JP2016183607A - Controller of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress deterioration of emission, during increment correction of a fuel injection amount after fuel cut operation of the internal combustion engine is ended.SOLUTION: A controller of an internal combustion engine executes fuel cut for suspending fuel injection, with establishment of a fuel cut condition, and ends fuel cut with establishment of a fuel cut end condition and further performs increment correction of a fuel injection amount. During increment correction, the controller changes a target value of an air fuel ratio of gas flowing into a catalyst according to the flow rate of gas flowing from a cylinder into a catalyst for exhaust emission control.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a control device that controls operation of an internal combustion engine.

  In an internal combustion engine mounted on a vehicle, it is known to perform a fuel cut that temporarily interrupts fuel injection in accordance with the driving situation (see, for example, the following patent document). Normally, fuel cut is started 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. When one of the conditions such as the accelerator pedal depression amount exceeding the threshold value or the engine speed decreasing to the fuel cut return speed is satisfied, the fuel cut is finished and the fuel injection is restarted.

  As described above, the fuel cut end condition includes a decrease in the engine speed. In order to extend the fuel cut period as much as possible to improve fuel efficiency, it is necessary to delay the deceleration of the engine rotation during the fuel cut. For this purpose, the throttle valve is deliberately opened during fuel cut when the amount of depression of the accelerator pedal is 0 or almost 0, thereby reducing the intake resistance of the internal combustion engine and hence the pumping loss.

During a fuel cut in which the internal combustion engine continues to rotate due to inertia, air that does not contain a fuel component flows from the cylinder into the exhaust purification catalyst via the exhaust passage. As a result, a large amount of oxygen is adsorbed on the catalyst, and the NO _x reduction ability of the catalyst is reduced. To recover the reducing ability of NO _x, the catalyst quickly release the oxygen stored in, it is necessary to consume.

  Therefore, after the fuel cut is completed, it has been conventionally performed to increase the fuel injection amount to enrich the air-fuel ratio of the air-fuel mixture and to promote the release of oxygen stored in the catalyst during the fuel cut (for example, (See the following patent document).

JP2015-010489A

The flow rate of the gas flowing from the cylinder into the catalyst during the increase correction of the fuel injection amount after the end of the fuel cut is not always constant, and can change every moment according to the operation of the accelerator pedal by the driver. Therefore, if the air-fuel ratio of the air-fuel mixture is maintained at a certain target rich air-fuel ratio during the increase correction, the amount of CO or C _m H _n (hydrocarbon) component flowing into the catalyst per unit time is reduced in the catalyst. Depending on the flow rate of the inflowing gas, it will greatly increase or decrease.

In order to purge excess oxygen stored in the catalyst, it is not sufficient to simply supply a gas having a low oxygen concentration to the catalyst. It is necessary to supply an appropriate amount of CO or C _m H _n to the catalyst. Necessary. If the amount of CO or C _m H _n flowing into the catalyst per unit time is insufficient, the atmosphere of excess oxygen in the catalyst is not relaxed, the discharge reduction efficiency of the NO _x in the catalyst is instantaneously reduced to NO _x It will increase. On the other hand, _if the amount of CO or C _m Hn flowing into the catalyst per unit time is too large, the oxidation efficiency of CO and HC in the catalyst is instantaneously reduced, leading to an increase in CO and HC emissions. .

  The present invention has been made by paying attention to the above-mentioned problem for the first time, and an object thereof is to suppress the deterioration of the emission during the fuel injection amount increase correction after the end of the fuel cut.

  In the present invention, the fuel cut that temporarily stops the fuel injection with the establishment of the fuel cut condition is performed, the fuel cut is ended with the establishment of the fuel cut end condition, and the fuel injection amount is increased and corrected, During the increase correction, the control device for the internal combustion engine is configured to change the target value of the air-fuel ratio of the gas flowing into the catalyst according to the flow rate of the gas flowing from the cylinder into the exhaust purification catalyst.

