JP2014141958A - Internal combustion engine control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To further improve fuel economy while suppressing NOemission when an internal combustion engine restarts after idling stop of the internal combustion engine.SOLUTION: Fuel cut is started for stopping fuel injection to follow satisfaction of a predetermined fuel cut condition, the fuel injection is not carried out until timing just before rotation of an internal combustion engine stops, and the rotation of the internal combustion engine is stopped upon injecting the fuel at the timing just before stopping the rotation. Thereupon, an amount of fuel injected at the timing just before stopping the rotation is set larger if a period since start of the fuel cut until the timing is longer.

Description

  The present invention relates to a control device for an internal combustion engine mounted on a vehicle.

  In an internal combustion engine mounted on a vehicle, it is known to perform a fuel cut that interrupts fuel injection in accordance with the operation state (see, for example, Patent Document 1 below). Normally, when the accelerator pedal depression amount is 0 or less than a threshold value close to 0 and the engine speed is equal to or higher than the fuel cut permission speed, the fuel cut is started assuming that the fuel cut condition is satisfied. Then, when any fuel cut end condition is satisfied, such as when the accelerator pedal depression amount exceeds the threshold value, or the engine speed decreases to the fuel cut return speed, the fuel cut ends and the fuel injection resumes. .

  Recently, it has also become common to implement an idle stop that stops the idle rotation of the internal combustion engine while the vehicle is stopped due to a signal waiting or the like (see, for example, Patent Document 2 below). In the known idling stop system, the internal combustion engine is stopped when various conditions such as the vehicle speed is lower than a predetermined value, the brake pedal is depressed, and the coolant temperature and the battery voltage are sufficiently high are satisfied. After the idling stop, the internal combustion engine is restarted when there is a restart request such as the driver removing his foot from the brake pedal or depressing the accelerator pedal.

  When the driver removes his or her foot from the accelerator pedal while the vehicle is running and the vehicle decelerates and stops, first the fuel cut condition is satisfied and the fuel cut is started, and then the engine shifts to idle stop. However, it does not mean that no fuel is injected between the start of fuel cut and the idle stop. Actually, when the vehicle speed drops to about 10 km / h, the fuel cut end condition is satisfied, and fuel injection and ignition combustion are temporarily resumed. Then, the idle stop condition is established at a vehicle speed of about 9 km / h, and the fuel injection is stopped again, whereby the internal combustion engine and the vehicle are further decelerated, leading to an idle stop and a stop.

This temporary fuel injection is a measure for purging excess oxygen stored in the three-way catalyst for exhaust purification. That is, during the fuel cut, since the free air fuel component flowing into the catalyst, the oxygen up to the upper limit of the oxygen storage capacity of the catalyst is occluded, reduced capacity of the NO _x is reduced. If the internal combustion engine is restarted in this state, the NO _x emission amount increases. Therefore, when the vehicle speed is about 10 km / h, the fuel is injected and the air-fuel ratio rich gas flows into the catalyst to reduce the oxygen storage amount of the catalyst.

Japanese Patent Laid-Open No. 10-030477 JP 2012-137018 A

  However, this temporary fuel injection also causes a deterioration in effective fuel consumption.

An object of the present invention is to further improve fuel consumption while suppressing NO _x emission during restart after an idle stop of an internal combustion engine.

  In order to solve the above-described problems, the present invention starts a fuel cut that stops fuel injection when a predetermined fuel cut condition is satisfied, and then restarts the fuel injection when a predetermined fuel cut end condition is satisfied. While the internal combustion engine is driven to rotate again, if the fuel cut end condition is not satisfied, the fuel injection is not resumed and the rotation of the internal combustion engine is stopped, and the fuel cut end condition is satisfied after the fuel cut condition is satisfied. In the case where the rotation of the internal combustion engine is stopped without using the internal combustion engine, fuel is injected before the rotation of the internal combustion engine stops.

  A fuel cut that stops fuel injection is started when a predetermined fuel cut condition is satisfied, and fuel is not injected until the time immediately before the rotation of the internal combustion engine stops, and fuel is injected at a time immediately before the rotation stops. If the rotation of the internal combustion engine is to be stopped, the amount of fuel to be injected at the time immediately before the rotation is stopped (the injection amount per injection and / or the number of injections to be executed at that time) It is preferable to increase as the period from the start of the cut to the time is longer.

