JP2002030978A - Control device for cylinder injection type engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simultaneously improve exhaust gas performance and ensure output performance, by correspondingly correcting ignition timing to suitable when correcting fuel injection timing so as to suppress a deterioration of the exhaust gas performance, with reference to a control device for a cylinder injection type engine. SOLUTION: This control device for the cylinder injection type engine has an intake stroke injection mode, and directly injects fuel into a combustion chamber to ignite by an ignition plug provided in the combustion chamber. The control device for the cylinder injection type engine comprises an injection timing correcting means 62B correcting the injection timing by calculating injection timing correcting amount for correcting a basic fuel injection timing set by a basic fuel injection timing setting means 62A to a delaying side, in a driving state deteriorating the exhaust gas performance; and an ignition timing correcting means 63B correcting a basic ignition timing set by a basic ignition timing setting means 63A to an advancing side, on the basis of the injection timing correcting amount.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an in-cylinder injection engine in which fuel is injected directly into a combustion chamber and ignited by a spark plug provided in the combustion chamber. The present invention relates to a device for controlling injection timing and ignition timing.

[0002]

2. Description of the Related Art In recent years, a spark ignition type direct injection gasoline engine (hereinafter also referred to as a direct injection gasoline engine) has been put to practical use as an engine for a vehicle. In an intake pipe injection gasoline engine, the fuel supply timing into the cylinder is limited only when the intake valve is opened, but in a direct injection gasoline engine, fuel can be supplied into the cylinder at free timing. For this reason, it is possible to obtain a larger output by performing fuel injection at an optimal timing for uniform combustion by premixing, and to perform ultra-lean stratified combustion at a partial load, thereby realizing a reduction in fuel consumption.

[0003] In uniform combustion by premixing, it is necessary to promote the atomization of fuel and the mixing with air, and the fuel is mainly injected into the intake stroke (intake stroke injection) for atomizing and mixing the fuel. I try to reserve time. When the engine is cold, uniform combustion is performed for reliable combustion. However, if the fuel is injected at the normal time (that is, after the engine warms up), the exhaust gas performance deteriorates, that is, the HC component in the exhaust gas is deteriorated. This leads to an increase in smoke and smoke.

In order to solve this problem, a technique has been developed which corrects the timing of fuel injection to a retard side (retard correction) in a cold state according to the temperature of the cooling water of the engine. Thus, when the fuel injection timing is retarded, the amount of fuel adhering to the piston can be reduced, which is considered to contribute to the reduction of the HC component and the reduction of smoke.

[0005]

By the way, when the fuel injection timing is changed as described above, the combustion characteristics change and MB
Although the optimum ignition timing also changes due to a change in T (fuel efficiency best ignition timing) and a knock point, the conventional technology does not particularly correct the ignition timing for such a change in the injection timing. For this reason, a loss occurs in terms of fuel efficiency performance and output performance.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and when the fuel injection timing is corrected in order to suppress the deterioration of the exhaust gas performance, the ignition timing is appropriately corrected in accordance with the correction. It is an object of the present invention to provide a control device for a direct injection engine, which is capable of achieving both improvement in performance and securing fuel efficiency and output performance.

[0007]

Therefore, in the control apparatus for a direct injection type engine according to the present invention, fuel is directly injected into the combustion chamber and ignition is performed by a spark plug provided in the combustion chamber. When the operating state is such that the exhaust gas performance is deteriorated, the injection timing correction means calculates an injection timing correction amount for correcting the basic fuel injection timing set by the basic injection timing setting means to the retard side. Thus, the basic fuel injection timing is corrected to the retard side with the injection timing correction amount, and the fuel injection timing is controlled based on the correction, but the ignition timing is also corrected in accordance with the correction of the fuel injection timing. I do. That is,
The ignition timing correction means corrects the basic ignition timing set by the basic ignition timing setting means to the advanced side based on the calculated injection timing correction amount. This makes it possible to improve engine performance such as fuel efficiency and output performance while improving exhaust gas performance.

Further, when the in-cylinder injection type engine further includes a compression stroke injection mode in which fuel is injected mainly in the compression stroke to perform stratified combustion, the fuel injection timing is adjusted in the compression stroke. If the delay is made, exhaust gas performance and engine performance are likely to be deteriorated, but when the compression stroke injection mode is selected, the injection timing correction means prohibits the correction of the basic fuel injection timing on the retard side. Alternatively, since the ignition timing correction means does not perform the advance side correction of the basic ignition timing, it is possible to avoid deterioration in exhaust gas performance and engine performance due to unstable combustion.

