduced. The invention according to claim 16 is characterized in that the fuel supply means directly injects and supplies fuel into a cylinder of the engine.

(Operation / Effect) The present invention can be applied to an engine in which fuel is injected directly into a cylinder in which an air-fuel mixture for stratified combustion is easily formed. The invention according to claim 17 is characterized in that the fuel supply means injects and supplies fuel to an intake passage of the engine.

(Operation / Effect) It is possible to perform stratified combustion by injecting fuel into the intake passage, and the present invention can be applied to such an engine.

[0033]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 shows a system configuration of an embodiment, and FIG. 3 shows a configuration of a circuit centering on the microcomputer of the embodiment. As means for detecting the operating state of the internal combustion engine 1, an intake air amount sensor 2 detects an intake air amount. A crank angle sensor 3 directly or indirectly connected to a crank angle shaft or a cam shaft rotating in conjunction with the crank angle shaft detects a crank angle position (crank angle) of the engine 1 and a rotation speed of the engine. I do.

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 ignition plug 5 so that lean combustion can be performed. In addition, a water temperature sensor 6 for detecting an engine cooling water temperature (hereinafter referred to as a water temperature) and an air-fuel ratio sensor 7 for detecting an air-fuel ratio by detecting an oxygen concentration in exhaust gas are provided.

The input / output of information to / from the outside and various calculations are realized by the circuit shown in FIG. The CPU 301 executes calculations, and the ROM 302 stores in advance control programs and various data described later. The RAM 303 temporarily stores information during execution of the program. Input port 30
4 is for inputting information from external sensors, etc.
The converter 305 performs A / D conversion on an external analog signal so as to be handled by a computer. The output port 306 outputs a signal for driving an external device.

Next, the operation of the above system will be described. As an advantage of performing stratified combustion, there is an improvement in fuel efficiency due to a significant leaning of the air-fuel ratio. Here, in order to achieve good combustion in an engine that performs stratified combustion, it is necessary to perform ignition when the combustible mixture reaches around 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, the ignition is performed when the ignition plug comes to the center of the combustible air-fuel mixture or slightly toward the advancing direction. Is also desirable from the point of efficiency.

By the way, when controlling the behavior of the vehicle, such as when securing the running stability of the vehicle, there is a case where a request to quickly change the output torque of the engine occurs. In a conventional engine that performs homogeneous mixed combustion, a method of increasing the fuel injection amount to make the fuel rich when increasing the torque, and decreasing the fuel injection amount to make the fuel lean when decreasing the torque is considered. However, when performing lean combustion by stratification, operation is performed at an ultra-lean air-fuel ratio that is close to the stability limit in order to achieve the greatest improvement in fuel efficiency, so it is possible to enrich when increasing torque. However, it is impossible to further increase the lean when the torque is reduced. In addition, in order to reduce the torque while keeping the air-fuel ratio constant, it is conceivable to decrease the fuel injection amount and simultaneously decrease the air amount. It is difficult to reduce the torque quickly.

Therefore, as a method of rapidly reducing the torque while maintaining the ultra-lean air-fuel ratio, there is a method of shifting the peak position of the in-cylinder pressure by changing the fuel injection timing and / or the ignition timing to reduce the torque. Conceivable. Normally, as shown in FIG. 4, ignition occurs when the spark plug comes to the center of the combustible air-fuel mixture, and as shown in FIG. 5, the in-cylinder pressure peak position (θpmax) at that time is a predetermined target value. (θtarg: MBT or knock limit point), the fuel injection timing and the ignition timing are set. 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. When the in-cylinder pressure peak position shifts later and the peak value of the in-cylinder pressure falls, the generated torque 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.

Therefore, if the maximum in-cylinder pressure timing (θpmax) is changed by controlling the fuel injection timing and the ignition timing, the torque can be reduced without changing the air-fuel ratio, and the fuel and fuel can be reduced. Since ignition 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 mixture is ignited, and it takes a long time for the combustion, so that the combustion waveform becomes as shown in FIG. The internal pressure peak moves later, and a decrease in torque can be realized from the relationship shown in FIG. Also, when the ignition timing is delayed, as shown in FIG. 9, the end of the combustible air-fuel mixture is ignited, and similarly, it takes a long time for the combustion, so that the combustion waveform is as shown in FIG. The in-cylinder pressure peak moves later, and a reduction in torque can be realized from the relationship in FIG.