  Alternatively, a fuel cut that stops fuel injection may be started when a predetermined fuel cut condition is satisfied, and the rotation of the internal combustion engine may be stopped after fuel is injected immediately after the start of the fuel cut.

  When fuel is injected a plurality of times before the fuel cut end condition is satisfied and before the rotation of the internal combustion engine stops, the injection amount in the second injection is made equal to or less than the first injection amount, and the injection in the third injection It is preferable that the subsequent injection amount does not exceed the previous injection amount, such that the amount is equal to or less than the second injection amount.

According to the present invention, it is possible to further improve fuel consumption while suppressing NO _x emission during restart after idle stop.

The figure which shows schematic structure of the internal combustion engine in one Embodiment of this invention. The flowchart which shows the example of the procedure of the process which the control apparatus of the internal combustion engine of the embodiment implements. The timing diagram which shows the content of the control implemented in the period until the idling stop after the control apparatus of the embodiment starts a fuel cut. The timing diagram which shows the content of the control implemented in the period until the idling stop after the control apparatus of the embodiment starts a fuel cut. The flowchart which shows the example of the procedure of the process which the control apparatus of the internal combustion engine of one Embodiment of this invention implements. The timing diagram which shows the content of the control implemented in the period until the idling stop after the control apparatus of the embodiment starts a fuel cut. The timing diagram which shows the content of the control implemented in the period until the idling stop after the control apparatus of the embodiment starts a fuel cut.

  <First Embodiment> An embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows an outline of an internal combustion engine for a vehicle in the present embodiment. The internal combustion engine in the present embodiment is a spark ignition type four-stroke engine and includes a plurality of cylinders 1 (one of which is shown in FIG. 1). In the vicinity of the intake port of each cylinder 1, an injector 11 for injecting fuel is provided. A spark plug 12 is attached to the ceiling of the combustion chamber of each cylinder 1. The spark plug 12 receives spark voltage generated by the ignition coil and causes spark discharge between the center electrode and the ground electrode.

  The intake passage 3 for supplying intake air takes in air from the outside and guides it to the intake port of each cylinder 1. On the intake passage 3, an air cleaner 31, an electronic throttle valve 32, a surge tank 33, and an intake manifold 34 are arranged in this order from the upstream.

  The exhaust passage 4 for discharging the exhaust guides the exhaust generated as a result of burning the fuel in the cylinder 1 from the exhaust port of each cylinder 1 to the outside. An exhaust manifold 42 and an exhaust purification three-way catalyst 41 are disposed on the exhaust passage 4.

  An ECU (Electronic Control Unit) 0 that is a control device of the present embodiment is a microcomputer system having a processor, a memory, an input interface, an output interface, and the like.

  The input interface includes a vehicle speed signal a output from a vehicle speed sensor that detects the actual vehicle speed of the vehicle, a crank angle signal b output from an engine rotation sensor that detects the rotation angle and engine speed of the crankshaft, and depression of an accelerator pedal. An accelerator opening signal c output from a sensor that detects the amount or the opening of the throttle valve 32 as an accelerator opening (engine output required by the driver, so-called required load), and output from a sensor that detects the amount of depression of the brake pedal Indicating the brake pedaling amount signal d, the intake air temperature / intake pressure signal e output from the temperature / pressure sensor for detecting the intake air temperature and the intake pressure in the intake passage 3 (particularly, the surge tank 33), and the temperature of the internal combustion engine The coolant temperature signal f output from the coolant temperature sensor that detects the coolant temperature to be detected, the intake camshaft or the exhaust camshaft A cam angle signal g outputted by the cam angle from the cam angle sensor, battery status signal h or the like to be output from the sensor for detecting the battery current and the battery temperature suggesting the state of charge of the vehicle battery is input.

  From the output interface, an ignition signal i is output to the igniter of the spark plug 12, a fuel injection signal j is output to the injector 11, an opening operation signal k is output to the throttle valve 32, and the like.

