JP2009162203A - Evaporative fuel processing device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an evaporated fuel treatment device capable of quickly treating evaporated fuel adsorbed by a canister commonly used by a plurality of cylinder groups. <P>SOLUTION: This evaporated fuel treatment device 20 is provided with a purge passage 22 provided to guide purge gas from the canister 21 to respective banks 3R, 3L, purge valves 23R, 23L respectively provided at branch parts 22R, 22L of the purge passage 22, and EUCs 14R, 14L controlling each purge valve. The EUC 14R, 14L are connected via a communication circuit 15 and concentration information of purge gas is shared between the EUCs 14R, 14L. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an evaporated fuel processing apparatus that processes evaporated fuel generated from a fuel tank of an internal combustion engine.

  The canister that adsorbs the evaporated fuel generated in the fuel tank is not provided for each bank, even for an internal combustion engine having a plurality of cylinder groups such as a V-type engine, and is provided for each engine. Most of them. Therefore, in order to process the evaporated fuel adsorbed by a single canister, it is necessary to branch a purge passage connected to the canister and introduce purge gas containing evaporated fuel into each cylinder group. Since the purge gas contains a fuel component, if there is variation among the cylinder groups, combustion worsens. Therefore, a purge passage for guiding purge gas from a canister shared between a plurality of cylinder groups to the intake system is branched for each cylinder group, and a purge valve for adjusting the flow rate of the purge gas at each of the branched branches There has been proposed an evaporative fuel processing apparatus provided with

  By the way, in order to relieve the calculation load of the control device of the internal combustion engine provided with a plurality of cylinder groups, a control device is provided for each cylinder group, and the idling speed is determined by connecting the control devices for each cylinder group through a communication line. A technique for controlling each is known (Patent Document 1). Similarly, there is also known a technique for controlling the cooling water temperature for each cylinder group by connecting the control devices provided for each cylinder group with a communication line (Patent Document 2). In addition, Patent Documents 3 to 5 exist as prior art documents related to the present invention.

JP 10-196439 A Japanese Patent Laid-Open No. 10-196445 JP-A-10-196446 Japanese Patent Laid-Open No. 5-248314 Japanese Patent Laid-Open No. 6-10780

  In the case of the fuel vapor processing apparatus having the above-described configuration, in order to determine the flow rate of the purge gas introduced into each cylinder group, it is necessary to specify the purge gas concentration and operate each barge valve in accordance with the concentration. However, as in the above-described prior art, when the purge valve for each branch portion is controlled separately by the control device provided for each cylinder group, the concentration of the purge gas is not shared between the control devices for each cylinder group. Even though the concentration is known in one cylinder group, a situation may occur in which the other cylinder group is treated as unknown. In such a situation, the flow rate of the purge gas cannot be increased efficiently, and prompt processing of the evaporated fuel adsorbed on the canister is hindered.

  Therefore, an object of the present invention is to provide an evaporative fuel processing apparatus that can quickly process evaporative fuel adsorbed by a canister shared by a plurality of cylinder groups.

  The fuel vapor processing apparatus of the present invention is provided so as to guide purge gas from a single canister to each of the first cylinder group and the second cylinder group, and is shared by the first cylinder group and the second cylinder group. And a purge passage having a first branch portion and a second branch portion branched from the shared portion for each cylinder group, and a first purge that is provided in the first branch portion of the purge passage and adjusts the flow rate of the purge gas A valve, a second purge valve provided at the second branch of the purge passage for adjusting the flow rate of the purge gas, and a first purge gas based on a change in the air-fuel ratio accompanying the introduction of the purge gas to the first cylinder group. First control means for executing first concentration learning control that is completed by specifying the concentration, and specifying the second concentration of the purge gas based on the change in the air-fuel ratio accompanying the introduction of the purge gas to the second cylinder group The second control means for executing the second density learning control completed by the step, and the first density and the second density so that the first control means and the second control means can acquire each other. Communication means for connecting the first control means and the second control means, and the first control means obtains the flow rate of the purge gas corresponding to the first concentration after the first concentration is specified. As described above, while operating the first purge valve, before specifying the first concentration, the flow rate of the purge gas corresponding to the second concentration obtained via the communication means is obtained. After the first purge valve is operated and the second control means specifies the second concentration, the second purge valve operates the second purge valve so as to obtain a flow rate of the purge gas corresponding to the second concentration. Before specifying the second concentration. As the flow rate of the purge gas in accordance with the first concentration obtained through the means is obtained, operating the second purge valve, to solve the problems described above by (claim 1).