[0009]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a control device for a direct injection type engine according to an embodiment of the present invention; FIG. First, a configuration of a spark ignition type direct injection gasoline engine (hereinafter, also referred to as a direct injection gasoline engine or simply an engine) according to the present embodiment will be described. It is assumed that the engine is mounted on an automobile.

As shown in FIG. 2, the cylinder head 2 of the engine 1 has a spark plug 4 for each cylinder 3 and a fuel injection valve 6 as a fuel injection means which opens directly into the combustion chamber 5.
The ignition plug 4 is driven by an ignition coil 4A, and the fuel injection valve 6 is driven by a driver 6A.
A piston 8 connected to a crankshaft 7 is provided in the cylinder 3, and a hemispherically concave cavity 9 is formed on a top surface of the piston 8. Fuel injection valve 6
Can directly inject fuel into the cylinder during the intake stroke of the engine, and also functions as intake stroke fuel injection means.

The cylinder head 2 has an intake port 11 that can communicate with the combustion chamber 5 via an intake valve 10 and an exhaust port 13 that can communicate with the combustion chamber 5 via an exhaust valve 12. The intake port 11 is disposed substantially vertically above the combustion chamber 5, and cooperates with the cavity 9 on the top surface of the piston 8 to form a reverse tumble flow by intake air in the combustion chamber 5. A water temperature sensor 16 for detecting a cooling water temperature is provided on a water jacket 15 on the outer periphery of the cylinder 3, and a crank angle sensor 17 for outputting a signal at a predetermined crank angle position is provided on the crankshaft 7. Each of the camshafts 18 and 19 for driving the cylinder 12 is provided with a cylinder identification sensor (cam angle sensor) 20 for outputting a cylinder identification signal according to the position of the camshaft. Since the engine rotation speed can be calculated based on the crank angle signal, the crank angle sensor 17 also functions as engine rotation speed detection means.

The intake system includes an air cleaner 21,
Intake pipe 22, throttle body 23, surge tank 2
4, the intake manifold 25 is arranged in this order, and the intake port 11 is provided at the downstream end of the intake manifold 25. The throttle body 23 is provided with an electronically controlled throttle valve (ETV) 30 as air amount adjusting means for adjusting the amount of air flowing into the combustion chamber 5.
The opening degree control of 0 can perform not only control according to the accelerator opening degree, but also idle speed control and control for introducing a large amount of intake air during lean operation described later.

Further, an air flow sensor 37 for detecting an intake air flow rate is provided immediately downstream of the air cleaner 21.
The throttle body 23 has a throttle position sensor 38 for detecting the throttle opening of the ETV 30 and an ETV 3
And an idle switch 39 for detecting the fully closed state of 0 and outputting an idle signal. Since the volume efficiency Ev can be calculated from the intake air flow rate, the air flow sensor 3
Reference numeral 7 also functions as a volume efficiency calculating means.

The exhaust system includes an exhaust manifold 26 having an exhaust port 13 and an exhaust pipe 27 in this order from the upstream side. A three-way catalyst 29 for purifying exhaust gas is interposed in the exhaust pipe 27, and the exhaust manifold 26 is provided in the exhaust manifold 26. , O ₂ sensor 40 are provided. Although the fuel supply system is not shown, the pressure is a predetermined high pressure [several tens of atmospheres (for example, 2 to 7MP
a) is adjusted to the fuel injection valve 6,
High-pressure fuel is injected from the fuel injection valve 6.

Further, an accelerator position sensor (hereinafter, referred to as APS) 42 for detecting an amount of accelerator pedal depression (accelerator position) θap is provided. Then, in order to control the operation of each engine control element such as the spark plug 4, the fuel injection valve 6, and the ETV 30, an electronic control unit (E) having a function as control means of the internal combustion engine is provided.
CU) 60 is provided. This ECU 60 includes:
An input / output device, a storage device for storing control programs and control maps, etc., a central processing unit, a timer and a counter, etc., are provided. Based on the detection information from the various sensors described above and the key switch position information, etc. This ECU6
0 controls the above-described engine control elements.

