JP7655166B2 - Engine equipment - Google Patents

Description

The present invention relates to an engine device.

Conventionally, as an engine device of this type, a device has been proposed that performs air-fuel ratio learning by determining a steady-state deviation from the progress of the air-fuel ratio deviation in air-fuel ratio feedback control based on the air-fuel ratio deviation from the target air-fuel ratio of the engine, and storing the steady-state deviation as a learning value (see, for example, Patent Document 1).

WO 2004/094800

In an engine device that updates the learning value based on the feedback value in air-fuel ratio feedback control as air-fuel ratio learning when the learning conditions are met, depending on the combination of the sign of the feedback value when the learning conditions are met and the sign of the air-fuel ratio deviation (the magnitude relationship between the air-fuel ratio and the target air-fuel ratio), the learning value may be erroneously learned, resulting in a larger air-fuel ratio deviation.

The main purpose of the engine device of the present invention is to prevent erroneous learning of the air-fuel ratio learning value.

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

The engine device of the present invention comprises:
an engine having a fuel injection valve;
a control device that controls the fuel injector by setting a target injection amount based on a base injection amount which is based on a load factor of the engine, a first correction value which is based on a feedback value by feedback control for canceling a difference between an air-fuel ratio of the engine and a target air-fuel ratio, and a second correction value which is based on a learned value by air-fuel ratio learning, and that updates the learned value based on the feedback value as the air-fuel ratio learning when a learning condition is established;
An engine device comprising:
the learning conditions include a condition in which the feedback value is equal to or greater than a value of 0 and an air-fuel ratio-related value related to the air-fuel ratio is equal to or greater than a target air-fuel ratio-related value related to the target air-fuel ratio, and a condition in which the feedback value is less than a value of 0 and the air-fuel ratio-related value is less than the target air-fuel ratio-related value.
The gist of the present invention is as follows.

In the engine device of the present invention, the target injection amount is set based on a base injection amount based on the load factor of the engine, a first correction value based on a feedback value for canceling the difference between the engine's air-fuel ratio and the target air-fuel ratio, and a second correction value based on a learning value obtained by air-fuel ratio learning, and the fuel injection valve is controlled by setting the target injection amount based on the feedback value as air-fuel ratio learning when the learning condition is satisfied. The learning condition includes a condition in which the feedback value is equal to or greater than 0 and the air-fuel ratio related value associated with the air-fuel ratio is equal to or greater than the target air-fuel ratio related value associated with the target air-fuel ratio, and a condition in which the feedback value is less than 0 and the air-fuel ratio related value is less than the target air-fuel ratio related value. Therefore, when the feedback value is equal to or greater than 0 and the air-fuel ratio related value is less than the target air-fuel ratio related value, or when the feedback value is less than 0 and the air-fuel ratio related value is equal to or greater than the target air-fuel ratio related value, the learning condition is not satisfied and the learning value is not updated, so that erroneous learning of the learning value of the air-fuel ratio learning can be suppressed. Here, the "first correction value" is obtained by adding a value of 1 to the feedback value, the "second correction value" is obtained by adding a value of 1 to the learning value, and the "target injection amount" may be obtained by multiplying the basic injection amount by the first correction value and the second correction value.

In the engine device of the present invention, the air-fuel ratio related value may be a slowly changing value obtained by applying a slow change process to the air-fuel ratio. In this way, the slowly changing value is compared with the target air-fuel ratio related value, so that when the air-fuel ratio is disturbed by noise or the like, it is possible to suppress the learning condition from being erroneously established and to suppress erroneous learning of the air-fuel ratio, compared to the case where the air-fuel ratio is compared with the target air-fuel ratio related value.

In the engine device of the present invention, the target air-fuel ratio related value may be a compensation value obtained by applying response delay compensation to the target air-fuel ratio or a value related to the compensation value. In this way, the time lag between the air-fuel ratio related value and the target air-fuel ratio related value can be suppressed, and the two can be compared more appropriately. In this case, the target air-fuel ratio related value may be a value offset to the rich side with respect to the compensation value when the feedback value is greater than a value of 0, and a value offset to the lean side with respect to the compensation value when the feedback value is less than a value of 0. In this way, when the air-fuel ratio related value fluctuates around the compensation value (becoming larger or smaller than the compensation value), the learning condition can be more easily established. This can suppress a decrease in opportunities to learn the learning value.

