JP2013096359A - Fuel injection control device of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent drivability and noise from getting worse, while well cleaning an exhaust with a catalyst.SOLUTION: A fuel allocation ratio to pre-injection is set at 1.0 and a corrected pre-injection amount Qpmod is calculated (S10). When the corrected pre-injection amount Qpmod is larger than a single pre-correction lower limit Qpsmin, the fuel allocation ratio to the pre-injection is set at 1.0 and a corrected main injection amount Qmmod is set at a main injection amount Qm before correction (S12, S14-S16). When the corrected pre-injection amount Qpmod is the single pre-correction lower limit Qpsmin or smaller, the corrected pre-injection amount Qpmod is calculated (S12, S18). When the corrected pre-injection amount Qpmod is larger than a pre-injection amount lower limit Qpmin, the corrected main injection amount Qmmod is calculated (S20, S22). When the corrected pre-injection amount Qpmod is the pre-injection amount lower limit Qpmin or smaller, the corrected pre-injection amount Qpmod is set at the pre-injection amount lower limit Qpmin, and the fuel allocation ratio to pre-injection and corrected main injection amount Qmmod are calculated (S20, S24-S26).

Description

  The present invention relates to a fuel injection control device for an internal combustion engine, and more particularly to a technique for correcting torque increase associated with in-cylinder post injection.

  Conventionally, in a diesel engine, fuel injection control is performed to adjust the fuel injection timing and the fuel injection amount from the fuel injection valve in accordance with the operating state of the engine. The diesel engine exhaust system also captures diesel particulate filters (DPF) that collect particulate matter (PM) contained in the exhaust from the engine, hydrocarbons (THC), and nitrogen oxides (NOx). An oxidation catalyst (DOC) that collects or redox, a NOx trap catalyst (NTC), and the like are provided. In order for these oxidation catalyst and NOx trap catalyst to obtain a high purification rate, it is necessary to raise the temperature of the catalyst to a predetermined activation temperature or higher. When the catalyst is at a temperature lower than the activation temperature, the purification rate of the catalyst is extremely low, and the exhaust purification function is not fully exhibited. Furthermore, in order to exhibit the exhaust purification function of the NOx trap catalyst, it is also required that the catalyst or the surrounding part be a reducing atmosphere.

Therefore, so-called post-injection is performed in which fuel is injected from the fuel injection valve in the exhaust stroke from the latter stage of the engine expansion stroke, and unburned fuel is supplied to the exhaust system so that it remains unburned on or around the catalyst of the oxidation catalyst or NOx trap catalyst. Fuel injection control is known in which fuel is burned, the temperature of a catalyst is raised to an activation temperature or higher, and a reducing atmosphere is created.
However, when there is little heat energy present in the exhaust system, for example, immediately after the cold start of the engine, unburned fuel can be sufficiently burned on or around the oxidation catalyst or NOx trap catalyst. There are things that cannot be done.

Therefore, as a technique for improving the ignitability of unburned fuel, for example, the amount of fuel injection in the main injection injected before the post injection is increased, and the temperature of the exhaust discharged from the combustion chamber is increased to increase the exhaust system. The temperature is such that the unburned fuel can be combusted on or around the catalyst of the oxidation catalyst or the NOx trap catalyst.
However, since the injection amount in the main injection greatly affects the output torque of the engine, increasing the fuel injection amount in the main injection in this manner increases the engine torque and deteriorates drivability. .

  For this reason, the fuel is injected before the post-injection and burned after the main injection so that most of the combustion energy of the injected fuel is obtained as exhaust heat energy without being converted into engine torque. If the exhaust heat injection is performed and the exhaust heat injection is converted into engine torque, the injection amount of the main injection in the same stroke is reduced to suppress the increase of the engine torque and the exhaust system. A technique for raising the temperature has been developed (Patent Document 1).

