JP3912032B2 - In-cylinder direct injection engine control device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a technique for suppressing and avoiding the occurrence of pre-ignition while suppressing deterioration of exhaust emission.
[0002]
[Prior art]
In a spark ignition type in-cylinder direct injection engine, preignition and knocking that cause combustion noise and vibration may occur. Both pre-ignition and knocking are phenomena in which the pressure fluctuation in the combustion chamber due to combustion becomes excessively large and causes combustion noise and vibration.Pre-ignition is a phenomenon in the combustion chamber before spark ignition by the spark plug. The air-fuel mixture spontaneously ignites (premature ignition) due to the heat of the spark plug tip or the like, and knocking is a phenomenon in which end gas around the combustion chamber self-ignites (abnormal combustion) in the combustion process after ignition.
[0003]
Such a phenomenon is not only accompanied by noise and vibration, but also may cause a decrease in output or damage to the engine. Therefore, techniques for avoiding such occurrence have been proposed.
For example, in Japanese Patent Laid-Open No. 10-231744, in a low-rotation and high-load operation region where knocking is likely to occur, a small amount of fuel that does not self-ignite in the subsequent compression stroke is injected during the intake stroke, and the remaining fuel injection What controls (that is, main fuel injection) to perform by a compression stroke is disclosed.
[0004]
According to this technique, the air-fuel mixture around the combustion chamber is diluted to make it difficult for knocking to occur, and since the time from the main fuel injection to the execution of spark ignition is short, the occurrence of pre-ignition can be avoided.
[0005]
[Problems to be solved by the invention]
As described above, the compression stroke injection has an effect of suppressing and avoiding both knocking and pre-ignition. However, when the compression stroke injection is performed during a high load operation with a large amount of required injection fuel, unburned HC and smoke There is a problem that exhaust emissions increase and exhaust emissions deteriorate.
[0006]
The present invention has been made to solve the above-described conventional problems, and an object thereof is to suppress and avoid the occurrence of pre-ignition while suppressing deterioration of exhaust emission.
[0007]
[Means for Solving the Problems]
  Therefore, the invention according to claim 1 is a control device for a direct injection type engine having a fuel injection valve that directly injects fuel into the cylinder and an ignition plug that ignites an air-fuel mixture formed in the combustion chamber. The occurrence of pre-ignition is detected or predicted, and when the occurrence of pre-ignition is detected or predicted, the fuel injection timing is set to be retarded with respect to the reference fuel injection timing set based on the engine operating conditions. SettingThe ignition timing is set to the advance side with respect to the reference ignition timing set based on the engine operating conditions.It is characterized by that.
[0008]
  According to a second aspect of the present invention, the reference fuel injection timing is set to the intake stroke, and when the occurrence of pre-ignition is detected or predicted, the fuel injection timing is set to the first half of the compression stroke. FeaturesAnd
[0009]
  Claim3The invention according to claim is characterized in that the ignition timing is set to a knocking limit ignition timing at a fuel injection timing set on the retard side.
  Claim4The invention according to the invention detects the vibration intensity and the vibration generation timing of the vibration generated in the engine body, and the vibration generation timing is more advanced than the ignition timing when the vibration intensity exceeds a predetermined allowable range. Sometimes, occurrence of pre-ignition is detected.
[0010]
  Claim5The invention according to the invention is characterized in that the occurrence of pre-ignition is predicted when the engine is operating in a specific operation region and the engine coolant temperature is equal to or higher than a predetermined temperature.
  Claim6The invention according to the invention is characterized in that the occurrence of pre-ignition is predicted when the engine is operating in a specific operation region and the engine coolant temperature is equal to or higher than a predetermined temperature.
[0011]
  Claim7The invention according to the invention is characterized in that the occurrence of pre-ignition is predicted when the engine is operating in a specific operation region and the wall temperature of the engine combustion chamber is equal to or higher than a predetermined temperature.
  Claim8The invention according to claim is characterized in that the specific operation region is a low rotation high load region.
