JP2021134667A - Controller of internal combustion engine - Google Patents

Abstract

To suppress a discharge amount of harmful substances from increasing upon starting a stopped internal combustion engine.SOLUTION: A controller of an internal combustion engine is configured to, when fuel is combusted in a cylinder of the internal combustion engine to finish firing for operating the internal combustion engine and the rotation of the internal combustion engine is then stopped, variably adjust a time required for the internal combustion engine to stop rotating, according to an engine speed at the end of the firing and the output signal of the air-fuel ratio sensor downstream of the exhaust gas purification catalyst mounted in an exhaust passage.SELECTED DRAWING: Figure 4

Description

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

Recently, hybrid vehicles equipped with two types of power sources, an electric motor and an internal combustion engine, have seen a certain degree of widespread use. In series hybrid vehicles (see, for example, the patent documents below), an internal combustion engine drives a motor generator for power generation to generate electric power, and the generated electric power is used as a power storage device, that is, a lithium ion secondary battery or a nickel hydrogen secondary battery. It is stored in a battery and / or a capacitor such as, and is supplied to a traveling motor generator. Then, the drive wheels of the vehicle are rotated by the traveling motor generator to travel.

Not only the motor generator for power generation but also the motor generator for traveling can generate power by regenerative braking and store the generated power in the power storage device. When the electric power is already stored up to the capacity of the power storage device, the electric power obtained by the regenerative braking is intentionally supplied to the motor generator for power generation, and this is operated as an electric motor to rotate and drive the internal combustion engine. This consumes surplus power.

In a hybrid vehicle, the vehicle can be driven by the rotational driving force output by the traveling motor generator without the internal combustion engine burning the fuel to generate the rotational driving force. Therefore, even during the operation of the vehicle, the state in which the rotation of the internal combustion engine is stopped may continue.

When the amount of electric charge stored in the power storage device decreases or when the required output for the traveling motor generator is large, the internal combustion engine is started, and the power generation motor generator is driven by the rotational driving force output by the internal combustion engine to generate electric power. To charge the power storage device or increase the power supplied to the driving motor generator.

In a series hybrid vehicle, the power generation motor generator also serves to motor (or crank) the internal combustion engine in preparation for starting the stopped internal combustion engine. At the time of motoring, the necessary electric power is supplied from the power storage device.

Japanese Unexamined Patent Publication No. 2019-131035

When the firing of the internal combustion engine is completed and the rotation of the internal combustion engine is stopped, air containing no combustion gas flows into the three-way catalyst for exhaust gas purification installed in the exhaust passage. The time required for the internal combustion engine to stop rotating completely, and the amount of air flowing into the catalyst during that time, vary depending on the opportunity to stop the rotation of the internal combustion engine. Therefore, the atmosphere inside the catalyst, that is, the amount of oxygen occluded in the catalyst, varies from time to time when the stopped internal combustion engine is restarted and firing is restarted.

The amount of oxygen stored in the catalyst when the rotation of the internal combustion engine is stopped affects the purification efficiency of harmful substances of the catalyst at the time of later start-up or immediately after the start-up. If the oxygen storage amount is remarkably large, the NO _x emission amount may increase, and if the oxygen storage amount is remarkably small, the HC or CO emission amount may increase.

An object of the present invention made by paying attention to the above problems is to suppress an increase in emission of harmful substances when starting an internal combustion engine that has been stopped.

In the present invention, when fuel is burned in the cylinder of an internal combustion engine to end the firing for operating the internal combustion engine and the rotation of the internal combustion engine is stopped, the time required for the rotation of the internal combustion engine to stop is set to be fired. A control device for an internal combustion engine that variably adjusts according to the number of rotations at the time of termination and the output signal of the air-fuel ratio sensor downstream of the exhaust gas purification catalyst mounted on the exhaust passage is configured.

According to the present invention, it is possible to suppress an increase in emission of harmful substances when starting an internal combustion engine that has been stopped.