In particular, the present engine is a direct injection engine, which can perform fuel injection at an arbitrary timing, and achieves uniform injection while promoting fuel atomization and mixing with air by fuel injection mainly in the intake stroke. In addition to mixing and performing uniform combustion, stratified combustion can be performed by collecting the air-fuel mixture near the ignition plug 4 by utilizing the above-described reverse tumble flow by fuel injection mainly in the compression stroke. The operation modes of the present engine include a stoichiometric operation mode in which the air-fuel ratio is kept close to the stoichiometric air-fuel ratio by feedback control based on information detected by the O ₂ sensor 40, and an enrich operation mode in which the air-fuel ratio is made richer than the stoichiometric air-fuel ratio. A lean operation mode in which the air-fuel ratio is leaner than the stoichiometric air-fuel ratio to perform lean combustion, and an ultra-lean combustion (super-lean operation) using the above-described stratified combustion with the air-fuel ratio substantially leaner than the stoichiometric air-fuel ratio. A super lean operation mode is provided.

In the ECU 60, based on a map (not shown), one of the operation modes according to a target value (target Pe) of the engine rotational speed Ne (hereinafter referred to as the engine rotational speed) Ne and the average effective pressure Pe indicating the engine load state. When the engine speed Ne is small and the target Pe is small, the lean operation mode is selected.
As the engine speed Ne and the target Pe increase, the operation mode is selected in the order of stoichiometry and enrichment.

The engine speed Ne is calculated from the output signal of the crank angle sensor 17, and the target Pe is calculated from the engine speed Ne and the throttle opening detected by the throttle position sensor 38. Here, a control device for a direct injection engine of the present embodiment that performs such engine control will be described with reference to FIG.

As shown in FIG. 1, a combustion mode setting means 61 for setting a combustion mode (operation mode) from an engine operation state, and fuel injection valves 6 and 6 based on the operation mode and the like set by the combustion mode setting means 61. Each functional element such as a fuel injection valve control means 62 for controlling the operation of the ignition plug 4 and a spark plug control means 63 is provided. of course,
In addition, it also has a function of controlling various other engine control elements such as the ETV 30.

In the combustion mode setting means 61, as described above, the stoichiometric operation mode, the enrichment operation mode and the map are used based on the engine operating state, that is, the engine speed Ne and the engine load (eg, target Pe). ,
One of the lean operation mode (intake lean operation mode) and the super lean operation mode (compression lean operation mode) is selected.

The fuel injection valve control means 62 uses the maps and the like provided in accordance with the set operation modes to determine the engine operation state, that is, the engine speed Ne, the engine load [for example, target Pe or Ev (volume efficiency). )], The fuel injection amount and the fuel injection timing are set, and the fuel injection valve 6 is controlled. Specifically, the start timing and the end timing of the fuel injection (both corresponding to the crank angle) are set, and the fuel injection valve 6 is controlled based on this.

The ignition plug control means 63 also uses the map and the like provided according to the set operation mode, based on the engine operation state, that is, the engine speed Ne and the engine load (for example, target Pe or Ev). The ignition plug 4 is controlled by setting the ignition timing. By the way, paying attention to the function of the fuel injection timing control in the fuel injection valve control means 62, the fuel injection valve control means 62 has an operating state [engine speed Ne, engine load (for example, target Pe)].
And the like, and a basic injection timing setting means 62A for setting the basic fuel injection timing according to the above, and an injection timing correction for correcting the basic fuel injection timing to the retard side in order to suppress the deterioration of the exhaust gas performance when the engine is cold. An injection timing correction means 62B for calculating the amount and correcting the injection timing is provided.

That is, when the engine is cold, uniform combustion is mainly performed for reliable combustion. However, if fuel is injected at a normal time (ie, after the engine warms up), the exhaust gas performance deteriorates, that is, This leads to an increase in HC components in the exhaust gas and an increase in smoke. On the contrary,
When the fuel injection timing is corrected to the retard side when the engine is cold (retard correction), such deterioration in exhaust gas performance is suppressed. Therefore, in the injection timing correction means 62B, the engine cooling water temperature Tw detected by the water temperature sensor 16 is used.
Accordingly, when the engine is cold, the fuel injection timing is corrected to the retard side (retard correction).

In correspondence with the fuel injection valve control means 62, the ignition plug control means 63 has an operating state [engine speed Ne, engine load (for example, target Pe), etc.].
When the fuel injection timing is retard-corrected by the basic ignition timing setting means 63A that sets the basic ignition timing according to the injection timing correction means 62B, the basic ignition timing is advanced to the advanced side based on the injection timing correction amount at this time. Ignition timing correction means 63 for correction
B is provided.

The reason why the ignition timing is corrected by the ignition timing correction means 63B to advance the ignition timing in accordance with the retard correction is to prevent the fuel injection timing from deteriorating in fuel consumption performance and output performance due to the retard correction. To do that. That is, when the fuel injection timing is changed, the combustion characteristics change, the MBT (best fuel consumption ignition timing) and the knock point also change, and the optimum ignition timing changes to the advanced side. Therefore, by correcting the ignition timing to the advanced side, the combustion state is brought close to the MBT, so that a decrease in fuel consumption performance and output performance can be suppressed.

