JP2019052572A - Device and system for controlling internal combustion engine - Google Patents

Abstract

To restrain a temperature drop in an exhaust emission control device, and to restrain discharge of unburnt gas.SOLUTION: A control system (1) of an engine (2) includes an injector (10) for injecting fuel, a catalyst (21) for purifying exhaust gas, and a control device (3) for controlling the injector. The control device includes an injection amount calculating section (30) for calculating a fuel injection amount of the injector on the basis of request output to an internal combustion engine, a determining section (31) for determining whether the internal combustion engine is in a warming-up state or not, and a temperature calculating section (32) for calculating a temperature of an exhaust emission control device. The injection amount calculating section corrects a preliminarily set minimum fuel injection amount of the injector on the basis of the temperature of the exhaust emission control device when the internal combustion engine is determined to be in the warming-up state and the request output is equal to or less than a prescribed value.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an internal combustion engine control apparatus and an internal combustion engine control system.

  In accordance with recent exhaust gas regulations, an internal combustion engine of a vehicle is provided with an exhaust purification device that purifies exhaust gas (see, for example, Patent Document 1). In Patent Document 1, for example, a three-way catalyst is used as an exhaust purification device. The exhaust purification device is provided in the middle of the exhaust pipe.

  Incidentally, the purification performance of the catalyst depends on the temperature, and it is necessary to raise the temperature (in order to activate the temperature) in order to obtain a predetermined purification performance. For this reason, in patent document 1, fuel injection is performed in multiple steps. Specifically, main injection for obtaining an output and sub-injection for increasing the temperature of the catalyst are executed.

  The main injection ensures a predetermined engine output and realizes stable combustion. On the other hand, the fuel injected by the sub-injection flows into the exhaust pipe as exhaust gas with little combustion in the cylinder. Since this exhaust gas flows into the catalyst in a rich air-fuel ratio state, the chemical reaction of the catalyst is promoted. The catalyst is heated by the heat of reaction.

JP 2001-107790 A

  As described above, in Patent Document 1, the main injection and the sub-injection are executed at different timings. For example, the secondary injection is performed in the expansion stroke or the exhaust stroke. However, when the fuel is injected at a timing different from that of normal combustion, unburned gas increases. When the temperature of the catalyst does not reach a sufficient activation temperature, unburned gas is not purified but is discharged as white smoke. Thus, the exhaust gas purification performance may be deteriorated.

  The present invention has been made in view of the above points, and provides an internal combustion engine control device and an internal combustion engine control system capable of suppressing temperature decrease of an exhaust purification device and suppressing discharge of unburned gas. For the purpose.

  An internal combustion engine control device according to one aspect of the present invention is a control device for an internal combustion engine that controls a fuel injection amount of an injector based on a required output of the internal combustion engine, wherein the internal combustion engine is in a warm-up state and is required. When the output is less than or equal to a predetermined value, as the temperature of the exhaust emission control device is lower, a preset increase correction of the minimum fuel injection amount of the injector is performed.

  An internal combustion engine control system according to one aspect of the present invention is an internal combustion engine control system including an injector that injects fuel, an exhaust purification device that purifies exhaust gas, and a control device that controls the injector, The control device includes an injection amount calculation unit that calculates a fuel injection amount of the injector based on a required output to the internal combustion engine, a determination unit that determines whether or not the internal combustion engine is in a warm-up state, and the exhaust A temperature calculation unit that calculates the temperature of the purification device, wherein the injection amount calculation unit determines that the internal combustion engine is in a warm-up state, and is set in advance when a required output is equal to or less than a predetermined value. The minimum fuel injection amount of the injector is corrected based on the temperature of the exhaust gas purification device.

  ADVANTAGE OF THE INVENTION According to this invention, while suppressing the temperature fall of an exhaust gas purification apparatus, discharge | emission of unburned gas can be suppressed.

1 is an overall configuration diagram of a control system for an internal combustion engine according to the present embodiment. It is a functional block diagram of the control apparatus which concerns on this Embodiment. It is a figure which shows the relationship between fuel injection quantity and injector drive time. It is a graph which shows the relationship between catalyst temperature, fuel injection amount, and unburned component purification rate. It is a time chart of various parameters concerning this embodiment and a conventional example. It is a figure which shows the control flow of the internal combustion engine which concerns on this Embodiment.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following, an automobile will be described as an example of a vehicle to which the control device for an internal combustion engine according to the present invention is applied, but the application target is not limited to this and can be changed. For example, the control device for an internal combustion engine according to the present invention may be applied to other types of vehicles such as a motorcycle and a buggy type motor tricycle.