The figure which shows the schematic structure of the hybrid vehicle and the control device of the series type in one Embodiment of this invention. The figure which shows the outline of the internal combustion engine mounted on the hybrid vehicle of the same embodiment. The flow chart which shows the procedure example of the process which the control device of the same embodiment executes according to a program. The figure which shows the relationship between the time required to stop the internal combustion engine determined by the control device of the same embodiment, the engine speed at the end of firing, and the output signal of the air-fuel ratio sensor downstream of the catalyst.

An embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a schematic configuration of a main system of a hybrid vehicle according to the present embodiment. This hybrid vehicle includes an internal combustion engine 1, a power generation motor generator 2 driven by the internal combustion engine 1 to generate electricity, a power storage device 3 for storing the electric power generated by the power generation motor generator 2, a power generation motor generator 2 and /. Alternatively, it includes a traveling motor generator 4 that drives the drive wheels 62 of the vehicle by receiving power from the power storage device 3.

The hybrid vehicle of the present embodiment is a series hybrid type electric vehicle in which the internal combustion engine 1 is used only for power generation, and the driving force for traveling is supplied exclusively to the driving wheels 62 of the vehicle from the traveling motor generator 4. The internal combustion engine 1 and the drive wheels 62 are mechanically separated from each other, and the rotational driving force is not originally transmitted between the two. That is, the internal combustion engine 1 can rotate completely independently of the traveling motor generator 4 and the drive wheels 62, and can stop completely independently. Therefore, the power storage device 3 is sufficient even when the vehicle is in a state where the driver can step on the accelerator pedal during operation of the vehicle in which the ignition switch (power switch or ignition key) is turned on. Under the condition that the charge is stored and the brake booster 15 stores a sufficient negative pressure, the operation of the internal combustion engine 1 accompanied by the combustion of fuel may not be performed.

The crankshaft, which is the rotating shaft of the internal combustion engine 1, is mechanically connected to the rotating shaft of the power generation motor generator 2 via a gear mechanism. Then, by inputting the rotational driving force output by the internal combustion engine 1 to the power generation motor generator 2, the power generation motor generator 2 generates power. The generated electric power charges the power storage device 3 and / or supplies it to the traveling motor generator 4. Further, the power generation motor generator 2 also functions as a motoring motor that generates a rotational driving force by itself to rotationally drive the crankshaft of the internal combustion engine 1. For example, the power generation motor generator 2 executes motoring (cranking) in preparation for starting the stopped internal combustion engine 1.

The traveling motor generator 4 generates a driving force for traveling the vehicle, and inputs the driving force to the drive wheels 62 via the speed reducer 61. Further, the traveling motor generator 4 is rotated by being rotated by the drive wheels 62 to generate electricity, and recovers the kinetic energy of the vehicle as electric energy. The electric power generated by this regenerative braking charges the power storage device 3.

However, if the charge has already been stored up to the full capacity of the power storage device 3 and it is difficult to charge the battery any more, the traveling motor generator 4 dares to supply the regenerated electric power to the power generation motor generator 2 to generate electricity. The motor generator 2 is operated as an electric motor to drive the internal combustion engine 1 to rotate. As a result, the surplus electric power is exhausted while maintaining the braking performance of the vehicle. Further, at this time, since the rotation of the internal combustion engine 1 is maintained, it is possible to execute a fuel cut that temporarily stops the fuel supply to the cylinder 11 of the internal combustion engine 1.

The generator inverter 21 converts the AC power generated by the power generation motor generator 2 into DC power. Then, the DC power is input to the power storage device 3 or the drive unit inverter 41. Further, when the generator inverter 21 operates the power generation motor generator 2 as an electric motor, the power generation motor generator 2 converts the DC power supplied from the power storage device 3 and / or the drive inverter 41 into AC power. Enter in.

