JP7447776B2 - Internal combustion engine control device - Google Patents

Description

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

Conventionally, as this type of internal combustion engine control device, one has been proposed for use in an internal combustion engine device that includes an internal combustion engine, a purification catalyst (upstream catalyst), and an exhaust sensor (air-fuel ratio sensor). For example, see Patent Document 1). The internal combustion engine includes a fuel injection valve. The purification catalyst is attached to the exhaust system (exhaust passage) of the internal combustion engine and is capable of storing oxygen. The exhaust sensor is installed downstream of the purification catalyst in the exhaust system. In this device, when the internal combustion engine is operated, if the detected air-fuel ratio detected by the exhaust sensor reaches a rich side threshold value (rich setting air-fuel ratio) or less while rich correction is being performed on the fuel injection amount of the fuel injection valve, The system switches to execute lean correction for the fuel injection amount, and when the detected air-fuel ratio reaches a lean-side threshold value (lean set air-fuel ratio) or more during execution of lean correction, switches to execute rich correction. When the detected air-fuel ratio becomes equal to or less than the rich-side threshold value during rich correction, the amount of oxygen stored in the purification catalyst becomes zero. Then, when the detected air-fuel ratio reaches the lean side threshold value or more during execution of the lean correction, the oxygen storage amount of the purification catalyst reaches the maximum value. When the detected air-fuel ratio deviation amount is 0, the amount of oxygen stored as the amount of oxygen stored in the purification catalyst during lean correction is equal to the amount of desorbed oxygen as the amount of oxygen desorbed from the purification catalyst during rich correction. From this, deviation amount related learning is executed to update the deviation amount related learning value regarding the deviation amount of the detected air-fuel ratio using the difference between the oxygen storage amount during lean correction and the oxygen desorption amount during rich correction.

JP 2019-78169 Publication

In the internal combustion engine control device described above, when lean correction and calculation of the oxygen storage amount of the purification catalyst are started with the detected air-fuel ratio exceeding the rich side threshold value, the oxygen storage amount of the purification catalyst at the time of starting the calculation is changed to the value It may be greater than 0. In this case, since the calculated oxygen storage amount and the oxygen desorption amount during the next rich correction are not equal, the deviation amount related learning value cannot be updated to an appropriate value, and the learning error in deviation amount related learning becomes large. turn into. Additionally, if rich correction and calculation of the amount of oxygen desorbed from the purification catalyst are started when the detected air-fuel ratio exceeds the lean side threshold, the amount of oxygen desorbed from the purification catalyst at the time of starting the calculation will be greater than the value 0. There is. In this case, since the calculated oxygen desorption amount and the oxygen storage amount during the next lean correction are not equal, the deviation amount related learning value cannot be updated to an appropriate value, and the learning error in deviation amount related learning becomes large. turn into.

The main purpose of the internal combustion engine control device of the present invention is to suppress learning errors in deviation amount related learning.

The internal combustion engine control device of the present invention employs the following means to achieve the above-mentioned main objective.

The internal combustion engine control device of the present invention includes:
an internal combustion engine having a fuel injection valve;
a purification catalyst that is attached to the exhaust system of the internal combustion engine and is capable of storing oxygen;
an exhaust sensor installed downstream of the purification catalyst in the exhaust system;
used in internal combustion engine devices equipped with
When operating the internal combustion engine, if the detected air-fuel ratio detected by the exhaust sensor reaches a rich side threshold value or less while rich correction is being performed on the fuel injection amount of the fuel injection valve, lean correction is performed on the fuel injection amount. When the detected air-fuel ratio reaches a lean-side threshold value or more during execution of the lean correction, performing correction control to switch to the execution of the rich correction;
The amount of oxygen stored as the amount of oxygen stored in the purification catalyst during the lean correction is calculated, and the amount of oxygen desorbed as the amount of oxygen released from the purification catalyst during the rich correction is calculated. A control device for an internal combustion engine that executes deviation amount related learning for updating a deviation amount related learning value regarding the deviation amount of the detected air-fuel ratio using the difference between the oxygen storage amount and the oxygen desorption amount,
When the calculation of the oxygen storage amount is started in a state where the detected air-fuel ratio exceeds the rich-side threshold value, or when the calculation of the oxygen desorption amount is started in a state where the detected air-fuel ratio is less than the lean-side threshold value. The gist is to prohibit execution of the deviation amount related learning at a predetermined time when it is started.

In the internal combustion engine control device of the present invention, when the calculation of the oxygen storage amount is started with the detected air-fuel ratio exceeding the rich side threshold, or when the oxygen storage amount is started with the detected air-fuel ratio being less than the lean side threshold. At a predetermined time when calculation of the distance is started, execution of the distance-related learning is prohibited. If the deviation amount related learning value is updated at a predetermined time, it is considered that the deviation amount related learning value will not become an appropriate value. Since execution of deviation amount related learning is prohibited at such predetermined times, learning errors can be suppressed.

In such an internal combustion engine control device of the present invention, the period after the predetermined time until one of the lean corrections and the two rich corrections is completed, or the period after the predetermined time until the two lean corrections are completed. Execution of the deviation amount related learning is prohibited during a predetermined period until the correction and one of the rich corrections are completed, and the deviation amount related learning is permitted after the predetermined period. It is considered that the deviation amount related learned value cannot be updated to an appropriate value for a predetermined period. Therefore, by prohibiting execution of deviation amount related learning for a predetermined period, learning errors in deviation amount related learning can be suppressed. Moreover, it is considered that the deviation amount related learning value can be updated to an appropriate value after a predetermined period of time. Therefore, after a predetermined period of time, the deviation amount-related learning can be appropriately executed by allowing the deviation amount-related learning.