In the engine device of the present invention, the target air-fuel ratio related value may be a value offset to the rich side of the target air-fuel ratio when the feedback value is greater than a value of 0, and may be a value offset to the lean side of the target air-fuel ratio when the feedback value is less than a value of 0. In this way, when the air-fuel ratio related value is fluctuating near the target air-fuel ratio related value (becoming larger or smaller than the target air-fuel ratio related value), the learning condition can be more easily established. This can prevent a decrease in opportunities to learn the learning value.

1 is a schematic diagram showing the configuration of an automobile 10 equipped with an engine device 11 according to an embodiment of the present invention. 4 is a flowchart showing an example of a fuel injection control routine executed by an electronic control unit 70. 4 is a flowchart showing an example of an air-fuel ratio learning routine executed by an electronic control unit 70. 4 is a time chart showing an example of the load factor KL of the engine 12, the front air-fuel ratio AF1, the feedback value AFfb, and the learning value AFln. 4 is a flowchart showing an example of an air-fuel ratio learning routine executed by an electronic control unit 70. 4 is a flowchart showing an example of an air-fuel ratio learning routine executed by an electronic control unit 70. 4 is a flowchart showing an example of an air-fuel ratio learning routine executed by an electronic control unit 70.

Next, we will explain how to implement the present invention using examples.

Figure 1 is a schematic diagram showing the configuration of an automobile 10 equipped with an engine device 11 as one embodiment of the present invention. As shown in the figure, the automobile 10 of the embodiment is equipped with an engine 12, a starter (not shown) for cranking the engine 12, a transmission TM that changes the speed of the power from the engine 12 and transmits it to a drive shaft DS connected to the drive wheels DW via a differential gear DF, and an electronic control unit 70 as a control device that controls the engine 12, the starter, and the transmission TM. The engine device 11 of the embodiment mainly corresponds to the engine 12 and the electronic control unit 70.

The engine 12 is configured as an internal combustion engine that uses, for example, gasoline or diesel as fuel and outputs power through four strokes: intake, compression, expansion (explosive combustion), and exhaust. The engine 12 has an in-cylinder injection valve 26 that injects fuel into the cylinder, and an ignition plug 30. The engine 12 draws air cleaned by the air cleaner 22 into the intake pipe 23, passes it through the throttle valve 24, and then draws it into the combustion chamber 29 through the intake valve 28. In addition, fuel is injected from the in-cylinder injection valve 26 during the intake stroke and compression stroke, and explosive combustion is caused by an electric spark from the ignition plug 30. The reciprocating motion of the piston 32, which is pushed down by the energy of the explosive combustion, is converted into the rotational motion of the crankshaft 14. The exhaust gas discharged from the combustion chamber 29 to the exhaust pipe 34 through the exhaust valve 33 is discharged to the outside air through the purification device 35. The purification device 35 has a purification catalyst (three-way catalyst) 35a that purifies harmful components such as carbon monoxide (CO), hydrocarbons (HC), and nitrogen oxides (NOx).

The electronic control unit 70 includes a microcomputer having a CPU 71, a ROM 72, a RAM 73, a flash memory 74, and input/output ports. Signals from various sensors are input to the electronic control unit 70 via the input ports. Examples of signals input to the electronic control unit 70 include the crank angle θcr from the crank position sensor 14a that detects the rotational position of the crankshaft 14 of the engine 12, and the cooling water temperature Tw from the water temperature sensor 15 that detects the temperature of the cooling water of the engine 12. Cam angles θci and θco from the cam position sensor 16 that detects the rotational position of the intake camshaft that opens and closes the intake valve 28 and the rotational position of the exhaust camshaft that opens and closes the exhaust valve 33 can also be mentioned. Examples of the information include the throttle opening TH from the throttle position sensor 24a that detects the position (opening) of the throttle valve 24, the intake air amount Qa from the air flow meter 23a that is attached upstream of the throttle valve 24 of the intake pipe 23, and the intake air temperature Ta from the temperature sensor 23t that is attached upstream of the throttle valve 24 of the intake pipe 23. Examples of the information include the front air-fuel ratio AF1 from the front air-fuel ratio sensor 37 that is attached upstream of the purification device 35 of the exhaust pipe 34, and the rear air-fuel ratio AF2 from the rear air-fuel ratio sensor 38 that is attached downstream of the purification device 35 of the exhaust pipe 34. Examples of the information include the rotation speed of the input shaft of the transmission TM from a rotation speed sensor attached to the input shaft of the transmission TM, and the rotation speed of the output shaft of the transmission TM from a rotation speed sensor attached to the output shaft of the transmission TM. Examples of the information include the ignition signal IG from the ignition switch 80, and the shift position SP from the shift position sensor 82 that detects the operation position of the shift lever 81. Other examples include the accelerator opening Acc from an accelerator pedal position sensor 84 that detects the amount of depression of an accelerator pedal 83, a brake pedal position BP from a brake pedal position sensor 86 that detects the amount of depression of a brake pedal 85, and a vehicle speed V from a vehicle speed sensor 87.