  According to this fuel vapor processing apparatus, if the concentration learning control is completed by either one of the first control means or the second control means, the other control means uses the concentration learning control of one control means. The concentration of the purge gas obtained as a result of the above can be acquired via the communication means. As a result, the other control means can specify the concentration of the purge gas without performing concentration learning control, so that the purge valve can be operated so that a flow rate corresponding to the concentration of the purge gas can be obtained immediately. Therefore, since the operation of gradually increasing the flow rate of the purge gas from a slight flow rate to suppress the change in the air-fuel ratio accompanying the introduction of the purge gas is unnecessary, it is possible to quickly process the evaporated fuel adsorbed on the canister. .

  In one aspect of the present invention, the internal combustion engine includes a first fuel supply unit that supplies fuel to the first cylinder group, and a second fuel supply unit that supplies fuel to the second cylinder group. And the first control means operates the first fuel supply means so that the fuel supply amount to the first cylinder group is corrected according to the operation amount of the first purge valve, The second control means may operate the second fuel supply means so that a fuel supply amount to the second cylinder group is corrected in accordance with an operation amount of the second purge valve. . According to this aspect, since the fuel injection amount is corrected according to the operation amount of the purge valve, it is possible to prevent the deterioration of the emission and the deterioration of the combustion.

  In one aspect of the present invention, the first control unit determines an operation amount for the first purge valve when starting the first concentration learning control based on the second concentration, and the second control unit May determine an operation amount for the second purge valve when starting the second concentration learning control based on the first concentration. According to this aspect, when the concentration learning control by the other control unit is completed when the concentration learning control by one control unit is started, the purge is performed based on the purge gas concentration specified by the learning control. The amount of operation of the valve is determined. Thereby, it is possible to prevent the opening amount of the purge valve from being reduced more than necessary when the concentration learning control is started, and thus it is possible to quickly process the evaporated fuel.

  In one aspect of the present invention, in the first concentration learning control, the first purge rate, which is the ratio of the purge gas introduction amount to the intake gas amount of the first cylinder group, increases as time elapses from the start. The first purge valve is operated, and the second concentration learning control is a first purge that is a ratio of a purge gas introduction amount to an intake gas amount of the second cylinder group with the passage of time from the start. The second purge valve is operated so that the rate increases, and the first control means determines an increase rate of the first purge rate according to the first concentration or the second concentration, and The second control means may determine an increase rate of the second purge rate in accordance with the first concentration or the second concentration. According to this aspect, it is possible to process the evaporated fuel more quickly than when the concentration learning control is performed at a constant rate of increase.

  In one aspect of the present invention, the first control means further executes a first air-fuel ratio learning control for maintaining the air-fuel ratio of the intake gas guided to the first cylinder group at a target air-fuel ratio, and When the first concentration or the second concentration is higher than a first predetermined level, the first concentration learning control is executed in preference to the first air-fuel ratio learning control, while the first concentration or the second concentration The first air-fuel ratio learning control is executed in preference to the first concentration learning control when the air pressure is equal to or lower than the first predetermined level, and the second control means is configured to empty the intake gas introduced to the second cylinder group. The second air-fuel ratio learning control for maintaining the fuel ratio at the target air-fuel ratio is further executed, and the second air-fuel ratio learning control is performed when the first concentration or the second concentration is higher than a second predetermined level. The second concentration learning control is executed with priority, while the second concentration learning control is executed. May be performed the second air-fuel ratio learning control in priority to the second concentration learning control when the concentration or the second concentration of less than or equal to the second predetermined level (claim 5). According to this aspect, when the purge gas concentration exceeds a predetermined level, the concentration learning control is performed with priority over the air-fuel ratio learning control, and when the purge gas concentration is lower than the predetermined level, the air-fuel ratio learning control is performed with priority over the concentration learning control. Done. Therefore, the influence on the air-fuel ratio learning control due to the introduction of the purge gas can be reduced, and the accuracy of the air-fuel ratio learning control is improved.

  In one aspect of the present invention, the first control means further executes a first air-fuel ratio learning control for maintaining the air-fuel ratio of the intake gas guided to the first cylinder group at a target air-fuel ratio, and When the difference between the first concentration and the second concentration is larger than an allowable range, the first air-fuel ratio learning control is executed by prohibiting the execution of the first concentration learning control, and the second control means , Further executing a second air-fuel ratio learning control for maintaining the air-fuel ratio of the intake gas led to the second cylinder group at a target air-fuel ratio, and the difference between the first concentration and the second concentration is within an allowable range If the value is larger than the value, execution of the second concentration learning control may be prohibited and the second air-fuel ratio learning control may be executed (Claim 6). According to this aspect, it is possible to determine the correctness of the concentration learning control for each cylinder group by monitoring the concentration difference between the first concentration and the second concentration. If the result is inappropriate, the air-fuel ratio learning control is performed. Can be executed. Thereby, the correctness of the concentration learning control for each cylinder group can be compensated to a certain level.