In the case of correcting only the fuel injection timing or only the ignition timing, the ignition is performed when the combustible air-fuel mixture comes close to the spark plug, and in order to reliably ignite and burn without misfiring, it is necessary to use both. Because the width of the timing that can be corrected 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 and ignited, and FIG. As shown, the timing can be corrected in a larger range, and as a result, the torque can be corrected in a larger range. Therefore, according to this method, the combustible air-fuel mixture is completely burned, so that the emission is not deteriorated and a rapid decrease in torque can be realized.

The present invention focuses on the above points, and is based on correcting the fuel injection timing and the ignition timing synchronously when a quick torque change is required. However, even after the torque is reduced by this method, if the ignition timing and the fuel injection timing are delayed, the fuel supply amount for the required torque remains the same, and the efficiency is poor because the amount is large. In addition, when a request for lowering the torque occurs next time, there is no retardation allowance, and it is not possible to respond.

Therefore, after realizing a rapid decrease in torque as described above, the reduced torque is used for more efficient fuel supply, fuel injection timing and ignition timing (for example, MBT).
As shown in FIG. 13, while reducing the amount of intake air by an electronically controlled throttle or the like, the amount of fuel injection is adjusted so as to maintain a constant torque in accordance with the time constant of the change in cylinder intake air amount. The fuel injection timing and the ignition timing are corrected synchronously so as to be a predetermined value while decreasing the amount. This allows
Since the required torque can be realized by the highly efficient fuel injection amount, the fuel injection timing and the ignition timing, it is possible to cope with the next request for the torque reduction.

Hereinafter, specific control of the embodiment according to the present invention will be described with reference to flowcharts. 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 step 14 is executed.
In 02, a correction value of the fuel injection timing and a correction value of the ignition timing for changing the torque are calculated.

FIG. 15 shows a flow of the fuel supply control, which is executed in synchronization with a reference signal output from the crank angle sensor 3 at a constant crank angle cycle (180 ° in the case of a four-cylinder engine). In step 1501, fuel supply,
Make settings for hardware to actually perform ignition.

Next, different embodiments of the specific processing of each step of FIGS. 14 and 15 will be described. FIG.
Corresponds to step 1401 in FIG. 14 in the first embodiment.
This shows a specific process of (torque change determination).
In step 1601, the current operation state is detected.

In step 1602, it is determined whether or not the torque needs to be changed 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 flow advances to step 1603 to set the value of the flag FLGTQR to 1. Next, in step 1604, a required torque change value (dTrq) is calculated, and the processing ends.

Here, the torque change value (dTrq) may be obtained by searching 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 rotation 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.

If it is determined in step 1602 that the torque does not need to be changed, the flow advances to step 1605 to reset the value of the flag FLGTQR to 0. Then step 16
At 06, the torque change value (dTrq) is set to 0, and the process ends. Fig. 17
Corresponds to step 1402 in FIG. 14 in the first embodiment.
(Correction of fuel injection timing and ignition timing).

At step 1701, it is determined whether or not the value of the flag FLGTQR is 0. If it is determined in step 1701 that the value of the flag FLGTQR is 0, that is, if there is no request to change the torque, 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 correction value (dTign) is set to 0, and the process ends. That is, since there is no request for changing the torque, the current values are maintained without changing the fuel injection timing and the ignition timing.

If it is determined in step 1701 that the value of the flag FLGTQR is 1, that is, if a request is made to change the torque, the flow 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 the limit value of the torque change that can be performed while maintaining the flammability only by the ignition timing correction.
Is for determining whether or not a request for torque change is possible only with the ignition timing. Generally, the optimal ignition timing (here, MB
Since the relationship shown in FIG. 25 is established between the ignition timing correction value from T) and the ratio of torque to torque at the optimal ignition timing (torque coefficient), the torque coefficient LTign at the retard limit dTign1 And dT1 is determined by the following equation from the torque (Trq) determined from FIG.

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, the torque can be changed only by correcting the ignition timing. So step 17
At 05, the fuel injection timing correction value (dTinj) is set to 0, and step 17
In 06, the 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. 25, and the processing ends.

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, step 17
07 and step 1708, the fuel injection timing correction value (dTinj) for the torque change value (dTrq) as in step 1706
And the ignition timing correction value (dTign) are calculated based on the table shown in FIG. 26, and the processing ends.

FIG. 26 is a characteristic diagram showing the rate of change in torque when the optimum ignition timing and the optimum fuel injection timing set accordingly are changed. FIG. 18 shows a specific process of step 1501 (fuel supply, ignition) in FIG. 15 in the first embodiment. Step 1801
Then, the current operation state is read.

