JP6932537B2 - Internal combustion engine control device - Google Patents

Description

The present invention relates to a control device for an internal combustion engine, and in particular, a fuel feedback learning process for adjusting a fuel feedback learning value referred to for air-fuel ratio control based on the fuel feedback value, and a fuel feedback learning process in a canister for an intake pipe. It relates to a control device that selectively executes a canister purge to be supplied.

An example of this type of device is disclosed in Patent Document 1. The technique of Patent Document 1 counts the number of times the air-fuel ratio learning value is updated, and executes purging when the number of times the learning value is updated is equal to or greater than a predetermined value, thereby achieving both air-fuel ratio learning control and canister purge control. Is to be.

Japanese Unexamined Patent Publication No. 6-101581

However, in Patent Document 1, since the air-fuel ratio learning control and the canister purge control are executed alternately, the canister purge is limited until a predetermined time elapses after the control to be executed is switched to the air-fuel ratio learning control. .. As a result, Patent Document 1 has a problem that a sufficient purge amount cannot be secured.

Therefore, a main object of the present invention is to provide a control device for an internal combustion engine capable of ensuring a sufficient purge amount while suppressing a deviation in the air-fuel ratio.

The control device according to the present invention includes a fuel feedback learning process that adjusts the fuel feedback learning value referred to for air-fuel ratio control based on the fuel feedback value, and a canister purge that supplies the evaporated fuel in the canister to the intake pipe. This is an internal combustion engine control device that selectively executes fuel feedback, and during fuel feedback learning processing, the fuel feedback value is within the numerical range assigned to the zone corresponding to the engine speed and intake pressure , and the fuel vapor It is a control device that stops the fuel feedback learning process and executes canister purge when the concentration is equal to or higher than the threshold value. Preferably, during the fuel feedback learning process, when the fuel feedback value is within a predetermined range and the concentration of the evaporated fuel is less than the threshold value, the fuel feedback learning process is continued without being stopped.

The fuel feedback learning process and the canister purge are selectively executed. When the fuel feedback value is within a predetermined range and the concentration of the evaporated fuel is equal to or higher than the threshold value, the fuel feedback learning control is interrupted and the canister purge is executed. , It is possible to secure a sufficient purge amount while suppressing the deviation of the air-fuel ratio.

The above-mentioned object, other object, feature and advantage of the present invention will be further clarified from the detailed description of the following examples made with reference to the drawings.

It is a block diagram which shows a part of the main part composition of the vehicle of this Example. It is a block diagram which shows the other part of the main part composition of the vehicle of this Example. It is a schematic diagram which shows an example of the map referred by the ECU shown in FIG. It is a schematic diagram which shows an example of the table referred by the ECU shown in FIG. It is a flow chart which shows a part of the operation of the ECU shown in FIG. It is a flow chart which shows the other part of the operation of the ECU shown in FIG. It is a flow chart which shows the other part of the operation of the ECU shown in FIG. It is a flow chart which shows the other part of the operation of the ECU shown in FIG. It is a flow chart which shows the other part of the operation of the ECU shown in FIG. It is a timing diagram which shows an example of the change of the evaporator concentration, the purge time counter, the purge valve opening degree, the fuel F / B learning time counter, the cooling water temperature, and the fuel F / B value.

With reference to FIGS. 1 and 2, the vehicle 10 of this embodiment includes a 4-stroke engine (internal combustion engine) 12 having three cylinders 141 to 143 as a power source. The intake pipe 32 branches into three at positions upstream of the cylinders 141 to 143. On the other hand, the exhaust pipes 36 are integrated from three to one at positions downstream of the cylinders 141 to 143. The combustion chambers 16 provided in each of the cylinders 141 to 143 communicate with the intake pipe 32 via the intake valve 18 and communicate with the exhaust pipe 36 via the exhaust valve 20.

A surge tank 44 for leveling the air flow rate is provided at the branch point of the intake pipe 32. An air cleaner 34 that separates dust from the atmosphere and a single throttle valve 38 whose opening degree is adjusted by a valve motor 42 are provided at a position upstream of the surge tank 44. Further, the surge tank 44 is provided with an intake pressure sensor 48. Further, a fuel injection device 40 assigned to each of the cylinders 141 to 143 for injecting fuel into the intake pipe 32 is provided at a position downstream of the surge tank 44.