International Publication No. WO2009 / 090941 A1

  However, according to the experiment by the inventor of the present application, as shown in FIG. 7, even with post-injection in which fuel is injected in the later stage of the expansion stroke (black symbol in the figure) without post-injection (black symbol in the figure), It was confirmed that the heat generation amount of the pre-injection or the main injection increases. This is because the exhaust heat injection disclosed in Patent Document 1 is different from the conversion to engine torque caused by ignition and combustion within the same cycle by the heat energy of the main injection. That is, when post injection is performed in the later stage of the expansion stroke, all of the injected fuel is not discharged in the exhaust stroke, and part of the fuel remains in the cylinder and is carried over to the next stroke before the main injection in the next stroke. It was confirmed that carry-over fuel burned by pre-injection or main injection was generated.

Thus, the generation of carry-over fuel increases the heat generation amount of the pre-injection and main injection in the next stroke, and the increase in the heat generation amount leads to an increase in engine torque and an increase in combustion noise. A torque change is generated, drivability is deteriorated and noise is increased.
The present invention has been made to solve such a problem, and an object of the present invention is an internal combustion engine that can prevent deterioration of drivability and noise while performing exhaust purification with a catalyst satisfactorily. An object of the present invention is to provide a fuel injection control device.

  In order to achieve the above object, in the fuel injection control apparatus for an internal combustion engine according to claim 1, pre-injection from the fuel injection means during one cycle of the compression self-ignition internal combustion engine having exhaust purification means, In a fuel injection control device for an internal combustion engine capable of sequentially performing a plurality of fuel injections including a main injection with a large injection amount and a post injection for supplying unburned fuel to an exhaust system, the post injection is based on the post injection amount. And a torque correction means for calculating a torque increase amount due to the carry-over fuel to the next stroke and correcting at least the pre-injection amount in the next stroke based on the torque increase amount.

Further, in the fuel injection control apparatus for an internal combustion engine according to claim 2, in claim 1, the torque correction unit is configured to cause all of the carry-over fuel to be generated based on the torque increase amount calculated from the post injection amount. When combustion is possible at the time of combustion of the fuel injected by injection, the pre-injection amount is corrected according to the torque increase amount.
Further, in the fuel injection control device for an internal combustion engine according to claim 3, in claim 1 or 2, the torque correction means can correct the pre-injection amount and the main injection amount in the next stroke based on the torque increase amount. And, based on the torque increase amount calculated from the post-injection amount, when all of the carry-over fuel is not combustible during combustion of the fuel injected by the pre-injection, the pre-injection amount is set. In addition, the main injection amount is corrected.

  According to a fourth aspect of the present invention, there is provided a fuel injection control apparatus for an internal combustion engine according to any one of the first to third aspects, wherein the torque correcting means is configured to determine the pre-injection amount and the main injection in the next stroke based on the torque increase amount. When the fuel injected by the pre-injection after the injection amount correction is combustible, the torque correction amount by correcting the pre-injection amount is changed to the torque correction amount by correcting the main injection amount. It is characterized by the above.

  According to the first aspect of the present invention, the torque increase amount due to the carry-over fuel to the next stroke of the post-injection is calculated based on the post-injection amount, and the pre-injection of the next stroke in which the influence of the carry-over fuel easily appears based on the torque increase amount. Since the amount is corrected, it is possible to correct the pre-injection amount based on the torque increase amount due to the carry-over fuel, reduce the torque generated by the pre-injection, and suppress the torque increase due to the post-injection carry-over fuel. . Thereby, it is possible to prevent the deterioration of drivability and noise due to an increase in the torque of the carry-over fuel, while controlling the exhaust purification means by post injection and performing the exhaust purification well.

According to the second aspect of the invention, only the pre-injection amount is corrected based on the torque increase amount calculated from the post-injection amount when all of the carry-over fuel is combustible during the pre-injection period. I am doing so.
In this way, when all of the carry-over fuel is combustible during the combustion period of the pre-injection, by correcting the pre-injection that greatly contributes to the torque change, for example, a small injection amount with respect to the torque increase due to the carry-over fuel It is possible to cope with this amount of correction.