  The processor of the ECU 0 interprets and executes a program stored in the memory in advance, calculates operation parameters, and controls the operation of the internal combustion engine. The ECU 0 acquires various information a, b, c, d, e, f, g, and h necessary for operation control of the internal combustion engine via the input interface, knows the engine speed, and is filled in the cylinder 1. Estimate the intake volume. Based on the engine speed, the intake air amount, and the like, various operating parameters such as required fuel injection amount, fuel injection timing (including the number of times of fuel injection for one combustion), fuel injection pressure, and ignition timing are determined. The ECU 0 applies various control signals i, j, k corresponding to the operation parameters via the output interface.

  Further, the ECU 0 inputs a control signal o to the electric motor (starter motor or motor generator) when the internal combustion engine is started (a cold start or a return from an idling stop). Cranking is performed by rotating the crankshaft. Cranking ends when the internal combustion engine starts from the first explosion to a continuous explosion and the engine speed, that is, the rotation speed of the crankshaft, exceeds a judgment value determined according to the cooling water temperature, etc. To do.

  The ECU 0 of the present embodiment executes a fuel cut that interrupts the fuel supply to the cylinder 1 in accordance with the driving situation. In addition, the ECU 0 also performs an idle stop for stopping the idle rotation of the internal combustion engine when the vehicle stops due to a signal waiting or the like.

  FIG. 2 shows a procedure example of processing executed by the ECU 0 when the vehicle decelerates and stops. When a predetermined fuel cut condition is satisfied (step S1), the ECU 0 stops fuel cut, that is, fuel injection from the injector 11 (step S2). In step S1, it is determined that the fuel cut condition is satisfied, at least when the accelerator pedal depression amount is 0 or less than a threshold value close to 0 and the engine speed is equal to or higher than the fuel cut permission speed.

  However, even if the fuel cut condition is satisfied, the fuel injection is not stopped immediately. If the fuel supply is cut off suddenly when the engine torque is relatively large, a torque shock that causes the engine speed and the vehicle speed to drop stepwise occurs, causing the passengers including the driver to feel the shock. In order to reduce the torque shock, the fuel injection is stopped only after the elapse of the delay time after the fuel cut condition is satisfied. During this delay time, the ignition timing is retarded and the engine torque is actively reduced.

  During the fuel cut, the spark ignition (discharge) by the spark plug 12 may be stopped or continued, but in this embodiment, the spark ignition is continued. If spark ignition is stopped, power consumption can be suppressed, which can contribute to improved fuel efficiency. On the other hand, if the spark ignition is continued repeatedly, the temperature of the electrode of the spark plug 12 and the surrounding temperature can be kept high, and the combustion failure at the time of restarting the fuel injection (step S5) or restarting the engine (step S10). Leads to prevention.

  When a predetermined fuel cut end condition is satisfied after the start of fuel cut and before an idle stop condition described later is satisfied (step S4), the fuel cut is ended and fuel injection (and ignition) is resumed. (Step S5). In step S4, it is determined that the fuel cut end condition is satisfied, for example, when the accelerator pedal depression amount exceeds the threshold value or the engine speed has decreased to the fuel cut return speed.

  Conversely, after the start of fuel cut, if the predetermined idle stop condition is satisfied without satisfying the fuel cut end condition (step S6), the routine proceeds from fuel cut to idle stop. In step S6, it is determined that the idle stop condition has been established when the vehicle speed is equal to or lower than the predetermined value, the brake pedal is depressed, and the coolant temperature and the battery voltage are sufficiently high.

  Thus, the ECU 0 counts the length of time (elapsed time or the number of rotations of the crankshaft) from the start of the fuel cut until the engine speed or the vehicle speed decreases to a predetermined value (step S3). The predetermined value is a value that suggests that it is immediately before the rotation of the internal combustion engine stops. For example, when comparing with the engine speed, the predetermined value is set to a value within the range of 100 rpm to 200 rpm.

  In addition, when the engine speed or the vehicle speed falls below the predetermined value (step S7), in other words, fuel is injected from the injector 11 several times just before the rotation of the internal combustion engine stops (step S7). S8).