  With reference to FIG.1 and FIG.2, the control system of the internal combustion engine which concerns on this Embodiment is demonstrated. FIG. 1 is an overall configuration diagram of a control system for an internal combustion engine according to the present embodiment. FIG. 2 is a functional block diagram of the control device according to the present embodiment. The control system for the internal combustion engine is not limited to the configuration shown below, and can be changed as appropriate.

  As shown in FIG. 1, the control system 1 for an internal combustion engine according to the present embodiment controls the operation of an engine 2 as an internal combustion engine and its peripheral configuration by an ECU 3 (Electronic Control Unit) as a control device. It is configured. The engine 2 is composed of, for example, an in-line multi-cylinder diesel engine. The engine 2 is not limited to a diesel engine, and may be a gasoline engine, for example.

  The engine 2 is provided with an injector 10 for each cylinder as a fuel injection device that directly injects fuel into the cylinder. High pressure fuel is supplied from the fuel tank 11 to the injector 10. Specifically, a fuel pump 12 and a common rail 13 are provided between the injector 10 and the fuel tank 11 from the downstream side. The fuel pump 12 boosts the fuel from the fuel tank 11 and generates a pressure necessary for fuel injection. The common rail 13 is connected to the injector 10 and temporarily stores the fuel boosted by the fuel pump 12.

  The common rail 13 is provided with a fuel pressure adjustment valve (not shown) for adjusting the fuel injection pressure. The fuel pressure regulating valve is constituted by, for example, a relief valve (also called a pressure limiter), and opens when the fuel pressure in the common rail 13 exceeds a predetermined pressure to limit the increase in the fuel pressure. Injector 10 receives a command from ECU 3 and injects high-pressure fuel into the combustion chamber at a predetermined timing.

  An intake pipe 15 is connected to the intake side of the engine 2 via an intake manifold 14. The intake pipe 15 is provided with a supercharger 16 (a compressor 16b described later), an intercooler 17, and an air amount sensor 18 from the upstream side. On the other hand, an exhaust pipe 20 is connected to the exhaust side of the engine 2 via an exhaust manifold 19. The exhaust pipe 20 is provided with a supercharger 16 (a turbine 16a described later), a catalyst 21 and a DPF 22 as an exhaust purification device, and a muffler 23 from the upstream side.

  The supercharger 16 is a turbocharger that rotates the turbine 16a with the pressure of exhaust gas to drive the compressor 16b, and compresses intake air by the compressor 16b. Specifically, the supercharger 16 is configured by coaxially connecting a turbine 16a provided on the exhaust pipe 20 side and a compressor 16b provided on the intake pipe 15 side via a turbo shaft 16c. The intercooler 17 cools the intake air compressed by the supercharger 16. The air amount sensor 18 is constituted by, for example, a MAF sensor (Mass Flow Sensor). The air amount sensor 18 detects the amount of intake air (mass flow rate) flowing through the intake pipe 15 through the intercooler 17 and outputs the detected value to the ECU 3.

  The catalyst 21 has a function of oxidizing the exhaust gas, and is composed of, for example, a three-way catalyst. The catalyst 21 converts (oxidizes) pollutants (carbon monoxide, hydrocarbons, nitrogen oxides, etc.) in the exhaust gas into harmless substances (carbon dioxide, water, nitrogen, etc.). The DPF (Diesel Particulate Filter) 22 is a filter that captures (collects) particulate matter in the exhaust gas.

  Further, in the present embodiment, an EGR system (Exhaust Gas Recirculation system) is employed in which part of the exhaust gas is returned to the intake side and recombusted. Specifically, the exhaust pipe 20 upstream of the turbine 16 a and the intake pipe 15 downstream of the compressor 16 b and upstream of the intercooler 17 are connected by a connection pipe 24. The connection pipe 24 is provided with an EGR cooler 25 for cooling the exhaust gas and an EGR valve 26 for adjusting the intake amount of the exhaust gas in order from the exhaust side.