Further, in the internal combustion engine control device of the present invention, the predetermined time may be a time when switching from execution of control different from the correction control to execution of the correction control. In this way, learning errors in deviation amount related learning can be suppressed compared to a case where deviation amount related learning is executed when switching from execution of control different from correction control to execution of correction control.

1 is a configuration diagram schematically showing the configuration of a hybrid vehicle 20 equipped with an internal combustion engine control device as an embodiment of the present invention. 2 is a configuration diagram showing an outline of the configuration of an engine 22. FIG. 2 is a control block diagram showing an example of a control block when fuel injection control of the engine 22 is performed by the engine ECU 24. FIG. 9 is a flowchart illustrating an example of a sub-feedback correction routine executed by a sub-feedback section 92. FIG. FIG. 3 is an explanatory diagram showing an example of the detected air-fuel ratio AFd and sub-feedback correction. 7 is a flowchart illustrating an example of a deviation amount related learning routine executed by the deviation amount related learning section 95. FIG. 9 is a flowchart illustrating an example of a learning permission flag setting routine executed by a learning permission unit 98. FIG. Explanation for explaining changes over time in the control air-fuel ratio AFu*, the oxygen storage amount Ost, the oxygen desorption amount Ods, the amount of oxygen actually stored in the purification catalyst 136a (actual oxygen storage amount), and the detected air-fuel ratio AFd It is a diagram.

Next, a mode for carrying out the present invention will be described using examples.

FIG. 1 is a block diagram schematically showing the structure of a hybrid vehicle 20 equipped with an internal combustion engine control device as an embodiment of the present invention, and FIG. 2 is a block diagram schematically showing the structure of an engine 22. As shown in FIG. As shown in FIG. 1, the hybrid vehicle 20 of the embodiment includes an engine 22, a planetary gear 30, motors MG1 and MG2, inverters 41 and 42, a battery 50, and a hybrid electronic control unit (hereinafter referred to as "HVECU"). ) 70.

The engine 22 is configured as an internal combustion engine that outputs power using gasoline, light oil, or the like as fuel. As shown in FIG. 2, the engine 22 sucks air purified by the air cleaner 122 into the intake pipe 123, passes it through the throttle valve 124 and the surge tank 125, and also causes the air to flow through the intake pipe 123 on the downstream side of the surge tank 125. Fuel is injected from the fuel injection valve 126 to mix air and fuel. Then, the engine 22 sucks this air-fuel mixture into a combustion chamber 129 through an intake valve 128, and causes the sucked air-fuel mixture to explode and burn using electric sparks from a spark plug 130. The reciprocating motion of the piston 132, which is pushed down by the energy of this explosion and combustion, is converted into rotational motion of the crankshaft 26. Exhaust gas discharged from the combustion chamber 129 to the exhaust pipe 134 via the exhaust valve 133 is discharged to the outside air via purifiers 136 and 138. The purification devices 136 and 138 each have purification catalysts (three-way catalysts) 136a and 138a that purify harmful components such as carbon monoxide (CO), hydrocarbons (HC), and nitrogen oxides (NOx) in exhaust gas. The purification catalysts 136a and 138a are configured to be able to store and desorb oxygen, respectively.

The engine 22 is operationally controlled by an engine electronic control unit (hereinafter referred to as "engine ECU") 24. Although not shown, the engine ECU 24 is configured as a microprocessor centered on a CPU, and in addition to the CPU, includes a ROM for storing processing programs, a RAM for temporarily storing data, input/output ports, and communication ports. Be prepared.

Signals from various sensors necessary to control the operation of the engine 22 are input to the engine ECU 24 via an input port. Signals input to the engine ECU 24 include, for example, the crank angle θcr from the crank position sensor 140 that detects the rotational position of the crankshaft 26 of the engine 22, and the water temperature sensor 142 that detects the temperature of the cooling water of the engine 22. One example is the cooling water temperature Tw. Further, the cam position θca from the cam position sensor 144 that detects the rotational position of the intake camshaft that opens and closes the intake valve 128 and the exhaust camshaft that opens and closes the exhaust valve 133 can also be mentioned. Furthermore, the throttle opening TH from the throttle valve position sensor 124a that detects the position of the throttle valve 124, the intake air amount Qa from the air flow meter 148 attached to the intake pipe 123, and the temperature sensor 149 attached to the intake pipe 123 , and the surge pressure Ps from the pressure sensor 150 attached to the surge tank 125. In addition, the detected air-fuel ratio AFu from the upstream air-fuel ratio sensor 152 installed upstream of the purification device 136 of the exhaust pipe 134 and the detected air-fuel ratio AFu of the exhaust pipe 134 downstream of the purification device 136 and upstream of the purification device 138. The detected air-fuel ratio AFd from the downstream air-fuel ratio sensor 154 attached to the side can also be mentioned.

The engine ECU 24 outputs various control signals for controlling the operation of the engine 22 via an output port. Examples of the signals output from the engine ECU 24 include a drive control signal to the throttle motor 124b that adjusts the position of the throttle valve 124, a drive control signal to the fuel injection valve 126, and a control signal to the spark plug 130. Can be done.

Engine ECU 24 is connected to HVECU 70 via a communication port. The engine ECU 24 calculates the rotation speed Ne of the engine 22 based on the crank angle θcr of the engine 22 from the crank position sensor 140. Also, based on the intake air amount Qa from the air flow meter 148 and the rotation speed Ne of the engine 22, the volumetric efficiency (ratio of the volume of air actually taken in one cycle to the stroke volume per one cycle of the engine 22) KL Calculate.