In step 1802, the fuel injection amount is calculated based on the operation 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 a map determined from the driving state.

In step 1805, settings are made to actually output the fuel injection pulse. In step 1806, the reference fuel injection timing (Tinj s), the fuel injection timing (Tin
j) is set. In step 1807, the reference ignition timing (Tig
n map) is set to the ignition timing (Tign) subjected to the ignition timing correction (dTign), and the process ends.

Based on these set values, the hardware performs fuel injection and ignition at the set fuel injection timing (dTinj) and ignition timing (Tign). In the present embodiment, the characteristics of the torque coefficient shown in FIGS. 25 and 26 are constant irrespective of the operating conditions. However, this may be a configuration having a plurality of these tables for each operating condition. improves.

Next, a second embodiment will be described.
In the above-described embodiment, when the required torque change value is small, the correction is performed only by the ignition timing. However, in the present embodiment, when the torque change value is small, the correction is performed only by the fuel injection timing. Things. Fig. 14, Fig. 15, Fig. 16, Fig. 18
Can be used in the same manner as in the first embodiment, but in the second embodiment, FIG. 14 is a diagram showing a specific process of step 1402 (correction of fuel injection timing and ignition timing) in FIG. FIG. 19 is used instead of 17.

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 request to change the torque, the process proceeds to step 1902. Go to the fuel injection timing correction value
(dTinj) is set to 0, and the ignition timing correction value (dTi
gn) is set to 0, and the fuel injection timing and the ignition timing are not corrected.

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 to change the torque, the flow 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 the limit value of the torque change that can be performed while maintaining the combustibility only by correcting the fuel injection timing.
04 is for judging whether it is possible to request a torque change only by correcting the fuel injection timing. Here, the fuel injection timing correction value from the optimum fuel injection timing (for example, the fuel injection timing such that the ignition timing is MBT and FIG. 4 can be realized), and the ratio of the torque to the torque at the optimum fuel injection timing (torque coefficient)
Since a relationship as shown in FIG. 27 is generally established between the torque coefficient LTinj at the retard limit dTinj1,
From the torque (Trq) obtained from FIG. 24, dT2 is obtained by the following equation.

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 can be changed only by the fuel injection timing. So step 19
The fuel injection timing correction value (dTinj) corresponding to the correction coefficient KTrq obtained from the torque change value (dTrq) by
Is calculated based on the table shown in FIG.

KTrq = 1−dTrq / Trq Next, at step 1906, the ignition timing correction value (dTinj) is set to 0, and the process is terminated. 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 step
The torque change value (dTr
The fuel injection timing correction value (dTinj) and the ignition timing correction value (dTign) for q) are calculated based on the table shown in FIG. 26, and the processing ends.

Next, a third embodiment will be described.
In this embodiment, after realizing a rapid decrease in torque by the fuel injection timing or the ignition timing, the intake air amount is corrected by an electronically controlled throttle or the like, and the torque is kept constant in synchronization with a change in the cylinder intake air amount. Fuel supply amount and fuel injection timing,
By changing the ignition timing, a highly efficient operating condition (ignition timing
By recovering to the MBT or knock limit, it is possible to cope with the next request for torque reduction.

FIGS. 14, 15 and 16 can be used in the same manner as in 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 or not the flag ADJUST is 0. Here, the 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.
If it is determined that ADJUST is 0 and no correction has been performed, the process proceeds to step 2002, where the flag FLGTRQ is set to 0.
It is determined whether or not.

If the value of the flag FLGTQR is determined to be 0 in step 2002, the fuel injection timing correction value is determined in step 2003.
(dTinj) is set to 0, and in step 2004, the ignition timing correction value
(dTinj) is set to 0, and the fuel injection timing and the ignition timing are not corrected. In step 2005, the flag FLGADJ is set to 0, and in step 2006, 1 is substituted for the fuel supply amount correction coefficient αf, and the process ends.

In step 2002, the flag FLGTRQ is set to 1;
If it is determined that there is a torque change request,
Proceed to 2007. In step 2007, the absolute value of the torque change value
It is determined whether (| dTrq |) is smaller than a predetermined value (dT1). Here, the calculation of the predetermined value (dT1) is the same as in the first embodiment.

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 0. Step 2009
Then, the ignition timing correction value corresponding to the torque change value (dTrq)
(dTign) is calculated based on the table shown in FIG. 25 as in the first embodiment.