  The ECU 3 controls the overall operation of the vehicle including various configurations inside and outside the engine 2. The ECU 3 includes a processor that executes various processes, a memory, and the like. The memory is configured by a storage medium such as a ROM (Read Only Memory) or a RAM (Random Access Memory) according to the application. The memory stores a control program for controlling the various configurations described above. For example, the ECU 3 determines the state of the vehicle from various sensors provided in the vehicle, and controls driving of the injector 10, the EGR valve 26, and the like.

  For example, the ECU 3 has a plurality of functional blocks according to the configuration to be controlled. Specifically, the ECU 3 includes an injection amount calculation unit 30 that calculates the fuel injection amount of the injector 10, a determination unit 31 that determines the warm-up state of the engine 2, and a temperature calculation unit 32 that calculates the temperature of the catalyst 21. doing. Note that these functional blocks are merely examples, and the ECU 3 is not limited to these functional blocks, and may have other functional blocks. Further, the ECU 3 stores various threshold values necessary for control described later.

  The injection amount calculation unit 30 calculates the fuel injection amount of the injector 10 based on (according to) the required output of the engine. Here, the required output is calculated according to the depression amount of an accelerator pedal (not shown). That is, the fuel injection amount corresponding to the required output means a fuel injection amount that satisfies the required output corresponding to the depression amount of the accelerator pedal. Although details will be described later, when the engine 2 is in a warm-up state and the required output is less than or equal to a predetermined value, the injection amount calculation unit 30 determines the preset minimum fuel injection amount of the injector 10 as the temperature of the exhaust purification device. Correct based on

  For example, the determination unit 31 determines the warm-up state of the engine 2 from the engine water temperature. The temperature calculation unit 32 calculates (calculates) the temperature of the catalyst 21 based on various parameters. Specifically, as shown in FIG. 2, the temperature calculation unit 32 determines the exhaust temperature (exhaust gas temperature) based on the intake air amount, the fuel injection amount, the temperature (intake manifold temperature) and the pressure (intake manifold pressure) of the intake manifold 14. ) Is calculated. Examples of the exhaust temperature include the exhaust temperature in the cylinder, the exhaust temperature of the exhaust port, the exhaust temperature of the turbine 16a, the exhaust temperature of the catalyst 21, and the like. It is possible to calculate the temperature of the catalyst 21 (hereinafter sometimes referred to as catalyst temperature) from these exhaust temperatures. Thus, since it is not necessary to separately provide a sensor for detecting the catalyst temperature, the configuration is simplified.

  In this way, the ECU 3 calculates a predetermined fuel injection amount from various parameters, and controls the injector 10 so as to inject fuel at the fuel injection amount. For example, the ECU 3 controls the energization time for the injector 10.

  By the way, for the discharge processing of unburned gas due to unstable combustion of the diesel engine, it is conceivable to improve the combustion by purifying with an oxidation catalyst or correcting the injection parameters when the engine is cold. However, no effective countermeasures have been taken for the case where the engine is warmed up but the catalyst temperature is low. If the catalyst temperature is low, the exhaust gas purification performance deteriorates, so that the unburned gas may be discharged as white smoke without being purified. In the first place, since the exhaust temperature of a diesel engine is lower than that of a gasoline engine, the temperature of the catalyst tends to decrease.

  For example, when the driver continues to depress the accelerator pedal slightly, such as when traveling on a long downhill like an expressway, a small amount of fuel corresponding to the amount of depression is injected from the injector. .

  Here, the fuel injection amount of the injector will be described with reference to FIG. FIG. 3 is a diagram showing the relationship between the fuel injection amount and the injector drive time. The horizontal axis indicates the injector drive time, and the vertical axis indicates the fuel injection amount.

  As described above, the pressurized fuel is supplied to the injector, and a predetermined amount of fuel is injected from the injector by opening and closing a needle valve (not shown) provided at the tip. That is, the fuel injection amount of the injector can be controlled by the time during which the needle valve is opened (injector drive time) and the fuel pressure (fuel injection pressure). In this case, it is assumed that the size (cross-sectional area) of the injection hole at the tip of the injector is determined structurally.

