JP2013204575A - Canister purge control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a canister purge control device suitable for motorcycles.SOLUTION: In order to purge a transpiration fuel adsorbed by a canister 39 to an intake passage 24, a solenoid-driven type purge control valve 52 is provided which controls a flow rate of the transpiration fuel flowing in a purge passage 40. Based on a fuel injection correction amount KO2 obtained in target air-fuel ratio control, a duty determination section 103 determines an energization duty value of the purge control valve 52. An energization duty determination section 103 determines the energization duty value of the purge control valve 52, such that the fuel injection correction amount KO2 is settled within a predetermined range when there is a purge request in a target air-fuel ratio control region. A learning value storage section 106 is provided in which, when getting out of the target air-fuel ratio control region, an energization duty value used for purge amount control at such a time is stored. In the next purge request, the energization duty value is read out of the learning value storage section 106, and control is started by using the read energization duty value as an initial value.

Description

  The present invention relates to a canister purge control device, and in particular, fuel injection when vaporized fuel stored in a canister is recirculated to an intake system (hereinafter referred to as “purge”) in order to suppress the outflow of the vaporized fuel to the outside. The present invention relates to a canister purge control device capable of controlling a purge amount based on a correction amount value.

  In Patent Document 1, in order to prevent the vaporized fuel generated in the fuel tank when the vehicle is stopped from being released into the atmosphere, the vaporized fuel is temporarily stored in a canister provided in the fuel system, and purge control is performed during engine operation. A canister purge control device that purges the intake system while performing flow control with a valve to perform combustion processing is disclosed. In this canister purge control device, the purge control valve is controlled based on the feedback correction coefficient of the basic fuel injection amount.

Japanese Patent No. 3212211

  In the canister purge control device described in Patent Document 1, based on the output of an O2 sensor (oxygen concentration sensor), target air-fuel ratio feedback control (hereinafter simply referred to as “target air-fuel ratio”) is used to converge the air-fuel ratio to the theoretical air-fuel ratio. In “control”, the duty ratio of the purge control valve is controlled so that the feedback correction coefficient falls within a predetermined range. However, if the conventional technique described in Patent Document 1 is applied as it is to an engine having a region where target air-fuel ratio control is performed and a region where target air-fuel ratio control is not performed, such as an engine in a motorcycle, the target air-fuel ratio is simply applied. Since the duty ratio of the purge control valve cannot be calculated according to the target air-fuel ratio control in the region where the fuel ratio control is not performed, if the purge control is stopped, a large amount of vaporized fuel accumulates in the canister, and the intake system in the next purge control There is a problem that the amount returned to is increased, emission becomes worse, and drivability is lowered.

  An object of the present invention is to solve the above-described problems and provide a canister purge control device that is better suited for a motorcycle.

  To achieve the above object, the present invention provides a purge passage (40) for purging the vaporized fuel adsorbed by the canister (39) for adsorbing the vaporized fuel generated in the fuel tank to the intake passage (24) of the engine. A solenoid-driven purge control valve (52) for controlling the flow rate of the flowing vaporized fuel, and the energization duty of the purge control valve (52) based on the fuel injection correction amount (KO2) obtained during the target air-fuel ratio control of the engine In a canister purge control device having a purge amount control unit (63) for determining a value and driving the purge control valve (52), the purge amount control unit (63) controls a preset target air-fuel ratio of the engine. When the purge request is made in the region, the energization duty of the purge control valve (52) is adjusted so that the fuel injection correction amount (KO2) converges within a predetermined range. An energization duty determination unit (103) for determining a value; and a learning value storage means (106) for storing an energization duty value when the value is out of the target air-fuel ratio control region. However, when the next purge request is made in the target air-fuel ratio control region, the previous energization duty value stored in the learning value storage means (106) is read and determined as the current initial value. The first feature is that the purge control valve (52) is controlled using the initial value. A second feature is that the purge amount is controlled by determining a value changed stepwise from the determined initial value as the energization duty value.