  In one aspect of the present invention, the first control means further executes a first air-fuel ratio learning control for maintaining the air-fuel ratio of the intake gas guided to the first cylinder group at a target air-fuel ratio, and When the difference between the first concentration and the second concentration is greater than an allowable range and the first air-fuel ratio learning control has been executed, it is determined that there is an abnormality in the location that affects the purge gas flow rate. The second control means further executes second air-fuel ratio learning control for maintaining the air-fuel ratio of the intake gas guided to the second cylinder group at a target air-fuel ratio, and the first concentration and the second When the difference from the concentration is larger than the allowable range and the second air-fuel ratio learning control has been executed, it may be determined that there is an abnormality in the location that affects the flow rate of the purge gas. ). According to this aspect, it is possible to determine whether or not there is an abnormality at a location that affects the flow rate of the purge gas. Therefore, for example, a warning can be displayed to the driver or the like as a response to the abnormality.

  As described above, according to the present invention, if the concentration learning control has been executed by either one of the first control means or the second control means, the other control means The concentration of the purge gas obtained as a result of the concentration learning control can be acquired via the communication means. As a result, the other control means can specify the concentration of the purge gas without performing concentration learning control, so that the purge valve can be operated so that a flow rate corresponding to the concentration of the purge gas can be obtained immediately. Therefore, since the operation of gradually increasing the flow rate of the purge gas from a slight flow rate to suppress the change in the air-fuel ratio accompanying the introduction of the purge gas is unnecessary, it is possible to quickly process the evaporated fuel adsorbed on the canister. .

(First form)
FIG. 1 shows an outline of an internal combustion engine to which an evaporated fuel processing apparatus according to an embodiment of the present invention is applied. The internal combustion engine 1 is mounted as a driving power source for a vehicle (not shown). The internal combustion engine 1 is configured as a V-type 8-cylinder engine having a pair of left and right first banks 3R and second banks 3L in which four cylinders 2 are arranged in one direction. The cylinders 2 in the first bank 3R constitute a first cylinder group, and the cylinders 2 in the second bank 3L constitute a second cylinder group.

  The intake passage 4 connected to the internal combustion engine 1 branches into a first intake passage 4R and a second intake passage 4L corresponding to the banks 3R, 3L. The first intake passage 4R has a surge tank portion 5R shared by each cylinder 2 of the first bank 3R and a branch portion 6R branched for each cylinder 2. Similarly, the second intake passage 4L has a surge tank portion 5L shared by each cylinder 2 of the second bank 3L and a branch portion 6L branched for each cylinder 2.

  In the internal combustion engine 1, a throttle valve 7R for restricting intake air is provided for each branch portion 6R, and one throttle valve 7L is provided for each branch portion 6L. The intake passage 4 is provided with an air flow meter 8 for measuring the intake flow rate upstream of the branch position where the first intake passage 4R and the second intake passage 4L branch.

  Further, in order to supply fuel to the banks 3R and 3L, a fuel supply device 9 is provided for each bank. The fuel supply device 9 for each bank has a fuel injection valve 10 provided for each cylinder 2, and each fuel injection valve 10 is connected to a delivery pipe 12. The fuel drawn from the fuel tank 13 is supplied to the delivery pipe 9 through a fuel passage (not shown).

  The opening degree of the throttle valves 7R, 7L or the fuel injection operation of the fuel injection valve 10 is individually controlled for each bank by engine control units (ECUs) 14L, 14R configured as computer units. That is, the operating state of the internal combustion engine 1 is individually controlled by the ECUs 14R and 14L for each bank, in other words, for each cylinder group. However, the ECUs 14R and 14L are connected by a communication line 15 as communication means, and can communicate bidirectionally via the communication line 15. By exchanging information via the communication line 15, the ECUs 14 </ b> R and 14 </ b> L control the other bank (hereinafter referred to as another bank) in order to control the operation of the bank that the ECU 14 </ b> R, 14 </ b> L is responsible for. The information regarding the driving state of the system may be referred to and acquired.

  The internal combustion engine 1 is provided with idle control devices 16R and 16L for controlling the idling state for each bank. The idle control devices 16R and 16L include bypass passages 17R and 17L that connect surge tank portions 5R and 5L and branch portions 22R and 22L of a purge passage 22 described later, and idle control valves 18R provided in the bypass passages 17R and 17L. , 18L. The opening degree of each idle control valve 18R, 18L is controlled by ECU 14R, 14L.

  The internal combustion engine 1 is provided with an evaporated fuel processing device (hereinafter abbreviated as a processing device) 20 that guides the evaporated fuel generated in the fuel tank 13 to the banks 3R and 3L as purge gas. The processing device 20 includes a canister 21 that adsorbs the evaporated fuel generated in the fuel tank 13, a purge passage 22 that guides purge gas from the canister 21 to the first intake passage 4R and the second intake passage 4L of each cylinder group, Purge valves 23R and 23L for adjusting the flow rate of the purge gas guided to the intake passages 4R and 4L via the purge passage 22 are provided.