In a system that performs air-fuel ratio feedback control for converging the output voltage of the O ₂ sensor installed upstream of the catalyst in the exhaust passage to a target value, the flow rate of gas flowing from the cylinder into the catalyst during the increase correction is large. Accordingly, the target value of the air-fuel ratio of the gas flowing into the catalyst can be changed by changing the target value of the output voltage according to the above.

  It is easy to determine the target value of the output voltage based on (constant / flow rate of gas flowing from the cylinder into the catalyst).

  According to the present invention, it is possible to suppress the deterioration of the emission during the fuel injection amount increase correction after the end of the fuel cut.

The figure which shows schematic structure of the internal combustion engine for vehicles and control apparatus in one Embodiment of this invention. The timing diagram which shows the pattern of the air fuel ratio feedback control which referred the output signal of the air fuel ratio sensor of the upstream of a catalyst. The graph which illustrates the relationship between control center correction amount FACF and delay time TDR, TDL. The timing diagram which shows the pattern of the air fuel ratio feedback control which referred the output signal of the air fuel ratio sensor of the downstream of a catalyst. The graph which shows the output characteristic of the air-fuel ratio sensor of the upstream side of a catalyst, and the relationship between the intake flow rate and the target value of the output voltage of the air-fuel ratio sensor in the increase correction of the fuel injection amount after the end of fuel cut.

  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 gas 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.

Air-fuel ratio sensors 43 and 44 for detecting the air-fuel ratio of the gas flowing through the exhaust passage are installed upstream and downstream of the catalyst 41 in the exhaust passage 4. Each of the air-fuel ratio sensors 43 and 44 may be an O ₂ sensor having a non-linear output characteristic with respect to the air-fuel ratio of the exhaust gas, or a linear A / F sensor having an output characteristic proportional to the air-fuel ratio of the exhaust gas. There may be. In the present embodiment, an O ₂ sensor that outputs a voltage signal corresponding to the oxygen concentration in the exhaust gas is assumed for each of the upstream and downstream air-fuel ratio sensors 43 and 44 of the catalyst 41. The characteristics of the output voltages f and g of the O ₂ sensors 43 and 44 show that the output change rate with respect to the air-fuel ratio has a large and steep slope in a certain range (window) near the theoretical air-fuel ratio, and the air-fuel ratio is larger than that. A so-called Z characteristic curve is drawn, which gradually approaches the low saturation value in the region and gradually approaches the high saturation value in the rich region where the air-fuel ratio is small.

  The external EGR (Exhaust Gas Recirculation) device 2 realizes a so-called high pressure loop EGR, and an EGR passage 21 communicating the upstream side of the catalyst 41 in the exhaust passage 4 and the downstream side of the throttle valve 32 in the intake passage 3. The EGR cooler 22 provided on the EGR passage 21 and the EGR valve 23 that opens and closes the EGR passage 21 and controls the flow rate of the EGR gas flowing through the EGR passage 21 are used as elements. The inlet of the EGR passage 21 is connected to the exhaust manifold 42 in the exhaust passage 4 or a predetermined location downstream thereof. The outlet of the EGR passage 21 is connected to a predetermined location downstream of the throttle valve 32 in the intake passage 3, specifically to a surge tank 33.

  An ECU (Electronic Control Unit) 0 serving as a control device for an internal combustion engine according to the present embodiment is a microcomputer system having a processor, a memory, an input interface, an output interface, and the like.

  The input interface of the ECU 0 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 of the crankshaft and the engine speed, and an accelerator pedal. Accelerator opening signal c output from a sensor that detects the amount of depression of the engine as an accelerator opening (so-called required load), temperature / pressure for detecting intake air temperature and intake air pressure in the intake passage 3 (especially, the surge tank 33) An intake air temperature / intake pressure signal d outputted from the sensor, a cooling water temperature signal e outputted from a water temperature sensor for detecting a cooling water temperature suggesting the temperature of the internal combustion engine, and an air-fuel ratio of the exhaust gas upstream of the catalyst 41 are detected. An air-fuel ratio sensor 44 for detecting an air-fuel ratio signal f output from the air-fuel ratio sensor 43 and an air-fuel ratio of the exhaust gas downstream of the catalyst 41. The air-fuel ratio signal g which is et output cam angle signal h or the like to be output from the cam angle sensor is input in a plurality of cam angle of the intake camshaft.