[0012]
  Claim9In the invention according to the present invention, when the occurrence of pre-ignition is not detected or predicted, and when the vibration intensity exceeds a predetermined allowable range, the ignition timing is set based on engine operating conditions. Is set on the retard side.
[0013]
【The invention's effect】
According to the invention of claim 1,
By setting the fuel injection timing to the retard side with respect to the reference fuel injection timing, the time from fuel injection to ignition can be shortened, and the occurrence of pre-ignition can be avoided.
[0014]
  Further, since the above control is executed only when the occurrence of pre-ignition is detected or predicted, it is possible to minimize the deterioration of exhaust emission accompanying the pre-ignition avoidance.Furthermore, by setting the ignition timing to an advance side with respect to the reference ignition timing, it is possible to compensate for the decrease in engine torque associated with the retarded fuel injection timing.
  According to the invention of claim 2, by setting the fuel injection timing in the first half of the compression stroke, it is possible to avoid the occurrence of pre-ignition while suppressing the decrease in engine torque as much as possible.
[0015]
  According to the invention of claim 3The aboveBy making the ignition timing the knocking limit ignition timing, it is possible to compensate for the decrease in the engine torque as much as possible.
[0016]
  Claim4According to the invention according to the present invention, it is possible to detect the occurrence of pre-ignition by using a vibration sensor conventionally used for detecting knocking without newly providing a device.
  Claim5According to the invention according to the above, the occurrence of pre-ignition can be predicted by detecting the continuous operation time in the specific operation region by obtaining the pre-ignition occurrence state in the specific operation region in advance through experiments or the like.
[0017]
  Claim6According to the invention according to claim5Similarly to the invention according to the above, the occurrence of pre-ignition can be predicted by detecting the engine coolant temperature in the specific operation region (by the output signal of the water temperature sensor).
  Claim7According to the invention according to claim5, 6Similarly to the invention according to the above, by detecting the wall temperature of the combustion chamber in the specific operation region (by the output signal of the wall temperature sensor), the occurrence of pre-ignition can be predicted.
[0018]
  Claim8According to the invention according to the present invention, the specific operation region is a low-rotation and high-load region in which pre-ignition is likely to occur, thereby reducing the control burden and generating pre-ignition.AccuratePredictable.
  Claim9According to the invention according to the present invention, knocking is detected separately from pre-ignition, and when knocking is detected, the ignition timing is set to the retard side with respect to the reference ignition timing, so in addition to suppressing and avoiding the occurrence of pre-ignition. Thus, knocking can also be suppressed without deteriorating exhaust emissions.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
In the system diagram shown in FIG. 1, the combustion chamber 1 of the engine is defined by a cylinder head 2, a cylinder block 3 and a piston 4, and an intake port 5 and an exhaust port 6 connected to the combustion chamber 1 are the cylinder head 2. Is formed.
[0020]
An intake valve 7 that is driven to open and close by an intake cam 9 is provided at the opening end of the intake port 5 on the combustion chamber 1 side, and an opening end of the exhaust port 5 that is driven to open and close by the exhaust cam 10 is driven by the exhaust cam 10. An exhaust valve 8 is provided.
A fuel injection valve 11 that injects fuel into the combustion chamber 1 is provided below the intake port 5 of the cylinder head 2, and the spark plug 12 is disposed facing the substantially central portion of the combustion chamber 1.
[0021]
Then, fuel is injected from the fuel injection valve 11 to the air sucked through the intake valve 7 to form an air-fuel mixture, the air-fuel mixture is compressed in the combustion chamber 1, and a spark by the spark plug 11 is formed. Ignite by ignition.
Exhaust gas from the engine is discharged from the combustion chamber 1 to the exhaust port 6 via the exhaust valve 8 and discharged to the atmosphere via an exhaust purification catalyst (not shown).
[0022]
The engine control unit (ECU) 13 includes a vibration sensor 14 that detects pressure fluctuation in the combustion chamber 1 as vibration of the engine block, a crank angle sensor 15 that detects the rotation angle position of the crankshaft, and an engine coolant temperature. Signals from a water temperature sensor 16, a wall temperature sensor 17 that detects the wall temperature in the combustion chamber 1, an accelerator opening sensor (not shown), and the like are input, and the engine rotational speed Ne is based on an output signal from the crank angle sensor 15. Calculated.
