JP4784467B2 - Premixed compression ignition internal combustion engine - Google Patents

Description

  The present invention relates to a premixed compression ignition internal combustion engine, and more particularly to a technique for controlling fuel injection timing.

In Patent Document 1, fuel injection is performed twice during one cycle, and the first stage combustion is performed by spark-igniting an air-fuel mixture generated by the second fuel injection with a spark plug. It is disclosed that the surrounding air-fuel mixture undergoes compression self-ignition due to the temperature rise in the combustion chamber due to the combustion of the fuel, thereby performing the second stage combustion and controlling the fuel injection timing according to the fuel rotation speed and the load. .
JP 2002-155780 A

By the way, in the control of the fuel injection timing described in Patent Document 1, the fuel injection timing is advanced as the engine load increases, so that the fuel is dispersed in the combustion chamber to prevent a sudden pressure increase. Like to do.
However, if the fuel injection timing is advanced as the engine load increases, the ignition timing is advanced, resulting in an increase in combustion noise, thus limiting the premixed compression ignition combustion region. was there.

  The present invention has been made in view of the above problems, and an object of the present invention is to suppress an increase in combustion noise accompanying an increase in engine load, and thereby to expand a premixed compression ignition combustion region to a high load side. And

Therefore, in the premixed compression ignition internal combustion engine in which the fuel injected before the intake bottom dead center is compressed and self-ignited and combusted , the present invention retards the fuel injection timing as the fuel injection amount increases, and The retard limit of the fuel injection timing at which the fuel injection timing is fixed in a region greater than a predetermined maximum fuel injection amount is a range from 60 ° after the intake top dead center to the intake bottom dead center, and the engine speed, intake valve Is set based on at least one of the in-cylinder temperature and the compression ratio at the closing timing .

According to the above invention, when the fuel injection amount (engine load) increases, the fuel injection timing is retarded, and conversely, the fuel injection timing is advanced for a decrease in the fuel injection amount (engine load). (Advance).
When the fuel injection timing is retarded with respect to the increase in the fuel injection amount, the interference between the fuel spray and the wall surface of the combustion chamber is minimized, and the air-fuel mixture in the combustion chamber becomes non-uniform. Cooling reduces the in-cylinder temperature. As a result, since the ignition timing is retarded, an increase in combustion noise can be suppressed, and the premixed compression ignition combustion region can be expanded to the high load side.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
1 and 2 show a premixed compression ignition internal combustion engine in an embodiment.
In the internal combustion engine 101 shown in FIGS. 1 and 2, air is sucked into each cylinder via an intake manifold 102 and an intake valve 103.
A throttle valve 105 is interposed in the intake duct 104 connected to the upstream side of the intake manifold 102.

The throttle valve 105 is an electronically controlled throttle that is opened and closed by a motor (not shown).
A spark plug 107 for spark-igniting the fuel in the combustion chamber 106 and a fuel injection valve 108 for directly injecting the fuel into the combustion chamber 106 are provided at the center of the combustion chamber 106 of each cylinder.
Combustion gas is discharged from the combustion chamber 106 through an exhaust valve 109, and the exhaust gas of each cylinder is merged by an exhaust manifold 110, and then passes through a downstream catalytic converter and muffler (not shown). Released into the atmosphere.

The opening degree of the throttle valve 105, the ignition timing by the spark plug 107, and the fuel injection amount and fuel injection timing by the fuel injection valve 108 are controlled by an electronic control unit 120 incorporating a microcomputer.
The electronic control unit 120 includes an air flow meter 121 that detects the intake air amount of the engine 101, an accelerator opening sensor 122 that detects the amount of depression of the accelerator pedal (accelerator opening), and a crank angle that detects the rotation angle of the crankshaft. Detection signals from the sensor 123, the water temperature sensor 124 for detecting the coolant temperature of the engine 101, and the like are input.