In step 2010, the fuel injection timing immediately after the torque change request is made or the presence or absence of the ignition timing correction is shown.
(1 when present) Set the flag FLGADJ to 1. 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.

That is, in steps 2012 and 2013, the fuel injection timing correction value (dTin) for the torque change value (dTrq)
j) and the ignition timing correction value (dTign) are calculated based on the table shown in FIG. 26 in the same manner as in the first embodiment, and thereafter, the processing proceeds to step 2010, step 2011, and step 2006, and the processing described above is performed. And exit. 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 order to achieve the optimal ignition timing and the associated optimal fuel injection timing), the intake air amount, the fuel supply amount, the fuel injection timing, and the ignition timing are corrected in step 2014, and the process ends.

FIG. 21 specifically shows the process of step 2014 in FIG. In step 2101, the flag
It is determined whether or not FLGAIR is 0. 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 if the intake air amount has been corrected, and set to 0 if not. Step 21
If the flag FLGAIR is determined to be 0 in 01, that is, if the correction of the intake air amount has not been performed, the process proceeds to step 2102, where the current torque Trq obtained by performing the above correction based on the ignition timing and the fuel injection timing. 'Is calculated by the following equation.

Trq ′ = Trq−dTrq In step 2103, based on the current torque Trq ′, FIG.
Calculate the fuel supply amount from the characteristics of the current target air-fuel ratio,
A target cylinder intake air amount is calculated from the fuel supply amount. In step 2104, it is determined whether the value of the counter C set in step 2011 in FIG. 20 has become 0 or less, that is, whether a predetermined time has elapsed since the correction of the fuel injection timing and the ignition timing was performed. If it is 0 or less, step 2105
Otherwise, in step 2112, the value of the counter C is decremented by one, and the process ends.

If it is determined in step 2104 that the value of the counter C is equal to or less than 0, 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 electronic throttle opening. In step 2106, since the intake air amount was corrected, the flag FLGAIR
Is set to 1.

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 from a map created from data previously checked for each operating condition. In step 2108, the current cylinder intake air amount after the throttle is corrected is estimated, the target fuel supply amount is calculated from the estimated value and the target air-fuel ratio, and the current fuel supply amount is used as the target fuel supply amount. The correction coefficient αf (T0) is calculated.

In steps 2109 and 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). Is calculated. In step 2111, the value of the counter T is decremented by 1, and the processing ends. Step 2101
If the flag FLAGAIR is not 0, that is, if the correction of the intake air amount has already been performed, the routine proceeds to step 2113, where it is determined whether or not the value of the counter T is 0 or less.

If the value of the counter T is not less than 0, that is, if it is determined that the time constant T0 has not elapsed and the intake air amount is changing, the cylinder corresponding to the current counter T is determined in step 2114. A correction coefficient αf for estimating the intake air amount, calculating a target fuel supply amount from the estimated value and the target air-fuel ratio, and setting the current fuel supply amount as the target fuel supply amount.
Calculate (T).

In steps 2115 and 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). Is calculated. In step 2117, the value of the counter T is decremented by 1, and the processing ends. If it is determined in step 2113 that the value of the counter T has become 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, the fuel injection timing, Since it is determined that the ignition timings are also corrected to the optimum values, the flag FLAGAIR is set to 0 in step 2118, and the
In step 2119, the flag ADJUST is set to 0, and the process ends.

FIG. 22 is a view showing the state of FIG.
Step 1501 (fuel supply, ignition correction) is specifically shown. In step 2201, the current operation state is read. In step 2202, the basic fuel supply amount (Qfuel s), and step 2203
Then, the reference fuel injection timing (Tinj s)
In step 2204, the reference ignition timing (Tign ma
p) is calculated based on a map determined from the operating state.

In step 2205, the basic fuel supply amount (Q
fuel s) is set to actually output a fuel injection pulse corrected by αf, and in step 2206, the reference fuel injection timing (Tinj s) is set to the fuel injection timing (Tinj) corrected by dTinj, and in step 2207, the reference ignition timing (Tignj) is set. Set the ignition timing (Tign) corrected by dTign to map).

In step 2208, it is determined whether or not the flag FLGADJ is 0. If the flag is 0, the flag ADJUSTU is set in step 2209.
Is set to 0, and if not 0, the flag AD is set in step 2210.
Set JUSTU to 1 and exit. Then, based on the set values from step 2205 to step 2207,
The hardware performs the actual fuel injection and ignition.