  The purge passage 22 includes a single shared portion 22A shared between the cylinder groups, and branch portions 22R and 22L branched from the end of the shared portion 22A for each bank. The shared portion 22 </ b> A also includes an internal passage of the canister 21. The branch portions 22R and 22L are connected to the intake passages 4R and 4L downstream of the throttle valves 7R and 7L. More precisely, as indicated by broken lines in FIG. 1, the branch portions 22R are connected to positions downstream of the throttle valve 7R with respect to the branch portions 6R of the first intake passage 4R, and the branch portions 22L are connected to the second intake air. Each branch portion 6L of the passage 4L is connected to a position downstream of the throttle valve 7L. The purge valves 23R and 23L are provided at the branch portions 22R and 22L, respectively. The branch portions 22R and 22L have the same configuration, and the purge valves 23R and 23L also have the same configuration.

  The purge valves 23R and 23L are generated in the intake passages 4R and 4L downstream of the throttle valves 7R and 7L by switching on (energization) and off (energization stop) energization of a solenoid unit (not shown) as an example. It is configured as a vacuum switching valve that is opened and closed by controlling the introduction and stoppage of negative pressure. The opening degree of the purge valves 23R and 23L is adjusted by controlling the duty ratio of the excitation current applied to each solenoid unit. The duty ratio of the excitation current applied to the purge valves 23R and 23L is controlled independently for each bank by the ECUs 14R and 14L. That is, the duty ratio of the purge valve 23R corresponding to one bank 3R is controlled by the ECU 14R, and the duty ratio of the purge valve 23R corresponding to the other bank 3L is controlled by the ECU 14L. Note that the duty ratio here means the ratio of on-time in one cycle of control, that is, the on-duty ratio.

  Next, control performed by each ECU 14R, 14L will be described. In addition, the control which each ECU14R and 14L implements in relation to this invention is substantially the same. Hereinafter, in order to avoid redundant description, the control of the ECU 14R in charge of the first bank 3R will be described, and the description of the control of the ECU 14L on the opposite side will be omitted unless particularly mentioned.

  The ECU 14R performs purge control for purging the evaporated fuel adsorbed on the canister 21 during operation of the internal combustion engine 1. During the purge control, the purge valve 23R is opened / closed at an appropriate duty ratio. When the purge valve 23R is opened, the intake negative pressure is guided to the canister 21. As a result, air is sucked from an air inlet (not shown), and the evaporated fuel is purged from the canister 21 by the air. Thereby, the purge gas containing the evaporated fuel is introduced into each branch portion 6R of the first intake passage 4R via the branch portion 22R of the purge passage 22.

  During normal operation of the internal combustion engine 1, the ECU 14R executes air-fuel ratio feedback control for setting the air-fuel ratio of the air-fuel mixture introduced into the combustion chamber to the target air-fuel ratio. If the purge gas is richer than the target air-fuel ratio, the air-fuel ratio is biased toward the rich side. On the other hand, if the purge gas is lean, the air-fuel ratio also becomes a lean value. For this reason, the concentration of the purge gas (the ratio of the HC component in the purge gas) can be estimated based on the change in the air-fuel ratio accompanying the introduction of the purge gas, and the concentration of the purge gas can be specified by the estimation.

  The ECU 14R executes concentration learning control for specifying the concentration of the purge gas based on the change in the air-fuel ratio accompanying the introduction of the purge gas while executing the air-fuel ratio feedback control during the normal operation. When the concentration of the purge gas is specified by executing the concentration learning control, the amount of fuel supplied to the internal combustion engine 1 accompanying the purge control can be estimated based on the flow rate of the purge gas. Therefore, by performing increase / decrease correction on the fuel injection amount so that the influence of the purge gas is offset, it is possible to process the evaporated fuel adsorbed on the canister 21 without deteriorating the emission.

  In the purge control, the air-fuel ratio varies to some extent until the purge gas concentration can be correctly learned. Therefore, in order to prevent the emission from being deteriorated as much as possible, the concentration learning control starts with the flow rate of the purge gas sufficiently reduced and gradually increases the flow rate. Note that the control described above is not the main part of the present invention and is the same as a known method, and thus detailed description thereof is omitted.

  The control feature of this embodiment is that the own bank and the other bank share the result of specifying the concentration of the purge gas, and the purge gas concentration obtained as a result of the concentration learning control of the other bank is used to purge the own bank. There is to control.

  FIG. 2 is a flowchart showing an example of a control routine performed by the ECU 14R. A program of this routine is held in a storage device such as a ROM possessed by the ECU 14R, and is read out in a timely manner and repeatedly executed. First, in step S1, the ECU 14R determines whether a purge control execution condition for the bank is satisfied. The execution condition may be determined as appropriate. If the execution condition is satisfied, the process proceeds to step S2, and if not, the subsequent process is skipped and the current routine is terminated.

