Method and device for controlling an internal combustion engine during flushing of a collecting tank at idle speed

Abstract

A method for controlling an internal combustion engine during accumulator purge at idle, the method comprising: Determining by a controller (100) whether the current operating information of a vehicle satisfies an idle purge condition; Performing a purge of the collection container (20) by the controller (100) during a partial load condition; Determining by the controller (100) whether the learning time of the accumulator purge performed during the part-load condition is greater than or equal to a target time when a purge operation condition is met; and Carrying out a flushing of the collecting tank (20) at idle by the controller (100) if the learning time of the collecting tank flushing carried out during the partial load condition is greater than or equal to a target time, wherein the idle purging is performed at an idle condition of less than 700 rpm without operation of an accelerator pedal; Determining whether an idle purge termination condition is met; Calculating a reduction rate of the idle purge when the idle purge is completed when the idle purge completion condition is met; and Controlling the closing of a purge valve (40) according to the calculated idle purge reduction rate after idle purge has ended, wherein the idle purge reduction rate is different from a purge reduction rate during the part-load condition.

Description

BACKGROUND(a) Area of ​​Revelation

[0001] Embodiments of the present disclosure relate to a method and apparatus for controlling an internal combustion engine during idle purge of a sump, and more particularly to a method and apparatus for controlling an internal combustion engine during idle purge of a sump, which method and apparatus differ from controlling an internal combustion engine during a part-load condition and can ensure stable combustion in certain situations such as concentrated purge. (b) Description of related art

[0002] In general, the purge volume in a collection tank has been increased by a maximum amount during idling and while driving due to stricter regulations imposed by the authorities on evaporative gas.

[0003] A device and method for controlling the flushing of a collecting tank during idle operation are disclosed in the published Korean patent application KR 10 2004 0 017 635 A, published on February 27, 2004. As disclosed in this published patent application, vehicles are designed to collect the evaporative gas (HC) harmful to human organism generated in a fuel tank and then to guide the collected evaporative gas (HC) through a purge valve to the surge tank for the internal combustion engine and to supply it to a combustion chamber.

[0004] Evaporative gas (HC) is mostly generated when the fuel remaining in a fuel tank evaporates, so it is important to collect the evaporative gas (HC) generated by the volatilization in a collection tank and prevent the saturation of the collection tank by appropriately supplying the collected evaporative gas (HC) to an internal combustion engine.

[0005] According to the relevant regulatory requirements for evaporative gas (HC), control is performed to maximize the purge amount of a receiver purge valve, i.e., the opening ratio of a purge valve.

[0006] In order to control the purging of the evaporative gas (HC) collected in a collecting tank as described above, the amount (concentration) of the evaporative gas (HC) collected in the collecting tank is determined by determining a feedback level of a fuel amount depending on the amount (concentration) of oxygen in the exhaust gas detected by an oxygen sensor, and then the opening ratio of a purge valve, thereby controlling.

[0007] However, with a header purge, the purge rate and purge gas concentration may be incorrect, so manufacturers must cope with sudden disturbances caused by the purge gas supplied to the combustion engine by increasing the reserve torque to stabilize combustion.

[0008] From US 5 404 862 A, a flushing of the collecting tank when the engine is idling and, depending on the duration of a learning time of the flushing in the idle or partial load range, is known.

[0009] US 2003 / 0 047 172 A1 discloses a system and method for controlling the fuel injection of a vehicle, in which a MAP sensor (manifold absolute pressure sensor) is used to calculate fluctuations in the intake pressure in a purge interval in order to compensate the final fuel quantity, thereby improving the drive performance and minimizing fuel consumption.

[0010] DE 60 2005 005 531 T2 describes a fuel injection control device for an internal combustion engine. The engine includes a direct injection device for directly injecting fuel into a combustion chamber of the engine, an intake manifold injection device for injecting fuel into an intake manifold of the engine, and a fuel vapor treatment unit for discharging exhaust gas containing vaporized fuel into the intake manifold.