Various control signals are output from the electronic control unit 70 via the output port. Examples of signals output from the electronic control unit 70 include a control signal to the throttle valve 24 of the engine 12, a control signal to the in-cylinder injection valve 26, and a control signal to the spark plug 30. Other examples include a control signal to a starter (not shown) and a control signal to the transmission TM.

The electronic control unit 70 calculates the rotation speed Ne of the engine 12 based on the crank angle θcr from the crank position sensor 14a. The electronic control unit 70 also calculates the load factor KL of the engine 12 (the ratio of the volume of air actually taken in one cycle to the stroke volume per cycle of the engine 12) based on the intake air amount Qa from the air flow meter 23a and the rotation speed Ne of the engine 12. Furthermore, the electronic control unit 70 estimates the temperature Tc of the purification catalyst 35a of the purification device 35 based on the cooling water temperature Tw from the water temperature sensor 15, the rotation speed Ne of the engine 12, and the load factor KL.

In the automobile 10 of the embodiment thus configured, the electronic control unit 70 sets the target gear Gs* of the transmission TM based on the accelerator opening Acc and the vehicle speed V, and controls the transmission TM so that the gear Gs of the transmission TM becomes the target gear Gs*. In addition, the electronic control unit 70 sets the target torque Te* of the engine 12 based on the accelerator opening Acc, the vehicle speed V, and the gear Gs of the transmission TM, and performs intake air amount control, fuel injection control, ignition control, etc. of the engine 12 so that the engine 12 is operated based on the target torque Te*.

In intake air volume control, the electronic control unit 70 sets a target air volume Qa* based on the target torque Te* of the engine 12, sets a target opening TH* of the throttle valve 24 so that the intake air volume Qa becomes the target air volume Qa*, and controls the throttle valve 24 using the set target opening TH*. Fuel injection control will be described later. In ignition control, the electronic control unit 70 sets a target ignition timing Ti* of the spark plug 30 based on the engine speed Ne and load factor KL of the engine 12, and controls the spark plug 30 using the set target ignition timing Ti*.

The fuel injection control will be described. FIG. 2 is a flowchart showing an example of a fuel injection control routine executed by the electronic control unit 70. This routine is executed repeatedly. When this routine is executed, the electronic control unit 70 first inputs data such as the load rate KL of the engine 12, the front air-fuel ratio AF1, the rear air-fuel ratio AF2, and the learning value AFln of the air-fuel ratio learning (step S100). Here, the load rate KL is input with a value calculated based on the intake air amount Qa from the air flow meter 23a and the rotation speed Ne based on the crank angle θcr from the crank position sensor 14a. The front air-fuel ratio AF1 is input with a value detected by the front air-fuel ratio sensor 37. The rear air-fuel ratio AF2 is input with a value detected by the rear air-fuel ratio sensor 38. The learning value AFln of the air-fuel ratio learning is input with a value set by the air-fuel ratio learning routine described later.

When the data is input in this manner, the rich side value AFra or the lean side value AFla is set to the target air-fuel ratio AF1* based on the rear air-fuel ratio AF2 from the rear air-fuel ratio sensor 38 (step S110). In this process, when the value AFra is set to the target air-fuel ratio AF1*, if the rear air-fuel ratio AF2 is smaller than the theoretical air-fuel ratio AFth and larger than the rich side threshold value AFrb that is equal to or larger than the value AFra, the target air-fuel ratio AF1* is held at the value AFra, and when the rear air-fuel ratio AF2 reaches the rich side threshold value AFrb or less, the target air-fuel ratio AF1* is changed from the value AFra to the value AFla. In addition, when the target air-fuel ratio AF1* is set to the value AFla, if the rear air-fuel ratio AF2 is greater than the theoretical air-fuel ratio Afth and less than the lean side threshold value AFlb, which is equal to or less than the value AFla, the target air-fuel ratio AF1* is maintained at the value AFla, and when the rear air-fuel ratio AF2 reaches or exceeds the lean side threshold value AFlb, the target air-fuel ratio AF1* is changed from the value AFla to the value AFra.