  Here, the electronic control unit 120 forms the combustion mode of the engine 101 into a spark ignition combustion in which a flame is propagated by ignition of the spark plug 107, and a compression self-ignition combustion (premixing) in which premixed gas is ignited at multiple points all at once. Compression ignition combustion) and controlling the injection amount and injection timing by the fuel injection valve 108 according to each combustion mode, and when performing spark ignition combustion, the ignition timing by the spark plug 107 is changed. Control.

Next, the control function of the electronic control unit 120 will be described in detail according to the flowchart of FIG.
In the flowchart of FIG. 3, in step S <b> 101, various detection data indicating the engine operating state such as the accelerator pedal depression amount indicating the required torque T and the engine rotation speed Ne are read.

In step S102, as shown in FIG. 4, a map in which the spark ignition combustion region and the compression self-ignition combustion region are stored in advance according to the required torque T and the engine rotational speed Ne is referred to. It is determined whether or not the combustion mode corresponding to the rotation speed is compression self-ignition combustion.
Here, if the current required torque T and the engine rotational speed Ne do not correspond to the compression self-ignition combustion region but correspond to the spark ignition combustion region, the process proceeds to step S109, and spark ignition combustion is performed.

In the spark ignition combustion, the intake air amount of the engine 101 is controlled by controlling the opening degree of the throttle valve 105 in accordance with the required torque T (accelerator opening degree), and the target air amount is determined with respect to the intake air amount. The fuel injection timing and the fuel injection amount are determined in order to generate an air-fuel mixture with a fuel ratio and to perform spark ignition combustion.
An injection pulse signal is output to the fuel injection valve 108 based on the fuel injection timing and the fuel injection amount.

Further, the ignition timing is determined from the fuel injection amount and the engine rotational speed Ne, the spark plug 107 is controlled to spark discharge at the ignition timing, and the fuel injected from the fuel injection valve 108 into the combustion chamber 106 is discharged. Then, the ignition plug 107 is ignited and burned by spark ignition.
On the other hand, if it is determined that the current required torque T and the engine rotational speed Ne correspond to the compression self-ignition combustion region, the process proceeds to step S103, and the fuel injection amount (fuel injection amount) to the engine 101 is determined according to the required torque T. To decide.

Here, the fuel injection amount is determined based on the table shown in FIG. 5, and is set to a larger value as the required torque T at that time is higher.
In the spark ignition combustion region, the engine load is controlled by controlling the intake air amount of the engine 101. In the compression self-ignition combustion region, the engine load is controlled by the amount of fuel input to the engine 101.

In the next step S104, the fuel injection timing is determined based on the fuel injection amount.
As shown in FIG. 6, the fuel injection timing is retarded (retarded) as the fuel injection amount (required torque) increases, and advanced (advanced) as the fuel injection amount (required torque) decreases. ing.
Further, as shown in FIG. 6, in a region below a predetermined minimum fuel injection amount (minimum required torque), the fuel injection timing is fixed at a predetermined advance limit value and is equal to or greater than a predetermined maximum fuel injection amount (maximum required torque). In this region, the fuel injection timing is fixed at a predetermined retard limit value.
The retard limit value is set to the most retarded value (for example, intake bottom dead center ATDC 180 deg.) Among the retard limit values that are varied according to operating conditions as will be described later.

In step S105, the retard limit of the fuel injection timing is determined based on at least one of the engine speed Ne, the in-cylinder temperature at the closing timing IVC of the intake valve 103, and the compression ratio.
The retard limit value is set to a more advanced side as the engine speed Ne is higher and the combustion speed is faster (see FIG. 7), and is set to a retard side as the in-cylinder temperature at the closing timing IVC of the intake valve 103 is higher ( Further, the larger the compression ratio, the more retarded it is set (see FIG. 9).