[0011] From DE 699 17 115 T2, a device is known for measuring the vapor concentration in an internal combustion engine with combustion of a lean mixture, which device has a device for switching, when the concentration of the fuel vapor is detected during the lean combustion operation of the internal combustion engine, from the lean combustion operation to the homogeneous combustion operation and for detecting the concentration of the fuel vapor during the homogeneous combustion operation.

[0012] DE 697 18 386 T2 provides a fuel vapor treatment device for an engine provided with an intake passage, comprising a purge control valve for controlling a fuel vapor purge amount to be purged to the intake passage; air-fuel ratio detecting means for detecting the air-fuel ratio; purge action starting means for starting a fuel vapor purge action when the intake air amount is greater than a predetermined amount which is greater than the intake air amount at idling of the engine; valve opening control means for gradually opening the purge control valve from the fully closed state to a target opening degree when the fuel vapor purge action is started; and purge action authorization means for allowing a fuel vapor purge action at idling of the engine after the fuel vapor purge action is started.

[0013] Furthermore, DE 691 23 559 T2 shows a control system for a vehicle with a device for the recirculation of fuel vapors, which is mounted between the fuel supply and an intake manifold of an internal combustion engine. OVERVIEW

[0014] As described above, torque control is required for an internal combustion engine to increase reserve torque during each purge operation of a reservoir to stabilize combustion in the related art. However, for the purpose of fuel efficiency, it is preferable to minimize reserve torque instead of fuel control, or, if necessary, to use reserve torque only to a minimum.

[0015] Furthermore, the required reserve torque during a part-load condition with a relatively large intake air volume and the required reserve torque at idle with a small intake air volume are not differentiated in the related art. However, it is necessary to selectively determine the amount of reserve torque and whether to use the reserve torque differently depending on the situation in order to improve fuel efficiency.

[0016] For example, the following problems arise when reserve torque is minimized to improve fuel efficiency.

[0017] Fig. Figure 5 shows a phenomenon where the engine speed drops rapidly from 700 rpm to 610 rpm when purging is terminated at idle before purge gas concentration learning is completed at a high evaporative gas concentration in a collection canister. This condition may be uncomfortable for the driver, and consequently, the engine may shut down.

[0018] Specifically, when the air-fuel ratio is rich, a purge valve is immediately closed due to dense purge gas, the flow of the dense purge gas is terminated, and the engine speed fluctuates due to the lean peak during a transition period when the air-fuel ratio should be controlled only by fuel injection based on feedback from an oxygen sensor. Given this problem, there is a need to adjust the lean peak air-fuel ratio through precise mapping. However, there are fundamental differences between purge valves, so the problem is limited by mapping alone.

[0019] Fig. 6 shows a phenomenon whereby the speed fluctuations occur due to an excessively high fuel / air ratio during idle purge in an evaporative gas leak diagnosis with highly concentrated evaporative gas in a collection tank.

[0020] The speed fluctuations of an internal combustion engine are caused by the excessively rich air-fuel ratio due to the inflow of a highly concentrated purge gas during receiver purge for evaporative gas leak diagnosis with highly concentrated evaporative gas in a receiver. To solve this problem, the reserve torque or speed of the internal combustion engine must be increased, but a technical solution to this problem has not yet been proposed in the related art.

[0021] It is therefore the object of the present disclosure to provide a method and apparatus for controlling an internal combustion engine that can eliminate an unstable condition due to speed fluctuations of the internal combustion engine during idle purge and improve fuel efficiency.

[0022] The object is achieved by a method having the features of claim 1 and a device having the features of claim 7. Advantageous further developments can be found in the subclaims.

[0023] Other objects and advantages of the present disclosure will become apparent from the following description and will become apparent from the embodiments of the present disclosure. Furthermore, it will be apparent to one of ordinary skill in the art to which this disclosure pertains that the objects and advantages of the present disclosure may be realized by the claimed means and combinations thereof.

