JP2007198210A - Evaporated fuel control device for engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To inhibit evaporated fuel trapped in a canister from being a saturated condition and inhibit overflow even if a range where purge of evaporated fuel from the canister is possible at a time of idling is narrowed with accompanying drop of idling rotation speed. <P>SOLUTION: When a condition of the canister 43 is judged (S1) and overflow possibly occurs, ignition is cut off (S4) even during deceleration fuel cut and purging is forcibly executed, and purge quantity is adjusted to set air fuel ratio detected based on an O<SB>2</SB>sensor output in a downstream of a catalyst to a predetermined value (S7-S16). However, if intake manifold negative pressure (master back negative pressure) is predetermined value or less (S5) or temperature of the catalyst is low (S6), purging is limited (prohibited or reduced). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an evaporated fuel control device for an engine, and more particularly to an evaporated fuel control device for an engine capable of suppressing an overflow of evaporated fuel from a canister.

In a vehicle engine, evaporated fuel generated in a fuel tank is trapped by a canister, and the trapped evaporated fuel is discharged by introducing air into the canister when a predetermined condition is satisfied, and is supplied to an engine intake system. Then, the deviation of the air-fuel ratio due to the supply (purge) of evaporated fuel is detected by an air-fuel ratio sensor (O ₂ sensor) disposed in the exhaust system, and the control amount of the air-fuel ratio feedback control is corrected based on the sensor output. . In that case, since there is a response delay in the feedback correction of the air-fuel ratio, particularly when there is a large amount of evaporated fuel trapped in the canister and the evaporated fuel concentration (evaporative gas concentration) in the purge gas is high, the air-fuel ratio The feedback correction cannot be followed and the time during which the air-fuel ratio shifts to the rich side becomes longer, and the emission performance deteriorates. Therefore, the purge amount is gradually increased from zero to the required amount at the start of the purge, and the evaporated fuel concentration (evaporative gas concentration) in the purge gas is learned, and the fuel injection amount is estimated in advance by taking into account the deviation of the air-fuel ratio according to the evaporated fuel concentration. Control is performed such that the amount of fuel is reduced or the purge rate gradually increases as the fuel vapor concentration (evaporative gas concentration) increases. Recently, purging has been carried out in almost all engine operating areas including idling, and the evaporative gas concentration is learned in all areas other than when the deceleration fuel is cut, so that it does not affect drivability, idle performance, etc. Control is performed to increase the purge amount (evaporative gas suction amount) to the limit).

  As described above, the purging is performed in almost the entire region including the idle. However, in recent years, the engine idling speed has been decreasing more and more for measures such as fuel efficiency and environmental problems, and the air amount during idling has decreased accordingly. In this case, if the air amount is reduced by idling purge (idle purge), the air-fuel ratio becomes too dense unless the purge amount is also reduced. Therefore, the purge rate decreases as the air volume decreases. However, as a characteristic of the purge valve, there is a limit (minimum opening) for lowering the purge volume. It disappears and it becomes impossible to control. For this reason, when the idling speed is further reduced, the purge must be cut in the area where the idling purge has been performed until now. Therefore, the purgeable area is narrowed, the evaporated fuel (evaporative gas) of the canister increases, and the overflow tends to occur.

As a related prior art, as a technique for ensuring the adsorption capacity of the canister, a technique in which the deceleration fuel cut area is reduced and the purge area can be expanded when the evaporation gas adsorption capacity of the canister is low is known (for example, , See Patent Document 1).
JP-A-8-218915

  As described above, in the prior art, when the evaporative gas adsorption capacity of the canister is low, the deceleration fuel cut region is reduced, and thus the purge region is enlarged. However, even if the deceleration fuel cut region is reduced, the purge is still cut in the reduced deceleration fuel cut region, so the expansion of the purge region is limited, and the overflow of the evaporated fuel is sufficiently suppressed. It is not possible.