The drive machine inverter 41 converts the DC power supplied from the power storage device 3 and / or the generator inverter 21 into AC power, and then inputs the DC power to the traveling motor generator 4. Further, the drive inverter 41 converts the AC power generated by the traveling motor generator 4 into DC power when performing regenerative braking of the vehicle, and then inputs the AC power to the power storage device 3 or the generator inverter 21. The generator inverter 21 and the drive inverter 41 form a part of the PCU (Power Control Unit).

The power storage device 3 is a battery and / or a capacitor or the like. The battery is a high-voltage secondary battery having a high energy density, such as a lithium ion secondary battery or a nickel-hydrogen secondary battery. The power storage device 3 charges and stores the electric power generated by each of the power generation motor generator 2 and the traveling motor generator 4. Further, the power storage device 3 discharges electric power for operating each of the power generation motor generator 2 and the traveling motor generator 4 as an electric motor, and supplies the electric power required for the motor generators 2 and 4.

FIG. 2 shows an outline of the internal combustion engine 1 mounted on the hybrid vehicle of the present embodiment. The internal combustion engine 1 is a spark-ignition 4-stroke engine, and includes a plurality of cylinders 11 (for example, three cylinders, one of which is shown in FIG. 1). An injector 111 for injecting fuel toward the intake port is provided in the vicinity of the intake port of each cylinder 11. Further, a spark plug 112 is attached to the ceiling of the combustion chamber of each cylinder 11. The spark plug 112 receives an induction voltage generated by the ignition coil to induce a spark discharge between the center electrode and the ground electrode.

The intake passage 13 for supplying intake air takes in air from the outside and guides it to the intake port of each cylinder 11. An air cleaner 131, an electronic throttle valve 132, a surge tank 133, and an intake manifold 134 are arranged in this order from the upstream on the intake passage 13. The air cleaner 131 is located at the most upstream position in the intake passage 13, that is, at the intake port that takes in air. The intake port is opened in front of the vehicle in order to take in cold air and improve the filling efficiency of the internal combustion engine.

The exhaust passage 14 for discharging the exhaust guides the exhaust generated as a result of burning the fuel in the cylinder 11 to the outside from the exhaust port of each cylinder 11. An exhaust manifold 142 and a three-way catalyst 141 for exhaust purification are arranged on the exhaust passage 14. Air-fuel ratio sensors 143 and 144 for detecting the air-fuel ratio of the gas flowing through the exhaust passage 4 are installed upstream and downstream of the catalyst 41 in the exhaust passage 4. _{Each of the air-fuel ratio sensors 143 and 144 may be an O 2} sensor having a non-linear output characteristic with respect to the air-fuel ratio of the exhaust gas, and may be a linear A / F sensor having an output characteristic proportional to the air-fuel ratio of the exhaust gas. There may be. _{The output characteristics of the O 2} sensor, which outputs a voltage signal according to the oxygen concentration in the exhaust gas, show a steep slope with a large rate of change in output with respect to the air-fuel ratio in a certain range (window) near the stoichiometric air-fuel ratio. In the lean region where the air-fuel ratio is large, it approaches the low saturation value, and in the rich region where the air-fuel ratio is small, it approaches the high saturation value, that is, a so-called Z characteristic curve is drawn.

The external EGR (Exhaust Gas Recirculation) device 12 opens and closes the external EGR passage 121 that connects the exhaust passage 14 and the intake passage 13, the EGR cooler 122 provided on the EGR passage 121, and the EGR passage 121, and the EGR passage 121. The element is an EGR valve 123 that controls the flow rate of the EGR gas flowing through the EGR gas. The inlet of the EGR passage 121 is connected to a predetermined position downstream of the catalyst 141 in the exhaust passage 14. The outlet of the EGR passage 121 is connected to a predetermined position downstream of the throttle valve 132 in the intake passage 13, particularly to the surge tank 133.

