JPH11201010A - Ignition timing control device for internal combustion engine - Google Patents

Abstract

(57) [Problem] To provide a stratified engine capable of setting an ignition timing as required even when the EGR amount at the time of transition changes, and preventing misfiring, fuel consumption and deterioration of exhaust. SOLUTION: In a stratified engine 1 which injects fuel by an in-cylinder injection valve 9 to stratify and operate an air-fuel mixture, a basic ignition timing is set by a fuel injection amount and an engine speed, and further, an EGR rate is estimated. And an ignition advance correction is made based on the EGR rate and the intake air amount.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art An example of a conventional ignition timing control device for an internal combustion engine is shown in FIG. 16 (see Japanese Patent Application Laid-Open No. 5-240134). In the figure, 101 is an engine, 102 is an air flow meter, 103 is an intake pipe pressure sensor, 104 is an EGR valve for adjusting the recirculation amount of exhaust gas, 105 is a spark plug, 106 is an electromagnetic pickup for detecting the engine speed, 107 is A control unit 108 is an accelerator opening sensor that detects the throttle valve opening TVO. Control unit 10
7, calculates the basic ignition timing in accordance with the loading and engine speed N and the intake pipe pressure P _b and the engine rotational speed N intake pipe pressure P _b. On the other hand, regarding the EGR, the engine speed N
And calculating a required EGR rate according to the intake pipe pressure P _b, are the EGR rate advancing the ignition timing according to the correction (see Japanese Patent Laid-Open No. 5-332186). FIG. 17 is a control flowchart, and FIG. 18 is an ignition advance correction .DELTA.ADV characteristic diagram. In the prior art, the ignition advance correction .DELTA.ADV is increased in accordance with the EGR rate as shown in the figure. This is EGR
This is because the burning rate is reduced due to the increase of the inert gas therein.

[0003]

However, when the conventional ignition timing control device for an internal combustion engine as described above is applied to a gasoline direct injection type engine, stratified combustion and homogeneous combustion are switched according to the operating state. Considering the case where the combustion state is switched from stratified combustion to homogeneous combustion in order to introduce a large amount of EGR during stratified combustion and stop introducing EGR during lean homogeneous combustion, the ignition timing immediately corresponds to homogeneous combustion. and it is switched to, for gradually decreasing not become actual EGR rate is zero immediately in the intake passage, and correcting the ignition timing according to the engine rotational speed N and the intake pipe pressure P _b in the determined EGR rate according to However, there is a problem that such a delay in the EGR rate is not reflected, which may lead to misfiring and deterioration of fuel efficiency and exhaust. The present invention has been made in view of such a conventional problem, and the EGR is performed during a transient operation.
It is an object of the present invention to solve the above problem by providing a means for estimating the amount to correct the ignition timing.

[0004]

SUMMARY OF THE INVENTION Therefore, the present invention provides a stratified engine that injects fuel in a cylinder to stratify an air-fuel mixture to operate in a stratified engine based on a fuel injection amount and an engine speed. And a means for estimating the EGR rate is provided, and the advance angle is corrected based on the EGR rate and the intake air amount. According to a second aspect of the present invention, in the ignition timing control device for an internal combustion engine according to the first aspect, the EGR rate is estimated based on the intake pipe pressure and the intake air amount. According to a third aspect of the present invention, in the ignition timing control device for an internal combustion engine according to the first aspect, the EGR rate is estimated based on the intake pipe pressure and the throttle valve opening. According to a fourth aspect of the present invention, in the ignition timing control apparatus for an internal combustion engine according to the first aspect, the EGR
The rate is estimated based on the opening of the EGR valve. According to a fifth aspect of the present invention, in the ignition timing control device for an internal combustion engine according to the first aspect, the EGR rate is estimated based on the opening degree of the EGR valve and the differential pressure across the EGR valve.

[0005]

Embodiments of the present invention will be described below with reference to the drawings. <First Embodiment> FIG. 1 is a diagram showing a first embodiment. First, the configuration will be described. The engine 1 is a direct injection type spark ignition engine, and has a fuel injection valve 9 for directly injecting fuel into a cylinder. The engine 1 can switch the combustion state in accordance with the operating conditions, and at low load and low speed, stratified combustion in which fuel is injected in the latter half of the compression stroke to form a rich mixture near the ignition plug 5. On the high load side or high rotation side adjacent to the stratified combustion region, the fuel is injected in the intake stroke to form a homogeneous and lean air-fuel mixture in the cylinder, and the homogeneous lean combustion is performed. Further, on the high-load side or high-speed side, fuel is injected in the intake stroke to perform homogeneous combustion in which a homogeneous and stoichiometric mixture is formed in the cylinder. The intake passage 11 has an E
The EGR passage 11 for returning the GR is connected, and the EGR valve 4 is opened and closed to open and close the EGR during the intake air.
It is possible to control the amount. Further, the intake passage 10
An air flow meter 2 for detecting an intake air amount, an intake pressure sensor 3 for detecting an intake pipe pressure, a throttle valve 13 for adjusting an intake air amount, and a throttle opening sensor 8 for detecting an opening degree of the throttle valve 13 are provided. ing. The signals of the air flow meter 2, the intake pressure sensor 3, and the throttle opening sensor 8 are transmitted to the control unit 7 together with the signal of the electromagnetic pickup 6 for detecting the rotation speed of the engine.
The control unit 7 calculates the intake air amount, the ignition timing, the EGR amount, the fuel injection amount, and the fuel injection timing based on such information.