[0023]
Further, the ECU 13 grasps the engine operating conditions based on these input signals, and performs control such as calculation of the target engine torque tT, setting of the fuel injection amount Tp, fuel injection timing IT, and ignition timing ADV.
In this engine, in a low rotation and low load region (region C in FIG. 2), a fuel mixture is easily burned around the spark plug by injecting fuel into the combustion chamber 1 during the compression stroke. A stratified lean operation is performed to form an air layer without fuel. In other regions, that is, in the middle, high rotation, and high load regions (regions A and B in FIG. 2), fuel is injected into the combustion chamber 1 during the intake stroke. A homogeneous stoichiometric operation or a homogeneous rich operation is performed to make the air-fuel mixture homogeneous by injecting it into
[0024]
Further, in this engine, pre-ignition and knocking are separately detected (or predicted), and particularly when the occurrence of pre-ignition is detected or predicted in the low rotation high load region (region A in FIG. 2), fuel injection By controlling the timing to the retard side, preignition is suppressed and avoided, and when knocking is detected, knocking is suppressed by controlling the ignition timing to the retard side.
[0025]
Hereinafter, fuel injection timing IT control and ignition timing ADV control performed by the ECU 13 will be described.
First, calculation of the fuel injection timing IT and the ignition timing ADV will be described.
FIG. 3 is a flow showing a fuel injection timing IT calculation routine, which is executed at predetermined time intervals.
[0026]
In step 1 (denoted as S1 in the figure, the same applies hereinafter), the current engine operating conditions (engine speed Ne, target engine torque tT) are in the low rotation high load region (region A in FIG. Determine whether or not. If it is area A, the process proceeds to step 2.
In step 2, it is determined whether or not the fuel injection timing flag fIT is 2.
[0027]
This fuel injection timing flag fIT indicates the setting of the fuel injection timing in the region A. If fIT = 1, the fuel injection timing is set to the first injection timing, and if fIT = 2, the fuel injection timing is set. Set to the second injection timing.
Here, the first injection timing and the second injection timing will be described with reference to FIG.
FIG. 4 shows engine torque characteristics when the fuel injection timing is changed while controlling the ignition timing to the knocking limit.
[0028]
As shown in the figure, the maximum engine torque can be obtained when fuel injection is performed at a predetermined time during the intake stroke. This is because the temperature of the intake air decreases due to the latent heat of vaporization when the injected fuel is vaporized, and the charging efficiency of the intake air increases. The injection timing at which this maximum engine torque is obtained is defined as the first injection timing.
Note that the engine torque decreases as the fuel injection timing is set to the retard side, and this is due to a decrease in intake charging efficiency and a deterioration in mixing of injected fuel and air.
[0029]
When the fuel injection timing is retarded to the first half of the compression stroke, the engine torque is once recovered, and when further retarded, the engine torque thereafter monotonously decreases. The engine torque is maximized in the first half of the compression stroke in this way because the knocking limit ignition timing is advanced (that is, the ignition timing is advanced) as the mixing of the injected fuel and air deteriorates. However, the injection timing at which the engine torque becomes maximum is set as the second injection timing.
[0030]
Returning to step 2, if the fuel injection timing flag fIT is 2 (fIT = 2), the routine proceeds to step 3 where the fuel injection timing IT is set to the second injection timing in the first half of the compression stroke. Specifically, the set value IT2m is set to the fuel injection timing IT with reference to a preset second injection timing map based on the engine operating conditions.
If the fuel injection timing flag fIT is not 2 (that is, if fIT = 1), the routine proceeds to step 4 where the fuel injection timing IT is set to the first injection timing during the intake stroke. Specifically, the map set value IT1m is set to the fuel injection timing IT with reference to a preset first injection timing map based on the engine operating conditions.