On the other hand, a muffler 50 having an exhaust gas purification catalyst (hereinafter, simply referred to as "catalyst") 52 is provided at a position downstream of the aggregation point of the exhaust pipe 36. Further, the engine 12 is cooled by the cooling water circulating in the radiator hose (not shown). Here, the radiator hose is provided with a thermostat 56, and the temperature of the cooling water is detected by the thermostat 56.

When the IG on operation is performed by the ignition key (not shown), the ECU 64 turns on the relay 72 shown in FIG. 2 in order to start the engine 12. The power of the battery 74 is supplied to the starter 76 via the relay 72 in the on state, and the starter 76 executes cranking by the power of the battery 74. As a result, the engine 12 is started.

When the engine 12 starts, the ECU 64 adjusts the opening degree of the throttle valve 38 through the valve motor 42 so that the idle state is maintained. The amount of intake air that has passed through the air cleaner 34 is defined by the throttle valve 38, and the fuel injection amount of the fuel injection device 40 is adjusted so that an air-fuel mixture showing a stoichiometric air-fuel ratio is generated.

When the accelerator pedal (not shown) is depressed from this state, the ECU 64 drives the valve motor 42. The throttle valve 38 is opened by a valve motor 42, which increases the intake air amount and the fuel injection amount of the fuel injection device 40 while maintaining the stoichiometric air-fuel ratio.

The air-fuel mixture is supplied to the combustion chamber 16 when the intake valve 18 is opened. The supplied air-fuel mixture is ignited by the spark plug 30 just before the piston 22 coupled to the crankshaft 26 via the connecting rod 24 reaches top dead center. The piston 22 moves up and down due to the explosion of the air-fuel mixture, which causes the crankshaft 26 to rotate.

A flywheel 28 is attached to the crankshaft 26, and the fluctuation of the rotation speed of the crankshaft 26, that is, the rotation speed of the engine 12 is suppressed by the flywheel 28. Further, the rotation speed of the engine 12 is detected by the engine rotation sensor 46.

The rotational force of the crankshaft 26, that is, the power of the engine 12, is transmitted to the drive shaft (not shown) via the transmission 66 shown in FIG. As a result, the vehicle 10 moves forward or backward. The rotational force of the crankshaft 26 is also transmitted to the rotating shaft 70s of the alternator 70 via the belt 68. The rotational force of the rotating shaft 70s is converted into electric power, and the converted electric power is stored in the battery 74.

Returning to FIG. 1, the air, that is, the combustion gas after burning the air-fuel mixture is discharged from the combustion chamber 16 when the exhaust valve 20 is opened, and is supplied to the muffler 50 via the exhaust pipe 36. The catalyst 52 oxidizes and reduces carbon monoxide, hydrocarbons and nitrogen oxides contained in the combustion gas to produce water, carbon dioxide and nitrogen. The gas thus purified is discharged from the vehicle 10.

A front O2 sensor 54 is provided at a position on the upstream side of the catalyst 52 in the exhaust pipe 36. The ECU 64 adjusts the injection amount of the fuel injection device 40 based on the output of the front O2 sensor 54, that is, the fuel F / B value. Specifically, the ECU 64 adjusts the fuel F / B learning value based on the fuel F / B value under the fuel F / B learning process. The ECU 64 further adjusts the injection amount under the air-fuel ratio control process with reference to the fuel F / B value and the fuel F / B learning value. This produces an air-fuel mixture that exhibits a stoichiometric air-fuel ratio. In addition, "F / B" is synonymous with "feedback".

The charcoal canister 58 is connected to the surge tank 44 via a purge valve 62. The ECU 64 estimates the concentration of the evaporated fuel accumulated inside the charcoal canister 58, that is, the evaporative concentration, based on the output of the evaporative concentration sensor 60, and opens the purge valve 62 for a different time according to the estimated evaporative concentration. By such a canister purge, evaporated fuel is supplied from the charcoal canister 58 to the intake pipe 32.

When performing the fuel F / B learning process, the canister purge is restricted. Therefore, the longer the duration of the fuel F / B learning process, the insufficient the purge amount. Therefore, in this embodiment, the fuel F / B learning time counter 64t and the purge execution counter 64p, the map MP1 shown in FIG. 3 and the table TBL1 shown in FIG. 4 are prepared in the memory 64m, and the air-fuel ratio control shown in FIG. The processing, the fuel F / B value determination support processing shown in FIG. 6, the main control processing shown in FIGS. 7 to 8, and the fuel F / B learning processing shown in FIG. 9 are executed.