[0024] According to one embodiment of the present disclosure, a method for controlling an internal combustion engine includes: determining whether the current operating information of a vehicle satisfies an idle purge condition; performing a reservoir purge by the controller during a partial load condition; determining whether the reservoir purge learning time performed during the partial load condition is greater than or equal to a target time when a purge operation condition is satisfied; and performing the reservoir purge at idle when the reservoir purge learning time performed during the partial load condition is greater than or equal to a target time, wherein the idle purge is performed at an idle condition of less than 700 rpm without operation of an accelerator pedal; determining whether an idle purge termination condition is satisfied;Calculating an idle purge reduction rate when the idle purge is completed when the idle purge completion condition is met; and controlling the closing of a purge valve according to the calculated idle purge reduction rate after completion of the idle purge, wherein the idle purge reduction rate is different from a purge reduction rate during the part-load condition.

[0025] According to another embodiment of the present disclosure, a method includes determining whether the diagnosis is for evaporative fuel gas leaks; setting a reserve torque amount depending on whether the diagnosis is for evaporative fuel gas leaks; and requesting the safe setting of a reserve torque amount from the torque control unit of the internal combustion engine.

[0026] The method may further include: setting the reserve torque to suppress fluctuations in the engine speed when the purge is completed if a learning time of the purge gas concentration of the accumulator is shorter than a predetermined target time; and requesting the safe setting of a reserve torque amount from the torque control unit of the engine when the idle purge is completed.

[0027] The method may further include: setting the reserve torque to suppress engine speed fluctuations when the purge is completed if an oxygen sensor output value is not within the predetermined range; and requesting the safe setting of a reserve torque amount from the engine torque control unit when the idle purge is completed.

[0028] The amount of reserve torque set during idle purge may be different from the amount of reserve torque set when idle purge is completed.

[0029] According to another embodiment of the present disclosure, an apparatus for controlling an internal combustion engine includes: a canister purge system that collects evaporative gas in a fuel tank connected to an intake system of an internal combustion engine via a purge valve and purges the collected evaporative gas to the intake system of the internal combustion engine, wherein the canister purge is performed during a partial load condition; an operation information detection unit that detects an operating state of the internal combustion engine; and a controller that determines whether idle purge is being performed and controls the purge valve based on operation information of a vehicle and the learning time of the purge gas concentration of the canister, thereby controlling the canister purge system;and wherein the controller is configured to open the purge valve and perform the idle purge of the accumulator when the current operating information of a vehicle satisfies an idle purge condition and the learning time for the purge concentration of the accumulator is greater than or equal to a set time, wherein the idle purge is performed under an idle condition of less than 700 rpm without operation of an accelerator pedal, wherein the controller determines whether an idle purge termination condition is satisfied, calculates an idle purge reduction rate when the idle purge is completed when the idle purge termination condition is satisfied, and controls the closing of the purge valve in accordance with the calculated idle purge reduction rate when the idle purge is completed, and wherein the idle purge reduction rate is different from a purge reduction rate during the part-load condition.;

[0030] The device may further include a torque control unit of the internal combustion engine, wherein the controller may determine during purging whether a diagnosis for fuel evaporative gas leakage is being performed, set an amount of reserve torque based on the determination result, and request the torque control unit of the internal combustion engine to safely set an amount of reserve torque.

[0031] When the concentration of the evaporative gas in the collection tank is equal to or higher than a predetermined level, the controller may set a reserve torque to suppress engine speed fluctuations when purging is completed, and request the torque control unit of the engine to safely set an amount of the reserve torque when purging is completed.

[0032] The device may further include an oxygen sensor for detecting an oxygen concentration in the exhaust gas, wherein, when an output value of a lambda sensor control using the oxygen sensor is outside the predetermined range, an amount of reserve torque for suppressing the speed fluctuations of the internal combustion engine can be set when the purging is completed, and the torque control unit of the internal combustion engine can be requested to safely set an amount of reserve torque.

[0033] According to the method and apparatus for controlling an internal combustion engine of the present disclosure, since the speed reduction of the internal combustion engine upon completion of the idle purge is eliminated, the unpleasant feeling of a driver due to noise and vibration is eliminated, so that the driving comfort and market quality of a vehicle are improved.