Next, a base injection amount Qfbs is calculated as a base value of the target injection amount Qf* of the in-cylinder injection valve 26 based on the load rate KL (step S120). Here, the base injection amount Qfbs can be calculated as the product of the unit injection amount Qfpu (injection amount per 1% of the load rate KL) of the in-cylinder injection valve 26 and the load rate KL.

Then, a feedback value AFfb is calculated by air-fuel ratio feedback control to cancel the difference between the front air-fuel ratio AF1 and the target air-fuel ratio AF1* (step S130), and a value of 1 is added to the calculated feedback value AFfb to calculate a feedback correction coefficient Kfb (step S140). Here, the feedback value AFfb can be calculated using the front air-fuel ratio AF1, the target air-fuel ratio AF1*, the proportional term gain kp, and the integral term gain ki, as shown in equation (1).

AFfb＝kp・(AF1−AF1*)＋ki・∫(AF1−AF1*)dt (1)

Furthermore, the learning correction coefficient Kln is calculated by adding a value of 1 to the learning value AFln of the air-fuel ratio learning (step S150), the base injection amount Qfbs is multiplied by the feedback correction coefficient Kfb and the learning correction coefficient Kln to calculate the target injection amount Qf* (step S160), and the in-cylinder injection valve 26 is controlled using the calculated target injection amount Qf* (step S170), and this routine ends.

Next, the process for setting the learning correction coefficient Kln used in the fuel injection control routine of FIG. 2 will be described. FIG. 3 is a flowchart showing an example of an air-fuel ratio learning routine executed by the electronic control unit 70. This routine is repeatedly executed in parallel with the fuel injection control routine of FIG. 2.

When the air-fuel ratio learning routine of FIG. 3 is executed, the electronic control unit 70 first inputs data such as the front air-fuel ratio AF1, the target air-fuel ratio AF1*, the feedback value AFfb, and the learning prerequisite flag F (step S200). Here, the value detected by the front air-fuel ratio sensor 37 is input as the front air-fuel ratio AF1. The target air-fuel ratio AF1* and the feedback value AFfb are input with values set by the fuel injection control routine of FIG. 2. The learning prerequisite flag F is input with a value set by a learning prerequisite flag setting routine (not shown). In the learning prerequisite flag setting routine, the electronic control unit 70 sets the learning prerequisite flag F to a value of 1 when the learning prerequisite for air-fuel ratio learning is satisfied, and sets the learning prerequisite flag F to a value of 0 when the learning prerequisite is not satisfied. As the learning prerequisite, for example, a condition that a predetermined period has passed since the previous air-fuel ratio learning, i.e., since the learning value AFln was learned (updated), or a condition that the front air-fuel ratio AF1 is stable (converged within a predetermined range) can be used.

Once the data has been input in this manner, the value of the learning precondition flag F is checked (step S210). If the learning precondition flag F is equal to 0, i.e., if the learning preconditions for air-fuel ratio learning are not met, air-fuel ratio learning is not performed, the learning value AFln is held at the previous value (step S270), and this routine ends.

When the learning precondition flag F is set to a value of 1 in step S210, that is, when the learning precondition for the learning value is satisfied, it is determined whether the feedback value AFfb is equal to or greater than a value of 0 (step S220). Then, when it is determined that the feedback value AFfb is equal to or greater than a value of 0, it is determined whether the front air-fuel ratio AF1 is equal to or greater than the target air-fuel ratio AF1* (step S230). On the other hand, when it is determined that the feedback value AFfb is less than a value of 0, it is determined whether the front air-fuel ratio AF1 is less than the target air-fuel ratio AF1* (step S240). Here, the process of step S220 is a process of determining whether the feedback correction coefficient Kfb (=AFfb+1) used in the calculation of the target injection amount Qf* (see step S150) is equal to or greater than a value of 1. The process of step S230 is a process of determining whether the front air-fuel ratio AF1 is the same as or leaner than the target air-fuel ratio AF1*. The process of step S240 is a process to determine whether the front air-fuel ratio AF1 is rich relative to the target air-fuel ratio AF1*. The processes of steps S220 to S240 are a process to determine whether the learning conditions for the air-fuel ratio learning are met.

When it is determined in step S220 that the feedback value AFfb is equal to or greater than 0, and it is determined in step S230 that the front air-fuel ratio AF1 is equal to or greater than the target air-fuel ratio AF1*, it is determined that the learning conditions for the air-fuel ratio learning are satisfied (step S260), the learning value AFln is updated as the air-fuel ratio learning (step S280), and this routine is terminated. Here, the learning value AFln can be updated, for example, by adding the product of the feedback value AFfb and the reflection coefficient γ to the previous learning value (previous AFln) as shown in equation (2) to calculate the learning value AFln. The reflection coefficient γ may be set to a value of 1, or a positive value less than 1. In this manner, the learning value AFln can be learned (updated).