  The number of fuel injections in step S8 and / or the fuel injection amount per injection is determined according to the length of the period counted after step S3. That is, the ECU 0 increases the number of fuel injections in step S8 and / or increases the fuel injection amount per injection as the fuel cut period until the rotation of the internal combustion engine reaches just before stopping is longer. If the fuel cut period until the rotation of the internal combustion engine is just before stopping is remarkably short, the number of fuel injections and the injection amount in step S8 may be set to 0 (no fuel injection is performed).

  At the time of fuel injection at the time immediately before the rotation of the internal combustion engine is stopped, the spark ignition by the spark plug 12 may be stopped or continued, but in this embodiment, the spark ignition is stopped. When the spark ignition is stopped, the fuel injected in step S8 does not burn, and a gas containing an unburned fuel component flows into the catalyst 41. Then, the oxygen stored in the catalyst 41 during the fuel cut reacts with the unburned fuel (the unburned fuel is oxidized or burned), and the oxygen storage amount of the catalyst 41 decreases. On the other hand, when the spark ignition is continued, the fuel injected in step S8 is fueled in the combustion chamber of the cylinder 1, and the combustion gas flows into the catalyst 41. If the air-fuel ratio of the combustion gas is rich, the oxygen stored in the catalyst 41 is released in the process of purification (oxidation reduction) of the combustion gas, and the oxygen storage amount of the catalyst 41 is also reduced.

  When a predetermined idle stop end condition is satisfied after the idle stop condition is satisfied (step S9), the internal combustion engine is restarted (step S10). In step S9, the driver lifts his / her foot from the brake pedal, the brake pedal is further depressed, the accelerator pedal is depressed, a predetermined time (for example, 3 minutes) has elapsed in the idle stop state, etc. It is determined that any one of them satisfies the idle stop termination condition.

  FIG. 3 illustrates the contents of fuel cut and idle stop control by ECU0. In FIG. 3, with respect to the fuel injection amount, a one-dot chain line represents conventional control, and a solid line and a broken line represent control of the present embodiment. The solid line represents the case where the period from the start of the fuel cut to the time immediately before the rotation stop of the internal combustion engine is relatively short, and the broken line represents the period from the start of the fuel cut to the time immediately before the rotation stop of the internal combustion engine. Represents a long case.

  When the fuel is injected a plurality of times before stopping the rotation of the internal combustion engine (step S8), as shown in FIG. 4 (a), (b) or (c), the second injection is performed. The injection amount in the subsequent injection may exceed the previous injection amount, such that the injection amount in the first injection is less than the first injection amount and the injection amount in the third injection is less than the second injection amount. It is also preferable not to have it. Here, one fuel injection corresponds to one cycle of one cylinder 1 (intake stroke-compression stroke-expansion stroke-exhaust stroke). When each cylinder 1 in the three-cylinder engine ignites and burns once, it means that fuel injection is executed three times in total.

  FIG. 4A shows an aspect in which the number of injections is reduced as much as possible by increasing the injection amount as much as possible. FIG. 4B shows a mode in which the first injection amount is maximized and the injection amount is gradually reduced every time the number of injections is repeated. Further, FIG. 4C is a mode in which the predetermined number of injections is increased as much as possible, and thereafter the injection amount is gradually decreased every time the number of injections is repeated. In any case, the total amount of the plurality of fuel injection amounts is increased as the fuel cut period until the rotation of the internal combustion engine reaches just before stopping, which is counted after step S3, is increased.

  The reaction between the unburned fuel that has reached the catalyst 41 and the oxygen stored in the catalyst 41 is promoted as the temperature of the catalyst 41 increases. Needless to say, the temperature of the catalyst 41 is highest immediately after the start of the fuel cut, and gradually decreases as time elapses. Therefore, if the fuel is injected a plurality of times, it is advantageous for the consumption of the stored oxygen to inject more fuel and deliver it to the catalyst 41 earlier. This is why the injection is performed in a pattern as shown in FIG.