  In addition, according to the present invention, when the energization duty determination unit (103) has requested purge outside the target air-fuel ratio control region, the learning value storage means (106) when the current duty-fuel ratio control unit has deviated from the previous target air-fuel ratio control region. The third characteristic is that the energization duty value stored in (1) is determined as the initial value of this time.

  Further, according to the present invention, the energization duty determination unit (103) includes an idle region, an acceleration region, and a fuel in which the state of the engine is determined based on at least the engine speed (NE) and the throttle opening (TH). A fourth feature is that a control region discriminating means (101) for judging that it is outside the target air-fuel ratio control region when it is at least one of the cut regions is included.

  In the present invention, the energization duty determination unit (103) sets the energization duty value at unequal intervals of 20%, 50%, and 80% between 0% and 100%. There is a fifth feature in that the energization duty value is changed stepwise with reference to the duty map.

  In the present invention, the energization duty determining unit (103) increases the energization duty value when the fuel injection correction amount (KO2) is equal to or greater than the correction amount upper limit value (KO2RFU) in the target air-fuel ratio control region. When the injection correction amount (KO2) is less than the correction amount upper limit value (KO2RFU) and greater than or equal to the correction amount lower limit value (KO2RFD), the energization duty value is maintained, and the fuel injection correction amount (KO2) is the correction amount lower limit value (KO2RFD). The sixth feature is that the power supply duty value is reduced when the value is less than.

  According to the present invention having the first and second characteristics, the energization duty value during the purge amount control is learned and reflected in the next purge amount control and used as an initial value, so that the purge amount control can be executed and stopped. In an engine that repeats frequently, purge amount control can be performed even when target air-fuel ratio control is not performed, preventing a large amount of vaporized fuel from accumulating in the canister, thereby suppressing the level of deterioration in emissions and drivability be able to. In particular, since the purge amount control can be started from the duty value corresponding to the concentration of the evaporated fuel contained during the previous purge, it is possible to suppress the air-fuel ratio from becoming overrich. As a result, a sudden change in the air-fuel ratio can be suppressed, a reduction in emission can be suppressed, and drivability can be improved.

  According to the present invention having the third and fourth characteristics, the purge amount control is started from the energization duty value which is the previous learning value even for the purge amount control requested in the region other than the target air-fuel ratio control region. Therefore, it is possible to suppress a rapid change in the air-fuel ratio, suppress a decrease in emissions, and improve drivability.

  In the present invention having the fifth feature, energization of 0% to 20%, which is substantially off, and 80% to 100%, which is substantially on, of the usable range of the energization duty value. Smooth energization control can be performed by using the energization duty value obtained by equally dividing the duty value.

  According to the present invention having the sixth feature, the target air-fuel ratio converges quickly and the fluctuation can be reduced, so that a reduction in emission can be suppressed and drivability can be improved.

1 is a left side view of a motorcycle to which a canister purge control device according to an embodiment of the present invention is applied. 1 is a system configuration diagram of a main part of a motorcycle including a canister purge control device according to an embodiment. It is a timing chart which shows operation | movement of a purge control part. It is a figure which shows an example of a target air fuel ratio control area | region. It is a figure which shows an example of the area | region which implements purge amount control. It is a block diagram which shows the principal part function of the microcomputer which implement | achieves a purge amount control part.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a left side view of a motorcycle to which a canister purge control apparatus according to an embodiment of the present invention is applied. In FIG. 1, a motorcycle 1 is equipped with a four-cycle water-cooled engine 2. The body frame 3 of the motorcycle 1 includes a main frame 31 having a tip end joined to the upper end of the head pipe 30 and extending obliquely downward and rearward, and a down frame 32 having a tip end joined to the lower end of the head pipe 30. A seat frame 33 extending obliquely upward and rearward from an intermediate portion of the main frame 31; a subframe 34 joined to the seat frame 33 at the rear portion; and a rear end portion of the main frame 31 and a front end portion of the subframe 34 A hanger bracket 35 that is joined and extends downward is included. Ribs 41 and 42 are provided between the seat frame 33 and the subframe 34.