  In step S2, it is determined whether or not density learning control for the own bank is completed. That is, it is determined whether or not the purge gas concentration is specified. If the density learning control is complete, the process proceeds to step S3, and if not complete, the process proceeds to step S4.

  In step S3, the purge gas concentration (own bank concentration) stored in the ECU 14R is used for purge control, and the process proceeds to step S6. The self-bank concentration here is the concentration of the purge gas specified when the concentration learning control is completed, and is stored in the middle of the concentration learning control before the concentration learning control is completed. Or the concentration of the purge gas given as a predetermined initial value.

  In step S4, the ECU 14R refers to the information of the ECU 14L via the communication line 15, and determines whether or not the concentration learning control performed by the ECU 14L with respect to another bank is completed. If the density learning control has been completed, the process proceeds to step S5, and if not, the process proceeds to step S3.

  In step S5, the ECU 14R proceeds with the process to step S6 on the assumption that the purge gas concentration (concentration of other banks) stored in the ECU 14L is used for purge control for the own bank.

  In step S6, the purge valve 23R is operated so that the flow rate of the purge gas according to the concentration of the purge gas determined to be used in steps S3 and S5 is obtained. The opening degree of the purge valve 23, that is, the operation amount, refers to the purge flow rate map (not shown) held in the ROM, and determines the target duty ratio of the purge valve 23R corresponding to the current intake pipe pressure and the target flow rate. Determined by calculation. The purge flow rate map shows the relationship between the duty ratio and the flow rate when the duty ratio of the purge valve 23R of its own bank is changed from the fully closed state to the fully open state with the purge valve 23L of the other bank completely closed. This data is described for each intake pipe pressure. The intake pipe pressure may be a value detected by an intake pressure sensor, or may be an estimated value calculated from operation control parameters such as an intake air amount, a throttle valve opening, and an engine speed.

  In step S7, each fuel injection valve 10 of the fuel supply device 9 is operated so that the fuel supply amount to the first bank 3R is corrected according to the operation amount of the purge valve 23R operated in step S6. Then, the current routine is terminated.

  According to the above routine, when executing the purge control for the own bank, if the density learning control for the other bank is completed, the other bank concentration obtained as a result of the density learning control for the other bank is automatically set. It can be used for bank purge control. As a result, the concentration of the purge gas can be specified without performing concentration learning control on the bank itself, and thus the purge valve 23R can be operated so that a flow rate corresponding to the concentration of the purge gas can be obtained immediately. Further, since the fuel injection amount is corrected according to the operation amount of the purge valve 23R, it is possible to prevent the deterioration of the emission and the deterioration of the combustion.

(Second form)
Next, a second embodiment of the present invention will be described with reference to FIG. Since the second form has the same configuration as the first form except for some of the control contents, the description of the common configuration will be omitted below. As for the configuration of the internal combustion engine 1, FIG. FIG. 3 is a flowchart showing an example of a control routine according to the second embodiment. A program of this routine is held in a storage device such as a ROM possessed by the ECU 14R, and is read out in a timely manner and repeatedly executed. In addition, about the process which is common in FIG. 2, the same referential mark is attached | subjected and description is abbreviate | omitted. In this embodiment, after the concentration of the purge gas used in the purge control for the own bank is determined in step S3 or step S5, the process proceeds to step S21.

  In step S21, the purge rate at the start of purge control (at the start of concentration learning control) is calculated according to the purge gas concentration determined in step S3 or step S5. The purge rate indicates the ratio of the purge gas introduction amount to the intake gas amount of the cylinder group. For example, the purge rate may be calculated by referring to a map that gives a lower purge rate as the concentration of the purge gas is higher. In the subsequent step S22, the operation amount of the purge valve 23R at the start of the purge control is determined based on the purge rate, and the purge valve 23R is operated so that the operation amount is realized.

  According to the second embodiment, when the concentration learning control of the other bank is completed when starting the concentration learning control of the own bank, based on the concentration of the purge gas of the other bank specified by the learning control. The operation amount of the purge valve 23R is determined. As a result, the amount of opening of the purge valve 23R when starting the concentration learning control can be prevented from being reduced more than necessary, so that the evaporated fuel can be processed quickly.

(Third form)
Next, a third embodiment of the present invention will be described with reference to FIG. Since the third mode has a configuration common to the first mode except for a part of the control contents, the description of the common configuration will be omitted below. As for the configuration of the internal combustion engine 1, FIG. FIG. 4 is a flowchart showing an example of a control routine according to the third embodiment. A program of this routine is held in a storage device such as a ROM possessed by the ECU 14R, and is read out in a timely manner and repeatedly executed. In addition, about the process which is common in FIG. 2, the same referential mark is attached | subjected and description is abbreviate | omitted. In this embodiment, after the concentration of the purge gas used in the purge control for the own bank is determined in step S3 or step S5, the process proceeds to step S31.