  According to the present invention, even when the area where the vaporized fuel can be purged from the canister becomes narrow at idling as the idling speed decreases, the vaporized fuel trapped in the canister is not saturated and overflow is suppressed. For the purpose.

  In the present invention, in a state where the evaporated fuel trapped in the canister is likely to overflow in a saturated state, the evaporated fuel is forcibly purged after cutting off the ignition even when the deceleration fuel cut that is not originally in the purge region is cut. The engine evaporative fuel control device is configured to suppress the evaporative fuel overflow from the canister.

  According to a first aspect of the present invention, there is provided an engine evaporative fuel control device comprising: deceleration fuel cut means for stopping fuel supply to a engine when a predetermined condition for performing fuel cut during deceleration is satisfied; Evaporated fuel supply means for supplying evaporated fuel trapped in the canister to the intake system when the purge execution condition is satisfied, determination means for determining a state in which the evaporated fuel is likely to overflow from the canister, and ignition for controlling engine ignition Control means, and when it is judged that the judgment means is likely to overflow when the fuel is decelerated, the ignition control means stops the ignition, and the evaporative fuel supply means forcibly supplies the evaporative fuel to the intake system. It is structured.

  In this way, the state of the canister is judged, and when the amount of evaporated fuel trapped in the canister is close to saturation and almost overflowed, the purge area is expanded and originally purged at the time of deceleration fuel cut Overflow can be suppressed by forcibly purging even in a region that was not. However, since it burns when it is ignited, the feeling of deceleration is reduced, so the purge is performed with the ignition cut off. By doing so, purging can be performed while maintaining a sense of deceleration, and overflow can be suppressed. The evaporated fuel purged at the time of the deceleration fuel cut is not burned but directly becomes an unburned gas and goes out to the exhaust system, but can be purified by an exhaust purification device such as a catalyst.

  According to a second aspect of the present invention, there is provided an engine evaporative fuel control device that detects the temperature of an exhaust purification device disposed in an exhaust passage in addition to the configuration of the engine evaporative fuel control device according to the first aspect. And when the temperature of the exhaust gas purification device detected by the temperature detecting means is lower than a predetermined value, the forced evaporative fuel supply by the evaporative fuel supply means at the time of deceleration fuel cut is suppressed. It is characterized by that.

  The evaporated fuel purged at the time of deceleration fuel cut is purified by the exhaust purification device, but this cannot be done when the temperature of the exhaust purification device such as the catalyst temperature is low. For this reason, when the temperature of the exhaust purification device is lower than a predetermined value, the supply of the evaporated fuel at the time of deceleration fuel cut is suppressed (prohibited or reduced). Thereby, it is possible to prevent the evaporated fuel from being discharged without being purified by the exhaust purification device.

  According to a third aspect of the present invention, there is provided an engine evaporative fuel control apparatus including an air fuel ratio detecting means for detecting an air fuel ratio of the engine in addition to the configuration of the engine evaporative fuel control apparatus according to the first aspect. The supply amount of the evaporated fuel is controlled based on the air-fuel ratio detected by the detection means.

  In this case, when supplying evaporated fuel during deceleration fuel cut, the amount of evaporated fuel is adjusted so that the air / fuel ratio of the engine, particularly the air / fuel ratio detected based on the output of the oxygen concentration detection sensor downstream of the exhaust purification device, becomes a predetermined value. By doing so, it is possible to supply the evaporated fuel when the deceleration fuel is cut while maintaining the purification performance of the evaporated fuel in the exhaust purification device.

  According to a fourth aspect of the present invention, there is provided a fuel vapor control apparatus for an engine according to a fourth aspect of the present invention. And determining the master back negative pressure based on the parameter detected by the master back negative pressure detecting means, and determining that the master back negative pressure is equal to or lower than a predetermined value, the evaporated fuel supply at the time of deceleration fuel cut It is characterized in that supply of forced fuel vapor by means is suppressed. The parameters related to the master back negative pressure are the output of a sensor that directly detects the master back negative pressure, the intake manifold negative pressure (negative pressure source), and the like.