  Here, it is assumed that the fuel injection pressure is increased to a predetermined pressure. In the injector, basically, the fuel injection amount changes in proportion to the injector driving time. However, due to the structure of the injector, there is a region where the fuel injection amount is not proportional to the injector driving time with a certain predetermined point as a boundary.

  As shown in FIG. 3, with the predetermined fuel injection amount F1 as a boundary, the region where the fuel injection amount is smaller than F1 is a non-linear region where the fuel injection amount is not proportional to the injector drive time. On the other hand, in the region where the fuel injection amount is F1 or more, the fuel injection amount is a linear region proportional to the injector drive time.

  In the non-linear region, since the fuel injection amount is not proportional to the injector driving time, it is difficult to appropriately control the fuel injection amount with the injector driving time. On the other hand, in the linear region, since the fuel injection amount is proportional to the injector drive time, the ECU can appropriately control the fuel injection amount by adjusting the injector drive time. Here, the fuel injection amount F1 indicating the starting point (lowest point) of the linear region is set as the minimum fuel injection amount of the injector. This minimum fuel injection amount represents the minimum value of the fuel injection amount that can be controlled by the ECU by adjusting the injector drive time.

  That is, if the injector drive time is too short, the fuel injection amount is not stable. Thus, there is a possibility that an appropriate amount of fuel may not be injected in the nonlinear region where the injector drive time is extremely short. For this reason, as described above, when the driver continues to depress the accelerator pedal slightly (small accelerator opening), the fuel injection is normally performed with the minimum fuel injection amount F1.

  However, when the fuel injection at the minimum fuel injection amount F1 is continued, the fuel necessary for stable combustion is not injected and the combustion becomes unstable. As a result, exhaust heat may be insufficient and the temperature of the catalyst may be lowered. The catalyst temperature drop is also caused by the fuel cut being performed, for example, when the accelerator pedal is not operated for a while while traveling on the downhill. As a result, exhaust gas containing a large amount of unburned components is generated. Further, as the temperature of the catalyst decreases, the exhaust gas cannot be sufficiently purified, and the exhaust gas is discharged as white smoke.

  Accordingly, the present inventor has conceived the present invention by paying attention to the temperature of the catalyst in the warm-up state of the engine and the preset minimum fuel injection amount F1 of the injector. In the present embodiment, when the engine 2 is in a warm-up state and the required output is less than or equal to a predetermined value, the ECU 3 temporarily reduces the preset minimum fuel injection amount of the injector 10 as the temperature of the catalyst 21 decreases. Perform increase correction. Specifically, as shown in FIG. 3, the ECU 3 calculates a corrected minimum fuel injection amount F2 by adding a predetermined correction amount X to a preset minimum fuel injection amount F1 (F2 = F1 + X). The drive of the injector 10 is controlled.

  According to this configuration, during idle-up such as warm-up, only the minimum fuel injection amount is increased and corrected according to the temperature of the catalyst 21, so that the temperature of the catalyst 21 can be decreased at a small accelerator opening on a downhill or the like. It is possible to suppress the discharge of unburned gas. Further, in the warm-up state, it is possible to stably continue self-ignition and combustion. For this reason, it is not necessary to correct the entire map for determining the fuel injection amount, and the above effect can be obtained by correcting only the minimum fuel injection amount. As a result, the control configuration can be simplified. Further, when the required output is larger than a predetermined value, the increase correction is not performed, so that deterioration of fuel consumption can be suppressed. Note that the correction amount X can be appropriately changed according to the catalyst temperature, whereby the catalyst temperature can be suitably secured.

  Next, the relationship between the catalyst temperature, the fuel injection amount, and the unburned component purification rate will be described with reference to FIG. FIG. 4 is a graph showing the relationship between the catalyst temperature, the fuel injection amount, and the unburned component purification rate. The horizontal axis indicates the catalyst temperature, and the vertical axis indicates the fuel injection amount or the unburned component purification rate. In FIG. 4, the solid line indicates the corrected minimum fuel injection amount, and the broken line indicates the unburned component purification rate.