  In step S31, the rate of increase of the purge rate in the concentration learning control is determined according to the purge gas concentration determined in step S3 or step S5. As described above, in the concentration learning control, the purge gas flow is started with the flow rate sufficiently reduced, and the flow rate is gradually increased. In other words, the purge rate increases with the passage of time from the start. In addition, the purge valve 23R is operated. That is, the larger the purge rate increase rate, the faster the evaporated fuel can be processed. Therefore, this increase rate may be determined by the ECU 14R referring to a map that gives a lower increase rate as the purge gas concentration is higher, for example. In the subsequent step S32, the purge valve 23R is operated so that the flow rate of the purge gas is obtained according to the increasing rate determined in step 31.

  According to the third embodiment, it is possible to process the evaporated fuel more quickly than when the concentration learning control is performed at a constant rate of increase.

(4th form)
Next, a fourth embodiment of the present invention will be described with reference to FIG. Since the fourth embodiment has the same configuration as the first embodiment except for a part of the control contents, the description of the common configuration will be omitted below. As for the configuration of the internal combustion engine 1, FIG. FIG. 5 is a flowchart showing an example of a control routine according to the fourth embodiment. A program of this routine is held in a storage device such as a ROM possessed by the ECU 14R, and is read out in a timely manner and repeatedly executed. In addition, about the process which is common in FIG. 2, the same referential mark is attached | subjected and description is abbreviate | omitted.

  In this embodiment, in addition to the air-fuel ratio feedback control described above, the ECU 14R executes an air-fuel ratio learning control for correcting the feedback correction coefficient and maintaining the air-fuel ratio sucked into the first bank 3R at the target air-fuel ratio. ing. This air-fuel ratio learning control is sometimes referred to as basic air-fuel ratio learning control, and is a well-known control for eliminating a steady air-fuel ratio shift that is difficult to deal with only by air-fuel ratio feedback control due to deterioration over time or the like. The feature of this embodiment is that the priority between the air-fuel ratio learning control and the concentration learning control is determined according to the purge gas concentration.

  As shown in FIG. 5, in this embodiment, after the concentration of the purge gas used in the purge control for the own bank is determined in step S3 or step S5, the process proceeds to step S41. In step S41, it is determined whether or not the concentration (use concentration) of the purge gas determined to be used exceeds a predetermined level. As a result of the determination, if it exceeds the predetermined level, the process proceeds to step S42, and if it is less than the predetermined level, the process proceeds to step S43.

  In step S42, concentration learning control (purge control) is executed in preference to the above-described air-fuel ratio learning control, and in step S43, air-fuel ratio learning control is executed in preference to concentration learning control. The predetermined level is set to such a level that the influence on the air-fuel ratio learning control due to the introduction of the purge gas is within an allowable range. The predetermined level may be the same value in each bank, or the predetermined level can be changed according to the state of each bank.

  According to the fourth embodiment, when the use concentration exceeds a predetermined level, the concentration learning control is performed with priority over the air-fuel ratio learning control, and when it is less than the predetermined level, the air-fuel ratio learning control is prioritized over the concentration learning control. Is done. Therefore, the influence on the air-fuel ratio learning control due to the introduction of the purge gas can be reduced, and the accuracy of the air-fuel ratio learning control is improved.

(5th form)
Next, a fifth embodiment of the present invention will be described with reference to FIG. This mode is for determining the necessity of executing the air-fuel ratio learning control, and can be implemented in combination with the fourth mode. Since the fifth embodiment has the same configuration as the first embodiment except for the control contents, the description of the common configuration will be omitted below. As for the configuration of the internal combustion engine 1, FIG. FIG. 6 is a flowchart showing an example of the fifth control routine. The program of this routine is held in a storage device such as a ROM possessed by the ECU 14R, and is read out in a timely manner and repeatedly executed.

  First, in step S51, the ECU 14R determines whether a purge control execution condition for the bank is satisfied. The execution condition may be determined as appropriate. If the execution condition is satisfied, the process proceeds to step S52. If not, the subsequent process is skipped and the current routine is terminated.

  In step S52, it is determined whether or not density learning control for the own bank is completed. If the density learning control has been completed, the process proceeds to step S53. If not completed, the subsequent processing is skipped and the current routine is terminated.

  In step S53, the ECU 14R refers to the information of the ECU 14L via the communication line 15, and determines whether or not the concentration learning control performed by the ECU 14L for the other bank is completed. If the density learning control has been completed, the process proceeds to step S54. If not, the subsequent process is skipped and the current routine is terminated.