The in-cylinder temperature at the closing timing IVC of the intake valve 103 can be estimated from the engine speed, the fuel injection amount, the coolant temperature (engine temperature), and the like.
The setting of the retard limit value according to the compression ratio is required in an engine in which the compression ratio is variable. For example, the retard limit value is compressed by a variable compression ratio mechanism as disclosed in JP-A-2006-177270. In addition to the case where the ratio is changed, the case where the compression ratio is changed by changing the valve timing by the variable valve timing mechanism is included. In this case, the compression ratio can be estimated from the control state of the variable compression ratio mechanism or the variable valve timing mechanism. .

When the retard limit value of the fuel injection timing is determined in step S105, in the next step S106, the fuel injection timing determined based on the fuel injection amount in step S104 exceeds the retard limit value determined in step S105. It is determined whether or not.
Then, if the fuel injection timing based on the fuel injection amount is retarded beyond the retard limit value, the process proceeds to step S107, and the retard limit value at that time is replaced with the fuel injection timing based on the fuel injection amount. By setting the fuel injection timing, fuel injection is prevented from being performed at the retard-side injection timing exceeding the retard limit value, and ignition stability is ensured.

When the fuel injection amount and the fuel injection timing are set as described above, in step S108, the fuel injection amount is corrected according to the outside air temperature and the like to determine the final fuel injection amount and the fuel injection timing. An injection pulse signal is output to the fuel injection valve 108 in accordance with the fuel injection amount and the fuel injection timing.
In the compression self-ignition combustion (premixed compression ignition combustion), if the fuel injection amount is increased as the required torque increases, the ignition timing is advanced as shown in FIG. 10, and the in-cylinder pressure increase rate is shown in FIG. As shown in FIG. 12, the combustion noise increases as the in-cylinder pressure increase rate increases.

  For this reason, the limit on the high load side that can be operated by compression self-ignition combustion is limited by the combustion noise. However, as described above, the fuel injection timing is retarded as the fuel injection amount increases. Thus, the combustion noise in the high load region can be reduced, and the region operated by the compression self-ignition combustion (premixed compression ignition combustion) can be expanded to the high load side.

  That is, as shown in FIG. 13, when the fuel injection timing is constant, the cylinder pressure increase rate increases as the fuel injection amount increases, and the combustion noise increases accordingly. Since the retard of the timing acts in the direction of decreasing the in-cylinder pressure increase rate, the in-cylinder pressure increase rate can be suppressed and the increase in combustion noise can be suppressed by retarding the injection timing with respect to the increase in the fuel injection amount.

When the fuel injection timing is retarded, the in-cylinder temperature is lowered due to the cooling effect of the air-fuel mixture by the spray, and thus the ignition timing is retarded, so that the advance timing of the ignition timing accompanying the increase in the fuel injection amount is suppressed, and the cylinder An increase in the internal pressure increase rate is suppressed, and an increase in combustion noise can be reduced.
The cooling effect of the air-fuel mixture by spraying is due to the minimization of the interference between the spray and the wall of the combustion chamber and the non-uniformity of the air-fuel mixture. .

However, if the fuel injection timing is retarded under the condition that the fuel injection amount is small and the air-fuel ratio is lean, the combustion stability decreases (see FIG. 14), so the fuel injection timing is increased as the fuel injection amount increases. By gradually retarding, combustion stability can be secured while reducing combustion noise.
It should be noted that the compression self-ignition combustion can be established even if the retard is performed beyond the vicinity of BTDC, which is the fuel injection timing for generating the maximum torque, and particularly when the stratified mixture is subjected to compression self-ignition combustion. It is possible to retard the time more greatly (see FIG. 15).

However, if the fuel injection timing is retarded beyond the vicinity of BTDC, the generated torque will decrease. For example, the fuel injection timing is set within the range of ATDC 60 deg to ATDC 180 deg (bottom dead center) according to the increase in required torque. To retard (see FIG. 15).
Incidentally, in the above embodiment, the fuel injection timing is retarded with respect to the increase in the fuel injection amount accompanying the increase in the required torque. However, in order to make the torque of each cylinder constant, the fuel injection amount is increased or decreased for each cylinder. In the case of correction, the fuel injection timing can be corrected according to the increase / decrease.