  According to the invention of claim 3, when all of the carry-over fuel is not combustible during the pre-injection period, the pre-injection amount is secured by correcting the main injection amount in addition to the pre-injection amount. Pre-injection combustion can be performed reliably, and the ignition delay of main injection can be suppressed. Therefore, it is possible to prevent the combustion noise from deteriorating due to the rapid combustion due to the ignition delay of the main injection.

  According to the invention of claim 4, when the fuel injected by the pre-injection after the injection amount correction is combustible, the torque correction amount by the correction of the pre-injection amount is changed to the torque correction amount by the correction of the main injection amount. As described above, by increasing the correction amount of the pre-injection amount that has a large influence on the torque correction as much as possible within the range where pre-combustion is established, the correction amount of the injection amount can be reduced even when correcting the same torque increase amount. Therefore, it is possible to easily control the injection amount.

1 is a schematic configuration diagram of an engine to which a fuel injection control device for an internal combustion engine according to the present invention is applied. It is a flowchart of the fuel injection control which ECU performs. It is a figure which shows the relationship between post injection amount and torque increase amount. It is a figure which shows the relationship between torque increase amount and pre injection correction amount. It is a figure which shows the relationship between torque increase amount and main injection amount correction amount. It is a figure which shows the distribution ratio to each injection in the pre-injection amount after torque correction. It is a figure which shows the relationship between the pre-injection amount and the heat generation amount in each injection.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic configuration diagram of an engine to which a fuel injection control device for an internal combustion engine is applied.
As shown in FIG. 1, an engine (internal combustion engine) 1 is a multi-cylinder direct injection internal combustion engine (for example, a common rail diesel engine). Specifically, high pressure fuel accumulated in the common rail is used as fuel for each cylinder. The fuel is supplied to the injection nozzle (fuel injection means) 2 and can be injected from the fuel injection nozzle 2 into the combustion chamber 3 of each cylinder at an arbitrary injection timing and injection amount.

Each cylinder of the engine 1 is provided with a piston 4 that can slide up and down. The piston 4 is connected to the crankshaft 6 via a connecting rod 5. A crank angle sensor 7 for detecting the rotational speed and a flywheel (not shown) are provided at one end of the crankshaft 6.
An intake port 8 and an exhaust port 9 are communicated with the combustion chamber 3.

The intake port 8 is provided with an intake valve 10 for communicating and blocking between the combustion chamber 3 and the intake port 8. In addition, the exhaust port 9 is provided with an exhaust valve 11 for performing communication and blocking between the combustion chamber 3 and the exhaust port 9.
Upstream of the intake port 8, an air cleaner 12 that removes dust in the fresh air sucked from the most upstream, a compressor housing (not shown) of a turbocharger 13 that compresses the sucked fresh air using the energy of the exhaust, and a compression An intercooler 14 that cools the fresh air that has become hot, an electronically controlled throttle valve 15 that adjusts the flow rate of the fresh air, and an intake manifold 16 that distributes the intake air to each cylinder are provided to communicate with each other. ing. The electronically controlled throttle valve 15 is provided with a throttle position sensor 17 for detecting the degree of opening of the throttle valve.

  An air flow sensor 18 for detecting the amount of fresh air sucked into the combustion chamber 3 is provided so as to protrude into the passage downstream of the air cleaner 12 and upstream of the compressor housing of the turbocharger 13. Further, a boost sensor 19 for detecting the pressure of intake air sucked into the combustion chamber 3 and an intake temperature sensor 20 for detecting the temperature of the intake air are provided so as to protrude into the intake manifold 16.

Downstream of the exhaust port 9, an exhaust manifold 21 that collects exhaust discharged from each cylinder, a turbine housing (not shown) that introduces exhaust into the turbocharger 13, and an exhaust pipe 22 are provided so as to communicate with each other.
The exhaust pipe 22 includes an oxidation catalyst (exhaust purification means) 23 for oxidizing an oxidizable component such as hydrocarbon (THC) or carbon monoxide (CO) in the exhaust in order from upstream, and nitrogen oxide ( NOx trap catalyst (exhaust gas purification means) 24 for storing and reducing NOx), and diesel particulate filter (exhaust gas purification means) 25 for collecting and burning particulate matter (PM) mainly composed of graphite in the exhaust gas. It is provided to communicate.

