JP2018184851A - Control device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To secure a sufficient purge amount while suppressing deviation of an air-fuel ratio.SOLUTION: An ECU 64 selectively executes fuel F/B learning processing for adjusting a fuel F/B learning value that is referred to for air-fuel ratio control on the basis of a fuel F/B value and canister purge for supplying evaporation fuel in a charcoal canister 58 to a suction pipe 32. More specifically, when the fuel F/B value is within a predetermined numerical range and a concentration of the evaporation fuel is a threshold value or more, the ECU 64 stops the fuel F/B learning processing and executes the canister purge.SELECTED DRAWING: Figure 1

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 an evaporated fuel in a canister to an intake pipe. The present invention relates to a control device that selectively executes a supplied canister purge.

  An example of this type of device is disclosed in Patent Document 1. The technique of Patent Literature 1 counts the number of times the air-fuel ratio learning value is updated, and makes the air-fuel ratio learning control and the canister purge control compatible by performing purge when the learning value is updated more than a predetermined value. It is what.

JP-A-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 that can secure a sufficient purge amount while suppressing a deviation in air-fuel ratio.

  The control device according to the present invention includes 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, a canister purge for supplying evaporated fuel in the canister to an intake pipe, In which the fuel feedback learning process is stopped and the canister purge is executed when the fuel feedback value is within a predetermined range and the concentration of the evaporated fuel is equal to or greater than the threshold value. The control device.

  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, the fuel feedback learning control is interrupted and the canister purge is executed. A sufficient purge amount can be ensured while suppressing the deviation of the air-fuel ratio.

  The above object, other objects, features and advantages of the present invention will become more apparent from the following detailed description of embodiments with reference to the drawings.

It is a block diagram which shows a part of principal part structure of the vehicle of this Example. It is a block diagram which shows the other part of principal part structure of the vehicle of this Example. It is an illustration figure which shows an example of the map referred by ECU shown in FIG. It is an illustration figure which shows an example of the table referred by ECU shown in FIG. It is a flowchart which shows a part of operation | movement of ECU shown in FIG. It is a flowchart which shows a part of other operation | movement of ECU shown in FIG. It is a flowchart which shows a part of other operation | movement of ECU shown in FIG. FIG. 6 is a flowchart showing still another part of the operation of the ECU shown in FIG. 1. It is a flowchart which shows a part of other operation | movement of ECU shown in FIG. It is a timing chart showing an example of change of evaporation concentration, purge time counter, purge valve opening, fuel F / B learning time counter, cooling water temperature, fuel F / B value.

  Referring to FIGS. 1 and 2, vehicle 10 of this embodiment includes a four-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 collected from three to one at positions downstream of the cylinders 141 to 143. The combustion chamber 16 provided in each of the cylinders 141 to 143 communicates with the intake pipe 32 via the intake valve 18 and communicates 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. 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. The engine 12 is cooled by cooling water circulating through a 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 an IG on operation is performed by an ignition key (not shown), the ECU 64 turns on the relay 72 shown in FIG. 2 to start the engine 12. The electric power of the battery 74 is supplied to the starter 76 via the relay 72 in the on state, and the starter 76 performs cranking with the electric power of the battery 74. As a result, the engine 12 is started.

  When the engine 12 is started, 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 a throttle valve 38, and the fuel injection amount of the fuel injection device 40 is adjusted so that an air-fuel mixture that shows the stoichiometric air-fuel ratio is generated.

  When an 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, whereby the intake air amount and the fuel injection amount of the fuel injection device 40 increase while maintaining the theoretical 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 immediately before the piston 22 connected to the crankshaft 26 via the connecting rod 24 reaches the top dead center. The piston 22 moves up and down by the explosion of the air-fuel mixture, whereby the crankshaft 26 rotates.

  A flywheel 28 is attached to the crankshaft 26, and fluctuations in the rotational speed of the crankshaft 26, that is, the rotational speed of the engine 12 are 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 a 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 70 s is converted into electric power, and the converted electric power is stored in the battery 74.

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

  A front O2 sensor 54 is provided at a position upstream 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 with reference to the fuel F / B value and the fuel F / B learning value under the air-fuel ratio control process. As a result, an air-fuel mixture showing the stoichiometric air-fuel ratio is generated. “F / B” is synonymous with “feedback”.