  The engine 2 includes a cylinder part 21, a crank chamber 22, and a speed reducer part 23. An intake pipe 24 is connected to the rear portion of the cylinder portion 21, and an end portion of the intake pipe 24 communicates with the inside of the air cleaner 4. A throttle body 38 is provided in the intake pipe 24, and the other end of the purge passage 40 whose one end is connected to the canister 39 is connected between the throttle body 38 and the cylinder portion 21. The vaporized fuel inlet of the canister 39 is connected to the upper part of the fuel tank 16. The canister 39 is not limited to the position shown in FIG.

  An exhaust pipe 25 is connected to the front part of the cylinder part 21, and the exhaust pipe 25 bypasses the lower part of the vehicle body and is connected to the muffler 5 at the rear part of the vehicle body. The engine 2 is coupled to and supported by the lower portions of the hanger bracket 35 and the down frame 32. A radiator 43 through which the cooling water of the engine 2 is circulated is attached to the down frame 32. A side stand 49 is pivotally supported on a stay 47 joined to the lower portion of the hanger bracket 35.

  A top bridge 26 and a bottom bridge 27 are coupled to the top and bottom of a steering stem (not shown) penetrating the head pipe 30 vertically. A front wheel WF is rotatably supported by a front wheel shaft 29 at a lower end portion of a front fork 28 supported by the top bridge 26 and the bottom bridge 27. The headlight 30 and the meter device 8 are supported on the head pipe 30 by a stay 36 protruding toward the front of the vehicle body. A steering handle 6 is attached to the top of the top bridge 26, and a grip 44 and a mirror 45 are attached to the left and right of the steering handle 6, respectively.

  The hanger bracket 35 is provided with a pivot 9 extending in the vehicle width direction. The pivot 9 supports the front portion of the swing arm 10 so as to be swingable in the vertical direction. The rear wheel WR is supported by a rear wheel shaft 11 provided at the rear end portion of the swing arm 10. A drive sprocket 37a is coupled to the output shaft 46 of the speed reducer section 23, and a driven sprocket 37b is coupled to the rear wheel shaft 11. The drive chain transmits the output of the engine 2 to the rear wheel WR between the two sprockets. 12 is passed.

  The swing arm 10 is supported at the front end by the pivot 9 and at the middle by the cushion unit 13. The cushion unit 13 is connected to the swing arm 10 and the vehicle body frame 3 between the pivot 9 of the swing arm 10 and the rear wheel WR. The upper end of the cushion unit 13 is supported by the hanger bracket 35 in front of the battery 19, and the lower end of the cushion unit 13 is supported by a stay 15 that projects downward from the swing arm 10 via a link mechanism 14 disposed below the swing arm 10. Connected. An occupant seat 17 is disposed at the rear of the fuel tank 16.

  FIG. 2 is a system configuration diagram of a main part of the motorcycle including the canister purge control device according to the present embodiment. In FIG. 2, a throttle valve 49 is provided in a throttle body 38 provided in an intake pipe 24 connected to the engine 2, and a fuel injection device 50 is provided between the throttle valve 49 and the engine 2. The throttle valve 49 is provided with a throttle sensor 51 for detecting the throttle opening TH. Further, one end of a purge passage 40 for the vaporized fuel is connected to the intake pipe 24 between the fuel injection device 50 and the throttle valve 49. The other end of the purge passage 40 is connected to the upper portion of the fuel tank 16 via the canister 39. The canister 39 contains activated carbon and adsorbs and stores the vaporized fuel generated in the fuel tank 16. Between the canister 39 and the intake pipe 24, the purge passage 40 is provided with a purge control valve 52 for controlling the opening amount of the purge passage 40 to adjust the purge amount (capacity flow rate). The purge control valve 52 is driven by a solenoid, and the opening / closing amount thereof is controlled by the drive duty of the solenoid, that is, the ON time ratio of the energization time (ON time / (ON time + OFF time)). A fuel passage 54 is connected to the fuel injection device 50 to supply fuel discharged from a fuel pump 53 provided in the fuel tank 16 to the fuel injection device. The exhaust pipe 25 is connected to a muffler 5 including a catalyst, and an oxygen concentration sensor (hereinafter referred to as “O2 sensor”) 55 for detecting the oxygen concentration in the exhaust gas is provided between the muffler 5 and the engine 2. An engine speed sensor 58 that detects the engine speed NE is provided in the crankshaft 56 of the engine 2 or the rotating portion 57 that rotates in relation to the crankshaft 56.