  As described above, in the present embodiment, it is determined whether or not to perform the increase correction of the minimum fuel injection amount based on the warm-up state of the engine 2, the required output, and the catalyst temperature. The correction amount is calculated based on the catalyst temperature or the like. As shown in FIG. 4, the increase correction is performed within a predetermined temperature range D between the catalyst temperature D1 and D2. The predetermined temperature range D constitutes a part of a threshold value for determining whether or not the increase correction is performed. The temperature D1 is a temperature indicating a lower limit value of the predetermined temperature range D, and is a temperature at which an unburned component purification rate described later becomes a predetermined value R. The temperature D2 is a temperature indicating the upper limit value of the predetermined temperature range D.

  When the increase correction is performed, the fuel injection amount is corrected between F1 and F3. As described above, F1 is a fuel injection amount indicating the start point (lowest point) of the linear region of the injector 10, that is, a preset minimum fuel injection amount. Within the predetermined temperature range D, the minimum fuel injection amount is corrected so as to decrease as the catalyst temperature decreases. In this case, the corrected minimum fuel injection amount is calculated by the minimum fuel injection amount F1 + correction amount. It should be noted that outside the predetermined temperature range D, the increase correction is not performed (not valid), and thus the correction amount is not calculated.

  Further, the unburned component purification rate indicated by the broken line is a parameter indicating the purification performance of the catalyst 21, and can be calculated based on the catalyst temperature. As shown in FIG. 4, the unburned component purification rate tends to increase as the catalyst temperature increases. Specifically, the unburned component purification rate gradually increases when the temperature exceeds D1, and settles to a constant value when the temperature exceeds D2.

  In the present embodiment, it is determined whether or not to increase the minimum fuel injection amount using not only the catalyst temperature but also the unburned component purification rate. Specifically, when the unburned component purification rate is lower than the predetermined value R, that is, when the catalyst temperature is lower than D1, the increase correction is stopped (prohibited). This is because when the unburned component purification rate is too low, that is, when the catalyst temperature is too low, the catalyst temperature does not rise even when the increase is corrected, which causes generation of white smoke. As a result, generation of white smoke can be suppressed. In this case, the combustion is improved by warming the combustion chamber with a glow plug (not shown).

  Next, with reference to FIG. 5, changes with time of various parameters accompanying the accelerator operation will be described. FIG. 5 is a time chart of various parameters according to the present embodiment and the conventional example. In addition, the time chart shown in FIG. 5 shows an example, and is not limited to these. The various parameters shown on the vertical axis indicate, in order from the top, white smoke generation amount, catalyst temperature, minimum fuel injection amount, and accelerator opening (required output). Further, the solid line indicates the parameter of the present application, and the broken line indicates the conventional parameter.

  As shown in FIG. 5, when the accelerator pedal is slightly depressed at the timing of T1, conventionally, fuel is injected at the minimum fuel injection amount F1. If fuel injection at the minimum fuel injection amount F1 is continued, the rate of increase in the catalyst temperature deteriorates, and it takes time for the catalyst 21 to reach the activation temperature. As a result, for example, after the timing of T2, the exhaust gas purification performance of the catalyst 21 is not sufficiently obtained (deteriorates), and the amount of white smoke generated increases.

  In contrast, in the present application, when the accelerator opening (required output) is equal to or smaller than a predetermined threshold value, a predetermined correction amount X is added to the preset minimum fuel injection amount F1 of the injector 10 to obtain a new minimum fuel injection amount. Implement fuel injection. Since the increase correction of the minimum fuel injection amount is performed, the activation of the catalyst 21 is promoted by increasing the catalyst temperature, so that it is possible to suppress the white smoke generation amount.

  Further, after the increase correction is performed, when the temperature of the catalyst 21 becomes equal to or higher than the predetermined temperature D3, the minimum fuel injection amount that has been temporarily corrected for the increase is gradually decreased to a preset minimum fuel injection amount F1. That is, the correction amount X is gradually approached to zero. If the catalyst temperature reaches a sufficient activation temperature, the correction of the increase amount is not necessary in the first place. Therefore, after the predetermined temperature D3, the correction amount X is gradually eliminated to prevent a sudden change in output and unnecessary fuel injection. It is possible to reduce the fuel efficiency.

  Next, with reference to FIG. 6, the control flow regarding the increase correction of the fuel injection amount will be described. FIG. 6 is a diagram showing a control flow of the internal combustion engine according to the present embodiment. In the control flow shown below, unless otherwise specified, the subject of operation (calculation, determination, etc.) is the ECU.