FIG. 2 shows a time change when acceleration is started during stratified combustion. When the vehicle accelerates at t ₀ , the throttle valve opening TVO increases. On the other hand, the throttle valve opening TV
Since the required torque increases with the increase of O, the combustion state is switched from stratified combustion to homogeneous lean combustion. However, since it is necessary to absorb the torque step, first the EGR is performed at time t ₀ .
At the time t ₁ when the actual EGR rate has become sufficiently small, and is switched to homogeneous lean combustion. In the conventional example, although the ignition timing can be the advance correction according to the change of the intake pipe pressure P _b, E
Since there is no means for correcting the GR delay, the angle is over-advanced from the actual required advance angle.

FIG. 3 shows the required ignition timing with and without EGR. During the stratified combustion to the advance requests combustion is deteriorated because the amount of vaporization decreases of fuel supplied in accordance with the intake air quantity Q _a increases. This is because the saturated vapor concentration of the fuel becomes low because the cylinder pressure and the temperature become high. Further, when the EGR increases, the amount of inert gas increases and the combustion deteriorates, so that the demand is further advanced. Because during the stratified combustion timing to reach the fuel to the spark plug about the period of spray rate and the injection of the fuel itself that is injected from the fuel injection valve 9 is determined, the timing of ignition in the injection pulse width T _i and the engine speed N Decided.

That is, in the first embodiment, as shown in the control flowchart of FIG.
1) The engine speed N and the injection pulse width Ti are read (S22), the basic ignition timing ADV is obtained based on the basic ignition timing map shown in FIG. 4, and then the actual EGR rate is estimated (S24). An ignition advance correction △ ADV is obtained from the actual EGR rate based on the ignition advance correction map shown in FIG. 5 (S25), and the ignition timing ADV is corrected (S26).

As described above, in this embodiment, the ignition timing A set by the engine speed N and the injection pulse width Ti is used.
DV is calculated based on the ignition advance correction ΔA obtained based on the actual EGR rate.
Since the correction is made by the DV, even when the EGR amount changes during a transition, the ignition timing as required can be set, and misfire and deterioration of fuel consumption and exhaust can be prevented.

Hereinafter, other embodiments will be described. However, since the basic configuration of each embodiment, that is, the configuration shown in FIG. 1 is common, the description is omitted.

[0011] Embodiment 2 <Embodiment 2> are in a form so as to obtain the intake pipe pressure P _b and estimating the actual EGR ratio from the intake air quantity Q _a to spark advance correction △ ADV. That is, in the second embodiment, as shown in the flowchart of FIG. 7, when performing stratified charge combustion, after calculating the basic ignition timing ADV, it reads the intake pipe pressure P _b and the intake air amount Q _a ( S34), thereby estimating the actual EGR ratio on the basis of the intake pipe pressure P _b and the intake air quantity Q _a to the map shown in FIG. 8 (S35), similarly actual EGR rate and an intake air quantity in accordance with the map shown in FIG. 8 determine the spark advance correction △ ADV from Q _a (S25). When stratified charge combustion is not being performed, the flow proceeds to the conventional flow shown in FIG.

As described above, in the present embodiment, the ignition timing A set by the engine speed N and the injection pulse width Ti
The DV, due to be corrected by the ignition advance angle △ ADV determined by estimating the EGR rate on the basis of the intake pipe pressure P _b and the intake air quantity Q _a, even if the EGR amount is changed during a transient, as requested Ignition timing can be set, and misfire and deterioration of fuel efficiency and exhaust can be prevented.

<Embodiment 3> In Embodiment 3, FIG.
As shown in the flowchart of FIG. 10, the intake pipe pressure _Pb and the throttle valve opening TVO are read (S44). First, the actual EGR rate is calculated from the intake pipe pressure _Pb and the throttle valve opening TVO based on the map shown in FIG. (S4
5), the estimated actual EGR rate and reads the intake air amount Q _a with (S46) further determines the spark advance correction △ ADV and the actual EGR rate estimated from the intake air quantity Q _a in accordance with the map shown in FIG. 11 (S25).