[0034] Further, according to the method and apparatus for controlling an internal combustion engine, when the learning of the purge gas concentration in the high-concentration accumulator idle state is not completed, an additional reserve torque may be selectively requested for purging, so that the amount of the requested reserve torque may be reduced compared to the reserve torque requested during the usual purging.

[0035] That is, in the related art, a simple control for increasing the reserve torque has been performed in order to stably control the combustion during the scavenging operation, but according to the present disclosure, a requested torque amount may be increased only when it is necessary to increase the reserve torque for scavenging, but otherwise, the requested amount of reserve torque may be minimized, so that the use of all the reserve torque in scavenging while the vehicle is being driven can be reduced and fuel efficiency can be improved. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a block diagram of the configuration of an apparatus for controlling an internal combustion engine according to an embodiment of the present disclosure; the Fig. 2A and Fig. 2B are flowcharts of a method for controlling an internal combustion engine according to an embodiment of the present disclosure; Fig. 3 is a signal diagram showing the speed change of an internal combustion engine during idle purge when the method for controlling an internal combustion engine according to an embodiment of the present disclosure is applied; Fig. 4 is a schematic view of the configuration of a sump flushing system for performing idle flushing; Fig. 5 is a signal diagram showing the rapid drop in engine speed when idle purge is completed before concentration learning is completed when the purge gas concentration is high; and Fig. Figure 6 is a signal diagram showing the engine speed fluctuation during idle purge in evaporative gas leak diagnosis when the purge gas concentration is high. DESCRIPTION OF SPECIFIC EMBODIMENTS

[0036] It is understood that the term "vehicle" or "vehicular" or other similar terms used herein generally encompasses motor vehicles such as passenger cars, including sports utility vehicles (SUVs), buses, trucks, various commercial vehicles, personal watercraft including various boats and ships, aircraft, and the like, and also includes hybrid vehicles, electric vehicles, plug-in hybrid electric vehicles (chargeable from a wall outlet), hydrogen-powered vehicles, and other alternative fuel vehicles (e.g., fuels derived from resources other than petroleum). As used herein, a hybrid vehicle is a vehicle with two or more power sources, e.g., vehicles with both gasoline and electric power.

[0037] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. As used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. Furthermore, it is to be understood that the terms “comprises” and / or “comprising,” when used in this specification, indicate the presence of stated features, integer quantities, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integer quantities, steps, operations, elements, components, and / or groups thereof. As used herein, the phrase “and / or” includes all combinations of one or more of the listed items.Unless otherwise expressly stated, throughout this description, the term "comprise" and its variants such as "comprises" or "having" are intended to include the specified elements but not to exclude other elements. Furthermore, the terms "unit," the word endings "-er," "-or," and the term "module" throughout this description refer to units for performing one or more functions or operations, and may be implemented by hardware or software components, and combinations thereof.

[0038] Furthermore, the control logic of the present disclosure may be embodied as non-transitory computer-readable media on a computer-readable medium having executable program instructions executed by a processor, controller, and the like. Examples of computer-readable media include, but are not limited to, ROMs, RAMs, compact disc (CD)-ROMs, magnetic tapes, floppy disks, USB flash drives, smart cards, and optical data storage devices. The computer-readable recording medium may also be distributed in network-coupled computer systems such that the computer-readable medium is stored and executed in a distributed manner, e.g., by a telematics server or a controller area network (CAN).

[0039] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings.

[0040] Fig. 1 is a block diagram of the configuration of an apparatus for controlling an internal combustion engine according to an embodiment of the present disclosure.

[0041] First, an operation information detection unit 110 detects information about an operating state of an internal combustion engine of a vehicle using various sensors and sends the information to a controller 100. The operation information detected by the operation information detection unit 110 is information such as the coolant temperature of an internal combustion engine, the rotational speed of the internal combustion engine, and the load of the internal combustion engine, which are factors that determine whether to start purging at idle or that determine the opening ratio of a purge valve during purging.

[0042] An oxygen sensor 120 is a component for measuring exhaust gas density by detecting the oxygen concentration in the exhaust gas. Typically located before and after a three-way catalyst, the oxygen sensor 120 detects the density of the combustion gas by measuring the oxygen concentration in the exhaust gas and transmits the density to the controller 100.