  As shown in FIG. 6, when the control is started, in step ST101, the ECU 3 acquires the engine water temperature. Specifically, the ECU 3 acquires the engine water temperature from a temperature sensor (not shown). Next, the process proceeds to step ST102.

  In step ST102, the ECU 3 calculates the catalyst temperature. As described above, the ECU 3 calculates the catalyst temperature based on the intake air amount, the fuel injection amount, the intake manifold temperature, the intake manifold pressure, and the like. Next, the process proceeds to step ST103.

In step ST103, it is determined whether or not the engine 2 is in a warm-up state. Specifically, the ECU 3 determines whether or not the engine water temperature is equal to or higher than a predetermined threshold value. When the engine water temperature is equal to or higher than a predetermined threshold (for example, 60 ° C.), the ECU 3 determines that the engine 2 is in a warm-up state (step ST103: YES), and proceeds to the process of step ST104. If the engine water temperature is lower than the predetermined threshold, the ECU 3 determines that the engine 2 is in a cold state (step ST103: NO), and the control ends without performing the increase correction. Note that step ST103 constitutes a part of a step of determining whether or not to perform the fuel injection amount increase correction.

  In step ST104, it is determined whether or not a small accelerator opening has occurred. Specifically, the ECU 3 determines whether the required output (which may be the fuel injection amount) is equal to or less than a predetermined threshold value. If the requested output is equal to or less than the predetermined threshold, the ECU 3 determines that a small accelerator opening has occurred (step ST104: YES), and proceeds to the process of step ST105. If the required output is larger than the predetermined threshold, the ECU 3 determines that a small accelerator opening has not occurred (step ST104: NO), and the control ends without performing the increase correction. Note that step S104 constitutes a part of the step of determining whether or not to perform the fuel injection amount increase correction, similarly to step ST103.

  In step ST105, it is determined whether or not an increase correction of the fuel injection amount is necessary. For example, the ECU 3 determines whether or not the catalyst temperature is below a predetermined threshold (for example, D2 shown in FIG. 4). When the catalyst temperature is lower than D2, the ECU 3 determines that an increase correction of the fuel injection amount is necessary (step ST105: YES), and proceeds to the process of step ST106. If the catalyst temperature is equal to or higher than D2, the ECU 3 determines that the fuel injection amount increase correction is not required (step ST105: NO), and the control ends without performing the increase correction.

  Note that, in step ST105, in addition to the determination of whether or not to increase the catalyst temperature, the presence or absence of the increase correction may be determined based on the unburned component purification rate. For example, the ECU 3 determines whether or not the unburned component purification rate of the catalyst 21 is not more than a predetermined value (for example, not more than R shown in FIG. 4). When the unburned component purification rate is higher than R, the ECU 3 determines that an increase correction of the fuel injection amount is necessary. On the other hand, when the unburned component purification rate is R or less, that is, when the catalyst temperature is D1 (see FIG. 4) or less, the ECU 3 determines that the increase correction is unnecessary and prohibits the increase correction (performs the previous increase correction). If yes, stop the increase correction).

  When it is determined in step ST105 that the catalyst temperature is too low and the increase correction is prohibited, the ECU 3 may switch to control for warming the combustion chamber with a glow plug to assist combustion. Thereby, even when the in-cylinder temperature does not reach a temperature suitable for combustion, combustion can be continued stably, and exhaust heat can be secured.

  In step ST106, a fuel injection amount increase correction amount (correction amount X) is calculated. The ECU 3 calculates an increase correction amount based on the catalyst temperature. Specifically, as shown in FIG. 4, the correction amount X is calculated so as to increase as the catalyst temperature decreases. The preset minimum fuel injection amount F1 + correction amount X is set as the corrected minimum fuel injection amount. Next, the process proceeds to step ST107.

  In step ST107, the ECU 3 determines whether the engine output obtained from the corrected minimum fuel injection amount is greater than the required output. When the engine output obtained by the corrected minimum fuel injection amount is equal to or less than the required output (step ST107: NO), the process proceeds to step ST108. If the engine output obtained by the corrected minimum fuel injection amount is larger than the required output, the ECU 3 determines that the increase correction is unnecessary, and prohibits the increase correction (if the previous increase correction has been performed, the increase correction correction Stop implementation). Then, the control ends.