[0031]
On the other hand, when the current operating condition is not the region A in step 1, the process proceeds to step 5 where the current operating condition is the middle load region or the middle / high rotation region (region B in FIG. Determine whether or not.
If the current operating condition is region B, the process proceeds to step 6 and the fuel injection timing IT is set to the first injection timing. The specific process is the same as the process in Step 4, and the map set value IT1m is set to the fuel injection timing IT with reference to a preset first injection timing map based on the engine operating conditions.
[0032]
If the current operating condition is not the region B (that is, the region C in FIG. 2), the process proceeds to step 7, and the fuel injection timing IT is set to the third injection timing in the latter half of the compression stroke. Specifically, the map set value IT3m is set to the fuel injection timing IT with reference to a preset third injection timing map based on the engine operating conditions. When fuel injection is performed in the latter half of the compression stroke, most of the injected fuel is concentrated in the recess provided on the crown surface of the piston 4, and the air-fuel mixture in the combustion chamber 1 is stratified.
[0033]
The fuel injection timing IT calculated by the above processing is stored in a memory in the ECM 13 and read by a control routine that outputs a fuel injection signal.
FIG. 5 is a flowchart showing an ignition timing ADV calculation routine, which is executed every predetermined time. The ignition timing ADV is a value indicating how many times ignition is performed before a reference crank angle (for example, compression top dead center), and the ignition timing is advanced when the value is larger.
[0034]
In step 11, it is determined whether or not the current engine operating condition is a low rotation high load region (region A). If the current engine operating condition is region A, the process proceeds to step 12 to determine whether or not the fuel injection timing flag fIT is 2.
If the fuel injection timing flag fIT is 2 (fIT = 2), the routine proceeds to step 13 where the ignition timing for the second injection timing (first half of the compression stroke) is set.
[0035]
Specifically, the map set value ADV2m is set to the ignition timing ADV with reference to a preset ignition timing map for the second injection timing based on the engine operating conditions. Here, the map setting value ADV2m is the knocking limit ignition timing at the second injection timing, and a value obtained in advance through experiments or the like is stored on the map.
[0036]
If the fuel injection timing flag fIT is not 2 (that is, if fIT = 1), the routine proceeds to step 14, where the ignition timing for the first injection timing (during the intake stroke) is controlled to the retard side. Specifically, a map set value ADV1m is calculated based on the engine operating conditions with reference to a preset ignition timing map for the first injection timing, and a delay for suppressing knocking is calculated from the map set value ADV1m. A value obtained by subtracting the angle correction amount RTD is set as the ignition timing ADV (ADV = ADV1m−RTD).
[0037]
Here, the map set value ADV1m is the knocking limit ignition timing at the first injection timing, and a value obtained by an experiment or the like in advance is stored on the map in the same manner as ADV2m.
On the other hand, if the current engine operating condition is not region A in step 11, the process proceeds to step 15 to determine whether or not the current operating condition is region B.
[0038]
If the current operating condition is the region B, the process proceeds to step 16 and the map set value ADV1m is set to the ignition timing ADV with reference to a preset ignition timing map for the first injection timing based on the engine operating condition. To do.
If the current engine operating condition is not the area B (that is, if it is the area C in FIG. 2), the process proceeds to step 17, and a preset ignition timing map for the third injection timing is referred to based on the engine operating condition. Then, the map set value ADV3m is set to the ignition timing ADV.
[0039]
The ignition timing ADV calculated by the above processing is stored in a memory in the ECM 13 and is read and used in a control routine that outputs an ignition signal.
Next, the fuel injection timing flag fIT and the retardation correction amount RTD used in the above routine will be described.
FIG. 6 is a flowchart showing a routine for setting the fuel injection timing flag fIT and the corrected retardation amount RTD, which is executed at a predetermined timing. The execution interval of this routine is the shortest every combustion cycle (for example, in the case of a four-cylinder engine, the crank angle is 180 °), and may be executed every plural combustion cycles.
[0040]
In step 101, it is determined whether or not the current engine operating condition is in a low rotation high load region (region A).