  The NOx trap catalyst 24 temporarily stores NOx in the exhaust gas, and performs NOx purge processing for setting the exhaust gas to a rich air-fuel ratio, thereby reducing the stored NOx and purifying NOx. Further, since the NOx trap catalyst 24 adsorbs the sulfur content (S) in the exhaust and the NOx purification performance deteriorates, it is necessary to perform an S purge process for desorbing the adsorbed sulfur with the exhaust as a rich air-fuel ratio. There is. The diesel particulate filter 25 oxidizes the exhaust gas having a rich air-fuel ratio with the oxidation catalyst 23 to perform high temperature exhaust gas, and performs PM combustion processing for removing the accumulated PM by inflowing the high temperature exhaust gas. Eliminate clogging with PM.

An exhaust temperature sensor 26 that detects the temperature of exhaust gas is provided in the exhaust pipe 22 so as to protrude into the exhaust pipe 22 downstream of the turbocharger 13 of the exhaust pipe 22.
An A / F sensor 27 that detects the oxygen concentration, which is the oxygen ratio in the exhaust gas, is provided so as to protrude into the passage downstream of the NOx trap catalyst 24 in the exhaust pipe 22 and upstream of the diesel particulate filter 25. Yes.

The intake manifold 16 and the exhaust manifold 21 are provided with an EGR passage 28 for returning a part of the exhaust gas to the intake air so as to communicate with each other. The EGR passage 28 is provided with an EGR valve 29 for adjusting the amount of exhaust gas returning to intake air, that is, an EGR amount, and an EGR cooler 30 for cooling the exhaust gas returning to intake air.
Various devices such as the fuel injection nozzle 2, the crank angle sensor 7, the throttle position sensor 17, the air flow sensor 18, the boost sensor 19, the intake air temperature sensor 20, the exhaust gas temperature sensor 26, the A / F sensor 27, and the EGR valve 29, The various sensors are control devices for performing overall control of the engine 1, and include an input / output device, a storage device (ROM, RAM, nonvolatile RAM, etc.), a timer, a central processing unit (CPU), and the like. Are electrically connected to an electronic control unit (ECU) (torque correction means) 40, and the ECU 40 controls the operation of various devices based on information from various sensors.

Sensors such as a crank angle sensor 7, a throttle position sensor 17, an air flow sensor 18, a boost sensor 19, an intake air temperature sensor 20, an exhaust gas temperature sensor 26, and an A / F sensor 27 are electrically connected to the input side of the ECU 40. Detection information from these various devices and various sensors is input.
On the other hand, the fuel injection nozzle 2 and the EGR valve 29 are electrically connected to the output side of the ECU 40.

  Thus, the ECU 40 optimally controls the fuel injection amounts and injection timings of the pre-injection, main injection and after-injection from the fuel injection nozzle 2 and the opening degree of the EGR valve 29 based on the detection values of the respective sensors. Further, the ECU 40 discriminates the driving state of the vehicle based on the detection value of each sensor, and adsorbs the sulfur content in the exhaust or NOx to the NOx trap catalyst 24 or the accumulated amount of PM accumulated on the diesel particulate filter 25. And post-injection in which fuel is injected into the combustion chamber 3 at the latter stage of the expansion stroke in order to set the exhaust to a rich air-fuel ratio to perform sulfur or NOx purge processing or PM combustion processing.