Here, the air-fuel ratio control process and the fuel F / B value determination support process are processes that are premised on the main control process, and are executed in parallel with the main control process. Further, the fuel F / B learning process is started / stopped by the main control process. The control program corresponding to the flow chart shown in FIGS. 5 to 9 is stored in the memory 64 m.

With reference to FIG. 3, the map MP1 has a horizontal axis and a vertical axis to which the engine speed and the intake pressure are assigned, respectively. Zones 1 to 15 are distributed in a matrix on the plane thus formed.

With reference to FIG. 4, the table TBL1 shows the numerical ranges assigned to zones 1 to 15, respectively. Specifically, the numerical range assigned to zone 1 indicates "K1 ± α", the numerical range assigned to zone 2 indicates "K2 ± α", and the numerical range assigned to zone 3 indicates "K3". Indicates ± α ”.

Similarly, the numerical range assigned to zone 14 indicates “K14 ± α” and the numerical range assigned to zone 15 indicates “K15 ± α”. That is, the numerical range assigned to the zone N (N: 1 to 15) has a width of "α" centered on the variable KN.

With reference to FIG. 5, in step S1, the output of the front O2 sensor 54, that is, the fuel F / B value is acquired, and in step S3, whether the air-fuel ratio is rich or lean is acquired based on the fuel F / B value. To determine. If it is determined that the air-fuel ratio is rich, the process proceeds to step S5, and the fuel injection amount is reduced with reference to the fuel F / B learning value. On the other hand, when it is determined that the air-fuel ratio is lean, the process proceeds to step S7, and the fuel injection amount is increased with reference to the fuel F / B learning value. When the process of step S5 or S7 is completed, the process returns to step S1.

With reference to FIG. 6, in step S11, the engine speed is detected through the engine speed sensor 46. In step S13, the intake pressure is detected through the intake pressure sensor 48. In step S15, the zone corresponding to the engine speed and the intake pressure thus detected is detected from the map MP1 shown in FIG. In step S17, the numerical range assigned to the detected zone is acquired from the table TBL1 shown in FIG. When the process of step S17 is completed, the process returns to step S11.

With reference to FIG. 7, in step S21, the temperature of the cooling water is detected through the thermostat 56, and it is determined whether or not the detected temperature is equal to or higher than the threshold value THt. If the determination result is NO, the process returns to step S21, and if the determination result is YES, the process proceeds to step S23.

In step S23, a predetermined time is set in the fuel F / B learning time counter 64t, and the countdown of the fuel F / B learning time counter 64t is started. In step S25, the fuel F / B learning process shown in FIG. 9 is started.

With reference to FIG. 9, in step S61, the average value of the fuel F / B values acquired in step S1 is calculated. In step S63, it is determined whether or not the latest fuel F / B value is equal to or higher than the calculated average value. If the determination result is YES, the process proceeds to step S65, and the fuel F / B learning value is reduced. On the other hand, if the discrimination result is NO, the process proceeds to step S67 to increase the fuel F / B learning value. When the process of step S65 or S67 is completed, the process returns to step S11.

Returning to FIG. 7, in step S27, it is determined whether or not the count value of the fuel F / B learning time counter 64t indicates “0”. Further, in step S29, it is determined whether or not the fuel F / B value is within the numerical range acquired in step S17. Further, in step S31, the evaporator concentration is estimated based on the output of the evaporator concentration sensor 60, and it is determined whether or not the estimated evaporator concentration is equal to or higher than the threshold value THc.

If the determination result in step S27 is NO and the determination result in step S29 or the determination result in step S31 is NO, the process returns to step S27. If the determination result in step S27 is YES, the process proceeds to step S35 as it is. Further, if the discrimination result in step S27 is NO and both the discrimination result in step S29 and the discrimination result in step S31 are YES, the countdown of the fuel F / B learning time counter 64t is stopped in step S33. The process proceeds to step S35.

In step S35, the fuel F / B learning process is stopped. In step S37, the evaporator concentration is estimated based on the output of the evaporator concentration sensor 60, and the initial value of the purge execution counter 64p is adjusted based on the estimated evaporator concentration.

In step S39, the adjusted initial value is set in the purge execution counter 64p, and the countdown of the purge execution counter 64p is started. In step S41, the purge valve 62 is opened to perform canister purging.