  In step S54, a difference between the concentration of the purge gas specified by the concentration learning control performed for the own bank and the concentration of the purge gas specified by the concentration learning control performed for the other bank is calculated. It is determined whether or not the density difference exceeds a permissible range. Originally, the concentration of the purge gas must be equal for each bank. Therefore, if the concentration difference is larger than the allowable range, it is expected that the result of concentration learning control is inappropriate. There are various factors that influence the result of the concentration learning control. Here, an attempt is made to redo the air-fuel ratio learning control. That is, if the concentration difference exceeds the allowable range in step S54, the process proceeds to step S55 to prohibit the purge control, and the air-fuel ratio learning control is executed in the subsequent step S56. On the other hand, if the density difference does not exceed the allowable range in step S54, it is presumed that the result of the density learning control is correct, so the subsequent processing is skipped and the current routine is terminated.

  According to the fifth embodiment, the correctness of the concentration learning control for each bank can be determined by monitoring the concentration difference. If the result is inappropriate, the air-fuel ratio learning control can be executed. Thereby, the correctness of the density learning control for each bank can be compensated to a certain level. Note that the control according to this embodiment may be performed only by one of the ECUs 14R and 14L, and need not be performed by both the ECUs 14R and 14L.

(Sixth form)
Next, a sixth embodiment of the present invention will be described with reference to FIG. This form is related to the fifth form and can be implemented in combination with the fourth form. Since the sixth embodiment has the same configuration as the first embodiment except for the control contents, the description of the common configuration will be omitted below. As for the configuration of the internal combustion engine 1, FIG. FIG. 7 is a flowchart showing an example of a control routine according to the embodiment. A program of this routine is held in a storage device such as a ROM possessed by the ECU 14R, and is read out in a timely manner and repeatedly executed. In addition, about the process which is common in FIG. 6, the same referential mark is attached | subjected and description is abbreviate | omitted. The process of FIG. 7 is started on the condition that the air-fuel ratio learning control described above has been executed.

  If the density difference exceeds the allowable range in step S54, the process proceeds to step 61. In step S61, it is determined that there is an abnormality at a location that affects the flow rate of the purge gas. For example, this corresponds to the case where the purge valves 23R and 23L are fixed or the purge passage 22 is clogged. In the subsequent step S62, a predetermined warning is displayed in order to notify the driver of such an abnormality.

  According to the sixth aspect, it is possible to determine whether or not there is an abnormality in the location that affects the flow rate of the purge gas, and it is possible to notify the driver or the like of the presence of such an abnormality. Note that the control according to this embodiment may be performed only by one of the ECUs 14R and 14L, and need not be performed by both the ECUs 14R and 14L.

  In the above embodiments, the control of the ECU 14R has been described, but the ECU 14L performs the same control at the same time. Accordingly, the ECUs 14R and 14L execute the routines shown in FIGS. 2 to 7, respectively, so that the ECU 14R functions as the first control means of the present invention and the ECU 14L functions as the second control means of the present invention. However, the present invention is not limited to the above embodiments, and can be implemented in various forms. It is not essential that each of the above-described embodiments is carried out independently, and these embodiments can be appropriately combined and implemented within a range that does not cause a contradiction. Further, the present invention is not limited to an internal combustion engine having two cylinder groups, but can be applied to an internal combustion engine having three or more cylinder groups. The internal combustion engine to which the present invention can be applied is not limited to the V type, and can be applied to other types of internal combustion engines.

The figure which showed the outline | summary of the internal combustion engine to which the evaporative fuel processing apparatus which concerns on one form of this invention was applied. The flowchart which showed an example of the control routine which concerns on a 1st form. The flowchart which showed an example of the control routine which concerns on a 2nd form. The flowchart which showed an example of the control routine which concerns on a 3rd form. The flowchart which showed an example of the control routine which concerns on a 4th form. The flowchart which showed an example of the control routine which concerns on a 5th form. The flowchart which showed an example of the control routine which concerns on a 6th form.

Explanation of symbols

1 Internal combustion engine 3R First bank (first cylinder group)
3L 2nd bank (2nd cylinder group)
9 Fuel supply device (fuel supply means)
14R ECU (first control means)
14L ECU (second control means)
15 Communication line (communication means)
20 Evaporative Fuel Processing Device 21 Canister 22 Purge Passage 22A Common Portion 22R First Branch Port 22L Second Branch Port 23R First Purge Valve 23L Second Purge Valve

Claims (7)