  In this way, when the master back negative pressure is less than the predetermined value and the braking effect is poor, the purge performance during the deceleration fuel cut is suppressed (prohibited or reduced) to reduce the brake performance accompanying the evaporated fuel supply. Can be suppressed.

  As described above, when the amount of fuel vapor trapped in the canister is close to saturation and is likely to overflow, the purge area is expanded and forced even in the area that was not purged when the deceleration fuel was cut. However, since it is burned when it is ignited, the feeling of deceleration is reduced. Therefore, by purging with the ignition cut off, purging can be performed while maintaining the feeling of deceleration, and overflow can be suppressed. The evaporated fuel purged when the deceleration fuel is cut can be purified by the exhaust gas purification device.

  When the temperature of the exhaust purification device is lower than a predetermined value, the supply of the evaporated fuel at the time of deceleration fuel cut is suppressed (prohibited or reduced), and the evaporated fuel is discharged without being purified by the exhaust purification device. Can be prevented.

  In addition, when supplying evaporated fuel during deceleration fuel cut, the amount of evaporated fuel is adjusted so that the air-fuel ratio of the engine, particularly the air-fuel ratio detected based on the output of the oxygen concentration detection sensor downstream of the exhaust purification device, becomes a predetermined value. Thus, it is possible to supply the evaporated fuel when the deceleration fuel is cut while maintaining the purification performance of the evaporated fuel in the exhaust purification device.

  In addition, when the master back negative pressure is less than the predetermined value and the braking effect is poor, the brake performance associated with the evaporative fuel supply can be reduced by suppressing (prohibiting or reducing) the purge during deceleration fuel cut. Can be suppressed.

  1 and 2 show an example of an embodiment of the present invention. FIG. 1 is an overall view of the engine system, and FIG. 2 is a flowchart showing an operation of purge control at the time of deceleration fuel cut.

  In FIG. 1, reference numeral 1 denotes an engine body, which has a cylinder block 2, and is connected to an engine drive shaft (crankshaft) via a connecting rod (not shown) in a cylinder bore 3 formed by the cylinder block 2. A piston 4 is incorporated so as to be reciprocally movable, and an engine combustion chamber 6 is formed by the top surface of the piston 4, the inner surface of the cylinder bore 3, and the lower surface recess of the cylinder head 5 connected to the upper portion of the cylinder block 2. Yes. The cylinder head 5 is provided with an intake port 7 and an exhaust port 8 that open to the combustion chamber 6, and a poppet type intake valve 9 and an exhaust valve 10 are provided at the intake port 7 and the exhaust port 8. The cylinder head 5 is provided with a spark plug 11 in the approximate center of the lower surface recess.

  An intake pipe 13 constituting an intake passage 12 is connected to the cylinder head 5 upstream of the intake port 7, and an exhaust pipe 15 constituting an exhaust passage 14 is connected upstream of the exhaust port 8.

  An air cleaner 16 is connected to the inlet of the intake pipe 13, an air flow meter 17 also serving as an intake air temperature sensor is disposed in the vicinity of the connection portion, and a throttle body 19 incorporating a throttle valve 18 is disposed downstream thereof. Further, a surge tank 20 is disposed downstream thereof. The throttle body 19 is provided with a throttle sensor 21 for detecting the throttle opening. Further, the outlet portion of the intake pipe 13 communicating with the intake port 7 is divided into two passages by a partition wall 22, and a swirl control valve 23 is disposed in one of the passages. At the outlet portion of the intake pipe 13, a fuel injection injector 24 is disposed toward the intake port 7 at a connection position facing the passage on the side where the swirl control valve 23 is not disposed.