  By prohibiting the increase correction in step ST107, it is possible to prevent output of torque that is too large with respect to the accelerator opening (required output), and to prevent deterioration of drivability. Note that step S107 constitutes part of a step of determining whether or not to perform the fuel injection amount increase correction, similarly to steps ST103 and ST104.

  In step ST108, the fuel injection amount increase correction is performed. Specifically, the ECU 3 controls the drive of the injector 10 so that the fuel is injected with the corrected minimum fuel injection amount set in step ST106. In step ST108, if the temperature of the catalyst 21 becomes equal to or higher than the predetermined temperature D3 (FIG. 5) after performing the previous increase correction, the minimum fuel injection amount temporarily corrected for the increase is set to a preset minimum. The fuel injection amount is gradually decreased to F1. That is, the ECU 3 controls the fuel injection amount of the injector 10 so that the correction amount X gradually approaches zero. Thus, the control ends.

  As described above, in the present embodiment, when the engine 2 is in the warm-up state and the required output is less than or equal to the predetermined value, the lower the temperature of the catalyst 21, the lower the preset fuel injection amount of the injector 10 temporarily. By performing such an increase correction, it is possible to suppress the temperature decrease of the catalyst 21 and to suppress the discharge of unburned gas.

  In the above embodiment, the diesel engine is described as an example of the internal combustion engine, but the present invention is not limited to this configuration. A gasoline engine may be used as the internal combustion engine.

  The embodiments of the present invention are not limited to the above-described embodiments, and various changes, substitutions, and modifications may be made without departing from the spirit of the technical idea of the present invention. Furthermore, if the technical idea of the present invention can be realized in another way by technological advancement or other derived technology, the method may be used. Accordingly, the claims cover all embodiments that can be included within the scope of the technical idea of the present invention.

  As described above, the present invention has an effect of suppressing the temperature decrease of the exhaust purification device and suppressing the discharge of unburned gas, and in particular, the control device for an internal combustion engine and the automobile. Useful for.

DESCRIPTION OF SYMBOLS 1 Control system of internal combustion engine 10 Injector 2 Engine (engine)
21 Catalyst (Exhaust gas purification device)
3 ECU (control device)
30 injection amount calculation unit 31 determination unit 32 temperature calculation unit F1 preset minimum fuel injection amount

Claims (6)

A control device for an internal combustion engine that controls a fuel injection amount of an injector based on a required output of the internal combustion engine,
When the internal combustion engine is in a warm-up state and the required output is less than or equal to a predetermined value, a temporary increase correction of the preset minimum fuel injection amount of the injector is performed as the temperature of the exhaust purification device decreases. A control device for an internal combustion engine characterized by the above.   After performing the increase correction, when the temperature of the exhaust gas purification device becomes equal to or higher than a predetermined value, the minimum fuel injection amount temporarily increased and corrected is gradually decreased to a preset minimum fuel injection amount. The control apparatus for an internal combustion engine according to claim 1.   The control device for an internal combustion engine according to claim 1 or 2, wherein when the unburned component purification rate indicating the purification performance of the exhaust purification device is equal to or less than a predetermined value, the increase correction is stopped.   4. The control device for an internal combustion engine according to claim 1, wherein when the output obtained by the corrected minimum fuel injection amount is larger than the required output, the increase correction is stopped.   The control device for an internal combustion engine according to any one of claims 1 to 4, wherein the exhaust purification device has a function of oxidizing exhaust gas. An injector for injecting fuel;
An exhaust purification device for purifying exhaust gas;
A control system for controlling the injector, and an internal combustion engine control system comprising:
The controller is
An injection amount calculation unit for calculating a fuel injection amount of the injector based on a required output to the internal combustion engine;
A determination unit for determining whether or not the internal combustion engine is in a warm-up state;
A temperature calculation unit for calculating the temperature of the exhaust purification device,
The injection amount calculation unit determines that the internal combustion engine is in a warm-up state and the required output is equal to or less than a predetermined value, the preset minimum fuel injection amount of the injector is based on the temperature of the exhaust purification device. A control system for an internal combustion engine, wherein

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