  Further, a control device 60 that determines the fuel injection amount based on information detected by the engine speed sensor 58, the throttle sensor 51, and the O2 sensor 55 and outputs a drive command to the fuel injection device 50 is provided. The control device 60 includes a basic fuel injection amount calculation unit 61 that determines a basic fuel injection amount (basic fuel injection time) Ti based on the engine speed NE and the throttle opening TH, and oxygen concentration information output from the O2 sensor 55. A fuel injection correction amount KO2 is determined by air-fuel ratio feedback using O2, and a fuel injection amount correction unit 62 for correcting the basic fuel injection amount Ti is provided. The O2 sensor inputs an on / off signal according to whether the oxygen concentration is higher or lower than the oxygen concentration corresponding to the stoichiometric air-fuel ratio as a detection signal to the control device 60. Further, the control device 60 includes a purge amount control unit 63 that performs solenoid duty control (purge amount control) in accordance with the fuel injection correction amount KO2. In addition to the fuel injection correction amount KO2, the basic fuel injection amount Ti is corrected using other parameters such as the engine temperature, the atmospheric temperature, the atmospheric pressure, and the intake pipe negative pressure in addition to the fuel injection correction amount KO2. May be. The control device 60 can be configured by a microcomputer.

  FIG. 3 is a timing chart showing the operation of the purge control unit. In FIG. 3, the uppermost stage is a control region determination signal indicating whether or not the target air-fuel ratio control is performed, an on signal indicating that the target air-fuel ratio control region is based on the engine speed NE and the throttle opening TH, An off signal indicating that the region is not subjected to the fuel ratio control (hereinafter referred to as “non-air-fuel ratio control region”) is output. The non-air-fuel ratio control region is, for example, during idling, when fuel is cut, or when sudden acceleration exceeds a predetermined value.

  The second stage is a diagram showing a change in the fuel injection correction amount KO2, which is a correction amount upper limit value KO2RFU and a correction amount lower limit value KO2RFD which are set to determine whether or not to purge the vaporized fuel. The change in the fuel injection correction amount KO2 is shown in relation. During the purge amount control, if the fuel injection correction amount KO2 exceeds the correction amount upper limit value KO2RFU (KO2> KO2RFU), the index INDEX as a function of the energization duty of the purge control valve 52 is increased and the purge control valve 52 Increase the opening. On the other hand, if the fuel injection correction amount KO2 is less than the correction amount lower limit value KO2RFD (KO2 <KO2RFD), the index INDEX is reduced to reduce the opening of the purge control valve 52. When the fuel injection correction amount KO2 is not more than the correction amount upper limit value KO2RFU and not less than the correction amount lower limit value KO2RFD (KO2RFU> KO2> KO2RFD), the previous index INDEX is maintained.

  The energization duty is set in advance in the purge amount control unit 63 as a map corresponding to the index INDEX, and the larger the energization duty is selected as the index INDEX becomes larger, the purge flow rate is increased. Here, the index INDEX is set in four stages, and the energization duties 20%, 50%, 80%, and 100% are associated with the indexes INDEX1 to INDEX4, respectively. The initial value of the index INDEX is the index INDEX1, but when the transition from the target air-fuel ratio control region to the non-air-fuel ratio control region is performed, the index INDEX at that time is stored, and when the next transition to the target air-fuel ratio control region is performed The index INDEX being read is read out, and the energization duty is increased or decreased using the index INDEX as an initial value.

  The third stage shows changes in the purge amount control determination signal obtained by the relationship between the fuel injection correction amount KO2, the correction amount upper limit value KO2RFU, and the correction amount lower limit value KO2RFD shown in the second stage. When the purge amount control is performed, the purge amount control determination signal is ON “1”. When the purge amount control is not performed, the purge amount control determination signal is OFF “0”.

  The bottom row shows an example of changes in the index INDEX. During the target air-fuel ratio control, the index INDEX is increased or decreased by a predetermined change width, that is, a change width according to a value stored in the index map, according to the change of the fuel injection correction amount KO2.