  The swirl control valve 23 is driven to open and close by a negative pressure diaphragm type actuator 26 via a link 25, and the operating pressure chamber of the actuator 26 is a check valve in a vacuum chamber 27 for accumulating negative pressure introduced from the surge tank 20. 28 is connected. A three-way solenoid valve 29 is arranged between the vacuum chamber 27 and the check valve 28 to switch the operating pressure introduced into the actuator 26 between the vacuum chamber 27 side (negative pressure) and the atmospheric side (atmospheric pressure). . When the engine is under a low load, the three-way solenoid valve 29 is switched to the vacuum chamber 27 side (negative pressure), and the actuator 26 is activated by the negative pressure to close the swirl control valve 23. As a result, the intake air flow rate increases and swirls are generated in the combustion chamber 6 of the engine. When the load is high, the three-way solenoid valve 29 is switched to the atmospheric side (atmospheric pressure), the actuator 26 is deactivated, and the swirl control valve 23 is opened. When the load is high, the passage area is increased, and the intake charge amount is secured.

In the exhaust pipe 15, a first catalytic converter 30A is disposed on the upstream side, and a second catalytic converter 30B is disposed on the downstream side. Then, O ₂ sensors (oxygen concentration sensors) 31A and 31B are provided on the upstream side and the downstream side of the first catalytic converter 30A, respectively, and the catalyst temperature sensor 32 is provided on the first catalytic converter 30A. The upstream O ₂ sensor 31A is a sensor that detects the oxygen concentration in the exhaust gas as feedback information for air-fuel ratio control, and the downstream O ₂ sensor 31B is a fault diagnosis of the upstream O ₂ sensor 31A. This is provided for the purpose of correcting deterioration of the upstream O ₂ sensor 31A. In this embodiment, as will be described later, the downstream O ₂ sensor 31B is used for purge control during deceleration fuel cut.

  The engine body 1 also includes, as various sensors, a crank angle sensor 33 that detects the rotation of the engine drive shaft (crankshaft), and a reference that determines the reference position of the ignition timing and injection timing based on the rotation angle of the intake camshaft. An angle sensor 34, a water temperature sensor 35 for detecting the engine water temperature, and the like are provided, and a knock sensor 36 is provided.

  The fuel supply system that supplies fuel to the injector 24 includes a fuel tank 37, and a fuel pump 38, a low-pressure fuel filter 39 A, a high-pressure fuel filter 39 B, and a pressure regulator 40 are provided in the fuel tank 37. Is arranged. A fuel passage 41 downstream of the pressure regulator 40 is disposed between the fuel tank 37 and the injector 24, and a pulsation damper 41 </ b> A is disposed in the middle of the fuel passage 41. The fuel is accommodated in the fuel tank 37 and sucked up by the fuel pump 38 through the low-pressure fuel filter 39A. Then, it passes through the high-pressure fuel filter 39B, is adjusted to a predetermined pressure by the pressure regulator 40, flows through the fuel passage 41, and is supplied to the injector 24 through the pulsation damper 41A.

  In addition, an evaporated fuel passage 42 is connected to the upper part of the fuel tank 37 as an evaporated fuel supply device that traps (adsorbs and captures) the evaporated fuel generated in the fuel tank 37, purges it when a predetermined condition is satisfied, and supplies it to the intake side. The other end of the evaporated fuel passage 42 is connected to an upper portion of a canister 43 that stores activated carbon for trapping adsorption. Further, a purge passage 44 connecting the upper portion of the canister 43 and the surge tank 20 of the intake system is provided, and a solenoid type purge valve 45 that controls the flow rate by duty control is disposed in the middle of the purge passage 44. . A catch tank 46 is provided between the canister 43 and the purge valve 45 to capture the liquefied evaporated fuel. An atmospheric passage 47 for introducing purge air is connected to the lower portion of the canister 43.

  Various controls of the engine are performed by an ECU (engine control unit) 48. Therefore, various signals that are outputs from the air flow meter 17, the air-fuel ratio sensors 31A and 31B, the catalyst temperature sensor 32, the crank angle sensor 33, the reference angle sensor 34, the water temperature sensor 35, the knock sensor 36, and the like are input to the ECU 48. The ECU 48 performs various control calculations based on these input signals. The ECU 48 outputs an ignition signal to the igniter 49 connected to the ignition plug 11, outputs an injection signal to the injector 24, outputs a swirl control signal to the three-way solenoid valve 29, and outputs a purge control signal to the purge valve 45. Is done. Thus, the ignition timing is controlled, the air-fuel ratio is controlled by adjusting the fuel injection amount, swirl control is performed, and purge control (evaporated fuel control) is performed.