The planetary gear 30 is configured as a single pinion type planetary gear mechanism. The sun gear of the planetary gear 30 is connected to the rotor of the motor MG1. A drive shaft 36 connected to drive wheels 39a and 39b via a differential gear 38 is connected to the ring gear of the planetary gear 30. A crankshaft 26 of the engine 22 is connected to the carrier of the planetary gear 30 via a damper 28.

The motor MG1 is configured, for example, as a synchronous generator motor, and has a rotor connected to the sun gear of the planetary gear 30, as described above. The motor MG2 is configured as, for example, a synchronous generator motor, and has a rotor connected to the drive shaft 36. Inverters 41 and 42 are used to drive motors MG1 and MG2, and are connected to battery 50 via power line 54. The motors MG1 and MG2 are rotationally driven by a motor electronic control unit (hereinafter referred to as "motor ECU") 40 that controls switching of a plurality of switching elements (not shown) of inverters 41 and 42.

Although not shown, the motor ECU 40 is configured as a microprocessor centered on a CPU, and in addition to the CPU, it also includes a ROM for storing processing programs, a RAM for temporarily storing data, an input/output port, and a communication port. Be prepared. Signals from various sensors necessary to drive and control the motors MG1 and MG2 are input to the motor ECU 40 via input ports. Examples of signals input to the motor ECU 40 include rotational positions θm1 and θm2 of the rotors of the motors MG1 and MG2 from rotational position sensors 43 and 44 that detect the rotational positions of the rotors of the motors MG1 and MG2, and the rotational positions θm1 and θm2 of the rotors of the motors MG1 and MG2, respectively. , MG2 can be cited as phase currents Iu1, Iv1, Iu2, and Iv2 of each phase of the motors MG1 and MG2 from a current sensor that detects the phase current flowing in each phase of the motors MG1 and MG2. The motor ECU 40 outputs switching control signals to a plurality of switching elements (not shown) of the inverters 41 and 42 via an output port. Motor ECU 40 is connected to HVECU 70 via a communication port. Motor ECU 40 calculates electrical angles θe1, θe2 and rotational speeds Nm1, Nm2 of motors MG1, MG2 based on rotational positions θm1, θm2 of the rotors of motors MG1, MG2 from rotational position sensors 43, 44.

The battery 50 is configured as, for example, a lithium ion secondary battery or a nickel metal hydride secondary battery, and is connected to the inverters 41 and 42 via the power line 54, as described above. This battery 50 is managed by a battery electronic control unit (hereinafter referred to as "battery ECU") 52.

Although not shown, the battery ECU 52 is configured as a microprocessor centered on a CPU, and in addition to the CPU, it also includes a ROM for storing processing programs, a RAM for temporarily storing data, an input/output port, and a communication port. Be prepared. Signals from various sensors necessary for managing the battery 50 are input to the battery ECU 52 via an input port. Examples of signals input to the battery ECU 52 include the voltage Vb of the battery 50 from the voltage sensor 51a attached between the terminals of the battery 50, and the voltage Vb of the battery 50 from the current sensor 51b attached to the output terminal of the battery 50. Examples include battery current Ib and temperature Tb of battery 50 measured from temperature sensor 51c attached to battery 50. Battery ECU 52 is connected to HVECU 70 via a communication port. The battery ECU 52 calculates the storage percentage SOC based on the integrated value of the battery current Ib from the current sensor 51b. The power storage ratio SOC is the ratio of the capacity of electric power that can be discharged from the battery 50 to the total capacity of the battery 50.

Although not shown, the HVECU 70 is configured as a microprocessor centered on a CPU, and includes, in addition to the CPU, a ROM for storing processing programs, a RAM for temporarily storing data, an input/output port, and a communication port. . Signals from various sensors are input to the HVECU 70 via input ports. Examples of signals input to the HVECU 70 include an ignition signal from an ignition switch 80 and a shift position SP from a shift position sensor 82 that detects the operating position of the shift lever 81. Further, the accelerator opening degree Acc from the accelerator pedal position sensor 84 which detects the amount of depression of the accelerator pedal 83, the brake pedal position BP from the brake pedal position sensor 86 which detects the amount of depression of the brake pedal 85, and the brake pedal position BP from the vehicle speed sensor 88. Vehicle speed V can also be mentioned. As described above, the HVECU 70 is connected to the engine ECU 24, motor ECU 40, and battery ECU 52 via the communication port.

The hybrid vehicle 20 of the embodiment configured in this manner can be operated in an electric driving mode (EV driving mode) in which the vehicle travels without the operation of the engine 22 or in a hybrid driving mode (HV driving mode) in which the vehicle travels with the operation of the engine 22. Run.

In the EV driving mode, the HVECU 70 first sets a required torque Td* required for driving (required to the drive shaft 36) based on the accelerator opening Acc and the vehicle speed V. Next, the torque command Tm1* of the motor MG1 is set to the value 0, and the torque command Tm2* of the motor MG2 is set so that the required torque Td* is output to the drive shaft 36, and the set torque of the motors MG1 and MG2 is The commands Tm1* and Tm2* are sent to the motor ECU 40. Motor ECU 40 performs switching control of a plurality of switching elements of inverters 41 and 42 so that motors MG1 and MG2 are driven by torque commands Tm1* and Tm2*.