AFln = previous AFln + AFfb γ (2)

If it is determined in step S220 that the feedback value AFfb is equal to or greater than 0, and it is determined in step S230 that the front air-fuel ratio AF1 is less than the target air-fuel ratio AF1*, it is determined that the learning conditions for air-fuel ratio learning are not met (step S250), and the learning value AFln is held at the previous value without performing air-fuel ratio learning (step S270), and this routine ends.

When the feedback value AFfb is equal to or greater than 0 and the front air-fuel ratio AF1 is less than the target air-fuel ratio AF1*, if the learning value AFln is updated using the above formula (2), the learning value AFln may be erroneously learned, resulting in the following inconvenience. Even though the front air-fuel ratio AF1 is richer than the target air-fuel ratio AF1*, the learning value AFln and thus the learning correction coefficient Kln may be updated to be larger, increasing the target injection amount Qf* (see step S150), and the deviation of the front air-fuel ratio AF1 from the target air-fuel ratio AF1* may increase (become richer than the target air-fuel ratio AF1*). In contrast, in the embodiment, the learning value AFln is held without performing air-fuel ratio learning at this time, thereby suppressing erroneous learning of the learning value AFln and suppressing the deviation of the front air-fuel ratio AF1 from the target air-fuel ratio AF1* from increasing.

When it is determined in step S220 that the feedback value AFfb is less than 0, and it is determined in step S240 that the front air-fuel ratio AF1 is less than the target air-fuel ratio AF1*, it is determined that the learning conditions for air-fuel ratio learning are met (step S260), the learning value AFln is updated by the above-mentioned equation (2) as the air-fuel ratio learning (step S280), and this routine is terminated. In this manner, the learning value AFln can be learned (updated).

If it is determined in step S220 that the feedback value AFfb is less than 0, and it is determined in step S240 that the front air-fuel ratio AF1 is equal to or greater than the target air-fuel ratio AF1*, it is determined that the learning conditions for air-fuel ratio learning are not met (step S250), and the learning value AFln is held at the previous value without performing air-fuel ratio learning (step S270), and this routine ends.

When the feedback value AFfb is less than 0 and the front air-fuel ratio AF1 is equal to or greater than the target air-fuel ratio AF1*, if the learning value AFln is updated using the above formula (2), the learning value AFln may be erroneously learned, resulting in the following inconvenience. Even though the front air-fuel ratio AF1 is leaner than the target air-fuel ratio AF1*, the learning value AFln and thus the learning correction coefficient Kln may be updated to a smaller value, reducing the target injection amount Qf* (see step S150), and the deviation of the front air-fuel ratio AF1 from the target air-fuel ratio AF1* may increase (become leaner than the target air-fuel ratio AF1*). In contrast, in the embodiment, the learning value AFln is held without performing air-fuel ratio learning at this time, thereby suppressing erroneous learning of the learning value AFln and suppressing the deviation of the front air-fuel ratio AF1 from the target air-fuel ratio AF1* from increasing.

Figure 4 is a time chart showing an example of the load factor KL of the engine 12, the front air-fuel ratio AF1, the feedback value AFfb, and the learning value AFln. In the figure, for the front air-fuel ratio AF1, the feedback value AFfb, and the learning value AFln, the solid lines show the state of the embodiment, and the dashed lines show the state of the comparative example. In the comparative example, when the learning preconditions for air-fuel ratio learning are met, the learning value AFln is learned regardless of whether the learning conditions of the embodiment are met or not. In other words, when the learning precondition flag F is set to a value of 1 in step S210, the processing of steps S220 to S260 is not executed, and the learning value AFln is updated in step S280.

In the comparative example, as shown by the dashed line in FIG. 4, when the learning preconditions are met at time t11, even if the feedback value AFfb is less than 0 and the front air-fuel ratio AF1 is equal to or greater than the target air-fuel ratio AF1*, the learning value AFln is updated as the air-fuel ratio learning. Therefore, the front air-fuel ratio AF1 becomes leaner than the target air-fuel ratio AF1*, and the feedback value AFfb is also disturbed. In contrast, in the embodiment, as shown by the solid line in FIG. 4, even if the learning preconditions are met at time t11, the feedback value AFfb is less than 0 and the front air-fuel ratio AF1 is equal to or greater than the target air-fuel ratio AF1*, so it is determined that the learning conditions are not met, and the learning value AFln is held without performing air-fuel ratio learning. This suppresses erroneous learning of the learning value AFln, suppresses the front air-fuel ratio AF1 from becoming leaner than the target air-fuel ratio AF1*, and suppresses disturbance of the feedback value AFfb.