Next, a fourth embodiment will be described.
Whereas the third embodiment is configured to correct only the ignition timing when the torque change value is small, the present embodiment is configured to correct only the fuel injection timing when the torque change value is small. FIG. 23 is used instead of FIG. Modifications of the third embodiment are the same as the modifications of the first embodiment of the second embodiment, and thus description thereof is omitted.

Next, a fifth embodiment will be described.
In the first to fourth embodiments, when the amount of change in the torque is small, the reduction in the torque is realized by correcting only the fuel injection timing or only the ignition timing. Regardless of the amount, it may be configured to always correct both the fuel injection timing and the ignition timing. In this case, the processing shown in FIG. 28 is performed instead of FIG. 17 and FIG. 19, and the processing shown in FIG. 29 is performed instead of FIG. 20 and FIG. The details of the processing are clear from the figure, and thus the description is omitted.

In the above-described embodiment, 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, the correction may be performed by dividing the combustion into N times of dTign / N, or from the characteristics of FIGS. 25 to 27, dTign may be set such that the torque change amount becomes equal each time. May be divided into N times of combustion for correction.

Further, in the above embodiment, an in-cylinder direct injection engine for directly injecting fuel into a cylinder has been described as an example. However, the present invention is not limited to this as long as it is an engine that performs stratified combustion.
Any engine that performs fuel injection in the intake passage can be applied to any engine that can perform stratified combustion. Further, in the above embodiment, the case where the torque is all reduced has been described, but the ignition timing and the fuel injection timing are not set to the MBT ignition timing and the fuel injection timing corresponding thereto, but are set to the retard side.
If a torque increase margin is secured (a point where the correction value is 0 on the retard side from FIGS. 25 to 27), the present invention can be applied to the case where the torque is increased.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the configuration and functions of the invention according to claim 4;

FIG. 2 is a diagram showing a system configuration according to an embodiment of the present invention.

FIG. 3 is an exemplary view showing a configuration of a circuit centering on the microcomputer of the embodiment.

FIG. 4 is a sectional view showing a combustion state during normal control of ignition timing and fuel injection timing.

FIG. 5 is a time chart showing a state change of an in-cylinder pressure and a volume change amount during the normal control.

FIG. 6 is a diagram showing the relationship between the in-cylinder pressure peak position and the indicated mean effective pressure.

FIG. 7 is a cross-sectional view showing a combustion state when ignition timing is controlled normally and 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 control.

FIG. 9 is a cross-sectional view showing a combustion state when the fuel injection timing is controlled normally and the 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 control.

FIG. 11 is a cross-sectional view showing a combustion state when ignition timing and fuel injection timing are both retarded.

FIG. 12 is a time chart showing a state change of an in-cylinder pressure and a volume change amount during the retard control.

FIG. 13 is a time chart showing changes in various state quantities when control according to the present invention is performed.

FIG. 14 is a flowchart for calculating a correction amount of a fuel injection amount and a correction amount of an ignition timing.

FIG. 15 is a flowchart of fuel supply control.

FIG. 16 is a flowchart illustrating a specific process of a 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 illustrating specific processing of fuel supply and ignition according to the first embodiment.

FIG. 19 is a flowchart illustrating a specific process of a torque change determination according to the second embodiment.

FIG. 20 is a flowchart illustrating specific processing of fuel injection timing and ignition timing correction according to the second embodiment.

FIG. 21 is a flowchart showing a specific process of re-correcting the fuel injection timing and the ignition timing during the above process.

FIG. 22 is a flowchart showing specific processing of fuel supply and ignition according to the second embodiment.

FIG. 23 is a flowchart showing specific processing of fuel injection timing and ignition timing correction according to the third embodiment.

FIG. 24 is a diagram illustrating a relationship between an engine rotation speed, a fuel supply amount, and an 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 a fuel injection timing and an 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]

 DESCRIPTION OF SYMBOLS 1 Internal combustion engine 2 Intake air amount sensor 3 Crank angle sensor 4 Fuel injection valve 5 Spark plug

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Claims (17)