A second embodiment for controlling the torque between the cylinders to be constant will be described below.
16 and 17 show a premixed compression ignition internal combustion engine in the second embodiment.
The internal combustion engine 101 shown in FIGS. 16 and 17 is different from the internal combustion engine 101 of the first embodiment shown in FIGS. 1 and 2 in that an in-cylinder pressure sensor 125 (combustion state detection means) is added to each cylinder. Only the point is different.

Accordingly, the same elements are denoted by the same reference numerals and description thereof is omitted.
The flowchart of FIG. 18 shows the control function of the electronic control unit 120 in the second embodiment in detail.
In step S201, various detection data indicating the engine operating state such as the accelerator pedal depression amount indicating the required torque T and the engine rotational speed Ne are read.

In step S202, a variable correlated with the torque generated in each cylinder is calculated from the signal of the in-cylinder pressure sensor 125 provided in each cylinder.
Specifically, a variable that correlates the peak value of in-cylinder pressure, the integrated value of in-cylinder pressure in a predetermined crank angle range, the amount of change in in-cylinder pressure per unit crank angle (in-cylinder pressure increase rate), and the generated torque for each cylinder. Calculate as

In the engine 101, intake cylinder distribution, residual gas amount, and the like may vary among the cylinders. In particular, when performing compression self-ignition combustion, the temperature at the top dead center also depends on variations in cooling efficiency. The pressure varies, and the torque between the cylinders becomes uneven.
Therefore, in step S202, the non-uniform state of torque due to the variation factors as described above is detected as variation in the in-cylinder pressure between the cylinders.

However, in place of the detection of the in-cylinder pressure by the in-cylinder pressure sensor 125, various known combustion state detection means can be employed. For example, a method for detecting the combustion state by detecting the ionic current in the combustion chamber 106, or an engine A method for detecting torque variation between cylinders from the rotational speed, a method for detecting vibration, and the like can be appropriately employed.
In step S203, based on the detection result in step S202, a correction amount for making the torque between the cylinders constant is calculated for each cylinder.

  For example, as shown in FIG. 19, when there is a variation in torque among cylinders, the generated torque is set for the cylinder having a generated torque larger than the average torque so that the generated torque of each cylinder is aligned with the average torque. A correction amount for reducing the generated torque to the average torque is set. For a cylinder having a generated torque smaller than the average torque, a correction amount for increasing the generated torque to the average torque is set.

The target for aligning the torque is not limited to the average value, but the target value is determined according to the accelerator opening at that time, the maximum value or the minimum value is set as a target, and the torque of a specific cylinder is set to other cylinders. The torque can be made uniform.
In step S204, as shown in FIG. 4, a map in which the spark ignition combustion region and the compression self-ignition combustion region are stored in advance according to the required torque T and the engine rotational speed Ne is referred to. It is determined whether or not the combustion mode corresponding to the rotation speed is compression self-ignition combustion.

Here, if the current required torque T and the engine rotational speed Ne do not correspond to the compression self-ignition combustion region but correspond to the spark ignition combustion region, the process proceeds to step S212, and spark ignition combustion is performed.
In the spark ignition combustion, the intake air amount of the engine 101 is controlled by controlling the opening degree of the throttle valve 105 in accordance with the required torque T (accelerator opening degree), and the target air amount is determined with respect to the intake air amount. The fuel injection timing and the fuel injection amount are determined in order to generate an air-fuel mixture with a fuel ratio and to perform spark ignition combustion.

An injection pulse signal is output to the fuel injection valve 108 based on the fuel injection timing and the fuel injection amount.
Further, while determining the basic ignition timing from the fuel injection amount and the engine speed Ne, the basic ignition timing is corrected based on the torque correction amount for making the torque between the cylinders constant in the spark ignition combustion region. The ignition timing corresponding to each cylinder is determined.