[0043] A purge gas amount detection unit 130 detects the amount of purge gas flowing into an intake manifold when a purge gas valve (a second valve 40 to be described later) is open. Specifically, the purge gas amount detection unit 130 calculates the purge gas amount based on the opening ratio of the purge gas valve and the pressure difference between a collector tank and the intake manifold.

[0044] A purge gas concentration detection unit 140 is a component for detecting the concentration of purge gas distributed from the header purge system through a purge line into an intake system of an internal combustion engine. The purge gas concentration detection unit 140 measures the purge gas concentration using a lambda value or the high / low air-fuel ratio measured by the oxygen sensor during purge, and the controller 100 performs purge learning based on the measurement result. For example, if the current purge learning value is 10, an HC amount corresponding to the value in a purge rate is subtracted from an amount of fuel injected at which the exhaust gas measured by the oxygen sensor is rich, which means that the actual purge rate is higher than 10, so the learning value is adjusted (increased).

[0045] A torque control unit 150 for an internal combustion engine is a component for ensuring reserve torque in response to a request from the controller 100. The torque control unit 150 for the internal combustion engine adjusts the intake amount of the internal combustion engine and the ignition timing of the internal combustion engine based on an amount of reserve torque required to ensure an amount of reserve torque requested by the controller 100, and ensures an increase in output torque due to an increase in the intake amount as reserve torque.

[0046] The reserve torque ensured by the torque control unit 150 of the internal combustion engine as described below serves to stabilize combustion by reducing the speed fluctuations of the internal combustion engine during purging of the accumulator at idle.

[0047] A header canister purge system 160 is a unit that collects an HC (hydrocarbon) component in the evaporative gas generated from a fuel tank and supplies the collected purge gas to the intake system of the internal combustion engine according to the pressure difference between the intake manifold and the header canister when the purge valve is open.

[0048] Fig. 4 shows a representative example of the sump flushing system 160. As in Fig. 4, the accumulator purge system 160 includes a fuel tank 10, an accumulator 20, a first valve 30, a second valve 40, and an intake system 80.

[0049] The fuel tank 10 contains volatile oil serving as fuel of a vehicle, and the collection container 20 collects and purges the evaporation gas generated by evaporation in the fuel tank 10 through a collection line 11.

[0050] The first valve 30, which is a receiver check valve arranged in a line connected to the atmosphere, allows fresh air from outside to flow into the receiver 20 when it is kept open by the controller 100.

[0051] The first valve 30 is closed by the controller 100 when a leak diagnosis of the fuel system is performed.

[0052] The second valve 40, which is a purge valve arranged in a purge line 21 connecting the collection tank 20 and the intake system 80 of the internal combustion engine, purges the evaporative gas collected in the collection tank 20 to the intake system 80 of the internal combustion engine or blocks the evaporative gas by being opened / closed by the controller 100.

[0053] The second valve 40 is opened by the controller 100 and purges the evaporative gas collected in the collection tank 20 to the intake system 80 of the internal combustion engine under a purge condition, but is closed by the controller 100 without the purge condition and blocks the spread of the evaporative gas collected in the collection tank 20 into the intake system 80 of the internal combustion engine.

[0054] The first valve 30, the second valve 40 and a third valve 50 can be solenoid valves and, depending on the design, different valve types.

[0055] The controller 100 receives the information detected by the operating information detection unit 110, the oxygen sensor 120, the purge gas amount detection unit 130, and the purge gas concentration detection unit 140, and controls the accumulator purge system 160 during idling, calculates an amount of reserve torque required to stabilize combustion, and requests the torque control unit 150 of the internal combustion engine to ensure the reserve torque. The detailed control method executed by the controller 100 is described below with reference to Fig. 2A and Fig. 2B described in detail.

[0056] The Fig. 2A and Fig. 2B are flowcharts of a method for controlling an internal combustion engine according to an embodiment of the present disclosure.

[0057] As in the Fig. 2A and Fig. 2B, the controller 100 first receives the current operating information of a vehicle from the operating information detection unit 110 and determines whether an idle purge condition is satisfied (S10).