In the engine device 11 provided in the automobile 10 of the embodiment described above, when the learning prerequisites for air-fuel ratio learning are satisfied, if the feedback value AFfb is equal to or greater than 0 and the front air-fuel ratio AF1 is equal to or greater than the target air-fuel ratio AF1*, or if the feedback value AFfb is less than 0 and the front air-fuel ratio AF1 is less than the target air-fuel ratio AF1*, it is determined that the learning conditions for air-fuel ratio learning are satisfied, and the learning value AFln is learned (updated) as air-fuel ratio learning. On the other hand, if the feedback value AFfb is equal to or greater than 0 and the front air-fuel ratio AF1 is less than the target air-fuel ratio AF1*, or if the feedback value AFfb is less than 0 and the front air-fuel ratio AF1 is equal to or greater than the target air-fuel ratio AF1*, it is determined that the learning conditions for air-fuel ratio learning are not satisfied, and the learning value AFln is held without performing air-fuel ratio learning. This makes it possible to suppress erroneous learning of the learning value AFln.

In the engine device 11 of the embodiment, the electronic control unit 70 executes the air-fuel ratio learning routine of FIG. 3. However, instead of this, the electronic control unit 70 may execute the air-fuel ratio learning routine of FIG. 5, FIG. 6, or FIG. 7. These will be explained in order below.

The air-fuel ratio learning routine of FIG. 5 will be described. This routine differs from the air-fuel ratio learning routine of FIG. 3 in that the processing of step S202 has been added and the processing of steps S230 and S240 have been replaced with the processing of steps S232 and S242. In the air-fuel ratio learning routine of FIG. 5, when data is input in step S200, the electronic control unit 70 performs slow change processing such as smoothing processing and rate processing on the front air-fuel ratio AF1 to calculate the front air-fuel ratio slow change value AF1s (step S202).

If it is determined in step S220 that the feedback value AFfb is equal to or greater than 0, it is determined whether the front air-fuel ratio slow change value AF1s is equal to or greater than the target air-fuel ratio AF1* (step S232). On the other hand, if it is determined that the feedback value AFfb is less than 0, it is determined whether the front air-fuel ratio slow change value AF1s is less than the target air-fuel ratio AF1* (step S242).

When it is determined in step S232 that the front air-fuel ratio slow change value AF1s is equal to or greater than the target air-fuel ratio AF1*, or when it is determined in step S242 that the front air-fuel ratio slow change value AF1s is less than the target air-fuel ratio AF1*, it is determined that the learning conditions for the air-fuel ratio learning are satisfied (step S260), the learning value AFln is learned (updated) as the air-fuel ratio learning (step S280), and this routine is terminated. On the other hand, when it is determined in step S232 that the front air-fuel ratio slow change value AF1s is less than the target air-fuel ratio AF1*, or when it is determined in step S242 that the front air-fuel ratio slow change value AF1s is equal to or greater than the target air-fuel ratio AF1*, it is determined that the learning conditions for the air-fuel ratio learning are not satisfied (step S250), the learning value AFln is held without performing air-fuel ratio learning (step S270), and this routine is terminated. By comparing the front air-fuel ratio slow change value AF1s with the target air-fuel ratio AF1* instead of comparing the front air-fuel ratio AF1 with the target air-fuel ratio AF1*, it is possible to prevent the learning conditions from being erroneously established and to prevent the learning value AFln from being erroneously learned when the front air-fuel ratio AF1 is disturbed by noise or the like.

The air-fuel ratio learning routine of FIG. 6 will be described. This routine differs from the air-fuel ratio learning routine of FIG. 3 in that the processing of step S204 has been added and the processing of steps S230 and S240 has been replaced with the processing of steps S234 and S244. In the air-fuel ratio learning routine of FIG. 6, when the electronic control unit 70 inputs data in step S200, it applies response delay compensation of the engine 12 to the target air-fuel ratio AF1* to calculate the target air-fuel ratio compensation value AF1c* (step S204). Here, the response delay compensation is compensation for the dead time and first-order delay of the engine 12. The response delay compensation for the target air-fuel ratio AF1* can be performed, for example, taking into consideration the time required for the effect of changing the target air-fuel ratio AF1* to appear in the front air-fuel ratio AF1.