[Claims] 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 lean combustion, at least when a change in engine torque is required, The control device for an internal combustion engine according to claim 1, wherein the engine torque is changed by synchronizing and correcting both the ignition timing and the fuel injection timing. 2. When a change in the engine torque less than a predetermined value is requested, one of the ignition timing and the fuel injection timing is corrected. 2. The control device 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. 3. An intake air amount and a fuel supply amount such that at least one of the ignition timing and the fuel injection timing is corrected to change the engine torque, and the changed engine torque is maintained in a desired combustion state. 2. The system according to claim 1, wherein the ignition timing and the fuel injection timing are corrected again while correcting the ignition timing.
A control device for an internal combustion engine according to claim 2 or 3. 4. An ignition timing control means for forming a combustible air-fuel mixture in a predetermined region in a combustion chamber, igniting the air-fuel mixture with an ignition plug to perform lean combustion, and controlling an ignition timing of the ignition 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, and fuel injection timing detection means for controlling the fuel injection timing from the fuel supply means. An internal combustion engine comprising: a torque change instructing means for instructing a rapid change in engine torque; and when the torque change instructing means instructs a change in torque, the ignition timing control means and the fuel And a torque changing means for changing the engine torque by synchronizing and correcting both the ignition timing and the fuel injection timing via the injection timing control means. A control device for an internal combustion engine, comprising: 5. The torque change means corrects one of an ignition timing and a fuel injection timing when a change in engine torque less than a predetermined value is instructed by the torque change instructing means, and corrects at least a predetermined value. 5. The control device for an internal combustion engine according to claim 4, wherein when the change of the engine torque is requested, the ignition timing and the fuel injection timing are simultaneously corrected to change the engine torque. 6. An intake air amount control means for controlling an intake air amount, wherein said torque changing means corrects at least one of an ignition timing and a fuel injection timing to change an engine torque, and The ignition timing and the fuel injection timing are re-corrected while the intake air amount and the fuel supply amount are corrected so that the engine torque after the change is maintained in the combustion state. 6. The control device for an internal combustion engine according to claim 5. 7. The correction values for the ignition timing and the fuel injection timing are as follows:
Calculated from the relationship between the current engine torque estimated from the operating state of the engine, the torque change value instructed by the torque change instructing means, and the amount of change in torque and the correction amount of ignition timing and fuel injection timing. The control device for an internal combustion engine according to any one of claims 4 to 6, wherein: 8. The system according to claim 1, wherein the predetermined value is calculated from a current engine torque estimated from an operating state of the engine and a relationship between a torque change amount, 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. 9. The correction of the intake air amount by the torque changing means corresponds to a target air-fuel ratio determined from a current operating state and a changed engine torque calculated based on an instruction of the torque change instructing means. And calculating the target cylinder intake air amount from the fuel supply amount and correcting the target cylinder intake air amount via the intake air amount control means so that the target cylinder intake air amount becomes the target cylinder intake air amount. A control device for an internal combustion engine according to any one of claims 4 to 8. 10. The correction of the fuel supply amount by the torque changing means is performed based on a target air-fuel ratio determined from a current operation state and an estimated value of a change in the cylinder intake air amount after the correction of the intake air amount. The method is performed by calculating an amount and correcting the amount of fuel supplied to the target amount of fuel supply through the fuel supply amount control means in synchronization with a change in the amount of cylinder intake air. Claims 4 to 9
The control device for an internal combustion engine according to any one of the above. 11. The torque change means, when a decrease in engine torque is instructed by the torque change instructing means,
11. The control device for an internal combustion engine according to claim 4, wherein the engine torque is reduced by controlling at least one of an ignition timing and a fuel injection timing to a retard side. 12. The ignition timing control means and the fuel injection timing control means delay the ignition timing and the fuel injection timing in advance so as to secure a torque increase margin in response to an engine torque increase instruction from the torque change instruction means. When the increase of the engine torque is instructed by the torque change instructing means, the torque changing means controls at least one of the ignition timing and the fuel injection timing to the advanced side to thereby increase the engine torque. The control device for an internal combustion engine according to any one of claims 4 to 11, wherein the control value is increased. 13. The control of an internal combustion engine according to claim 4, wherein the correction of the ignition timing and the fuel injection timing is executed separately for a plurality of combustion batches. apparatus. 14. The torque change instructing means, when controlling behavior such as running stability of a vehicle equipped with the internal combustion engine,
5. An instruction to change the engine torque.
The control device for an internal combustion engine according to any one of claims 13 to 13. 15. The torque change instructing means according to claim 4, wherein the torque change instructing means instructs a change in engine torque during a shift of an automatic transmission connected to the internal combustion engine. 3. The control device for an internal combustion engine according to claim 1. 16. The fuel supply device according to claim 4, wherein the fuel supply means directly injects and supplies fuel into a cylinder of the engine.
16. The control device for an internal combustion engine according to any one of 15. 17. The fuel supply device according to claim 4, wherein the fuel supply unit injects and supplies fuel to an intake passage of the engine.
The control device for an internal combustion engine according to any one of the above.