  The control of the air-fuel ratio is performed by calculating the basic fuel injection amount based on the engine speed calculated from the output of the crank angle sensor 33 and the intake air amount calculated from the output of the air flow meter 17, and converting the basic fuel injection amount to the water temperature. Various corrections according to the engine water temperature calculated from the output of the sensor 35 are added, and feedback correction based on the output of the air-fuel ratio sensor 32 is added to the correction so that the engine air-fuel ratio converges to the target air-fuel ratio.

  The purge control is executed when a predetermined purge execution condition based on the engine speed, the engine load, the engine water temperature, etc. is satisfied (purge is executed in the entire region including the idling time except when the deceleration fuel cut is performed. As will be described later, purge is executed when the predetermined condition is satisfied even when the deceleration fuel is cut.) When the purge execution condition is satisfied, the purge valve 45 is opened, and the evaporated fuel trapped in the canister 43 is purged. Supply to tank 20. At the start of evaporative fuel supply, the purge rate (the purge amount with respect to the intake air amount of the engine) is set so that the supply amount of air including purged evaporative fuel (purge amount) gradually increases from 0 to the required amount according to the engine operating state. The ratio is set, and the duty ratio for driving the purge valve 45 is controlled in accordance with the set purge rate and intake air amount.

  In the purge control, the learning of estimating the concentration of the evaporated fuel in the purge gas is performed based on the correction amount of the air-fuel ratio feedback. In this learning, the evaporated fuel concentration is estimated based on a value obtained by dividing the average value of the air-fuel ratio feedback correction amount a predetermined number of times during the purge, that is, during the supply of the evaporated fuel, by the average purge rate during that time. Then, the fuel injection amount reduction correction is performed according to the learned evaporated fuel concentration.

  The deviation of the air-fuel ratio due to the supply of the evaporated fuel is detected by the upstream air-fuel ratio sensor 31A, and the air-fuel ratio is feedback-corrected based on the sensor output. Moreover, the delay in feedback response is compensated by the fuel injection amount reduction correction based on the evaporative fuel concentration learning, and the purge amount is reduced when the air-fuel ratio feedback correction amount exceeds the threshold value. The deviation of the air-fuel ratio due to the supply is suppressed.

  Further, in the purge control, the state of the canister 43 is determined, and when the amount of evaporated fuel trapped in the canister 43 is close to the saturated state and is likely to overflow, the purge region is expanded, and originally the deceleration fuel Purging (supplying of evaporated fuel) is forcibly performed even in an area that was not purged at the time of cutting. However, the evaporated fuel purged at the time of deceleration fuel cut is purified by the catalyst (catalytic converters 30A and 30B), so this cannot be done when the catalyst temperature is low. For this reason, when the detected value of the catalyst temperature sensor 32 is lower than a predetermined value, purging at the time of deceleration fuel cut is prohibited (it may be reduced). Further, when the intake manifold negative pressure (parameter related to the master back negative pressure) is less than a predetermined value and the brake is ineffective, purging at the time of deceleration fuel cut is prohibited so as to suppress a decrease in brake performance ( You can lose weight).

In the purge control during the deceleration fuel cut, the air-fuel ratio detected based on the output of the downstream O ₂ sensor 31B is maintained so that the purification performance of the evaporated fuel in the catalyst (catalytic converters 30A, 30B) is maintained. The purge amount is adjusted to a predetermined value.

  The details of the purge control at the time of deceleration fuel cut in this embodiment will be described below with reference to the flowchart shown in FIG.