Next, fuel injection control in the ECU 40 will be described.
FIG. 2 is a flowchart of fuel injection control executed by the ECU 40. FIG. 3 is a diagram showing the relationship between the post injection amount and the torque increase amount, in which the horizontal axis indicates the post injection amount and the vertical axis indicates the torque increase amount ΔT. FIG. 4 is a diagram showing the relationship between the torque increase amount and the pre-correction amount. The horizontal axis represents the torque increase amount ΔT, the vertical axis represents the pre-correction amount, and more specifically, the injection amount correction amount in the pre-injection of the next stroke. Show. FIG. 5 is a diagram showing the relationship between the torque increase amount and the main correction amount. The horizontal axis represents the torque increase amount ΔT, the vertical axis represents the main correction amount, and more specifically, the correction amount of the injection amount in the main injection in the next stroke. Show. 3, 4 and 5 are each confirmed in advance by a test or the like and stored in the ECU 40. FIG. 6 is a diagram showing the distribution ratio to each injection at the corrected pre-injection amount, where the horizontal axis represents the corrected pre-injection amount Qpmod, the vertical axis represents the distribution ratio ratio to the pre-injection, and the lower Indicates the distribution ratio (1-ratio) to the main injection. The pre-injection amount lower limit Qpmin in the figure is the lower limit pre-injection amount at which stable pre-combustion can be performed, and the pre-single correction lower limit Q psmin is the lower limit at which the post-injection carryover fuel can be burned during the pre-injection period. Indicates the pre-injection amount. FIG. 6 is set in advance from the amount of heat generated in the pre-injection and main injection due to the change in the pre-injection amount as shown in FIG.

The routine shown in FIG. 2 is performed every time post injection is performed during NOx purge processing, S purge processing, or PM combustion processing.
As shown in FIG. 2, in step S10, the pre-injection distribution ratio ratio is assumed to be 1.0, and 1.0 is substituted into the pre-injection distribution ratio ratio in the following equation (1) to obtain a corrected pre-injection amount. Qpmod is calculated. Then, the process proceeds to step S12.

Qpmod = Qp-ΔT × ratio / ΔTqp (1)
Qpmod: post-correction pre-injection amount Qp: pre-correction pre-injection amount ΔT: torque increase amount due to carry-over fuel of post injection (determined using FIG. 3 based on post-injection amount)
ΔTqp: Torque increase amount per unit of pre-correction amount (corresponding to the reciprocal of the slope in FIG. 4 and calculated in advance)
In step S12, it is determined whether or not the corrected pre-injection amount Qpmod calculated in step S10 is larger than the pre-single correction lower limit Qpsmin. If the determination result is true (Yes) and the corrected pre-injection amount Qpmod is larger than the pre-single correction lower limit Qpsmin, the post-injection carryover fuel can be burned during the pre-injection period with the corrected pre-injection amount Qpmod. Assuming that the range is (I), the process proceeds to step S14. If the determination result is no (No) and the corrected pre-injection amount Qpmod is equal to or less than the pre-single correction lower limit Qpsmin, the post-injection carryover fuel cannot be burned during the pre-injection period with the corrected pre-injection amount Qpmod. That is, assuming that the carry-over fuel of the post injection is carried over to the period of the main injection, the process proceeds to step S18, assuming that it is within the range of FIG. 4 (II) or (III).

In step S14, the ratio of distribution to pre-injection is set to 1.0. Then, the process proceeds to step S16.
In step S16, the post-injection carry-over fuel can be burned out during the pre-injection period, and the corrected main injection amount Qmmod is set as the pre-correction main injection amount Qm. That is, the main injection amount Qm is not corrected. Then, this routine is returned.

In step S18, the corrected pre-injection amount Qpmod is calculated from the above equation (1) and the following equation (2). Then, the process proceeds to step S20.
ratio = Qpmod × α + β (2)
α: slope (constant) of range (II) in FIG.
β: intercept (constant) in range (II) of FIG.
In step S20, it is determined whether or not the corrected pre-injection amount Qpmod calculated in step S18 is greater than the pre-injection amount lower limit Qpmin. If the determination result is true (Yes) and the corrected pre-injection amount Qpmod is larger than the pre-injection amount lower limit Qpmin, the process proceeds to step S22 assuming that the range is in FIG. 4 (II). If the determination result is NO (No) and the corrected pre-injection amount Qpmod is equal to or less than the pre-injection amount lower limit Qpmin, the process proceeds to step S24 assuming that it is within the range of FIG.