If the current engine operating condition is region A, the process proceeds to step 102 to determine whether or not the fuel injection timing flag fIT is 2.
If the fuel injection timing flag fIT is 2 (fIT = 2), this routine ends as it is.
[0041]
If the fuel injection timing flag fIT is not 2 (that is, if fIT = 1), the routine proceeds to step 103.
If the engine operating condition is not in region A, the fuel injection timing flag fIT is set to 1 (since it was set in step 110 at the previous execution of this routine), so the engine operating condition is not in region A. The fuel injection timing flag fIT is set to 1 at the beginning when the shift to the region A is started.
[0042]
In step 103, a pre-ignition flag fPIG is set.
The pre-ignition flag fPIG indicates a situation where pre-ignition has occurred (fPIG = 2), a situation where the possibility of occurrence is high (fPIG = 1), and a situation where the possibility of occurrence is low (fPIG = 0). Yes, it is set by executing the control flow of FIG.
[0043]
In step 104, it is determined whether or not the pre-ignition flag fPIG is greater than zero.
When the pre-ignition flag fPIG is greater than 0, it is determined that pre-ignition avoidance control is necessary, and the routine proceeds to step 105 where the fuel injection timing flag fIT is set (changed) to 2.
[0044]
If the pre-ignition fPIG is 0, the process proceeds to step 106.
In step 106, it is determined whether knocking strength KNO is greater than a predetermined first threshold value KNOthA.
This knocking intensity KNO is a value calculated for each combustion based on the output signal from the vibration sensor 14, and the intensity of the engine block vibration generated during the immediately preceding combustion or the past multiple combustion components including the immediately preceding combustion. Represents the average intensity of engine block vibration.
[0045]
The first threshold value KNOthA is a value indicating whether or not the calculated current knocking strength KNO is strong enough to require suppression by control, and is a value obtained in advance through experiments or the like.
Since the knocking strength KNO is calculated for each combustion, the knocking strength KNO referred to this time is a value reflecting the result of the knocking suppression control performed during the previous execution of this routine.
[0046]
When the knocking strength KNO is larger than the first threshold value KNOthA, the routine proceeds to step 107, where a process for increasing the ignition timing retard correction amount RTD (updating to the retard side) is performed. Specifically, a predetermined value (2 ° in the crank angle in this routine) is added to the currently set retardation correction amount RTD to calculate the updated retardation correction amount RTD (+1).
[0047]
When the engine operating condition is not in the region A, the ignition timing retardation correction amount RTD is set to 0 (since it was set in step 110 at the previous execution of this routine), the engine operating condition is At the beginning of transition from the region A to the region A, the retardation correction amount RTD is set to zero.
On the other hand, if knocking strength KNO is equal to or smaller than the first threshold value, the routine proceeds to step 108, where it is determined whether knocking strength KNO is smaller than a predetermined second threshold value KNOthB.
[0048]
The second threshold value KNOthB is a value set smaller than the first threshold value KNOthA (to the knocking weak side).
When the knocking strength KNO is smaller than the second threshold value, the routine proceeds to step 109, where the ignition timing retardation correction amount RTD is reduced (updated to the advance side). Specifically, a predetermined value (1 ° in crank angle in this routine) is subtracted from the currently set retardation correction amount RTD to calculate the updated retardation correction amount RTD (+1).
[0049]
When the knocking strength KNO is greater than or equal to the second threshold value KNOthB, that is, when the knocking strength KNO is between the first threshold value KNOthA and the second threshold value KNOthB, this routine is performed without updating the retardation correction amount RTD. finish.
In step 101, when the current engine operating condition is not in the region A, the process proceeds to step 110 where the retard correction amount RTD is set to 0 and the fuel injection timing flag fIT is set to 1.
[0050]
Next, the process in step 103 of the control flow will be described.
FIG. 7 is a flowchart showing the processing in step 103, that is, setting of the pre-ignition flag fPIG.
In step 201, it is determined whether or not the engine operating condition (previous engine operating condition) when the routine shown in FIG. 6 was executed in the previous region is a region other than the low rotation high load region (region A). It is determined whether or not the execution is immediately after the engine operating condition has shifted to region A.