The internal combustion engine 1 is provided with a brake booster 15 for reducing the operating force required when braking the vehicle, that is, the pedaling force of the brake pedal. In this field, the brake booster 15 draws in intake negative pressure from a portion (or surge tank 133) on the downstream side of the throttle valve 132 in the intake passage 13, and uses the negative pressure to boost the pedaling force of the brake pedal. It is widely known. The brake booster 15 has a constant pressure chamber (negative pressure chamber) for storing negative pressure and a transformation chamber (atmospheric pressure chamber) to which atmospheric pressure is applied, and the constant pressure chamber is connected to an intake passage 13 via a negative pressure pipeline 151. ing. The negative pressure pipeline 151 guides the intake negative pressure on the downstream side of the throttle valve 132 to the constant pressure chamber. A check valve 152 is provided on the negative pressure conduit 151 to keep the negative pressure in the constant pressure chamber and prevent the positive pressure from being applied to the constant pressure chamber.

When the brake pedal is not operated by the driver, the constant pressure chamber and the transformer chamber communicate with each other, and the transformer chamber is isolated from the atmospheric pressure. When the brake pedal is operated, the space between the constant pressure chamber and the transformer chamber is cut off, and the atmosphere is introduced into the transformer chamber. As a result, the pressure difference between the constant pressure chamber and the transformer chamber becomes the control pressure that doubles the pedaling force of the brake pedal. The brake pedal force amplified by the brake booster 15 is converted into hydraulic pressure in the master cylinder 16. The master cylinder pressure output by the master cylinder 16, that is, the pressure of the brake liquid discharged by the master cylinder 16, is transmitted to a brake device such as a brake caliper or a wheel cylinder via a hydraulic pressure circuit, and the brake device brakes the vehicle. Used.

The ECU (Electronic Control Unit) 0, which is a control device that controls the internal combustion engine 1, the power generation motor generator 2, the power storage device 3, the inverters 21, 41, and the traveling motor generator 4, is a processor, a memory, an input interface, an output interface, and the like. It is a microcomputer system having. The ECU 0 is a plurality of ECUs, that is, an EFI (Electronic Fuel Injection) ECU 01 that controls an internal combustion engine 1, a generator ECU 02 that controls a generator motor generator 2 and a generator inverter 21, and a BMS (Battery Management) that controls a power storage device 3. System) ECU 03, drive motor ECU 04 that controls the driving motor generator 4 and drive inverter 41, and HV (Hybrid Battery) ECU, which is a higher-level controller that controls these controls, are CAN (Control Area Network), etc. It is connected so that it can communicate with each other via the telecommunications line of.

For ECU 0, the vehicle speed signal a output from the vehicle speed sensor that detects the actual vehicle speed of the vehicle, the crank angle signal b output from the crank angle sensor that detects the rotation angle of the crank shaft of the internal combustion engine 1 and the engine rotation speed. , Accelerator opening signal c output from a sensor that detects the amount of depression of the accelerator pedal by the driver as the accelerator opening (so to speak, the driving force required by the driver for the vehicle), the intake passage connected to the cylinder 11. Intake temperature / intake pressure signal d output from the temperature / pressure sensor that detects the intake air temperature and intake pressure in 13 (particularly surge tank 133), and output from the water temperature sensor that detects the temperature of the cooling water of the internal combustion engine 1. Cooling water temperature signal e, a signal output from a sensor that detects the amount of charge (or SOC (State Of Charge)) stored in the power storage device 3, especially a sensor that detects the terminal current and / or terminal voltage of the battery 3. f, an outside temperature signal g output from an outside temperature sensor that detects the outside temperature, a signal h output from a sensor that detects an applied current and / or an applied voltage to the power generation motor generator 2, and an exhaust upstream of the catalyst 141. A signal m output from the air fuel ratio sensor 143 that detects the air fuel ratio of the gas, a signal n output from the air fuel ratio sensor 144 that detects the air fuel ratio of the exhaust gas downstream of the catalyst 141, and the like are input.