  The operation will be described with reference to FIG. At timing t1, target air-fuel ratio control is started. Accordingly, the fuel injection correction amount KO2 that was “1.0” in the non-air-fuel ratio control region becomes smaller. At the timing t1 when the target air-fuel ratio control is started, since the fuel injection correction amount KO2 exceeds the correction amount upper limit value KO2RFU, the purge amount control execution determination signal is turned on, and the index INDEX1 is selected as the initial value of the index INDEX Is done. The index INDEX gradually increases until the fuel injection correction amount KO2 falls below the correction amount upper limit value KO2RFU. When the fuel injection correction amount KO2 becomes equal to or smaller than the correction amount upper limit value KO2RFU, the index INDEX is maintained while the fuel injection correction amount KO2 is equal to or larger than the correction amount lower limit value KO2RFD. When the fuel injection correction amount KO2 falls below the correction amount lower limit value KO2RFD at timing t2, the index INDEX is decreased. Then, the index INDEX is maintained until the fuel injection correction amount KO2 starts to rise, the fuel injection correction amount KO2 exceeds the correction amount lower limit value KO2RFD at timing t3, and further exceeds the correction upper limit value KO2RFU. At time t4, when the fuel injection correction amount KO2 exceeds the correction amount upper limit value KO2RFU, the index INDEX starts to increase again. That is, when the fuel injection correction amount KO2 is larger than the correction upper limit value KO2RFU, the index INDEX is increased. When the fuel injection correction amount KO2 is smaller than the correction lower limit value KO2RFD, the index INDEX is decreased. When it is, the control is performed so as to maintain the index INDEX.

  When the index INDEX increases and the fuel injection correction amount KO2 starts to decrease and the fuel injection correction amount KO2 falls below the correction amount lower limit value KO2RFD at timing t5, the index INDEX is decreased, and the index INDEX is continuously reduced until timing t6. When the target air-fuel ratio control area is deviated from at the timing t7, the index INDEX at that time (index INDEX2 in this example) is stored as a learning value, the output of the index INDEX is turned off, and the purge amount control is turned off.

  Even in the non-air-fuel ratio control region, a purge request can be met as necessary. In the example of FIG. 3, at timing t8, purge is performed in the non-air-fuel ratio control region and purge amount control is executed. In the purge performed between timing t8 and timing t9, the non-air-fuel ratio control region is Since the value “1” exceeding the correction amount upper limit value KO2RFU is referred to as the injection correction amount KO2, the index INDEX is increased. At this time, the index INDEX1 starts increasing with the index INDEX1 as an initial value. This is because a sudden change in the air-fuel ratio is suppressed by selecting and using the smallest index INDEX. Since the purge is completed at timing t9, the increase in the index INDEX is stopped, the output of the index INDEX is turned off, and the purge amount control is turned off.

  When the target air-fuel ratio control region is entered again at timing t10, the index INDEX2 starts increasing with the index INDEX2 stored as the learning value as the initial value at timing t7. Since the operation at timings t10 to t11 is the same as that at timings t1 to t7, description thereof is omitted. At timing t11, when the vehicle deviates from the target air-fuel ratio control region and enters the non-air-fuel ratio control region, the index INDEX (index INDEX4 here) at that time is stored as a learned value. Therefore, when the purge amount control is performed next time when entering the target air-fuel ratio control region, the index INDEX4 learned at the timing t11 is read, and a corresponding 100% energization duty is selected to perform the purge amount control. Done.

  In this way, during the target air-fuel ratio control, the index INDEX is determined based on where the fuel injection correction amount KO2 is relative to the correction amount upper limit value KO2RFU and the correction amount lower limit value KO2RFD, and corresponds to the determined index INDEX. The purge amount is controlled by the energization duty. When the purge amount control is ended, an index INDEX indicating the energization duty at the end is stored and learned, and the next purge amount control is started with the learning value as an initial value. By using the learning value, the purge amount control can be started from an appropriate energization duty corresponding to the concentration of the evaporated fuel that is changing sequentially.