  In this embodiment, a fuel cut that stops fuel injection is started when a predetermined fuel cut condition is satisfied. After that, when a predetermined fuel cut end condition is satisfied, the fuel injection is resumed and the internal combustion engine is rotationally driven again. On the other hand, if the fuel cut end condition is not satisfied, the fuel injection is not resumed and the rotation of the internal combustion engine is stopped, and the rotation of the internal combustion engine is not performed after the fuel cut condition is satisfied and the fuel cut end condition is not satisfied. In the case of stopping, the internal combustion engine control device 0 is configured to inject fuel before stopping the rotation of the internal combustion engine.

  In particular, the control device 0 of the present embodiment starts the fuel cut that stops the fuel injection when a predetermined fuel cut condition is satisfied, does not perform the fuel injection until the time immediately before the rotation of the internal combustion engine stops, The fuel is injected at the time immediately before the rotation stop and then the rotation of the internal combustion engine is stopped. The amount of fuel injected at the time immediately before the rotation stop is determined by the period from the start of the fuel cut to the time. The longer the control, the greater the control.

  According to the present embodiment, unlike the conventional control, fuel injection and ignition combustion are not performed for causing the air-fuel ratio rich gas to flow into the catalyst 41 when transitioning from fuel cut to idle stop, and fuel cut is performed. The fuel injection can be stopped consistently from the start of the engine to immediately before the stop of the rotation of the internal combustion engine.

Then, the amount of fuel injected at the time immediately before the stop of the rotation of the internal combustion engine is set to the length of the fuel cut period up to the time, that is, the amount of oxygen that would have been occluded in the catalyst 41 during the fuel cut. It can be adjusted and optimized according to the amount. When the fuel cut period is relatively short and the amount of oxygen stored in the catalyst 41 is relatively small, it is permitted to reduce the amount of fuel injected at a time immediately before the rotation of the internal combustion engine is stopped. Thus, while suppressing the emission of the NO _x in the restart after idle stop, it is possible to further improved fuel efficiency.

  As in the past, fuel injection and ignition combustion are not performed in the process of transition from fuel cut to idle stop, and fuel injection can be stopped from the fuel cut until just before the stop of the internal combustion engine. Change will lead to improved drivability.

  <Second Embodiment> Another embodiment of the present invention will be described with reference to the drawings. The configuration of the internal combustion engine and the ECU 0 as its control device can be the same as those in the first embodiment, and will be omitted here. The fuel cut condition, the fuel cut end condition, the idle stop condition, and the idle stop end condition are also the same as in the first embodiment.

  A major difference between the present embodiment and the first embodiment is the execution timing of fuel injection for consuming the stored oxygen of the catalyst 41. In the first embodiment, fuel is injected at a time when the rotation of the internal combustion engine stops. On the other hand, in this embodiment, fuel injection is performed immediately after the start of the fuel cut.

  As already described, the reactivity between the fuel component and the stored oxygen in the catalyst 41 is higher as the temperature of the catalyst 41 is higher. In the case where the fuel cut and the idle stop are consistently continuous (without the fuel injection and ignition combustion being restarted when the fuel cut end condition is satisfied), the temperature of the catalyst 41 is the highest immediately after the start of the fuel cut. It is. Therefore, in this embodiment, fuel is injected at a time immediately after the end of the fuel cut, a gas containing unburned fuel components is caused to flow into the catalyst 41, and the unburned fuel reacts with oxygen stored in the catalyst 41. (Unburnt fuel is oxidized or burned).

  FIG. 5 shows a procedure example of processing executed by the ECU 0 when the vehicle decelerates and stops. When a predetermined fuel cut condition is satisfied (step S11), the ECU 0 stops fuel cut, that is, fuel injection from the injector 11 (step S12). The actual fuel cut is started after a delay time for reducing the engine torque has elapsed after the fuel cut condition is satisfied. During the fuel cut, the spark ignition by the spark plug 12 may be stopped or continued, but it is necessary to stop the spark ignition at least during the following fuel injection step S14.

  In the present embodiment, fuel is injected from the injector 11 immediately after the start of the fuel cut step S12 (step S14). Since the spark ignition is stopped, the fuel injected in step S14 does not burn, and a gas containing an unburned fuel component flows into the catalyst 41. Then, the oxygen stored in the catalyst 41 reacts with the unburned fuel (the unburned fuel is oxidized or burned), and the oxygen storage amount of the catalyst 41 is reduced.