Here, when the engine is cold,
It is assumed that uniform combustion is performed by intake stroke injection. Therefore, when the engine is cold, the compression stroke injection is not selected, and the retard correction of the fuel injection timing and the advancement of the ignition timing are performed only in the intake stroke injection. FIG. 3 shows characteristics of the fuel injection end timing when the engine is cold. FIG. 3A shows the amount of smoke generated, FIG. 3B shows the ignition timing characteristics, and FIG.
(C) shows the engine output torque, respectively. In the cold state, as shown by the curve s1 in FIG. 3A, the amount of smoke generated on the advance side of the fuel injection end timing becomes larger than the characteristic (see the curve s2) in the normal state (after the warm-up). At the normal fuel injection end time t1 (after warm-up), the amount of smoke generated significantly increases as indicated by point P1. Therefore, in the cold state, the fuel injection end timing is retarded (retarded) until t2 to reduce the amount of smoke generated as indicated by point P2.

However, when the fuel injection end timing is retarded, the engine output torque decreases from point P3 to point P4, as shown in FIG. Here, focusing on the ignition timing, as shown in FIG. 3B, the advanceable line (knock point) of the ignition timing is the normal fuel injection end timing t.
1 is the line n0, whereas the fuel injection end timing is t2
When the retard is made, the angle changes to a more advanced angle as shown by the line n1. That is, when the fuel injection end timing is retarded, the ignition timing is easily advanced.

Therefore, when the ignition timing is advanced in accordance with the retard of the fuel injection end timing, the engine output torque characteristic changes from the curve tr1 to the curve tr2 on the torque increasing side. Therefore, when the fuel injection end timing is retarded, the engine output torque decreases from the point P3 to the point P4. In addition, when the ignition timing is advanced, the engine output torque increases from the point P4 to the point P5. You do it.

Here, the focus is on the fuel injection end timing, but the same can be said with respect to the fuel injection timing (a period region from the fuel injection start timing to the fuel injection end timing). When the retard is retarded, the engine output torque decreases. In addition, when the ignition timing is advanced, the output torque can be increased so as to compensate for the decrease in the engine output torque.

Since the control device for a direct injection type engine according to one embodiment of the present invention is configured as described above, for example, as shown in FIG. 4, the fuel injection timing and the ignition timing are set. Based on this, the fuel injection timing and the ignition timing are controlled. That is, first, the cooling water temperature Tw, the engine speed Ne, and the volumetric efficiency Ev (or the target Pe) detected or calculated by each sensor or the calculation unit are read (step S1).
0). Next, the basic fuel injection timing (basic injection timing) is set (step S20) and the basic ignition timing is set (step S30) based on the engine speed Ne and the volumetric efficiency Ev (or the target Pe).

[0031] Then, the cooling water temperature Tw is determined whether less than the predetermined value Tw ₀ (step S40), if the cooling water temperature Tw is less than the predetermined value Tw _0, the engine is in a cold-state, the cooling water temperature Tw Accordingly, the injection timing retard amount is calculated (step S50), and further, the ignition timing advance amount is calculated according to the injection timing retard amount (step S60). Then, the basic injection timing is corrected by the injection timing retard amount (step S70), and the basic ignition timing is corrected by the ignition timing advance amount (step S80).

Thus, when the engine is cold,
By retarding the fuel injection timing and performing the fuel injection in a state in which the piston is more distant from the opening of the fuel injection valve, the amount of fuel attached to the piston can be reduced, and the exhaust gas performance deteriorates, that is, To increase the output torque to compensate for the decrease in engine output torque caused by the retarded fuel injection timing by suppressing the increase in HC component and smoke in the exhaust gas and advancing the ignition timing accordingly. Can be. In addition, it is possible to compensate for a decrease in fuel efficiency caused by a retard of the fuel injection timing.

In this embodiment, the compression stroke injection is not selected when the engine is cold. However, when the compression stroke injection can be selected when the engine is cold, even when the engine is cold, the compression stroke injection is not performed. It is preferable that the retard correction and the advance correction of the ignition timing at the fuel injection timing be prohibited or suppressed. In other words, if the fuel injection timing is corrected during the compression stroke, fuel injection will be performed with the piston closer to the opening of the fuel injection valve, and the fuel adhering to the piston will instead increase the HC component in the exhaust gas or cause smoke. May lead to an increase in
In order to avoid this, such control is prohibited or suppressed during the compression stroke injection.