ECU0 senses through various sensors, such as the accelerator opening operated by the driver, the shift position, that is, the position of the shift lever (selector lever), the ON / OFF of the switch operated by the driver, and the current vehicle. The traveling motor generator 4 outputs according to the vehicle speed, the slope of the road surface, the amount of charge stored in the power storage device 3, the magnitude of the negative pressure stored in the brake booster 15, the generated power of the power generation motor generator 2, and the like. The rotational driving force to be generated, the rotational driving force output by the internal combustion engine 1, the electric power generated by the power generation motor generator 2, or the rotational driving force output by the power generation motor generator 2 is controlled to increase or decrease.

As a general rule, if the power storage device 3 currently stores sufficient electric charge and the output required for the traveling motor generator 4 is small, the supply of fuel to the internal combustion engine 1 is cut off and the internal combustion engine 1 is operated. do not. On the other hand, if the amount of charge stored in the power storage device 3 is reduced or the output required for the traveling motor generator 4 is large, the internal combustion engine 1 is started and fuel is supplied to the cylinder 11. The generator motor generator 2 is driven by the rotational driving force output from the internal combustion engine 1 to generate electricity to charge the power storage device 3 or supply the power to be supplied to the traveling motor generator 4. Strengthen.

The internal combustion engine 1 is started while the drive wheels 62 are driven by the traveling motor generator 4 to drive the vehicle without supplying fuel to the cylinder 11 of the internal combustion engine 1 to operate the internal combustion engine 1. In order to execute power generation by the power generation motor generator 2, first, the power generation motor generator 2 is operated as an electric motor, and motoring for starting the internal combustion engine 1 is performed. Then, after the crankshaft of the internal combustion engine 1 rotates a predetermined number of times or more or a predetermined angle or more, and the cylinder determination for knowing the current stroke of each cylinder 11 of the internal combustion engine 1 or the position of the piston is completed, each cylinder of the internal combustion engine 1 is completed. Inject fuel at an appropriate timing according to the process of, and start firing to ignite and burn the fuel at an appropriate timing. The rotation angle and rotation speed of the crankshaft of the internal combustion engine 1, that is, the engine speed can be detected via the resolver attached to the power generation motor generator 2 (in the generator ECU 02), and the crank angle attached to the internal combustion engine 1. It can also be detected via a sensor (in the EFI ECU 01).

When the rotation of the internal combustion engine 1 is accelerated by motoring and firing and the rotation speed exceeds the start determination value, the internal combustion engine 1 is started and is in a state of autonomous rotation (motor generator 2 for power generation). The engine speed can still maintain an upward trend even if the output of the engine is reduced), and the output of the power generation motor generator 2 operating as an electric motor is reduced to 0 to end the motoring. ..

After the start determination of the internal combustion engine 1, the internal combustion engine 1 rotationally drives the power generation motor generator 2. Further, the power generation motor generator 2 is operated as a generator, and the generated power is increased from 0.

The EFI ECU 01, which forms a part of the ECU 0, acquires various information a, b, c, d, e, f, g, h, m, n necessary for the operation control of the internal combustion engine 1 via the input interface. , The engine speed is known and the amount of air sucked into the cylinder 11 (so to speak, the engine load factor) is estimated. Then, the required fuel injection amount (necessary to achieve the target air-fuel ratio), fuel injection timing (including the number of fuel injections per combustion), fuel injection pressure, and ignition timing (once) corresponding to the intake air amount. The operating parameters of the internal combustion engine 1 such as the required number of ignitions for combustion), the required EGR ratio (or the amount of EGR gas), and the like are determined. The EFI ECU 01 outputs various control signals i, j, k, l corresponding to the operation parameters to the igniter, injector 111, throttle valve 132, EGR valve 123, etc. of the spark plug 112 via the output interface.