If the oxygen in the catalyst 41 is deficient, the fuel injected in step S14 and flowing into the catalyst 41 becomes redundant. However, the surplus fuel component is adsorbed by the catalyst 41 and reacts with oxygen contained in new air flowing into the catalyst 41 during the subsequent fuel cut period. on the suitably suppress NO _x emissions after completion (restart), unburned fuel component is also avoided the problem of leakage from the catalyst 41 to the outside.

  The fuel injection in step S14 is performed a plurality of times. However, if the total amount of fuel injected by the multiple injections reaches the required upper limit (step S13), no further fuel injection is performed. Thereby, the discharge of HC or CO after the end of the fuel cut or the end of the idle stop is suppressed, and leakage of unburned fuel components to the outside of the catalyst 41 is prevented. The upper limit value may be constant or variable. For example, it is conceivable that the upper limit value is set higher as the amount of oxygen stored in the catalyst 41 at the start of fuel cut increases.

  If a predetermined fuel cut end condition is satisfied after the start of fuel cut and before an idle stop condition described later is satisfied (step S15), the fuel cut is ended and fuel injection (and ignition) is restarted (step S15). S16). When the fuel cut end condition is satisfied, the fuel injection step S14 for consuming the stored oxygen of the catalyst 41 is also terminated. As a result, the longer the period from the start of the fuel cut to the satisfaction of the fuel cut end condition, the more fuel is injected (within the range below the upper limit).

  On the other hand, after the fuel cut is started, if the predetermined idle stop condition is satisfied without satisfying the fuel cut end condition (step S17), the fuel cut is shifted to the idle stop.

  After entering the idle stop, the fuel should not be injected after the rotation of the internal combustion engine (crankshaft and intake / exhaust camshaft) has stopped substantially or completely. The fuel injected while the internal combustion engine is stopped does not go to the catalyst 41 but stays in the intake manifold 34 or the combustion chamber of the cylinder 1 and does not contribute to the purpose of consuming oxygen stored in the catalyst 41 during the fuel cut. This is because the air-fuel ratio of the air-fuel mixture filled in the cylinder 1 is disturbed when the internal combustion engine is restarted, which may cause a delay in starting and an increase in HC or CO emissions.

  When a predetermined idle stop end condition is satisfied after the idle stop condition is satisfied (step S18), the internal combustion engine is restarted (step S19).

FIG. 6 illustrates the contents of fuel cut and idle stop control by the ECU 0. In FIG. 6, t ₀ is the time when fuel cut starts.

  When the fuel is injected a plurality of times before stopping the rotation of the internal combustion engine (step S14), as shown in (a), (b) or (c) of FIG. 7, the injection in the second injection is performed. The amount of injection in the third injection is less than the injection amount in the third injection, and the injection amount in the third injection is not more than the injection amount in the second injection. It is preferable that One fuel injection corresponds to one cycle of one cylinder 1 (intake stroke-compression stroke-expansion stroke-exhaust stroke).

  FIG. 7A shows an aspect in which the number of injections is reduced as much as possible by increasing the injection amount as much as possible. FIG. 7B is a mode in which the first injection amount is maximized and the injection amount is gradually decreased every time the number of injections is repeated. In addition, FIG. 7C is a mode in which the predetermined number of injections is increased as much as possible, and thereafter the injection amount is gradually decreased every time the number of injections is repeated. In any case, the total amount of the plurality of fuel injection amounts does not exceed the upper limit value described in step S13.

  The reaction between the unburned fuel that has reached the catalyst 41 and the oxygen stored in the catalyst 41 is promoted as the temperature of the catalyst 41 increases. Needless to say, the temperature of the catalyst 41 is highest immediately after the start of the fuel cut, and gradually decreases as time elapses. Therefore, if the fuel is injected a plurality of times, it is advantageous for the consumption of the stored oxygen to inject more fuel and deliver it to the catalyst 41 earlier. This is why the injection is performed in a pattern as shown in FIG.