  From the output interface of the ECU 0, an ignition signal i for the igniter 13 of the spark plug 12, a fuel injection signal j for the injector 11, an opening operation signal k for the throttle valve 32, and an opening degree for the EGR valve 23. The operation signal l and the like are output.

  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 amount of intake (fresh air). Based on the engine speed and intake air amount, etc., the required fuel injection amount, fuel injection timing (including the number of times of fuel injection for one combustion), fuel injection pressure, required EGR rate (or EGR amount), Various operating parameters such as ignition timing are determined. The ECU 0 applies various control signals i, j, k, and l corresponding to the operation parameters via the output interface.

The ECU 0 performs feedback control of the air-fuel ratio of the air-fuel mixture filled in the cylinder 1 and, consequently, the air-fuel ratio of the exhaust gas discharged from the cylinder 1 and guided to the catalyst 41. The ECU 0 first determines a basic injection amount TP commensurate with the amount of intake air (fresh air) charged into the cylinder 1. Next, the basic injection amount TP is corrected with a feedback correction coefficient FAF determined according to the air-fuel ratio upstream of the catalyst 41, and further various correction coefficients K determined according to the state of the internal combustion engine and the invalid injection time of the injector 36. The final fuel injection time (energization time for the injector 11) T is calculated in consideration of TAUV. The fuel injection time T is
T = TP × FAF × K + TAUV
It becomes. Then, the signal j is input to the injector 11 for the fuel injection time T, and the injector 11 is opened to inject fuel.

The feedback control with reference to the air-fuel ratio signal f on the upstream side of the catalyst 41 is performed, for example, when the coolant temperature of the internal combustion engine is equal to or higher than a predetermined temperature, the fuel is not being cut, and a predetermined time has elapsed since the start of the internal combustion engine. _2. Performed when all conditions such as the sensor 43 is active and the intake pressure is normal are all satisfied.

As shown in FIG. 2, the ECU 0 corresponds to the output voltage f of the front O ₂ sensor 43, which is a sensor for detecting the air-fuel ratio of the gas upstream of the catalyst 41, with the target air-fuel ratio of the gas upstream of the catalyst 41. Compared to a target value (target voltage value; indicated by a one-dot chain line) to be rich, if it is higher than its upstream target value, it is determined to be lean, and if it is lower than its upstream target value, it is determined to be lean. Usually, the target value is a value corresponding to the theoretical air-fuel ratio or the vicinity thereof.

  Then, the ECU 0 adjusts the feedback correction coefficient FAF to increase or decrease based on the determination result of the air / fuel ratio of the gas upstream of the catalyst 41. Specifically, the feedback correction coefficient FAF is decreased by the skip value RSM when the air-fuel ratio determination result is reversed from lean to rich (a delay time TDR described later has elapsed). In addition, while it is determined that the air-fuel ratio is rich, the feedback correction coefficient FAF is decreased by the lean integral value KIM per unit time (or control cycle, calculation cycle).

  On the other hand, the feedback correction coefficient FAF is increased by the skip value RSP when the determination result of the air-fuel ratio is reversed from rich to lean (a delay time TDL described later has elapsed). In addition, while it is determined that the air-fuel ratio is lean, the feedback correction coefficient FAF is increased by the rich integral value KIP per unit time.

  When the feedback correction amount FAF decreases, the fuel injection amount by the injector 11 is reduced, and the air-fuel ratio of the air-fuel mixture moves toward lean. On the contrary, when the feedback correction amount FAF increases, the fuel injection amount by the injector 11 is increased, and the air-fuel ratio of the air-fuel mixture becomes richer.

However, when the output voltage f of the front O ₂ sensor 43 fluctuates so as to cross the target voltage value, the determination result of the air-fuel ratio of the gas upstream of the catalyst 41 is not immediately reversed, but the delay times TDL, TDR The judgment result is inverted after waiting for elapse of time. That is, when the output voltage f of the front O ₂ sensor 43 is switched from rich to lean (below the target voltage value), it is determined that the air-fuel ratio has been reversed from rich to lean after the lean determination delay time TDL has elapsed. . In addition, when the output voltage f of the front O ₂ sensor 43 is switched from lean to rich (exceeding the target voltage value), it is determined that the air-fuel ratio has been reversed from lean to rich after the elapse of the rich determination delay time TDR. .