The above embodiment is merely an example, and the present invention is not limited to the embodiment. Various modifications of the above embodiment may be made without departing from the spirit of the present invention. be able to. For example, in the above-described embodiment, in the cold state, the injection timing retard amount is calculated according to the cooling water temperature Tw, and the ignition timing advance amount is calculated according to the injection timing retard amount. In a cold state, a fixed amount of the injection timing may be set irrespective of the cooling water temperature Tw, and the ignition timing advance may be set to a fixed value regardless of the injection timing retard.

Further, in the present invention, the basic fuel injection timing is corrected to the retard side in the operating state where the exhaust gas performance is deteriorated. However, the deterioration of the exhaust gas performance is limited to the increase of the HC component in the exhaust gas and the increase of the smoke. Not something.

[0036]

As described above in detail, according to the control apparatus for a direct injection type engine of the present invention, in the operating state where the exhaust gas performance is deteriorated, the fuel injection timing is corrected to the retard side so that the exhaust gas performance can be corrected. In addition to suppressing the deterioration, the ignition timing is corrected to the advanced side in accordance with the correction of the fuel injection timing, so that the deterioration of fuel efficiency and output performance caused by the correction of the fuel injection timing is avoided. And improved exhaust gas performance,
Ensuring engine performance such as fuel efficiency and output performance,
You will be able to balance both.

If the fuel injection timing is retarded in the compression stroke, the exhaust gas performance and the engine performance tend to be rather deteriorated, but when the compression stroke injection mode is selected, the basic fuel injection timing is retarded. By prohibiting or suppressing both the side correction and the advance angle correction of the basic ignition timing, it is possible to avoid deterioration of exhaust gas performance and deterioration of engine performance.

[Brief description of the drawings]

FIG. 1 is a control block diagram showing a control device for a direct injection engine as one embodiment of the present invention.

FIG. 2 is a schematic configuration diagram showing a direct injection engine according to an embodiment of the present invention.

FIG. 3 is a diagram showing characteristics of an engine according to a control device for a direct injection engine as one embodiment of the present invention.

FIG. 4 is a flowchart showing control contents according to a control device for a direct injection type engine as one embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 1 engine 61 combustion mode setting means 62 fuel injection valve control means 62A basic injection timing setting means 62B injection timing correction means 63 spark plug control means 63A basic ignition timing setting means 63B ignition timing correction means

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F02D 41/04 335 F02D 41/04 335A F02P 5/15 F02P 5/15 B F-term (Reference) 3G022 AA07 BA01 DA01 DA02 EA01 FA08 GA01 GA05 GA08 GA09 3G084 AA04 BA15 BA17 CA02 DA01 DA02 DA10 EB11 FA07 FA10 FA18 FA20 FA29 FA33 FA38 3G301 HA01 HA04 HA16 HA17 JA01 JA02 JA21 KA05 LA03 LB04 MA19 MA20 NC02 ND03 NE11 NE12 NE13ZBZZZZZZZZZZZZZZBZZZZBZZZZZBZZZZZBZBZBZZZZBZZZBZZZBZZZZZZBZZZZZZZZZZZBZYZZZZZBZYZZZZZBZZBZZBZZVZ PE01Z PE03Z PE05Z PE08Z PF03Z

Claims (2)

[Claims] 1. A cylinder having an intake stroke injection mode in which fuel is injected mainly in an intake stroke to perform uniform combustion, in which fuel is directly injected into a combustion chamber and ignited by a spark plug provided in the combustion chamber. In the control device for the internal injection engine, the basic injection timing setting means for setting the basic fuel injection timing according to the operating state, and the basic injection timing setting means for setting the operating state when the exhaust gas performance deteriorates. Injection timing correction means for correcting the injection timing by calculating an injection timing correction amount for correcting the basic fuel injection timing to the retard side; basic ignition timing setting means for setting a basic ignition timing of the spark plug; An in-cylinder injection type engine control device, comprising: an ignition timing correction means for correcting the basic ignition timing to an advanced side based on the injection timing correction amount. 2. The fuel injection mode of the in-cylinder injection engine further includes a compression stroke injection mode in which fuel is injected mainly in a compression stroke to perform stratified combustion, and when the compression stroke injection mode is selected, The injection timing correction output means inhibits or suppresses the retard correction of the basic fuel injection timing, and the ignition timing correction means inhibits or suppresses the advance correction of the basic ignition timing. A control device for a direct injection type engine according to claim 1.