  In this embodiment, a fuel cut that stops fuel injection is started when a predetermined fuel cut condition is satisfied. After that, when a predetermined fuel cut end condition is satisfied, the fuel injection is resumed and the internal combustion engine is rotationally driven again. On the other hand, if the fuel cut end condition is not satisfied, the fuel injection is not resumed and the rotation of the internal combustion engine is stopped, and the rotation of the internal combustion engine is not performed after the fuel cut condition is satisfied and the fuel cut end condition is not satisfied. In the case of stopping, the internal combustion engine control device 0 is configured to inject fuel before stopping the rotation of the internal combustion engine.

  In particular, the control device 0 of the present embodiment starts a fuel cut that stops fuel injection when a predetermined fuel cut condition is established, and injects fuel at a time immediately after the start of the fuel cut, and then rotates the internal combustion engine. Implement control to stop.

  According to the present embodiment, unlike the conventional control, fuel injection and ignition combustion are not performed for causing the air-fuel ratio rich gas to flow into the catalyst 41 when transitioning from fuel cut to idle stop, and fuel cut is performed. Except for the unburned fuel injection step S14 immediately after the start of, the fuel injection can be stopped consistently from the fuel cut to immediately before the stop of the rotation of the internal combustion engine.

Then, the amount of fuel injected at the time immediately after the start of the fuel cut will be occluded by the catalyst 41 during the length of the period from the start of the fuel cut until the fuel cut end condition is satisfied, that is, during the fuel cut. It can be adjusted and optimized according to the amount of oxygen. When the fuel cut end condition is satisfied in a short time after starting the fuel cut (and the engine does not enter the idle stop), that is, when the fuel cut period is relatively short and the amount of oxygen stored in the catalyst 41 is relatively small. The fuel injection over a plurality of times (step S14) is stopped halfway to reduce the amount of fuel to be injected. Thus, while suppressing the emission of the NO _x in the restart after idle stop, it is possible to further improved fuel efficiency.

  As in the past, fuel injection and ignition combustion are not performed in the process of transition from fuel cut to idle stop, and fuel injection can be stopped from the fuel cut until just before the stop of the internal combustion engine. Change will lead to improved drivability.

  The present invention is not limited to the embodiment described in detail above. Various modifications can be made to the specific configuration of each part, processing procedure, and the like without departing from the spirit of the present invention.

  The present invention can be applied to control of an internal combustion engine mounted on a vehicle.

0 ... Control unit (ECU)
DESCRIPTION OF SYMBOLS 1 ... Cylinder 11 ... Injector 12 ... Spark plug

Claims (4)

When the predetermined fuel cut condition is satisfied, the fuel cut to stop the fuel injection is started. After that, when the predetermined fuel cut end condition is satisfied, the fuel injection is resumed and the internal combustion engine is rotated again, while the fuel cut ends. If the condition is not satisfied, the fuel injection is not resumed and the rotation of the internal combustion engine is stopped.
A control apparatus for an internal combustion engine, wherein fuel is injected before the rotation of the internal combustion engine is stopped when the rotation of the internal combustion engine is stopped without the fuel cut end condition being satisfied after the fuel cut condition is satisfied. A fuel cut that stops fuel injection is started when a predetermined fuel cut condition is satisfied, and fuel is not injected until the time immediately before the rotation of the internal combustion engine stops, and fuel is injected at a time immediately before the rotation stops. In order to stop the rotation of the internal combustion engine,
2. The control device for an internal combustion engine according to claim 1, wherein the amount of fuel injected at a time immediately before the rotation stop is increased as the period from the start of fuel cut to the time is increased. 2. The control of an internal combustion engine according to claim 1, wherein a fuel cut for stopping the fuel injection is started when a predetermined fuel cut condition is established, and the rotation of the internal combustion engine is stopped after the fuel is injected immediately after the start of the fuel cut. apparatus. Before the fuel cut end condition is satisfied and before the rotation of the internal combustion engine stops, fuel is injected a plurality of times,
The subsequent injection amount is the previous injection amount, such that the injection amount in the second injection is less than or equal to the first injection amount and the injection amount in the third injection is less than or equal to the second injection amount. 4. The control apparatus for an internal combustion engine according to claim 1, 2, or 3, wherein

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