  When this control starts, it is first determined whether or not the evaporation gas is likely to overflow, whether or not the evaporation gas concentration is greater than or equal to a predetermined value (high), whether or not the canister trap amount is greater than or equal to a predetermined value ( Step S1). Here, the evaporation gas concentration is estimated from the average value of the feedback correction amount when the evaporation gas (evaporated fuel) is purged, for example. In addition, the trap amount of the canister is directly detected by providing an HC sensor at the drain position of the canister, or is obtained by a method such as estimation from the evaporation gas concentration or the purge amount.

  And when the determination is YES and the evaporation gas concentration is greater than or equal to a predetermined value (deep) or the trap amount of the canister is greater than or equal to a predetermined value, the trap amount is close to saturation and is likely to overflow. It is determined whether the deceleration fuel cut condition is satisfied (step S2). This is determined, for example, by determining whether the engine is coasting (decelerating) in a state where the throttle is fully closed and the engine speed is higher than the speed at which the fuel is cut (rotation slightly higher than the idling speed).

  If the determination is YES and the deceleration fuel cut condition is satisfied, it is determined whether or not the deceleration fuel cut purge condition is satisfied (step S3). This means that it is determined whether or not a condition for purging is satisfied. For example, the engine water temperature is stable at a predetermined water temperature (for example, 60 ° C.), and the engine speed is lower than the fuel cut condition. Judgment is made based on whether the rotation speed is equal to or higher than the predetermined rotation speed and equal to or lower than the predetermined rotation speed on the high rotation side. The speed of fuel cut condition is set to the high speed side in addition to the low speed side. If the purge is performed at a very high speed, the amount of air is large while the amount of the vapor is insufficient and the air-fuel ratio becomes lean. It is because there is a case to do.

  If the determination is YES and the purge execution condition for deceleration fuel cut is satisfied, the ignition is first cut (step S4), and then whether the intake manifold negative pressure is greater than a predetermined value (negative pressure side) or not. If the master back negative pressure state is determined (step S5) and it is determined that the master back negative pressure is sufficient (YES), then the catalyst temperature is a temperature that can sufficiently purify the evaporated fuel discharged by the purge. (Higher than a predetermined value) is determined (step S6).

  Then, when the master back negative pressure is sufficient and the catalyst temperature is sufficiently high, it is determined whether or not the purge at the time of deceleration fuel cut was executed in the previous process (step S7). When it is the first time, an initial value of the purge rate (target purge rate at the time of fuel cut) is set (step S8). When purging is performed, the amount of fuel is added as fuel. Therefore, the fuel injection amount is corrected (purge gas correction) so that the amount is subtracted from the injector 24, and the total air-fuel ratio is controlled to the stoichiometric air-fuel ratio. In this case, the evaporation gas concentration correction A / F (cevrln), which is a purge reduction amount correction target (target purge reduction amount), is obtained by the product of the purge rate (rprg) and the evaporation gas concentration learning value (cevlof). The fuel injection amount is reduced accordingly. During the fuel cut, the purge rate (rprg) was calculated by dividing the evaporation gas concentration correction A / F (cevlrn) by the evaporation gas concentration learning value (cevlof), with the injected fuel being 0 and all being covered with the purge gas. Value.

  When the initial value of the purge rate is thus set, the process proceeds to a purge amount calculation process. Also, the purge rate is set only for the first time, and the process proceeds to the purge amount calculation process from the next time.

  Then, the purge amount is calculated from the intake air amount, intake manifold negative pressure, purge rate, and evaporation gas concentration at that time, and the purge valve is driven (step S9).

In this state, the purge rate is decreased or increased depending on whether the output (rear O2F / B amount) of the downstream O ₂ sensor is smaller than a predetermined value. That is, when the rear O2F / B amount is smaller than the predetermined value (YES), the purge rate is corrected to be reduced (corrected to close the purge valve), the purge valve drive amount is corrected (step S11), and the rear O2F / B is corrected. If the amount is greater than or equal to the predetermined value (NO), the purge rate is corrected to increase (corrected to open the purge valve), and the purge valve drive amount is corrected (step S12).