[0051]
When the previous engine operating condition is other than the region A (when the engine operating condition is immediately after shifting to the region A), the process proceeds to step 202, and the timer value T is set to 0 in order to measure the operation continuation time in the region A. (T = 0) and the process proceeds to step 204.
When the previous engine operating condition is area A (when the engine operating condition is not immediately after shifting to area A, that is, when operating in area A continuously from the previous time), the routine proceeds to step 203 and the previous timer value A predetermined timer amount T is added to T (−1) to calculate a new timer value T (= T (−1) + ΔT), and the process proceeds to step 204.
[0052]
In step 204, it is determined whether or not the knocking strength KNO is larger than the first threshold value KNOthA.
The determination process in this step is the same as the process performed in step 106 in FIG. That is, since the knocking strength KNO is a parameter indicating the strength of engine block vibration generated during combustion, its value increases even when pre-ignition occurs, and can therefore be used to detect the occurrence of pre-ignition.
[0053]
When the knocking strength KNO is greater than the first threshold value KNOthA, the routine proceeds to step 205, where it is determined whether or not the engine block vibration generation timing θKNO is greater than the ignition timing ADV (that is, on the advance side).
The vibration generation timing θKNO is calculated in accordance with the calculation of the knocking strength. The crank angle at the time when the engine block vibration starts to increase (how many times before the same reference crank angle as the ignition timing ADV) is calculated. Show.
[0054]
When the vibration generation timing θKNO is larger than the ignition timing ADV (when it is on the advance side), the routine proceeds to step 206, where the pre-ignition flag fPIG = 2 (pre-ignition occurs).
That is, when the engine block vibration is large and the generation timing θKNO is before the ignition timing ADV, it is considered that pre-ignition has occurred, and the occurrence of pre-ignition is detected.
[0055]
When the knocking strength KNO is less than or equal to the first threshold value KNOthA at step 204, or when the vibration generation timing θKNO is smaller than the ignition timing ADV (when it is on the retard side) at step 205, the routine proceeds to step 207, where the timer It is determined whether or not the value T is greater than a predetermined threshold value Tth.
When the timer value T is larger than the threshold value Tth, the routine proceeds to step 208, where the pre-ignition flag fPIG = 1 (high possibility of occurrence of pre-ignition) is set. That is, even if the occurrence of pre-ignition is not detected at the present time, when the operation time in the region A becomes longer than the threshold value Tth, it is predicted that the pre-ignition will occur after the next cycle and the pre-ignition is performed in advance. Implement avoidance control.
[0056]
The threshold value Tth is, for example, a continuous operation time immediately before the occurrence of pre-ignition in the region A, and is obtained beforehand through experiments or the like.
When the timer value T is equal to or smaller than the threshold value Tth, the routine proceeds to step 209, where it is determined whether or not the engine coolant temperature TW based on the output signal from the water temperature sensor 16 is higher than a predetermined threshold value TWth.
[0057]
When the engine coolant temperature TW is higher than the threshold value TWth, the routine proceeds to step 210, where the pre-ignition flag fPIG = 1 (high possibility of occurrence of pre-ignition) is set.
That is, even when the engine coolant temperature TW becomes higher than the threshold value TWth in the region A, preignition avoidance control is performed in advance by predicting that preignition will occur after the next cycle.
[0058]
When the engine coolant temperature TW is equal to or lower than the threshold TWth, the routine proceeds to step 211, where it is determined whether or not the wall temperature TC of the combustion chamber 1 based on the output signal from the wall temperature sensor 17 is higher than a predetermined threshold TCth. .
When the wall temperature TC is higher than the threshold value TCth, the routine proceeds to step 212, where the pre-ignition flag fPIG = 1 (high possibility of occurrence of pre-ignition) is set.
[0059]
That is, even when the wall temperature TC is higher than the threshold value TCth in the region A, preignition avoidance control is performed in advance by predicting that preignition will occur after the next cycle.