The lean determination delay time TDL and the rich determination delay time TDR are provided because the air / fuel ratio lean / rich determination result is inverted several times in a short time when noise is mixed in the output signal of the O ₂ sensor 43. It is intended to prevent chattering that increases or decreases so that the fuel injection amount vibrates.

  The delay times TDL and TDR increase or decrease according to the control center correction amount FACF. FIG. 3 illustrates the relationship between the correction amount FACF and the delay times TDL and TDR. As the correction amount FACF increases, the lean determination delay time TDL (represented by a broken line) is shortened, and the rich determination delay time TDR (represented by a solid line) is extended. In this case, the time when the feedback correction coefficient FAF starts to decrease is delayed, and the time when the feedback correction coefficient FAF starts to increase increases. As a result, the fuel injection amount increases on average, and the control center of the air-fuel ratio feedback control is displaced to the rich side.

  In turn, the smaller the correction amount FACF, the longer the lean determination delay time TDL and the shorter the rich determination delay time TDR. Then, the time when the feedback correction coefficient FAF starts to decrease from the increase is advanced, and the time when the feedback correction coefficient FAF starts to increase is delayed. As a result, the fuel injection amount decreases on average, and the control center of the air-fuel ratio feedback control is displaced to the lean side.

The ECU 0 also calculates the control center correction amount FACF during the air-fuel ratio feedback control. This correction amount FACF is determined according to the air-fuel ratio on the downstream side of the catalyst 41. The feedback control with reference to the air-fuel ratio signal g on the downstream side of the catalyst 41 is performed, for example, when the cooling water temperature is equal to or higher than a predetermined temperature and a predetermined time has elapsed since the start of the air-fuel ratio feedback control, and the front O ₂ sensor 43 and / or rear All conditions such as a predetermined time elapses after the O ₂ sensor 44 is activated and the vehicle speed is 0 or less than a predetermined value close to 0 in the idle state or in a predetermined driving range in the non-idle state are satisfied. Do it if you have.

As shown in FIG. 4, the ECU 0 corresponds to the output voltage g of the rear O ₂ sensor 44, which is a sensor for detecting the air-fuel ratio of the gas downstream of the catalyst 41, with the target air-fuel ratio of the gas downstream of the catalyst 41. Compared to a target value (target voltage value; indicated by a chain line), it is determined to be rich if it is higher than the downstream target value, and lean if it is lower than the downstream target value. This downstream target value may not match the upstream target value that is compared with the output signal f of the front O ₂ sensor 43.

  The ECU 0 increases or decreases the control center correction amount FACF based on the determination result of the air-fuel ratio of the gas downstream of the catalyst 41. Specifically, while it is determined that the air-fuel ratio is rich, the control center correction amount FACF is decreased by the lean integrated value FACFKIM per unit time (or control cycle, calculation cycle), while the air-fuel ratio is lean. While it is determined that there is, the control center correction amount FACF is increased by the rich integral value FACFKIP per unit time.

  As already described, when the control center correction amount FACF decreases, the air-fuel ratio control center moves toward lean. Conversely, when the control center correction amount FACF increases, the air-fuel ratio control center moves toward rich.

  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. The ECU 0 stops fuel cut, that is, fuel injection from the injector 11 when a predetermined fuel cut condition is satisfied. The ECU 0 determines 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.

  During the fuel cut, the throttle valve 32 is opened to an opening that does not depend on the accelerator pedal depression amount (0 or close to 0). This operation is performed in order to reduce the pumping loss of the internal combustion engine during the fuel cut and to delay the deceleration of the engine rotation. The opening of the throttle valve 32 at this time may be a constant value or may be increased or decreased according to the vehicle speed or the like, but in any case, it is a relatively large opening.