In step S43, as in step S29 , it is determined whether or not the fuel F / B value is within the numerical range acquired in step S17. Further, in step S45, it is determined whether or not the count value of the purge execution counter 64p indicates “0”.

If the determination result in step S43 is YES and the determination result in step S45 is NO, the process returns to step S43. If both the determination result in step S43 and the determination result in step S45 are YES, the process proceeds to step S47 , and the purge valve 62 is closed to interrupt the canister purge. When the process of step S47 is completed, the process returns to step S23.

Further, if the determination result in step S43 is NO, the count value of the purge execution counter 64p is set to "0" in step S49, and the purge valve 62 is closed in step S51. Further, in step S53, the countdown of the fuel F / B learning time counter 64t is restarted, and in step S55, the fuel F / B learning process is started. When the process of step S55 is completed, the process returns to step S27.

With reference to FIG. 10, the temperature of the cooling water reaches the threshold THt at time T1. Then, a predetermined value is set in the fuel F / B learning time counter 64t, and the countdown of the fuel F / B learning time counter 64t is started. The fuel F / B learning value is adjusted by the fuel F / B learning process that is started at the same time.

The count value of the fuel F / B learning time counter 64t indicates “0” at time T2. Then, the fuel F / B learning process is stopped, the initial value corresponding to the evaporator concentration is set in the purge execution counter 64p, and the countdown of the purge execution counter 64p is started.

The purge valve 62 is opened at the same time as the start of the countdown, whereby the evaporated fuel in the charcoal canister 58 is supplied to the intake pipe 32. When the count value of the purge execution counter 64p drops to "0", the purge valve 62 is closed.

When the purge valve 62 is closed, a predetermined value is set in the fuel F / B learning time counter 64t, and the countdown of the fuel F / B learning time counter 64t is started. However, the fuel F / B value falls within the numerical range at time T3. Further, the evaporative concentration at time T3 shows a value equal to or higher than the threshold value THc. Therefore, the countdown of the fuel F / B learning time counter 64t is stopped, and at the same time, the fuel F / B learning process is stopped.

An initial value corresponding to the evaporation concentration is set in the purge execution counter 64p, and the countdown of the purge execution counter 64p is started. The purge valve 62 is opened at the same time as the start of the countdown, whereby the evaporated fuel in the charcoal canister 58 is supplied to the intake pipe 32.

The fuel F / B value deviates from the predetermined range at time T4. Then, the purge execution counter 64p is set to “0” and the purge valve 62 is closed. Further, the countdown of the fuel F / B learning time counter 64t is restarted, and the fuel F / B learning process is started.

The count value of the fuel F / B learning time counter 64t indicates “0” at time T5. Then, the fuel F / B learning process is stopped, the initial value corresponding to the evaporator concentration is set in the purge execution counter 64p, and the countdown of the purge execution counter 64p is started.

As can be seen from the above description, the ECU 64 has a fuel F / B learning process that adjusts the fuel F / B learning value referred to for air-fuel ratio control based on the fuel F / B value, and a fuel F / B learning process in the charcoal canister 58. The canister purge that supplies the evaporated fuel to the intake pipe 32 is selectively executed. Specifically, when the fuel F / B value is within a predetermined numerical range and the evaporator concentration is equal to or higher than the threshold value THc, the ECU 64 stops the fuel F / B learning process and executes canister purging (S29 to S41). ..

As a result, it is possible to secure a sufficient purge amount while suppressing the deviation of the air-fuel ratio.

10 ... Vehicle 12 ... Engine 16 ... Combustion chamber 38 ... Throttle valve 52 ... Catalyst 58 ... Charcoal canister 60 ... Evaporator concentration sensor 66 ... ECU

Claims (2)

An internal combustion engine that selectively executes a fuel feedback learning process that adjusts the fuel feedback learning value referred to for air-fuel ratio control based on the fuel feedback value, and a canister purge that supplies the evaporated fuel in the canister to the intake pipe. It is a control device of
During the fuel feedback learning process, when the fuel feedback value is within the numerical range assigned to the zone corresponding to the engine speed and the intake pressure and the concentration of the evaporated fuel is equal to or higher than the threshold value, the fuel feedback learning process is performed. A control device for executing the canister purge. The control according to claim 1, wherein the fuel feedback learning process is continued without stopping when the fuel feedback value is within the predetermined range and the concentration of the evaporated fuel is less than the threshold value during the execution of the fuel feedback learning process. Device.

Images