  Note that the memory learning of the index INDEX is not limited to being performed when the target air-fuel ratio control area is deviated, but when the index INDEX is deviated from the target air-fuel ratio control area, the most frequently used index INDEX is used in the target air-fuel ratio control area. The used value or the average value used may be stored as a learning value.

  The target air-fuel ratio control region is determined by the engine speed NE and the throttle opening TH. FIG. 4 is a diagram showing an example of the target air-fuel ratio control region, where the vertical axis represents the throttle opening TH and the horizontal axis represents the engine speed NE. The target air-fuel ratio control region O2F / B is between the upper limit engine speed O2NEH and the lower limit engine speed O2NEL, and is executed between the upper limit throttle opening degree O2THH and the lower limit throttle opening degree O2THL. The upper limit throttle opening degree O2THH and the lower limit throttle opening degree O2THL differ depending on the engine speed NE. A hysteresis width Hy can be provided for each of the upper and lower limit engine speeds O2NEH and O2NEL and the upper and lower limit throttle openings O2THH and O2THL. This is to avoid sensitively responding to slight fluctuations in the engine speed NE and the throttle opening TH. As shown in FIG. 4, an idle region where the engine speed NE is low, a region where the engine speed NE is extremely high and the engine speed NE needs to be limited by fuel cut or the like, and a throttle opening TH is extremely large (TH> In the (O2THH) acceleration region, the target air-fuel ratio control is not performed. Note that the target air-fuel ratio control can be performed even when the vehicle is stopped in the range of the low engine speed and the low throttle opening indicated by reference numeral 70 in FIG. 4, for example, in an idle state, and the emission is improved when the vehicle is stopped. This is for the purpose of illustration.

  FIG. 5 is a diagram showing an example of the region where the purge amount control is performed. As shown in FIG. 5, the purge control region is determined by the engine speed NE and the throttle opening TH as in the target air-fuel ratio control region. It is determined. The purge control upper limit throttle opening PTHH, the purge control lower limit throttle opening PTHL, the purge upper limit engine speed PNEH, and the purge control lower limit engine speed PNE can each have a hysteresis width Hy. This is to avoid sensitively responding to slight fluctuations in the engine speed NE and the throttle opening TH. Further, the purge amount control based on the engine speed NE and the throttle opening TH is used as a criterion for determining whether or not to perform the purge amount control when the engine coolant temperature, the atmospheric temperature, the vehicle speed, etc. are within predetermined ranges. You may make it judge whether it is an area | region.

  FIG. 6 is a block diagram showing main functions of a microcomputer that realizes the purge amount control unit 63. In FIG. 6, the air-fuel ratio control region determining unit 101 determines whether or not the range determined by the engine speed NE and the throttle opening TH is within a preset target air-fuel ratio control region. The purge execution determination unit 102 determines whether the range determined by the engine speed NE and the throttle opening TH is within a preset purge control amount execution region. When the air-fuel ratio control region determination unit 101 recognizes that the engine state is within the target air-fuel ratio control region, the purge execution determination unit 102 is activated. When the purge execution determination unit 102 recognizes that the engine state is within the purge control execution region, the duty value determination unit 103 is activated.

  The duty value determination unit 103 reads the fuel injection correction amount KO2 obtained by the target air-fuel ratio control, compares the fuel injection correction amount KO2 with the correction amount upper limit value KO2RFU and the correction amount lower limit value KO2RFD, and indexes based on the vertical relationship thereof. INDEX is determined, and the energization duty corresponding to the index INDEX is determined with reference to the index / energization duty map 104. The determined energization duty is supplied to a solenoid driver 105 that drives the purge control valve 52 to drive the purge control valve 52. The energization duty is set to a value obtained by adding or subtracting the index INDEX corresponding to the fuel injection correction amount KO2 to the duty initial value stored in the duty initial value storage unit 106. When it is recognized that the engine state is outside the target air-fuel ratio control region, the duty value determination unit 103 stores the current energization duty as a learning value in the duty initial value storage unit (learning value storage unit) 106, and this storage The value is used as an energization duty initial value at the next control. Note that a storage unit as a learning value storage unit may be provided separately from the duty initial value storage unit 106.