In the HV driving mode, the HVECU 70 first sets the required torque Td* similarly to the EV driving mode. Next, the required power Pd* required for driving is calculated by multiplying the required torque Td* by the rotational speed Nd of the drive shaft 36, and from the required power Pd*, the required charging/discharging power Pb* of the battery 50 (discharging from the battery 50) is calculated. The required power Pe* required of the engine 22 is calculated by subtracting the value (when the value is positive). Here, as the rotation speed Nd of the drive shaft 36, for example, the rotation speed Nm2 of the motor MG2 or the rotation speed obtained by multiplying the vehicle speed V by a conversion coefficient is used. Then, the target rotation speed Ne* of the engine 22, the target torque Te*, and the torque command Tm1 of the motors MG1 and MG2 are set so that the required power Pe* is outputted from the engine 22 and the required torque Td* is outputted to the drive shaft 36. *, Tm2* are set, and the target rotational speed Ne* and target torque Te* of the engine 22 are transmitted to the engine ECU 24, and torque commands Tm1* and Tm2* of the motors MG1 and MG2 are transmitted to the motor ECU 40. Engine ECU 24 performs intake air amount control, fuel injection control, ignition control, etc. of engine 22 so that engine 22 is operated based on target rotational speed Ne* and target torque Te*. The control of motors MG1 and MG2 (inverters 41 and 42) by motor ECU 40 has been described above.

Here, fuel injection control of the engine 22 by the engine ECU 24 will be explained. FIG. 3 is a control block diagram showing an example of a control block when the engine ECU 24 performs fuel injection control of the engine 22. As shown in the figure, the engine ECU 24 includes a base injection amount setting section 90, a main feedback section 91, a sub-feedback section 92, a target injection amount setting section 93, and an injection amount setting section 90 as control blocks for fuel injection control of the engine 22. It includes a valve control section 94, a deviation amount related learning section 95, an oxygen storage amount estimating section 96, and a learning permission section 98.

The base injection amount setting unit 90 sets the base injection amount, which is a base value of the target injection amount Qf* of the fuel injection valve 126 for setting the air-fuel ratio of the air-fuel mixture in the combustion chamber 129 to the target air-fuel ratio, based on the volumetric efficiency KL. Set the amount Qfb. Here, as the target air-fuel ratio, the stoichiometric air-fuel ratio (stoichiometric) is used in the embodiment. The base injection amount Qfb is calculated, for example, by multiplying the unit injection amount (injection amount per 1% of the volumetric efficiency KL) Qfpu by the volumetric efficiency KL to set the air-fuel ratio of the air-fuel mixture in the combustion chamber 129 to the target air-fuel ratio. be done. As described above, the volumetric efficiency KL is based on the intake air amount Qa from the air flow meter 148 and the rotation speed Ne of the engine 22, which is calculated based on the crank angle θcr of the engine 22 from the crank position sensor 140. Calculated.

The main feedback unit 91 calculates a correction value δaf by feedback control to make the detected air-fuel ratio AFu from the upstream air-fuel ratio sensor 152 the control air-fuel ratio AFu*, and sets the calculated correction value δaf to a value (-1). The correction coefficient Kaf is set to the value obtained by multiplying the value by 1 and then adding the value 1. Here, the control air-fuel ratio AFu* is set by the sub-feedback section 92. The correction value δaf is calculated using a relational expression of feedback control using the detected air-fuel ratio AFu, the control air-fuel ratio AFu*, the gain Kp of the proportional term, and the gain Ki of the integral term, as shown in equation (1). be done. The reason why the correction coefficient Kaf is set to a value obtained by multiplying the correction value δaf by a value (-1) and then adding the value 1 will be described later.

δaf=Kp・(AFu*-AFu)+Ki・∫(AFu*-AFu)dt (1)

The sub-feedback section 92 performs a rich correction to set the control air-fuel ratio AFu* to a rich side value based on the detected air-fuel ratio AFd from the downstream air-fuel ratio sensor 154, and a rich correction to set the control air-fuel ratio AFu* to a lean side value. Alternately perform lean correction and set values. Hereinafter, this process will be referred to as "sub-feedback correction." Further, a period including one rich correction and one lean correction is referred to as "one period of sub-feedback correction." Rich correction and lean correction are performed to adjust the amount of oxygen stored in the purification catalyst 136a. Details of the sub-feedback unit 92 will be described later.

The target injection amount setting unit 93 sets the target injection amount Qf* of the fuel injection valve 126 to a value obtained by multiplying the base injection amount Qfb by the correction coefficient Kaf. The injection valve control unit 94 controls the fuel injection valve 126 so that the fuel injection valve 126 injects fuel at a target injection amount Qf*.

Here, the reason why the main feedback unit 91 sets a value obtained by multiplying the correction value δaf by a value (-1) and then adding a value 1 to the correction coefficient Kaf will be explained. During lean correction, the detected air-fuel ratio AFu is smaller than the control air-fuel ratio AFu* (rich side), and according to equation (1), the correction value δaf basically becomes a positive value. Therefore, it is necessary to make the correction coefficient Kaf smaller than the value 1, to make the target injection amount Qf* smaller than the base injection amount Qfb, and to make the detected air-fuel ratio AFu larger than the current value (make it leaner). On the other hand, during rich correction, the detected air-fuel ratio AFu is larger than the control air-fuel ratio AFu* (lean side), and according to equation (1), the correction value δaf basically becomes negative. Becomes a value. Therefore, it is necessary to make the correction coefficient Kaf larger than the value 1, to make the target injection amount Qf* larger than the base injection amount Qfb, and to make the detected air-fuel ratio AFu smaller than the current value (make it richer). For this reason, a value obtained by multiplying the correction value δaf by a value (-1) and then adding a value 1 is set as the correction coefficient Kaf.