  Then, the ECU 0 ends the fuel cut when a predetermined fuel cut end condition is satisfied, and restarts fuel injection (and ignition). The ECU 0 determines 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.

  Needless to say, after the fuel cut end condition is satisfied, the opening degree of the throttle valve 32 is made to follow the opening degree corresponding to the depression amount of the accelerator pedal.

ECU0 after the fuel cut ends, in order to recover the reduced performance of the NO _x occluded oxygen in the catalyst 41 is purged during fuel cut, performing increasing correction of the fuel injection amount. The ECU 0 makes the air-fuel ratio of the gas flowing from the cylinder 1 into the catalyst 41 richer than the stoichiometric air-fuel ratio through feedback control that refers to the output signal f of the front O ₂ sensor 43. That is, the feedback correction coefficient FAF is increased and the fuel injection amount T is increased by raising the target value of the output voltage f of the front O ₂ sensor 43 to a value corresponding to the vicinity of the theoretical air-fuel ratio. If a gas having a low oxygen concentration and containing a large amount of CO or C _m H _n component is supplied to the catalyst 41, CO or C _m H _n is oxidized in the catalyst 41 and oxygen in the catalyst 41 is consumed. As a result, the inside of the catalyst 41 is not excessive in oxygen, and the NO _x reduction efficiency is improved.

  The ECU 0 of the present embodiment then sets the target value of the air-fuel ratio of the gas flowing into the catalyst 41 in accordance with the flow rate of the gas flowing from the cylinder 1 into the catalyst 41 during the fuel injection amount increase correction. change.

Specifically, the target air-fuel ratio is lowered and enriched as the amount of gas flowing from the cylinder 1 into the catalyst 41 per unit time is smaller. In other words, as the amount of gas flowing from the cylinder 1 into the catalyst 41 per unit time increases, the target air-fuel ratio is raised and leaned. As a result, the amount of CO or C _m H _n component flowing into the catalyst 41 per unit time is maintained in an appropriate range, and the hot water substances NO _x and CO 2 are purged while purging oxygen stored in the catalyst 41 during the fuel cut. In addition, an increase in HC emissions can be suppressed.

5, input-output characteristics of the front O ₂ sensor 43, and shows the relationship between the target value of the output voltage f of the intake air flow and the front O ₂ sensor 43 in the increasing correction of the fuel injection amount after the fuel cut ends . As is well known, the relationship between the electromotive voltage (electromotive force) of the zirconia O ₂ sensor 43 and the oxygen concentration of the exhaust gas is expressed by the following Nernst equation.
E = (RT / 4F) ln (P _a / P _b )
E is an electromotive voltage of the O ₂ sensor 43, R is a gas constant, T is an absolute temperature, and F is a Faraday constant. P _a is the oxygen partial pressure in the chamber A of the high oxygen concentration as a reference, usually an oxygen partial pressure of the atmosphere. P _b is the oxygen partial pressure in the B chamber having a low oxygen concentration, that is, the concentration of oxygen contained in the exhaust gas.

The flow rate of gas flowing from the cylinder 1 into the catalyst 41 per unit time is substantially equal to the flow rate of intake air flowing into the cylinder 1 from the intake passage 3 per unit time. Therefore, in this embodiment, the target voltage value of the output f of the front O ₂ sensor 43 is raised or lowered according to the current intake air flow rate. The current intake air flow rate can be estimated according to a known method from the engine speed at that time, the intake pressure in the surge tank 33, and the like. However, if a flow meter (air flow meter) for detecting the flow rate of intake air is installed in the intake passage 3 of the internal combustion engine, the current intake air flow rate may be directly measured via the flow meter.

In FIG. 5, a region X is a region where the flow rate of intake air, that is, the flow rate of exhaust gas is relatively large, and a region Y is a region where the flow rate of intake air is relatively small. The target voltage value of the output f of the front O ₂ sensor 43 when the current intake air flow rate belongs to the region Y is higher than the target voltage value when the current intake air flow rate belongs to the region X. That is, the target air-fuel ratio when the intake air flow rate belongs to the region Y is richer than the target air-fuel ratio when the intake air flow rate belongs to the region X.