A single canister is provided to guide purge gas to each of the first cylinder group and the second cylinder group. A purge passage having a branched first branch portion and a second branch portion; a first purge valve provided in the first branch portion of the purge passage for adjusting a flow rate of purge gas; and the first passage of the purge passage. A second purge valve that is provided in the two branch portions and adjusts the flow rate of the purge gas, and the first purge gas is determined by specifying the first concentration of the purge gas based on the change in the air-fuel ratio accompanying the introduction of the purge gas to the first cylinder group. A first control means for executing one concentration learning control, and a second concentration study completed by specifying a second concentration of the purge gas based on a change in the air-fuel ratio accompanying the introduction of the purge gas to the second cylinder group. Second control means for executing control, and the first control means and the second control means so that the first density and the second density can be mutually acquired between the first control means and the second control means. Communication means for connecting the control means,
After the first concentration is specified, the first control means operates the first purge valve while specifying the first concentration so that a flow rate of the purge gas corresponding to the first concentration is obtained. Before, operating the first purge valve so as to obtain a flow rate of the purge gas according to the second concentration obtained through the communication means,
After specifying the second concentration, the second control means operates the second purge valve so as to obtain a flow rate of the purge gas corresponding to the second concentration, and specifies the second concentration. The evaporative fuel processing apparatus for an internal combustion engine, wherein the second purge valve is operated before the second purge valve so as to obtain a flow rate of the purge gas corresponding to the first concentration obtained via the communication means. The internal combustion engine is provided with first fuel supply means for supplying fuel to the first cylinder group, and second fuel supply means for supplying fuel to the second cylinder group,
The first control means operates the first fuel supply means so that a fuel supply amount to the first cylinder group is corrected according to an operation amount of the first purge valve;
2. The evaporation according to claim 1, wherein the second control unit operates the second fuel supply unit so that a fuel supply amount to the second cylinder group is corrected in accordance with an operation amount of the second purge valve. Fuel processor. The first control means determines an operation amount for the first purge valve when starting the first concentration learning control based on the second concentration;
3. The fuel vapor processing apparatus according to claim 1, wherein the second control unit determines an operation amount for the second purge valve when starting the second concentration learning control based on the first concentration. 4. In the first concentration learning control, the first purge valve is operated so that the first purge rate, which is the ratio of the purge gas introduction amount to the intake gas amount of the first cylinder group, increases with the passage of time from the start. Is what
In the second concentration learning control, the second purge valve is operated so that the first purge rate, which is the ratio of the purge gas introduction amount to the intake gas amount of the second cylinder group, increases with the passage of time from the start. Is what
The first control means determines an increase rate of the first purge rate according to the first concentration or the second concentration,
3. The fuel vapor processing apparatus according to claim 1, wherein the second control unit determines an increase rate of the second purge rate according to the first concentration or the second concentration. The first control means further executes a first air-fuel ratio learning control for maintaining the air-fuel ratio of the intake gas led to the first cylinder group at a target air-fuel ratio, and the first concentration or the second concentration When the first concentration level is higher than the first predetermined level, the first concentration learning control is executed in preference to the first air-fuel ratio learning control, while the first concentration or the second concentration is equal to or lower than the first predetermined level. The first air-fuel ratio learning control is executed in preference to the first concentration learning control,
The second control means further executes second air-fuel ratio learning control for maintaining the air-fuel ratio of the intake gas led to the second cylinder group at a target air-fuel ratio, and the first concentration or the second concentration When the second concentration level is higher than the second predetermined level, the second concentration learning control is executed in preference to the second air-fuel ratio learning control, while the first concentration or the second concentration is equal to or lower than the second predetermined level. The evaporative fuel processing apparatus according to claim 1 or 2, wherein the second air-fuel ratio learning control is executed in preference to the second concentration learning control. The first control means further executes a first air-fuel ratio learning control for maintaining the air-fuel ratio of the intake gas guided to the first cylinder group at a target air-fuel ratio, and the first concentration and the second concentration The first concentration learning control is prohibited and execution of the first air-fuel ratio learning control is performed,
The second control means further executes second air-fuel ratio learning control for maintaining the air-fuel ratio of the intake gas guided to the second cylinder group at a target air-fuel ratio, and the first concentration and the second concentration 3. The evaporated fuel processing device according to claim 1, wherein the second air-fuel ratio learning control is executed while prohibiting the execution of the second concentration learning control when the difference between the two and the difference is larger than an allowable range. The first control means further executes a first air-fuel ratio learning control for maintaining the air-fuel ratio of the intake gas led to the first cylinder group at a target air-fuel ratio, and the first concentration and the second concentration When the first air-fuel ratio learning control has been executed and the difference is larger than the permissible range, it is determined that there is an abnormality in the location that affects the flow rate of the purge gas,
The second control means further executes second air-fuel ratio learning control for maintaining the air-fuel ratio of the intake gas guided to the second cylinder group at a target air-fuel ratio, and the first concentration and the second concentration When the second air-fuel ratio learning control is already executed, it is determined that there is an abnormality in a location that affects the flow rate of the purge gas. Evaporative fuel processing equipment.

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