  FIG. 6 shows a configuration in which the purge amount control is performed when the target air-fuel ratio control region and the purge region overlap, but even when a purge request is made outside the target air-fuel ratio control region, the target air-fuel ratio control region is outside the target air-fuel ratio control region. Instead of using a predetermined energization duty value to be used, the purge request can be met with the energization duty value learned in the target air-fuel ratio control region as the initial value of the energization duty. Therefore, the purge amount control can be performed as necessary regardless of whether the air-fuel ratio is rich or lean.

  DESCRIPTION OF SYMBOLS 1 ... Motorcycle, 2 ... Engine, 4 ... Air cleaner, 16 ... Fuel tank, 24 ... Intake pipe, 38 ... Throttle body, 39 ... Canister, 40 ... Purge passageway, 49 ... Throttle valve, 50 ... Fuel injection device, 51 ... Throttle valve, 52 ... Purge control valve, 55 ... O2 sensor, 58 ... Engine speed sensor, 60 ... Control device, 62 ... Fuel injection amount correction unit, 63 ... Purge amount control unit, 101 ... Air-fuel ratio control region determination unit, DESCRIPTION OF SYMBOLS 102 ... Purge execution determination part, 103 ... Duty determination part, 104 ... Index / energization duty map, 106 ... Duty initial value (learning value) storage part

Claims (6)

Solenoid drive type for controlling the flow rate of the vaporized fuel flowing through the purge passage (40) for purging the vaporized fuel adsorbed by the canister (39) adsorbing the vaporized fuel generated in the fuel tank to the intake passage (24) of the engine The purge control valve (52) and the duty ratio of the purge control valve (52) determined based on the fuel injection correction amount (KO2) obtained during the target air-fuel ratio control of the engine, and the purge control valve (52 A canister purge control device having a purge amount control unit (63) for driving
The purge amount control unit (63)
Energization duty for determining the energization duty value of the purge control valve (52) so that the fuel injection correction amount (KO2) converges within a predetermined range when a purge request is made in a preset target air-fuel ratio control region of the engine. A determination unit (103);
Learning value storage means (106) for storing an energization duty value when it deviates from the target air-fuel ratio control region,
The energization duty determination unit (103) reads the previous energization duty value stored in the learning value storage means (106) when the next purge request is made in the target air-fuel ratio control region, and reads the initial The canister purge control device, wherein the purge control valve (52) is controlled using the determined initial value.   2. The canister purge control apparatus according to claim 1, wherein the purge amount is controlled by determining a value changed stepwise from the determined initial value as an energization duty value. The energization duty determination unit (103)
When there is a purge request outside the target air-fuel ratio control region, the energization duty value stored in the learning value storage means (106) when the previous value is out of the target air-fuel ratio control region is determined as the current initial value. The canister purge control apparatus according to claim 1 or 2, characterized by the above-mentioned. The energization duty determination unit (103)
The target air-fuel ratio when the engine state is at least one of an idle region, an acceleration region, and a fuel cut region determined based on at least the engine speed (NE) and the throttle opening (TH). The canister purge control apparatus according to any one of claims 1 to 3, further comprising a control area discriminating means (101) for judging that the area is out of the control area.   The energization duty determining unit (103) has a duty map in which the energization duty value is set at non-uniform intervals of 20%, 50%, and 80% between 0% and 100%, The canister purge control apparatus according to any one of claims 1 to 4, wherein an energization duty value is changed stepwise with reference to the duty map. The energization duty determination unit (103)
In the target air-fuel ratio control region, when the fuel injection correction amount (KO2) is equal to or greater than the correction amount upper limit value (KO2RFU), the energization duty value is increased, and the fuel injection correction amount (KO2) is less than the correction amount upper limit value (KO2RFU). When the correction amount lower limit value (KO2RFD) is not less than the correction amount lower limit value (KO2RFD), the energization duty value is maintained. When the fuel injection correction amount (KO2) is less than the correction amount lower limit value (KO2RFD), the energization duty value is decreased. The canister purge control apparatus according to any one of claims 1 to 5, wherein