The deviation amount related learning unit 95 executes deviation amount related learning to update the deviation amount related learning value regarding the deviation amount of the detected air-fuel ratio AFd from the downstream air-fuel ratio sensor 154 (hereinafter referred to as "sensor deviation amount"). In the embodiment, the stoichiometric learning value AFdst is used as the deviation amount related learning value. The stoichiometric learning value AFdst is a learning value regarding the detected air-fuel ratio AFd when the detected air-fuel ratio AFd is near the stoichiometric reference value AFs. The stoichiometric reference value AFs is a reference value (preset value) of the detected air-fuel ratio AFd when the air-fuel ratio of the air-fuel mixture in the combustion chamber 129 is the stoichiometric air-fuel ratio. The value obtained by subtracting the stoichiometric reference value AFs from the stoichiometric learning value AFdst (AFdst-AFs) is a value that reflects the amount of sensor deviation. Details of the deviation amount related learning section 95 will be described later.

The oxygen storage amount estimating unit 96 calculates the following equation ( 2) is used to calculate the amount of oxygen ΔOca stored in the purification catalyst 136a (the side where oxygen is stored in the purification catalyst 136a is a positive value) at predetermined time intervals, and integrate the amount of oxygen ΔOca while performing lean correction. The amount obtained by integrating the oxygen amount ΔOca during execution of the rich correction is defined as the oxygen desorption amount Ods.

ΔOca=0.23・(AFu-AFu*)・Qa...(2)

The learning permission unit 98 allows or disallows the execution of deviation amount related learning. Details of the learning permission section 98 will be described later.

Next, details of the sub-feedback section 92 will be explained. FIG. 4 is a flowchart showing an example of a sub-feedback correction routine executed by the sub-feedback section 92. This routine is executed repeatedly. In the embodiment, when the repeated execution of this routine is started (when the first execution is started), the value 1 is set to the rich correction flag Fr, which will be described later.

In the sub-feedback correction routine of FIG. 4, the sub-feedback section 92 first inputs the detected air-fuel ratio AFd from the downstream air-fuel ratio sensor 154 (step S100), and checks the value of the rich correction flag Fr (step S110). ). Here, the rich correction flag Fr is a flag indicating whether rich correction or lean correction is being executed.

When the rich correction flag Fr is 1 in step S110, it is determined that rich correction is being executed, and the detected air-fuel ratio AFd is set to the rich side threshold value (AFs-εR) obtained by subtracting the sub-offset amount εR from the stoichiometric reference value AFs. (Step S120). This process is a process for determining whether the detected air-fuel ratio AFd has reached a value on the rich side to some extent, that is, whether the amount of unburned fuel in the exhaust downstream of the purification catalyst 136a has increased to some extent.

When the detected air-fuel ratio AFd is larger than the rich-side threshold value (AFs-εR) in step S120, it is determined that the detected air-fuel ratio AFd has not yet reached a certain rich-side value, and the main offset amount δR is calculated from the stoichiometric reference value AFs. The subtracted value (AFs-δR) is set as the control air-fuel ratio AFu* (step S170), and this routine ends. Here, the main offset amount δR is set within a range greater than or equal to the sub offset amount εR. For example, the main offset amount δR is set to a value obtained by adding a margin to the sub-offset amount εR. In this case, execution of rich correction will continue.

When the detected air-fuel ratio AFd is less than or equal to the rich-side threshold value (AFs-εR) in step S120, it is determined that the detected air-fuel ratio AFd has become a rich-side value to some extent, and the rich correction flag Fr is set to a value of 0 (step S130). , a value obtained by adding the main offset amount δL to the stoichiometric reference value AFs (AFs+δL) is set as the control air-fuel ratio AFu* (step S140), and this routine ends. Here, the main offset amount δL is set within a range equal to or greater than the sub-offset amount εL, which will be described later. For example, the main offset amount δL is set to a value obtained by adding a margin to the sub offset amount εL. In this way, execution of rich correction is switched to execution of lean correction.

When the rich correction flag Fr has a value of 0 in step S110, it is determined that lean correction is being executed, and the detected air-fuel ratio AFd is compared with a lean-side threshold value (AFs+εL), which is the sum of the sub-offset amount εL to the stoichiometric reference value AFs. (Step S150). This process is a process for determining whether the detected air-fuel ratio AFd has reached a value on the lean side to some extent, that is, whether the amount of oxygen in the exhaust gas downstream of the purification catalyst 136a has increased to some extent.

When the detected air-fuel ratio AFd is less than the lean side threshold value (AFs+εL) in step S150, it is determined that the detected air-fuel ratio AFd has not reached a lean side value to some extent, and the value (AFs+δL) is set by the process of step S140 described above. The control air-fuel ratio AFu* is set, and this routine ends. In this case, execution of lean correction will continue.

When the detected air-fuel ratio AFd is equal to or higher than the lean-side threshold (AFs+εL) in step S150, it is determined that the detected air-fuel ratio AFd has become a lean-side value to some extent, and the rich correction flag Fr is set to the value 1 (step S160), as described above. Through the processing in step S170, the value (AFs-δR) is set as the control air-fuel ratio AFu*, and this routine ends. In this way, execution of lean correction is switched to execution of rich correction.