Here, the ignition timing is corrected to advance for a torque increase request, and the ignition timing is retarded to respond to a torque decrease request.
Then, the spark plug 107 of each cylinder is controlled so as to perform spark discharge at the ignition timing corresponding to that cylinder, and the fuel injected from the fuel injection valve 108 into the combustion chamber 106 is ignited by spark ignition by the spark plug 107. Burn.

In addition, as a method for making the torque between the cylinders constant in the spark ignition combustion state, in addition to the method for correcting the ignition timing as described above, for example, a method for correcting the intake air amount for each cylinder or fuel injection There are methods for correcting the amount, etc., and these can be corrected in combination.
Further, in the spark ignition combustion state, the correction for making the torque between the cylinders constant can be omitted, and the correction can be executed only in the compression self-ignition combustion region.

On the other hand, if it is determined that the current required torque T and the engine rotational speed Ne correspond to the compression self-ignition combustion region, the process proceeds to step S205 and thereafter, and the injection control for each cylinder is executed.
The engine 101 in the present embodiment will be described below as a four-cylinder engine. In the flowchart of FIG. 18, steps S205 (# 1) to step S211 (# 1) indicate injection control in the first cylinder, and step S205 (# 2). ) To step S211 (# 2) indicate injection control in the second cylinder, steps S205 (# 3) to step S211 (# 3) indicate injection control in the third cylinder, and further, steps S205 (# 4) to Step S211 (# 4) indicates injection control in the fourth cylinder, and the processing for each cylinder is executed in parallel.

Since the contents of the processing for each cylinder are common, the injection control in steps S205 (# 1) to S211 (# 1) will be described below with the processing in the first cylinder as a representative example.
In step S205 (# 1), a basic fuel injection amount (fuel injection amount) common to each cylinder is determined according to the required torque T.
Here, the basic fuel injection amount is determined based on the table shown in FIG. 5, and is set to a larger value as the required torque T at that time is higher.

In the spark ignition combustion region, the engine load is controlled by controlling the intake air amount of the engine 101. In the compression self-ignition combustion region, the engine load is controlled by the amount of fuel input to the engine 101.
In the next step S206 (# 1), the basic fuel injection amount is increased or decreased based on the torque correction value set for the first cylinder in step S203, and the fuel injection amount in the first cylinder is corrected. Is determined so that the torque generated in the first cylinder is aligned with that of the other cylinders.

That is, when it is necessary to increase the generated torque of the first cylinder, the fuel injection amount for the first cylinder is corrected to be increased, and when the generated torque of the first cylinder needs to be decreased, the first cylinder Correct the amount of fuel injection for reduction.
In step S207 (# 1), the fuel injection timing in the first cylinder is determined based on the fuel injection amount for the first cylinder.

As shown in FIG. 6, the fuel injection timing is retarded as the fuel injection amount increases and advanced as the fuel injection amount decreases.
Further, as shown in FIG. 6, in a region below a predetermined minimum fuel injection amount (minimum required torque), the fuel injection timing is fixed at a predetermined advance limit value and is equal to or greater than a predetermined maximum fuel injection amount (maximum required torque). In this region, the fuel injection timing is fixed at a predetermined retard limit value.
The retard limit value is set to the most retarded value (for example, intake bottom dead center ATDC 180 deg.) Among the retard limit values that are varied according to operating conditions as will be described later.

When the injection amount of the first cylinder is increased with respect to the basic fuel injection amount common to each cylinder by the above-described injection timing setting, the injection timing is retarded compared with the basic fuel injection amount, and each cylinder is retarded. When the injection amount of the first cylinder is reduced with respect to the common basic fuel injection amount, the injection timing is advanced as compared with the basic fuel injection amount.
In step S208 (# 1), the retard limit common to each cylinder at the fuel injection timing is determined based on at least one of the engine speed Ne, the in-cylinder temperature at the closing timing IVC of the intake valve 103, and the compression ratio. .