Therefore, similarly to the above-described embodiment, even when the EGR amount changes during a transition, the ignition timing can be set as required, and misfire and deterioration of fuel consumption and exhaust can be prevented.

<Embodiment 4> In Embodiment 4, FIG.
As shown in the flowchart of FIG. 2, the EGR valve opening E
The GRO is read (S54), and the actual EGR rate is estimated based on the map of FIG. 13 (S55).
It reads the R ratio and the intake air amount Q _a (56) Embodiment 3
EGR estimated based on the map shown in FIG.
Rate as spark advance correction from the intake air quantity Q _a △ seek ADV (S25).

Therefore, similarly to the above-described embodiment, even when the EGR amount changes during a transition, the ignition timing can be set as required, and misfire and deterioration of fuel consumption and exhaust can be prevented.

<Embodiment 5> In Embodiment 5, the EG
A means for detecting the differential pressure across the R valve 4 is provided. As shown in the flowchart of FIG.
O and its differential pressure ΔP are read (S64), and FIG.
Based on the map to estimate the actual EGR rate from the EGR valve opening EGRO and its differential pressure △ P of the (S65), the estimated actual EGR rate and reads the intake air amount Q _a with (S6
6) Embodiment 3 Similarly in accordance with the map shown in FIG. 11 EGR estimated value and the spark advance correction from the intake air quantity Q _a △
ADV is obtained (S25).

Therefore, similarly to the above-described embodiment, even when the EGR amount changes during a transition, the ignition timing as required can be set, and misfire and deterioration of fuel consumption and exhaust can be prevented.

[0019]

As described above, according to the present invention, the configuration is estimated as the actual EGR rate, and the ignition advance angle is corrected based on the estimated EGR rate and the intake air amount. In addition, even when the EGR amount changes during the transition, the ignition timing can be set as required, and the effect of preventing misfire, fuel consumption and deterioration of exhaust can be obtained.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram illustrating a configuration of an ignition timing control device for an internal combustion engine according to an embodiment.

FIG. 2 is a transient characteristic diagram during stratified combustion.

FIG. 3 is a characteristic diagram of a required ignition timing.

FIG. 4 is a basic ignition timing map according to the first embodiment;

FIG. 5 is an ignition advance correction map according to the first embodiment;

FIG. 6 is a control flowchart according to the first embodiment.

FIG. 7 is a control flowchart according to the second embodiment.

FIG. 8 is an ignition advance correction map according to the second embodiment.

FIG. 9 is a control flowchart according to the third embodiment.

FIG. 10 is an EGR rate map according to the third embodiment.

FIG. 11 is an ignition advance correction map according to the third embodiment.

FIG. 12 is a control flowchart according to the fourth embodiment.

FIG. 13 is an EGR rate map according to the fourth embodiment.

FIG. 14 is a control flowchart according to the fifth embodiment.

FIG. 15 is an EGR rate map according to the fifth embodiment.

FIG. 16 is a configuration explanatory view showing a conventional injection timing control device for an internal combustion engine.

FIG. 17 is a control flowchart of a conventional example.

FIG. 18 is a characteristic diagram of the EGR rate and the ignition advance correction ΔADV.

[Explanation of symbols]

 Reference Signs List 1 stratified engine 2 air flow meter 3 intake pipe pressure sensor 4 EGR valve 5 spark plug 6 electromagnetic pickup 7 control unit 8 pressure opening sensor 9 injection valve 101 engine 102 air flow meter 103 intake pipe pressure sensor 104 EGR 105 ignition plug 106 electromagnetic pickup 107 Control unit 108 Accelerator opening sensor

Claims (5)

[Claims] In a stratified engine that injects fuel in a cylinder and stratifies an air-fuel mixture to operate, a basic ignition timing is set based on a fuel injection amount and an engine speed, and an EGR rate as an exhaust gas recirculation rate is estimated. An ignition timing control device for an internal combustion engine, wherein the ignition timing control device has an EGR rate and an intake air amount. 2. The ignition timing control device for an internal combustion engine according to claim 1, wherein the EGR rate is estimated based on an intake pipe pressure and an intake air amount. 3. The ignition timing control device for an internal combustion engine according to claim 1, wherein the EGR rate is estimated based on an intake pipe pressure and a throttle valve opening. 4. The ignition timing control device for an internal combustion engine according to claim 1, wherein the EGR rate is estimated based on an opening of the EGR valve. 5. The ignition timing control device for an internal combustion engine according to claim 1, wherein the EGR rate is estimated based on an opening of the EGR valve and a pressure difference between the opening and the rear of the EGR valve.