When the firing of the internal combustion engine 1 that had been fired and operated until then is completed and the rotation of the crankshaft of the internal combustion engine 1 is stopped, fuel is injected and burned until the rotation is completely stopped. Therefore, air containing a large amount of oxygen without combustion gas flows into the exhaust gas purification catalyst 141 through the intake passage 13, the cylinder 11, and the exhaust passage 14.

The time required for the rotation of the internal combustion engine 1 to completely stop, and the amount of air flowing into the catalyst 141 during that time, may vary depending on the opportunity to stop the rotation of the internal combustion engine 1. As a result, the atmosphere in the catalyst 141, that is, the amount of oxygen occluded in the catalyst 141 may vary from time to time when the stopped internal combustion engine 1 is restarted and firing is restarted. The oxygen occlusion amount of the catalyst 141 when the rotation of the internal combustion engine 1 is stopped affects the purification efficiency of harmful substances of the catalyst 141 at the time of the subsequent restart or the time immediately after the restart. If the oxygen storage amount is remarkably large, the NO _x emission amount may increase, and if the oxygen storage amount is remarkably small, the HC or CO emission amount may increase.

Therefore, as shown in FIG. 3, when the ECU 0 of the present embodiment ends the firing of the internal combustion engine 1 and stops it (step S1), at least the engine rotation speed indicated by the crank angle signal b at that time. And fuel injection from the injector 111 to the cylinder 11 and ignition combustion by the spark plug 112 are stopped according to the state of the atmosphere in the catalyst 141 indicated by the output signal n of the air-fuel ratio sensor 144 installed downstream of the catalyst 141 in the exhaust passage 14. Then, the length of time required to completely stop the rotation of the internal combustion engine 1 is determined (step S3).

As shown in FIG. 4, in step S2, the higher the engine speed at the end of firing, the shorter the time required to completely stop the rotation of the internal combustion engine 1 is set, and when the firing is completed. The lower the engine speed, the longer the time required to completely stop the rotation of the internal combustion engine 1.

In addition, the larger the amount of oxygen stored in the catalyst 141 when the firing is completed, the shorter the time required to completely stop the rotation of the internal combustion engine 1 is set, and the oxygen stored in the catalyst 141 when the firing is completed. The smaller the amount, the longer the time required to completely stop the rotation of the internal combustion engine 1 is set. In FIG. 4, the solid line represents the time required under the condition that the oxygen storage amount of the catalyst 141 is relatively small, the chain line represents the time required under the condition that the oxygen storage amount of the catalyst 141 is relatively large, and the broken line represents the time required under the condition that the oxygen storage amount of the catalyst 141 is relatively large. It shows the time required under the condition that the oxygen occlusion amount of is about halfway between the two. If the air-fuel ratio sensor 144 is an O ₂ sensor, it is considered that the higher the output voltage n, the smaller the oxygen storage amount of the catalyst 141, and the lower the output voltage n, the larger the oxygen storage amount of the catalyst 141. If the air-fuel ratio sensor 144 is a linear A / F sensor, it is considered that the lower the output voltage n, the smaller the oxygen storage amount of the catalyst 141, and the higher the output voltage n, the larger the oxygen storage amount of the catalyst 141.

Then, in the ECU 0 of the present embodiment, after the fuel injection and the ignition combustion are stopped, the rotation of the internal combustion engine 1 is completely stopped when the required time determined in step S3 elapses. The power generation motor generator 2 connected to the crankshaft is controlled (step S4). In step S4, for example, the power generation motor generator 2 is operated as a generator while keeping the opening degree of the throttle valve 132 on the intake passage 13 constant without injecting fuel from the injector 11, and the engine speed is decelerated. Executes feedback control for increasing or decreasing the magnitude of the electric power (terminal current and / or terminal voltage) output by the power generation motor generator 2 so that the engine rotation speed becomes 0 after the above-mentioned required time elapses. do.