The retard limit value is set to a more advanced side as the engine speed Ne is higher and the combustion speed is faster (see FIG. 7), and is set to a retard side as the in-cylinder temperature at the closing timing IVC of the intake valve 103 is higher ( Further, the larger the compression ratio, the more retarded it is set (see FIG. 9).
The in-cylinder temperature at the closing timing IVC of the intake valve 103 can be estimated from the engine speed, the fuel injection amount, the coolant temperature (engine temperature), and the like.

  The setting of the retard limit value according to the compression ratio is required in an engine in which the compression ratio is variable. For example, the retard limit value is compressed by a variable compression ratio mechanism as disclosed in JP-A-2006-177270. In addition to the case where the ratio is changed, the case where the compression ratio is changed by changing the valve timing by the variable valve timing mechanism is included, and the compression ratio can be estimated from the control signals of the variable compression ratio mechanism and the variable valve timing mechanism.

When the retard limit value of the fuel injection timing is determined in step S208 (# 1), the next step S209 (# 1) is determined based on the fuel injection amount for the first cylinder in step S207 (# 1). It is determined whether or not the fuel injection timing of one cylinder is retarded beyond the retard limit value determined in step S208 (# 1).
When the fuel injection timing of the first cylinder is retarded beyond the retard limit value, the process proceeds to step S210 (# 1), and the retard limit value is set to the fuel injection timing of the first cylinder. The fuel injection in the first cylinder is avoided at the injection timing exceeding the retard limit value, and the ignition stability in the first cylinder is ensured.

When the fuel injection amount and fuel injection timing for the first cylinder are set as described above, in step S211 (# 1), the fuel injection amount is corrected according to the outside air temperature and the like, and the final first cylinder is obtained. Determine the fuel injection amount and fuel injection timing.
Then, an injection pulse signal is output to the fuel injection valve 108 provided in the first cylinder according to the fuel injection amount and fuel injection timing for the first cylinder.

The control of the injection amount and the injection timing in the first cylinder is performed in the same manner in the other cylinders.
In the compression self-ignition combustion (premixed compression ignition combustion), if the fuel injection amount is increased for each cylinder in order to make the torque between the cylinders constant, the ignition timing is advanced as shown in FIG. As shown, the in-cylinder pressure increase rate increases, and as shown in FIG. 12, the combustion noise increases as the in-cylinder pressure increase rate increases.

On the other hand, in compression self-ignition combustion (premixed compression ignition combustion), if the fuel injection amount is decreased for each cylinder in order to make the torque between the cylinders constant, as shown in FIG. there's a possibility that.
Here, if the fuel injection timing is retarded along with the increase in the fuel injection amount, the in-cylinder temperature is lowered due to the cooling effect of the air-fuel mixture by the spray, and thereby the ignition timing is retarded. The advance angle of the ignition timing is suppressed, the increase in the cylinder pressure increase rate is suppressed, and the combustion noise can be reduced (see FIG. 13).

The cooling effect of the air-fuel mixture by spraying is due to the minimization of the interference between the spray and the wall of the combustion chamber and the non-uniformity of the air-fuel mixture, and the cooling effect is maximized by setting the fuel injection timing in the vicinity of BTDC. .
Further, if the fuel injection timing is advanced in accordance with the reduction of the fuel injection amount, the air-fuel mixture can be made uniform and the combustion stability can be improved (see FIG. 14), and the occurrence of misfire can be prevented.

Therefore, it is possible to prevent an increase in combustion noise and a decrease in combustion stability while keeping the torque between the cylinders constant.
For example, in a V-type engine, in order to make the torque between banks constant, the fuel injection amount is increased or decreased for each bank, and the injection timing is retarded or advanced in accordance with the increase or decrease correction of the injection amount for each bank. It can be.