If it is determined in step S220 that the feedback value AFfb is equal to or greater than 0, it is determined whether the front air-fuel ratio AF1 is equal to or greater than the target air-fuel ratio compensation value AF1c* (step S234). On the other hand, if it is determined that the feedback value AFfb is less than 0, it is determined whether the front air-fuel ratio AF1 is less than the target air-fuel ratio compensation value AF1c* (step S244).

When it is determined in step S234 that the front air-fuel ratio AF1 is equal to or greater than the target air-fuel ratio compensation value AF1c*, or when it is determined in step S244 that the front air-fuel ratio AF1 is less than the target air-fuel ratio compensation value AF1c*, it is determined that the learning conditions for the air-fuel ratio learning are satisfied (step S260), the learning value AFln is learned (updated) as the air-fuel ratio learning (step S280), and this routine is terminated. On the other hand, when it is determined in step S234 that the front air-fuel ratio AF1 is less than the target air-fuel ratio compensation value AF1c*, or when it is determined in step S244 that the front air-fuel ratio AF1 is equal to or greater than the target air-fuel ratio compensation value AF1c*, it is determined that the learning conditions for the air-fuel ratio learning are not satisfied (step S250), the learning value AFln is held without performing the air-fuel ratio learning (step S270), and this routine is terminated. Instead of comparing the front air-fuel ratio AF1 with the target air-fuel ratio AF1*, the front air-fuel ratio AF1 is compared with the target air-fuel ratio compensation value AF1c*, which reduces the time lag between the two and allows for a more appropriate comparison between the two.

In the air-fuel ratio learning routine of FIG. 6, the front air-fuel ratio AF1 is compared with the target air-fuel ratio compensation value AF1c*. However, instead of this, the front air-fuel ratio slow change value AF1s described above may be compared with the target air-fuel ratio compensation value AF1c*.

The air-fuel ratio learning routine of FIG. 7 will be described. This routine differs from the air-fuel ratio learning routine of FIG. 3 in that the processes of steps S222 and S224 have been added and the processes of steps S230 and S240 have been replaced with the processes of steps S236 and S246. In the air-fuel ratio learning routine of FIG. 7, when the electronic control unit 70 determines in step S220 that the feedback value AFfb is equal to or greater than 0, it subtracts the offset value δ1 from the target air-fuel ratio AF1* to calculate the comparison value AF1ref (step S222), and determines whether the front air-fuel ratio AF1 is equal to or greater than the comparison value AF1ref (step S236). On the other hand, when it determines that the feedback value AFfb is less than 0, it adds the offset value δ2 to the target air-fuel ratio AF1* to calculate the comparison value AF1ref (step S224), and determines whether the front air-fuel ratio AF1 is less than the comparison value AF1ref (step S246). Here, the offset values δ1 and δ2 may be the same or different.

When it is determined in step S236 that the front air-fuel ratio AF1 is equal to or greater than the comparison value AF1ref, or when it is determined in step S246 that the front air-fuel ratio AF1 is less than the comparison value AF1ref, it is determined that the learning conditions for the air-fuel ratio learning are satisfied (step S260), the learning value AFln is learned (updated) as the air-fuel ratio learning (step S280), and this routine is terminated. On the other hand, when it is determined in step S236 that the front air-fuel ratio AF1 is less than the comparison value AF1ref, or when it is determined in step S246 that the front air-fuel ratio AF1 is equal to or greater than the comparison value AF1ref, it is determined that the learning conditions for the air-fuel ratio learning are not satisfied (step S250), the learning value AFln is held without performing the air-fuel ratio learning (step S270), and this routine is terminated. By comparing the front air-fuel ratio AF1 with a comparison value AF1ref instead of comparing the front air-fuel ratio AF1 with the target air-fuel ratio AF1*, it is possible to make it easier for the learning conditions to be met when the front air-fuel ratio AF1 is fluctuating around the target air-fuel ratio AF1* (becoming larger or smaller than the target air-fuel ratio AF1*). This makes it possible to prevent a decrease in the opportunities to learn the learning value AFln.

In the air-fuel ratio learning routine of FIG. 7, when the feedback value AFfb is equal to or greater than 0, the comparison value AF1ref is calculated by subtracting the offset value δ1 from the target air-fuel ratio AF1*, and when the feedback value AFfb is less than 0, the comparison value AF1ref is calculated by adding the offset value δ2 to the target air-fuel ratio AF1*. However, when the feedback value AFfb is equal to or greater than 0, the comparison value AF1ref may be calculated by subtracting the offset value δ1 from the target air-fuel ratio compensation value AF1c* described above, and when the feedback value AFfb is less than 0, the comparison value AF1ref may be calculated by adding the offset value δ2 to the target air-fuel ratio compensation value AF1c*.