FIG. 5 is an explanatory diagram showing an example of the detected air-fuel ratio AFd and sub-feedback correction. As shown in the figure, when the detected air-fuel ratio AFd reaches the lean side threshold value (AFs+εL) or more during execution of the lean correction (times t1 and t3), a switch is made to the execution of the rich correction. Further, when the detected air-fuel ratio AFd becomes equal to or less than the rich side threshold value (AFs-εR) during the execution of the rich correction (time t2), a switch is made to the execution of the lean correction. Hereinafter, the period from the start of one of lean correction and rich correction to the end of the other (for example, from time t1 to t3) will be referred to as "one period of sub-feedback correction."

Note that during execution of rich correction, the fuel injection valve 126 is controlled by setting the target injection amount Qf* to a value larger than the base injection amount Qfb, so that the exhaust gas flowing into the purification catalyst 136a is It contains more unburned fuel than the amount of unburned fuel that reacts with oxygen in just the right amount. This large amount of unburned fuel is oxidized by oxygen in the exhaust gas and oxygen stored in the purification catalyst 136a, so the amount of oxygen in the exhaust gas and the amount of unburned fuel on the downstream side of the purification catalyst 136a are sufficiently reduced. . As a result, as shown in the figure, when the detected air-fuel ratio AFd is near the stoichiometric reference value AFs, the absolute value of the detected air-fuel ratio change rate ΔAFd, which is the amount of change in the detected air-fuel ratio AFd per unit time, becomes small.

Next, details of the deviation amount related learning section 95 will be explained. FIG. 6 is a flowchart showing an example of a deviation amount related learning routine executed by the deviation amount related learning section 95. This routine is executed repeatedly.

In the deviation amount related learning routine of FIG. The oxygen desorption amount Ods and the learning permission flag Flp are input (step S200). The learning permission flag Flp is set to a value of 1 when permitting execution of deviation amount related learning, that is, updating of stoichiometric learning value AFdst, and prohibits execution of deviation amount related learning, that is, updating of stoichiometric learning value AFdst. This is a flag that is set to the value 0 when (not permitted). Details of the learning permission flag Flp will be described later.

Subsequently, the value of the learning permission flag Flp is checked (step S210). When the learning permission flag Flp has a value of 1, execution of deviation amount related learning is permitted, so the difference obtained by subtracting the absolute value of the oxygen storage amount Ost |Ost| from the absolute value of the oxygen desorption amount Ods |Ods| Do is calculated (step S220), and the stoichiometric learning value AFdst is updated using the following equation (3) (step S230). In equation (3), "previous AFdst" is the stoichiometric learning value AFdst before update. “k” is a positive value gain representing the degree of change in the stoichiometric learning value AFdst with respect to the difference Do. As can be seen from equation (3), when the difference Do is a positive value, that is, when the absolute value of the oxygen desorption amount Ods |Ods| is larger than the absolute value |Ost| of the oxygen storage amount Ost, the stoichiometric learning value AFdst is updated to become smaller. When the difference Do is a negative value, that is, when the absolute value |Ods| of the oxygen desorption amount Ods is smaller than the absolute value |Ost| of the oxygen storage amount Ost, the stoichiometric learning value AFdst is updated to become larger.

AFdst=Previous AFdst - k・Do...(3)

If there is no sensor deviation in the detected air-fuel ratio AFd from the downstream side air-fuel ratio sensor 154, during lean correction, oxygen is stored in the purification catalyst 136a until the next rich correction, so the oxygen storage amount Ost increases from the value 0. do. Then, during the next rich correction, the oxygen stored in the purification catalyst 136a until the next lean correction is desorbed, and the oxygen desorption amount Ods decreases from the value 0. When there is no sensor deviation in the air-fuel ratio AFd detected from the downstream air-fuel ratio sensor 154, the absolute value of the oxygen desorption amount Ods |Ods| and the absolute value of the oxygen storage amount Ost |Ost| are equal, and the difference Do has the value 0. However, since the oxygen desorption amount Ods and the oxygen storage amount Ost are calculated using the detected air-fuel ratio AFd from the downstream air-fuel ratio sensor 154, there is a sensor deviation in the detected air-fuel ratio AFd from the downstream air-fuel ratio sensor 154. When this occurs, the absolute value |Ods| of the oxygen desorption amount Ods| and the absolute value |Ost| of the oxygen storage amount Ost are not equal, and the difference Do does not become the value 0. In the embodiment, taking this into consideration, the stoichiometric learning value AFdst is updated to a value corrected using the difference Do using the above equation (3).

After updating the stoichiometric learning value AFdst in this way, the sub-offset amount εR and the sub-offset amount εL are updated using the following equations (4) and (5) using the updated learned stoichiometric learning value AFdst (step S240), and the main routine end. In the embodiment, as shown in equation (4), the sub-offset amount εR is updated by subtracting the value obtained by subtracting the stoichiometric reference value AFs from the stoichiometric learned value AFdst (AFdst-AFs) from the initial value εRinit of the sub-offset amount εR. . Further, as shown in equation (5), the sub-offset amount εL is updated by adding the value (AFdst-AFs) to the initial value εLinit of the sub-offset amount εL. Therefore, when the stoichiometric learning value AFdst is set to the stoichiometric reference value AFs as the initial value, the sub-offset amount εR and the sub-offset amount εL are set to the initial value εRinit and the initial value εLinit, and the stoichiometric learning value AFdst is set to the stoichiometric standard. If the value deviates from the value AFs, the sub-offset amount εR and the sub-offset amount εL are set to values obtained by equations (4) and (5).