Furthermore, it is preferable to limit the fuel injection amount increase / decrease correction within a limit value so as to make the torque between cylinders or between banks constant.
In addition, the fuel injection timing is retarded or advanced with respect to the increase / decrease change of the fuel injection amount according to the normal required torque, and at the same time, the fuel injection amount increase / decrease correction is made to keep the torque constant between cylinders or banks. The fuel injection timing can be retarded or advanced.

  Also, the combustion timing (in-cylinder pressure increase rate, etc.) can be set so that the combustion noise can be suppressed to a predetermined level or less, no misfire occurs, and high torque can be generated as close to the bottom dead center as possible. ) Can be learned for each fuel injection amount.

The figure which shows the premixed compression ignition internal combustion engine in 1st Embodiment of this invention. The figure which shows the combustion chamber structure of the premixing compression ignition internal combustion engine in the said 1st Embodiment. The flowchart which shows the injection control in the said 1st Embodiment. The figure which shows the compression ignition area | region and spark ignition area | region in embodiment of this invention. The diagram which shows the correlation with the request | required torque and fuel injection quantity in embodiment of this invention. The diagram which shows the correlation with the request | required torque (fuel injection amount) and fuel injection timing in embodiment of this invention. The diagram which shows the correlation with the engine rotational speed and retard limit in embodiment of this invention. The diagram which shows the correlation with the cylinder temperature and retard limit in the closing timing of the intake valve in embodiment of this invention. The diagram which shows the correlation with the compression ratio and retard limit in embodiment of this invention. The diagram which shows the correlation with the fuel injection quantity and ignition timing in embodiment of this invention. The diagram which shows the correlation with the fuel injection quantity and cylinder pressure increase rate in embodiment of this invention. The diagram which shows the correlation with the cylinder pressure increase rate and combustion noise in embodiment of this invention. The diagram which shows that the correlation with fuel injection quantity and the cylinder pressure rise rate changes according to fuel injection timing in embodiment of this invention. The diagram which shows that the correlation of fuel injection quantity and combustion stability changes according to fuel-injection timing in embodiment of this invention. The diagram which shows the relationship between the fuel-injection timing and torque in embodiment of this invention. The figure which shows the premixed compression ignition internal combustion engine in 2nd Embodiment of this invention. The figure which shows the combustion chamber structure of the premixing compression ignition internal combustion engine in the said 2nd Embodiment. The flowchart which shows the injection control in the said 2nd Embodiment. The diagram which shows the correlation with the torque dispersion | variation between the cylinders in the said 2nd Embodiment, and torque correction.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 101 ... Internal combustion engine, 102 ... Intake manifold, 103 ... Intake valve, 104 ... Intake duct, 105 ... Throttle valve, 106 ... Combustion chamber, 107 ... Spark plug, 108 ... Main fuel injection valve, 109 ... Exhaust valve, 110 ... Exhaust Manifold 111 ... Exhaust gas recirculation passage 112 ... EGR valve 113 ... Catalyst 114 ... Sub fuel injection valve 120 ... Electronic control unit 121 ... Air flow meter 122 ... Accelerator opening sensor 123 ... Crank angle sensor 124 ... Water temperature sensor, 125 ... In-cylinder pressure sensor

Claims (2)

In a premixed compression ignition internal combustion engine that performs compression self-ignition combustion of fuel injected before the intake bottom dead center,
The retard limit of the fuel injection timing, in which the fuel injection timing is retarded as the fuel injection amount increases and the fuel injection timing is fixed in a region equal to or greater than the predetermined maximum fuel injection amount, starts from 60 ° after the intake top dead center. A premixed compression ignition internal combustion engine, which is set based on at least one of an engine rotational speed, an in-cylinder temperature at the closing timing of the intake valve, and a compression ratio within a range up to the intake bottom dead center . The fuel injection amount is individually increased or decreased for each cylinder to make the torque between the cylinders constant, and the fuel injection timing is individually set for each cylinder according to the increase or decrease of the fuel injection amount. premixed compression ignition internal combustion engine according to 1.

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