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

  When the fuel F / B learning process is executed, the canister purge is limited. Therefore, the purge amount becomes insufficient as the duration time of the fuel F / B learning process becomes longer. 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 process, the fuel F / B value determination support process shown in FIG. 6, the main control process shown in FIGS. 7 to 8, and the fuel F / B learning process 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 preconditions for the main control process, and are executed in parallel with the main control process. The fuel F / B learning process is started / stopped by the main control process. A control program corresponding to the flowcharts shown in FIGS. 5 to 9 is stored in the memory 64m.

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

  Referring to FIG. 4, a numerical range assigned to each of zones 1 to 15 is described in table TBL1. Specifically, the numerical value range assigned to zone 1 indicates “K1 ± α”, the numerical value range assigned to zone 2 indicates “K2 ± α”, and the numerical value range assigned to zone 3 is “K3”. ± α ″ is shown.

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

  Referring 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 acquired 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 decreased with reference to the fuel F / B learning value. On the other hand, if 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.

  Referring to FIG. 6, in step S11, the engine speed is detected through engine speed sensor 46. In step S 13, the intake pressure is detected through the intake pressure sensor 48. In step S15, a zone corresponding to the detected engine speed and intake pressure is detected from the map MP1 shown in FIG. In step S17, the numerical value 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.

  Referring to FIG. 7, in step S21, the temperature of the cooling water is detected through thermostat 56, and it is determined whether or not the detected temperature is equal to or higher than threshold value THt. If a determination result is NO, it will return to Step S21, and if a determination result is YES, it will progress to Step S23.

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

  Referring to FIG. 9, in step S61, an 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 greater than the calculated average value. If a determination result is YES, it will progress to step S65 and will reduce a fuel F / B learning value. On the other hand, if the determination 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”. In step S29, it is determined whether or not the fuel F / B learning value adjusted in step S55 or S57 is within the numerical range acquired in step S17. Further, in step S31, the evaporation concentration is estimated based on the output of the evaporation concentration sensor 60, and it is determined whether or not the estimated evaporation concentration is equal to or greater than a 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. Moreover, if the determination result of step S27 is YES, it will progress to step S35 as it is. Furthermore, if the determination result in step S27 is NO and both the determination result in step S29 and the determination result in step S31 are YES, the countdown of the fuel F / B learning time counter 64t is stopped in step S33. Proceed to step S35.

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

  In step S39, the adjusted initial value is set in the purge execution counter 64p, and the count-down of the purge execution counter 64p is started. In step S41, the purge valve 62 is opened to execute canister purge.

  In step S43, as in step S29, it is determined whether or not the fuel F / B learning value adjusted in step S55 or S57 is within the numerical range acquired in step S17. In step S45, it is determined whether or not the count value of the purge execution counter 64p indicates “0”.

  If the determination result of step S43 is YES and the determination result of 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 S49, and the purge valve 62 is closed to interrupt the canister purge. When the process of step S49 is completed, the process returns to step S23.

  Furthermore, if the determination result of 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, the countdown of the fuel F / B learning time counter 64t is restarted in step S53, and the fuel F / B learning process is started in step S55. When the process of step S55 is completed, the process returns to step S27.

  Referring to FIG. 10, the temperature of the cooling water reaches threshold value 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 a fuel F / B learning process that is started simultaneously.

  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 evaporation concentration is set in the purge execution counter 64p, and the purge execution counter 64p starts to count down.

  The purge valve 62 is opened simultaneously with 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 decreases 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 fuel F / B learning time counter 64t starts counting down. However, the fuel F / B value falls within the numerical range at time T3. Further, the evaporation concentration at time T3 indicates a value equal to or higher than the threshold value THc. Accordingly, 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.

  The purge execution counter 64p is set with an initial value corresponding to the evaporation concentration, and the purge execution counter 64p starts to count down. The purge valve 62 is opened simultaneously with 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 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 evaporation concentration is set in the purge execution counter 64p, and the purge execution counter 64p starts to count down.

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

  As a result, a sufficient purge amount can be secured while suppressing the deviation of the air-fuel ratio.

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

Claims (1)

An internal combustion engine that selectively executes fuel feedback learning processing for adjusting a fuel feedback learning value referred to for air-fuel ratio control based on the fuel feedback value, and canister purge for supplying evaporated fuel in the canister to the intake pipe A control device of
The control device, wherein when the fuel feedback value is within a predetermined range and the concentration of the evaporated fuel is equal to or greater than a threshold value, the fuel feedback learning process is stopped and the canister purge is executed.

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