The threshold values TWth and TCth are temperatures immediately before the occurrence of pre-ignition in the region A, and are obtained in advance by experiments.
[0060]
When the wall temperature TC is equal to or lower than the threshold value TCth, the pre-ignition flag fPIG = 0 (small possibility of occurrence of pre-ignition, that is, pre-ignition avoidance control is not required).
As described above, according to the present invention, the pre-ignition avoidance control is executed by retarding the fuel injection timing only when the pre-ignition and the knocking are separated and the occurrence of the pre-ignition is detected or predicted. Deterioration of emissions can be minimized.
[0061]
Further, when the occurrence of knocking is detected, the ignition timing is retarded and knocking suppression control is executed, so that knocking can be suppressed without deteriorating exhaust emissions.
[Brief description of the drawings]
FIG. 1 is a system diagram showing an embodiment of the present invention.
FIG. 2 is a diagram showing an engine operating region (engine rotation speed−target engine torque).
FIG. 3 is a flowchart showing a fuel injection timing IT calculation routine.
FIG. 4 shows engine torque characteristics when the fuel injection timing is changed (ignition timing is knocking limit ignition timing).
FIG. 5 is a flowchart showing an ignition timing ADV calculation routine.
FIG. 6 is a flowchart showing a routine for calculating a fuel injection timing flag fIT and an ignition timing correction delay amount RTD.
FIG. 7 is a flowchart showing processing for setting a pre-ignition flag fPIG.
[Explanation of symbols]
1 Combustion chamber
2 Cylinder head
3 Cylinder block
11 Fuel injection valve
12 Spark plug
13 Engine control unit (ECU)
14 Vibration sensor
15 Crank angle sensor
16 Water temperature sensor
17 Wall temperature sensor

Claims (9)

A control device for an in-cylinder direct injection engine comprising a fuel injection valve for directly injecting fuel into a cylinder and an ignition plug for igniting an air-fuel mixture formed in a combustion chamber,
Detect or predict the occurrence of pre-ignition,
When the occurrence of pre-ignition is detected or predicted, the fuel injection timing is set to the retard side with respect to the reference fuel injection timing set based on the engine operating conditions, and the ignition timing is set based on the engine operating conditions. And a control device for a direct injection type in-cylinder engine, which is set to an advance side with respect to a reference ignition timing set by The reference fuel injection timing is set to the intake stroke;
2. The direct injection engine control device according to claim 1, wherein when the occurrence of pre-ignition is detected or predicted, the fuel injection timing is set to the first half of the compression stroke. 3. The control device for a direct injection type in-cylinder engine according to claim 1 , wherein the ignition timing is a knocking limit ignition timing at a fuel injection timing set on the retard side . Detect the vibration strength and vibration generation time of the vibration generated in the engine body,
When the vibration intensity exceeds the predetermined allowable range, and, when the vibration occurrence timing is on the advance side of the ignition timing, claims 1 to 3, characterized in that detecting the occurrence of preignition The control apparatus for a direct injection type in-cylinder engine according to any one of the above. The in-cylinder direct injection engine control according to any one of claims 1 to 4, wherein the occurrence of pre-ignition is predicted when the engine operation in the specific operation region continues for a predetermined time or more. apparatus. 6. The occurrence of pre-ignition is predicted when the engine is operating in a specific operating region and the engine coolant temperature is equal to or higher than a predetermined temperature. 6. In-cylinder direct injection engine control device. 7. The pre-ignition occurrence is predicted when the engine is operating in a specific operation region and the wall temperature of the engine combustion chamber is equal to or higher than a predetermined temperature. A control device for an in-cylinder direct injection engine described in 1. The in-cylinder direct injection engine control device according to any one of claims 5 to 7 , wherein the specific operation region is a low rotation high load region . When the occurrence of pre-ignition is not detected or predicted,
Billing when the vibration intensity exceeds a predetermined allowable range, the ignition timing, claim 4, characterized in that setting the retard side with respect to the reference ignition timing that is set based on an engine operating condition Item 9. The direct-injection direct-injection engine control device according to any one of items 8 to 9 .

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