  Then, it is determined whether the purge rate is equal to or greater than the purge valve minimum opening (rprgmn) (step S13). If the purge valve is equal to or greater than the purge valve minimum opening (rprgmn) (YES), is the purge rate equal to or less than the purge valve maximum opening (rprgmx)? It is determined whether or not (step S14). If it is greater than the maximum purge valve opening (rprgmx), the purge rate is set to the maximum purge valve opening (rprgmx) that is a guard value, and the drive amount of the purge valve is corrected (step S15).

  Then, it is determined whether or not the state where the rear O2F / B amount is equal to or greater than a predetermined value is less than a predetermined time (step S16).

  When it is determined that the state where the rear O2F / B amount is equal to or greater than a predetermined value has continued for a predetermined time or longer, a process for prohibiting purge execution at the time of deceleration fuel cut is performed (step S17), and the purge valve is closed (step S18).

  Further, when it is determined that the deceleration fuel cut condition is not satisfied (step S2), when it is determined that the deceleration fuel cut purge condition is not satisfied (step S3), the intake manifold negative pressure is equal to or less than a predetermined value (atmospheric pressure). Side) (step S5), when the catalyst temperature is determined to be equal to or lower than a predetermined value (step S6), and when it is determined that the purge rate is smaller than the minimum purge valve opening (rprgmn) (step S13). Then, the process proceeds to the process of prohibiting the execution of purge when decelerating fuel cut (step S17), and the purge valve is closed (step S18).

  As mentioned above, although an example of embodiment was demonstrated, this invention is not limited to this, It is possible to implement in various aspects.

1 is an overall view of an engine system according to an embodiment of the present invention. It is a flowchart which shows the operation | movement of the purge control at the time of the deceleration fuel cut of embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Engine main body 11 Spark plug 12 Intake passage 14 Exhaust passage 17 Air flow meter 18 Throttle valve 20 Surge tank 21 Throttle sensor 24 Injector 30A, 30B Catalytic converter 31A, 31B O ₂ sensor 32 Catalyst temperature sensor 33 Crank angle sensor 35 Water temperature sensor 37 Fuel Tank 42 Evaporative fuel passage 43 Canister 44 Purge passage 45 Purge valve 48 ECU

Claims (4)

Decelerating fuel cut means for stopping fuel supply to the engine when a predetermined condition for performing fuel cut during deceleration is established, and evaporative fuel trapped in the canister when a predetermined purge execution condition is established other than during deceleration fuel cut Evaporative fuel supply means for supplying fuel to the intake system, determination means for determining a state in which the evaporative fuel is likely to overflow from the canister, and ignition control means for controlling the ignition of the engine,
When it is determined that the determination unit is likely to overflow when the deceleration fuel is cut, the ignition control unit stops the ignition, and the evaporative fuel supply unit forcibly supplies the evaporative fuel to the intake system. An evaporated fuel control device for an engine. Temperature detection means for detecting the temperature of the exhaust gas purification device arranged in the exhaust passage, and when the temperature of the exhaust gas purification device detected by the temperature detection device is lower than a predetermined value, the evaporation at the time of deceleration fuel cut 2. The evaporated fuel control device for an engine according to claim 1, wherein the forced fuel fuel supply by the fuel supply means is suppressed. The air-fuel ratio detecting means for detecting the air-fuel ratio of the engine is provided, and the supply amount of the evaporated fuel is controlled based on the air-fuel ratio detected by the air-fuel ratio detecting means. Evaporative fuel control device for engines. Master back negative pressure detecting means for detecting a parameter related to the master back negative pressure is provided, the master back negative pressure is determined based on the parameter detected by the master back negative pressure detecting means, and the master back negative pressure is 2. The evaporative fuel control device for an engine according to claim 1, wherein when it is determined that the evaporative fuel supply means is below a predetermined value, forced evaporative fuel supply by the evaporative fuel supply means at the time of deceleration fuel cut is suppressed.

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