εR=εRinit-(AFdst-AFs) (4)
εL=εLinit+(AFdst-AFs) (5)

As described above, the value obtained by subtracting the stoichiometric reference value AFs from the stoichiometric learning value AFdst (AFdst-AFs) is a value that reflects the amount of sensor deviation. Then, in the process of step S240, the sub-offset amount εR and the sub-offset amount εL are updated using a value obtained by subtracting the stoichiometric reference value AFs from the stoichiometric learned value AFdst (AFdst-AFs). This prevents one of the oxygen desorption amount Ods and the oxygen storage amount Ost of the purification catalyst 136a from becoming excessive with respect to the other in one cycle of sub-feedback correction (one lean correction and one rich correction). It's suppressed.

When the learning permission flag Flp has a value of 0 in step S210, it is determined that the execution of deviation amount related learning is prohibited (updating of the stoichiometric learning value AFdst is prohibited (not permitted)), and step S220 This routine ends without performing the processing of ~S240.

Here, the setting of the learning permission flag Flp will be explained. FIG. 7 is a flowchart showing an example of a learning permission flag setting routine executed by the learning permission section 98. This routine is executed repeatedly.

In the learning permission flag setting routine of FIG. 7, first, it is determined whether a predetermined period has elapsed (step S300). Here, the "predetermined period" is 1.5 cycles of subfeed correction (one rich correction and two lean corrections, or one lean correction and two rich corrections) from the time when abnormality diagnosis of the engine 22 is completed. The period is until the end of the period. For abnormality diagnosis of the engine 22, sub-feedback correction is stopped and the control air-fuel ratio AFu* of the engine 22 is adjusted at predetermined intervals to a value obtained by adding the main offset amount δLobd, which is larger than the sub-offset amount εL, to the stoichiometric reference value AFs. or diagnosing whether or not an abnormality has occurred in the upstream air-fuel ratio sensor 152 by subtracting the main offset amount δRobd, which is larger than the sub-offset amount εR, from the stoichiometric reference value AFs. Can be done.

If it is determined in step S300 that the predetermined period has not elapsed, the learning permission flag Flp is set to the value 1 (step S310), and this routine ends. As described above, when the learning permission flag Flp is 1 in step S210 of the deviation amount related learning routine illustrated in FIG. Updated. Then, the sub-feedback section 92 executes sub-feedback correction using the updated sub-offset amounts εR and εL.

If the predetermined period has elapsed in step S300, the learning permission flag Flp is set to the value 0 (step S320), and this routine ends. As described above, when the learning permission flag Flp is 0 in step S210 of the deviation amount related learning routine illustrated in FIG. 6, steps S220 to S240 are not executed. is not updated. Therefore, the sub-feedback unit 92 executes sub-feedback correction using the last updated sub-offset amounts εR and εL.

Here, the reason why the deviation amount related learning is prohibited and the stoichiometric learning value AFdst and the sub-offset amounts εR and εL are not updated during a predetermined period will be explained. FIG. 8 illustrates temporal changes in the control air-fuel ratio AFu*, the oxygen storage amount Ost, the oxygen desorption amount Ods, the amount of oxygen actually stored in the purification catalyst 136a (actual oxygen storage amount), and the detected air-fuel ratio AFd. FIG. In FIG. 8, it is assumed that no sensor shift occurs. While the abnormality diagnosis of the engine 22 is being performed, the sub-feedback correction is stopped (time t0 to t1). When the abnormality diagnosis of the engine 22 is completed and sub-feedback correction is started, lean correction and calculation of the oxygen storage amount Ost are started in FIG. 8 (time t1). Since we are now considering a time when no sensor deviation has occurred, if the oxygen storage amount Ost in lean correction is calculated properly, then the absolute value of oxygen storage amount Ost in lean correction |Ost| It is considered that the absolute value |Ods| of the oxygen desorption amount Ods in the rich correction is equal to |Ods|. However, as shown in the figure, when the lean correction and the calculation of the oxygen storage amount Ost are started in a state where the detected air-fuel ratio AFd exceeds the rich side threshold value (AFs-εR), the actual oxygen storage amount at the time of starting the calculation is is larger than 0, the oxygen storage amount Os at time t2 is calculated using the oxygen storage amount Os at the start of the calculation as 0, and the absolute value of the oxygen storage amount Os at time t2 is calculated. |Ost| and the absolute value |Ods| of the oxygen desorption amount Ods at time t3 calculated in the next rich correction are not equal. When the stoichiometric learning value AFdst is updated using the set of the oxygen storage amount Ost and the oxygen desorption amount Ods calculated in this way, the stoichiometric learning value AFdst cannot be updated to an appropriate value, and the learning error in deviation amount related learning becomes large. turn into. In the embodiment, the operation is performed until a set of properly calculated oxygen storage amount Ost and oxygen desorption amount Ods is completed, that is, until 1.5 cycles of sub-feedback have elapsed from the time when the abnormality diagnosis of the engine 22 is completed. During a predetermined period (times t1 to t4 in FIG. 8), execution of deviation amount related learning is prohibited and the stoichiometric learning value AFdst and sub-offset amounts εR and εL are not updated. After that, execution of the deviation amount related learning is permitted, and the stoichiometric learning value AFdst and the sub-offset amounts εR and εL are updated (time t4). Thereby, learning errors in deviation amount related learning can be suppressed. In this way, by prohibiting execution of deviation amount related learning during a predetermined period and permitting execution of deviation amount related learning after the predetermined period, learning errors in deviation amount related learning can be suppressed.

According to the hybrid vehicle 20 equipped with the internal combustion engine control device of the embodiment described above, the deviation amount is Since execution of association learning is prohibited, learning errors in deviation amount association learning can be suppressed.