In the air-fuel ratio learning routine of FIG. 7, the front air-fuel ratio AF1 is compared with the comparison value AF1ref. However, instead of this, the front air-fuel ratio slow change value AF1s described above may be compared with the comparison value AF1ref.

In the engine device 11 of the embodiment, the engine 12 is equipped with an in-cylinder injection valve 26 that injects fuel into the cylinder. However, in addition to or instead of this, the engine 12 may be equipped with a port injection valve that injects the same amount of fuel into the intake port.

In the embodiment, the engine device 11 is provided in an automobile 10 that is an engine vehicle that runs using power from an engine 12. However, the engine device may be provided in a hybrid vehicle that has a motor in addition to an engine.

The following explains the relationship between the main elements of the embodiment and the main elements of the invention described in the section on means for solving the problem. In the embodiment, the engine 12 corresponds to the "engine" and the electronic control unit 70 corresponds to the "control device."

The correspondence between the main elements of the Examples and the main elements of the invention described in the Means for Solving the Problem column does not limit the elements of the invention described in the Means for Solving the Problem column, since the Examples are examples for specifically explaining the form for implementing the invention described in the Means for Solving the Problem column. In other words, the interpretation of the invention described in the Means for Solving the Problem column should be based on the description in that column, and the Examples are merely a specific example of the invention described in the Means for Solving the Problem column.

The above describes the form for carrying out the present invention using examples, but the present invention is not limited to these examples in any way, and it goes without saying that the present invention can be carried out in various forms without departing from the scope of the invention.

The present invention can be used in the engine equipment manufacturing industry, etc.

10 automobile, 11 engine device, 12 engine, 14 crankshaft, 14a crank position sensor, 15 water temperature sensor, 16 cam position sensor, 22 air cleaner, 23 intake pipe, 23a air flow meter, 23t temperature sensor, 24 throttle valve, 24a throttle position sensor, 26 in-cylinder injection valve, 28 intake valve, 29 combustion chamber, 30 spark plug, 32 piston, 33 exhaust valve, 34 exhaust pipe, 35 purification device, 35a purification catalyst, 37 front air-fuel ratio sensor, 38 rear air-fuel ratio sensor, 70 electronic control unit, 71 CPU, 72 ROM, 73 RAM, 74 flash memory, 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, 87 vehicle speed sensor.

Claims (5)

an engine having a fuel injection valve;
a control device which controls the fuel injector by multiplying a base injection amount based on a load factor of the engine by a first correction value obtained by adding a value 1 to a feedback value in a feedback control for canceling a difference between an air-fuel ratio of the engine and a target air-fuel ratio, and by a second correction value obtained by adding a value 1 to a learned value in air-fuel ratio learning, and which adds a product of the feedback value and a reflection coefficient to the previous learned value as the air-fuel ratio learning to update the learned value when a learning condition is established;
An engine device comprising:
the learning condition includes at least one of a condition that the feedback value is equal to or greater than a value of 0 and an air-fuel ratio related value related to the air-fuel ratio is equal to or greater than a target air-fuel ratio related value related to the target air-fuel ratio, or a condition that the feedback value is less than a value of 0 and the air-fuel ratio related value is less than the target air-fuel ratio related value .
Engine equipment. 2. The engine device according to claim 1,
The air-fuel ratio related value is a slowly changing value obtained by performing a slowly changing process on the air-fuel ratio.
Engine equipment. 3. The engine device according to claim 1 or 2,
The target air-fuel ratio related value is a compensation value obtained by applying a response delay compensation to the target air-fuel ratio or a value related to the compensation value.
Engine equipment. 4. The engine device according to claim 3,
The target air-fuel ratio related value is
When the feedback value is greater than 0, the feedback value is a value offset to the rich side with respect to the compensation value,
When the feedback value is smaller than 0, the feedback value is a value offset to the lean side with respect to the compensation value.
Engine equipment. 3. The engine device according to claim 1 or 2,
The target air-fuel ratio related value is
When the feedback value is greater than 0, the feedback value is a value offset to the rich side with respect to the target air-fuel ratio,
When the feedback value is smaller than 0, the feedback value is a value offset to the lean side with respect to the target air-fuel ratio.
Engine equipment.

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