In step S22, the distribution ratio ratio to pre-injection is calculated from the above equation (2), and corrected from the distribution ratio ratio to the pre-injection, the corrected pre-injection amount Qpmod calculated in step S18, and the following equation (3). The rear main injection amount Qmmod is calculated. Then, this routine is returned.
Qmmod = Qm-ΔT × (1-ratio) / ΔTqm (3)
Qmmod: main injection amount after correction Qm: main injection amount before correction ΔTqm: torque increase amount per unit of main correction amount (corresponding to the reciprocal of the slope in FIG. 5 and calculated in advance)
In step S24, the corrected pre-injection amount Qpmod is set as the pre-injection amount lower limit Qpmin. Then, the process proceeds to step S26.

In step S26, a distribution ratio ratio to pre-injection is calculated from the following equation (4). Then, the corrected main injection amount Qmmod is calculated from the calculated distribution ratio to pre-injection and the above equation (3). Then, this routine is returned.
ratio = (Qp−Qpmod) × ΔTqm / ΔT (4)
As described above, in the fuel injection control of the internal combustion engine of the present invention, the torque increase amount ΔT due to the carry-over of fuel to the next stroke of the post injection is calculated based on the relationship between the post injection amount and the torque increase amount ΔT confirmed in advance by a test or the like. calculate. Then, the corrected pre-injection amount Qpmod for keeping the torque output from the engine 1 constant is calculated as the distribution ratio ratio to pre-injection = 1.0 in the equation (1). If the corrected pre-injection amount Qpmod is larger than the pre-single correction lower limit Qpsmin, it is assumed that the post-injection carry-over fuel can be burned during the pre-injection period with the corrected pre-injection amount Qpmod. Pre-injection amount in the stroke. Further, assuming that the corrected pre-injection amount Qpmod is equal to or less than the pre-single correction lower limit Qpsmin and that the post-injection carryover fuel cannot be burned during the pre-injection period with the corrected pre-injection amount Qpmod, the equations (1) and (2 ) To calculate the corrected pre-injection amount Qpmod again. If the corrected pre-injection amount Qpmod is larger than the pre-injection amount lower limit Qpmin again, the corrected main injection amount Qmmod is calculated from Equation (3), and the corrected pre-injection amount Qpmod is calculated again and the corrected main injection amount is calculated. Let Qmmod be the pre-injection amount and main injection amount for the next stroke. Further, if the corrected pre-injection amount Qpmod is equal to or less than the pre-injection amount lower limit Qpmin, the distribution ratio ratio to pre-injection is calculated from the equation (4), the corrected main injection amount Qmmod is calculated, and the pre-injection amount is calculated. The lower limit Qpmin and the calculated corrected main injection amount Qmmod are set as the main injection amount for the next stroke. The pre-injection amount in the next stroke is set to a pre-injection amount lower limit Qpmin that enables stable pre-fuel.

  That is, the amount of torque increase is calculated from the carry-over fuel of the post injection, the corrected pre-injection amount Qpmod is larger than the pre-single correction lower limit Qpsmin, and the carry-over fuel is all burned out during the pre-injection period at the corrected pre-injection amount Qpmod. If it is possible, torque correction is performed only for the pre-injection amount. Further, the carry-over fuel cannot be completely burned out during the pre-injection period with the corrected pre-injection amount Qpmod, and the corrected pre-injection amount Qpmod is not more than the pre-injection amount lower limit Qpmin at which the pre-injection combustion becomes unstable. For example, the pre-injection amount is set to the pre-injection amount lower limit Qpmin, and torque correction of the main injection amount is performed based on the pre-injection amount. If the corrected pre-injection amount Qpmod is within the range between the pre-single correction lower limit Qpsmin and the pre-injection amount lower limit Qpmin, the torque correction between the pre-injection amount and the main injection amount is performed based on FIG.