The amount of CO or C _m H _n flowing into the catalyst 41 from the cylinder 1 is considered to be approximately equal to (the flow rate of intake air x the target voltage value of the output f of the front O ₂ sensor 43). In the region X where the flow rate of intake air is large, the amount of CO or C _m H _n flowing into the catalyst 41 varies greatly only by slightly changing the target air-fuel ratio, and the influence of the oxygen stored in the catalyst 41 on the purge. Is big. Therefore, the ECU 0 of the present embodiment removes the current intake air flow rate from the constant determined in advance by a conformance test or the like for the target voltage value of the output f of the front O ₂ sensor 43 during the fuel injection amount increase correction. Ask for. The constant depends on the displacement of the internal combustion engine and the capacity (volume, amount of noble metal carried) of the catalyst 41. By setting the target voltage value of the output f of the front O ₂ sensor 43 to (constant / flow rate of gas flowing into the catalyst from the cylinder), in the region X where the intake air flow rate is relatively high, the target sky against the change in the intake air flow rate. In the region Y where the change in the fuel ratio becomes small and the flow rate of the intake air is relatively large, the change in the target air-fuel ratio with respect to the change in the flow rate of intake air becomes larger than in the region X.

  In this embodiment, a fuel cut that temporarily stops fuel injection is performed when the fuel cut condition is satisfied, and the fuel cut is ended and a fuel injection amount increase correction is performed when the fuel cut end condition is satisfied. The control device 0 for the internal combustion engine is configured to change the target value of the air-fuel ratio of the gas flowing into the catalyst 41 according to the flow rate of the gas flowing into the exhaust gas purification catalyst 41 from the cylinder 1 during the increase correction. .

  According to the present embodiment, the oxygen stored in the catalyst 41 during the fuel cut can be consumed at an appropriate speed during the increase correction of the fuel injection amount, and the instantaneous and local oxygen in the catalyst 41 can be consumed. It is possible to avoid the appearance of an excessive atmosphere and the appearance of an instantaneous / local oxygen-deficient atmosphere. Therefore, the deterioration of the emission during the increase correction of the fuel injection amount is suppressed.

The present invention is not limited to the embodiment described in detail above. For example, even if the air-fuel ratio sensor 43 installed upstream of the catalyst 41 in the exhaust passage 4 is not a zirconia O ₂ sensor but a linear A / F sensor, the output signal f of the linear A / F sensor 43 Of course, it is possible to feedback control the air-fuel ratio of the gas by setting the target value. In the increase correction of the fuel injection amount after the end of the fuel cut, the target value is set so as to lower the target air-fuel ratio as the flow rate of the gas flowing from the cylinder 1 into the catalyst 41 decreases. The target value is set so as to raise the target air-fuel ratio as the flow rate of the inflowing gas increases.

  Other specific configurations of each part can be variously modified 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)
1 ... cylinder 11 ... injector 3 ... fuel ratio sensor upstream of the intake passages 4 exhaust passage 41 ... catalyst 43 ... catalyst (O ₂ sensor)
b ... crank angle signal d ... intake air temperature / intake pressure signal f ... air-fuel ratio signal j ... fuel injection signal

Claims (3)

When the fuel cut condition is satisfied, the fuel cut is temporarily stopped, and the fuel cut is ended when the fuel cut end condition is satisfied, and the fuel injection amount is increased and corrected.
A control apparatus for an internal combustion engine that changes a target value of an air-fuel ratio of gas flowing into the catalyst in accordance with a flow rate of gas flowing from the cylinder into the exhaust purification catalyst during the increase correction. Air-fuel ratio feedback control is performed to converge the output voltage of the O ₂ sensor installed upstream of the catalyst in the exhaust passage to a target value,
2. The control device for an internal combustion engine according to claim 1, wherein the target value of the output voltage is changed according to the flow rate of the gas flowing into the catalyst from the cylinder during the increase correction. The control apparatus for an internal combustion engine according to claim 2, wherein a target value of the output voltage is determined based on (constant / flow rate of gas flowing from the cylinder into the catalyst).

Images