In the hybrid vehicle 20 equipped with the internal combustion engine control device of the embodiment, the deviation amount related learning is executed during a predetermined period from when the abnormality diagnosis is completed until 1.5 cycles of sub-feedback correction have elapsed. It is prohibited. However, execution of deviation amount related learning may be prohibited for a period longer than 1.5 cycles of sub-feedback correction after the abnormality diagnosis is completed.

In the hybrid vehicle 20 equipped with the internal combustion engine control device of the embodiment, execution of deviation amount related learning is prohibited when abnormality diagnosis is completed. However, when the calculation of the oxygen storage amount Ost is started with the detected air-fuel ratio AFd exceeding the rich side threshold (AFs-εR), or when the detected air-fuel ratio AFd is less than the lean side threshold (AFs+εL), Since it is sufficient to prohibit the execution of the deviation amount related learning when the calculation of the oxygen desorption amount Ods is started, for example, from control that is different from sub-feedback correction and in which deviation amount related learning is not executed, When switching control to sub-feedback correction, execution of deviation amount related learning may be prohibited.

In the embodiment, a control device for an internal combustion engine is installed in a hybrid vehicle 20 that includes an engine 22, a planetary gear 30, and motors MG1 and MG2. However, it may also be in the form of a control device for an internal combustion engine mounted on a so-called one-motor hybrid vehicle that includes an internal combustion engine and one motor. Furthermore, the present invention may be in the form of a control device for an internal combustion engine installed in a vehicle that runs using only power from the internal combustion engine. Furthermore, it may be in the form of a control device for an internal combustion engine installed in equipment other than automobiles, such as construction equipment.

The correspondence between the main elements of the embodiments and the main elements of the invention described in the column of means for solving the problems will be explained. In the embodiment, the engine 22 corresponds to an "internal combustion engine", the purification catalyst 136a corresponds to a "purification catalyst", the downstream air-fuel ratio sensor 154 corresponds to an "exhaust sensor", and the engine ECU 24 corresponds to an "internal combustion engine control". This corresponds to "equipment".

The correspondence relationship between the main elements of the examples and the main elements of the invention described in the column of means for solving the problem is that the example implements the invention described in the column of means for solving the problem. Since this is an example for specifically explaining a form for solving the problem, it is not intended to limit the elements of the invention described in the column of means for solving the problems. In other words, the interpretation of the invention described in the column of means for solving the problem should be based on the description in that column, and the examples are based on the description of the invention described in the column of means for solving the problem. This is just one specific example.

Although the embodiments of the present invention have been described above using examples, the present invention is not limited to these examples in any way, and may be modified in various forms without departing from the gist of the present invention. Of course, it can be implemented.

INDUSTRIAL APPLICATION This invention can be utilized for the manufacturing industry of the control device of an internal combustion engine, etc.

20 hybrid vehicle, 22 engine, 24 engine ECU, 26 crankshaft, 28 damper, 30 planetary gear, 36 drive shaft, 38 differential gear, 39a, 39b drive wheel, 40 motor ECU, 41, 42 inverter, 43, 44 rotational position sensor , 50 battery, 51a voltage sensor, 51b current sensor, 51c temperature sensor, 52 battery ECU, 54 power line, 70 HVECU, 80 ignition switch, 81 shift lever, 82 shift position sensor, 83 accelerator pedal, 84 accelerator pedal position sensor, 85 brake pedal, 86 brake pedal position sensor, 88 vehicle speed sensor, 90 base injection amount setting section, 91 main feedback section, 92 sub feedback section, 93 target injection amount setting section, 94 injection valve control section, 95 deviation amount related learning section , 96 oxygen storage amount estimation section, 98 learning permission section, 122 air cleaner, 123 intake pipe, 124 throttle valve, 124a throttle valve position sensor, 124b throttle motor, 125 surge tank, 126 fuel injection valve, 128 intake valve, 129 combustion chamber , 130 spark plug, 132 piston, 133 exhaust valve, 134 exhaust pipe, 136, 138 purification device, 136a, 138a purification catalyst, 140 crank position sensor, 142 water temperature sensor, 144 cam position sensor, 148 air flow meter, 149 temperature sensor, 150 pressure sensor, 152 upstream air-fuel ratio sensor, 154 downstream air-fuel ratio sensor, MG1, MG2 motor.

Claims (1)

an internal combustion engine having a fuel injection valve;
a purification catalyst that is attached to the exhaust system of the internal combustion engine and is capable of storing oxygen;
an exhaust sensor installed downstream of the purification catalyst in the exhaust system;
used in internal combustion engine devices equipped with
When operating the internal combustion engine, if the detected air-fuel ratio detected by the exhaust sensor reaches a rich side threshold value or less while rich correction is being performed on the fuel injection amount of the fuel injection valve, lean correction is performed on the fuel injection amount. When the detected air-fuel ratio reaches a lean-side threshold value or more during execution of the lean correction, performing correction control to switch to the execution of the rich correction;
The amount of oxygen stored as the amount of oxygen stored in the purification catalyst during the lean correction is calculated, and the amount of oxygen desorbed as the amount of oxygen released from the purification catalyst during the rich correction is calculated. A control device for an internal combustion engine that executes deviation amount related learning for updating a deviation amount related learning value regarding the deviation amount of the detected air-fuel ratio using the difference between the oxygen storage amount and the oxygen desorption amount,
When the calculation of the oxygen storage amount is started in a state where the detected air-fuel ratio exceeds the rich-side threshold value, or when the calculation of the oxygen desorption amount is started in a state where the detected air-fuel ratio is less than the lean-side threshold value. A control device for an internal combustion engine, wherein execution of the deviation amount related learning is prohibited at a predetermined time when it is started.

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