  Therefore, based on the post injection amount, the amount of torque increase due to the carry-over fuel to the next stroke of the post injection is calculated, and the pre injection amount and the main injection amount of the next stroke are corrected based on the torque increase amount. By correcting the pre-injection amount and the main injection amount by the torque increase amount by the carry-over fuel, the torque generated by the pre-injection and the main injection is reduced, and the torque increase by the carry-over fuel of the post injection is corrected. In this way, the NOx purge catalyst, the S purge process, or the PM combustion process is performed by correcting the pre-injection amount and the main injection amount based on the amount of torque increase due to the carryover fuel of the post injection, thereby performing the NOx trap catalyst. 24 or the diesel particulate filter 25 can be satisfactorily purified, and drivability and noise deterioration due to an increase in the torque of the carry-over fuel can be prevented.

  Further, in the present embodiment, based on the torque increase amount calculated from the post injection amount, all of the carry-over fuel can be combusted during the pre-injection period, or the pre-injection amount is unstable in the pre-injection combustion. If all the carry-over fuel can be combusted during the pre-injection period, the pre-injection that greatly contributes to the torque change is preferentially corrected. Thereby, for example, it is possible to cope with an increase in torque due to carry-over fuel with a small correction amount of the injection amount.

  In addition, since the main injection amount is corrected in addition to the pre-injection amount when all of the carry-over fuel cannot be combusted during the pre-injection period, the pre-injection amount is set so that the pre-injection combustion does not become weak. Can be secured. Therefore, the pre-injection combustion is reliably performed, and it is possible to suppress the ignition delay of the main injection, and it is possible to prevent the deterioration of the combustion noise due to the rapid combustion due to the ignition delay of the main injection.

This is the end of the description of the embodiment of the invention, but the invention is not limited to this embodiment.
For example, in FIGS. 3, 4, and 5, the injection amount and the torque increase amount are represented by a proportional relationship, but the present invention is not limited to this, and for example, the relationship between the injection amount and the torque increase amount by another function or a map or the like. May be defined.

  Further, for example, in the present embodiment, when all of the carry-over fuel can be combusted during the pre-injection period, only the pre-injection is corrected as shown in FIG. For example, both the pre-injection and the main injection may be corrected so that the torque correction amount based on the pre-injection correction amount is equal to or greater than the torque correction amount based on the main injection correction amount. Good. In this way, by increasing the correction amount of the pre-injection amount that has a large effect on the torque increase, the correction amount of the injection amount can be reduced even for correction for the same torque increase amount. Can be easily.

1 engine (internal combustion engine)
2 Fuel injection nozzle (fuel injection means)
23 Oxidation catalyst (exhaust gas purification means)
24 NOx trap catalyst (exhaust gas purification means)
25 Diesel particulate filter 40 ECU (torque correction means)

Claims (4)

Plural types including pre-injection from fuel injection means, main injection having a larger injection amount than the pre-injection, and post-injection for supplying unburned fuel to the exhaust system in one cycle of a compression self-ignition internal combustion engine having exhaust purification means In the fuel injection control device for an internal combustion engine capable of sequentially performing the fuel injections of times,
Torque correction means for calculating a torque increase amount due to carry-over fuel to the next stroke of the post injection based on the post injection amount, and correcting at least the pre-injection amount of the next stroke based on the torque increase amount. A fuel injection control device for an internal combustion engine.   Based on the torque increase amount calculated from the post-injection amount, the torque correction means increases the torque when all of the carry-over fuel is combustible during combustion of the fuel injected by the pre-injection. The fuel injection control device for an internal combustion engine according to claim 1, wherein the pre-injection amount is corrected according to the amount.   The torque correction means can correct the pre-injection amount and the main injection amount in the next stroke based on the torque increase amount, and based on the torque increase amount calculated from the post injection amount, 3. The main injection amount is corrected in addition to the pre-injection amount when all of the fuel is not combustible when the fuel injected by the pre-injection is combusted. Fuel injection control device for internal combustion engine.   The torque correction means can correct the pre-injection amount and the main injection amount in the next stroke based on the torque increase amount, and the fuel injected by the pre-injection after the injection amount correction is combustible. 4. The fuel injection of the internal combustion engine according to claim 1, wherein the torque correction amount by the correction of the pre-injection amount is equal to or greater than the torque correction amount by the correction of the main injection amount. Control device.

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