The electric power generated by the power generation motor generator 2 in step S4 is charged and recovered in the power storage device 3. In the control of steps S3 and S4, the amount of electric charge stored in the power storage device 3 when the firing of the internal combustion engine 1 is completed is not the full capacity of the power storage device 3, and the amount of electricity stored at that time is the power storage device 3. It is preferable to carry out only when the capacity is smaller than a certain level (step S2) when viewed from the upper limit of the capacity. As a matter of course, if the electric charge is already stored up to the capacity of the power storage device 3, it becomes difficult to operate the power generation motor generator 2 as a generator. Further, it is necessary to leave a certain amount of capacity of the power storage device 3 in order to recover the kinetic energy of the vehicle by regenerative braking and improve the overall efficiency and fuel efficiency.

Alternatively, if it takes a long time to completely stop the rotation of the internal combustion engine 1 determined in step S3, that is, if the oxygen in the catalyst 141 is deficient at the end of firing, the step is taken. In S4, the motor generator 2 for power generation is operated not as a generator but as an electric motor, whereby the crankshaft of the internal combustion engine 1 is rotationally driven so that the rotation of the inner edge engine 1 is completely stopped after the required time has elapsed. It is also possible to control it.

In the present embodiment, when fuel is burned in the cylinder 11 of the internal combustion engine 1 to end the firing for operating the internal combustion engine 1 and the rotation of the internal combustion engine 1 is stopped, the rotation of the internal combustion engine 1 is stopped. Internal combustion engine control device 0 that variably adjusts the required time according to the engine speed at the end of firing and the output signal n of the air-fuel ratio sensor 144 downstream of the exhaust purification catalyst 141 mounted on the exhaust passage 14. Was configured.

According to the present embodiment, the oxygen storage amount of the catalyst 141 when the rotation of the internal combustion engine 1 is stopped can be equalized without being dispersed for each opportunity to stop the internal combustion engine 1. In other words, the atmosphere in the catalyst 141 when the rotation of the internal combustion engine 1 is stopped can be adjusted in advance to a state advantageous for the oxidation / reduction treatment _{of the harmful substances HC, CO and NO x.} Therefore, it is possible to effectively suppress an increase in emission of harmful substances when the internal combustion engine 1 is restarted later.

If an excessive amount of oxygen is occluded in the catalyst 141 before the restart of the internal combustion engine 1, the fuel injection amount is increased after the restart to purge the oxygen, and the gas flows into the catalyst 141. It is necessary to enrich the air-fuel ratio, but according to the present embodiment, it is possible to effectively prevent an excessive amount of oxygen from being occluded in the catalyst 141 when the internal combustion engine 1 is stopped, so that a large amount of oxygen is stored at the time of restarting. It is possible to contribute to further improvement of fuel efficiency by being freed from the need to inject fuel.

The present invention is not limited to the embodiments described in detail above. The present invention can also be applied to the control of an internal combustion engine mounted on a hybrid vehicle other than a series hybrid vehicle or a vehicle that does not correspond to a so-called hybrid vehicle (particularly, control at the time of restarting an internal combustion engine that has been idle-stopped).

In addition, the specific configuration of each part and the content of the process can be variously modified without departing from the spirit of the present invention.

0 ... Control device (ECU)
1 ... Internal combustion engine 11 ... Cylinder 111 ... Injector 14 ... Exhaust passage 141 ... Catalyst 144 ... Air-fuel ratio sensor on the downstream side of the catalyst 2 ... Generator (motor generator for power generation)
b ... Crank angle signal j ... Fuel injection signal n ... Air-fuel ratio signal on the downstream side of the catalyst

Claims (1)

When the firing is completed, the time required until the rotation of the internal combustion engine is stopped is the time required to stop the rotation of the internal combustion engine by burning the fuel in the cylinder of the internal combustion engine to end the firing to operate the internal combustion engine. A control device for an internal combustion engine that variably adjusts according to the output signal of the air-fuel ratio sensor downstream of the exhaust gas purification catalyst mounted on the exhaust passage.

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