[0058] That is, the controller 100 determines whether to perform idle purge based on the information from the operation information detection unit 110 based on the engine coolant temperature, the engine speed, the intake air temperature, the engine load, and an air amount, and determines the opening ratio of the second valve (purge valve) 40 of the accumulator purge system 160 required for idle purge based on the corresponding information.

[0059] Thereafter, the controller 100 opens the second valve 40 based on the calculated opening ratio and checks the learning time of the purge gas concentration during a partial load condition before an idle state before purging to the intake system of the internal combustion engine and then compares the learning time with a predetermined target time (S20).

[0060] It was experimentally found that the lean peak value of an air-fuel ratio was reduced and a speed reduction of the internal combustion engine after the completion of purging was smaller when the purge gas concentration learning was performed at part load under the same conditions.

[0061] The result is in Fig. 3. As shown in Fig. 3, it can be seen that as the learning time of the purge gas concentration elapses, the lean peak value of the air-fuel ratio of the purged fuel after the purge is completed is lower, and the rotational speed (682 rpm) of an internal combustion engine is very close to the idle speed (700 rpm).

[0062] Accordingly, the controller 100 should first determine whether the purge gas concentration learning time during a partial load condition is a preset target time or longer in order to suppress a reduction in the lean peak air-fuel ratio and the engine speed (S20). If the purge gas concentration learning time during the partial load condition is shorter than the predetermined target time, the controller 100 terminates the purge. On the other hand, if the purge gas concentration learning time during the partial load condition is equal to or longer than the predetermined target time, a reduction in the engine speed upon completion of the purge is not large, so the controller 100 controls the accumulator purge system 160 for idle purge.

[0063] According to one embodiment of the present disclosure, the controller determines whether a leak diagnosis of the evaporative gas occurs during the idle purge.

[0064] Evaporative gas leak diagnosis, which is a diagnosis to determine whether evaporative gas is leaking from a fuel supply line including the fuel tank, typically involves measuring the evaporative pressure, applying a negative pressure to the fuel tank, maintaining the negative pressure for a predetermined period of time, and measuring a leakage amount.

[0065] When measuring the evaporation pressure, the second valve 40 and the first valve 30 of the accumulator purge system 160 for measuring the pressure value of the gas during natural evaporation in the fuel tank 10 are closed, this value being a predetermined input value.

[0066] When the negative pressure is applied, the internal pressure of the fuel tank 10 becomes a predetermined target negative pressure by slowly opening the second valve 40.

[0067] After the internal pressure of the fuel tank 10 has reached the predetermined target negative pressure, the second valve 40 is closed in a standby state until the internal pressure has reached the target negative pressure.

[0068] When testing the leakage quantity, escaping evaporation gas is determined based on the gradient of a pressure change until the target negative pressure is reached.

[0069] When idle purge is performed during evaporative gas leak diagnosis, highly concentrated purge gas flows into the engine, causing the fuel / gas ratio to become excessively rich, resulting in engine speed fluctuations (see Fig. 5). Compared to idle purging without evaporative gas leak diagnosis, idle purging increases the engine's speed fluctuations, so that a higher reserve torque must be ensured.

[0070] Therefore, if it is determined that idle purge is being performed during evaporative gas leak diagnosis, the controller sets the reserve torque for purge leak diagnosis and requests the engine torque control unit 150 to ensure the set reserve torque (S50). Further, if it is determined that evaporative gas leak diagnosis is not being performed, the controller 100 sets an amount of reserve torque for general idle purge and requests the engine torque control unit 150 to ensure the set reserve torque (S50).

[0071] During part-load operation, high torque is generated due to a large intake air flow, so a high reserve torque is not required. Instead, low torque is generated due to the low intake air flow at idle, making it sensitive to sudden intervention (e.g., by operating a windshield wiper or window). Consequently, it is necessary to take precautions against this intervention by providing a reserve torque.

[0072] As described above, by distinguishing between the reserve torque for a part-load condition and idling, it is possible to stabilize combustion and improve fuel efficiency.

[0073] After starting the idle purge, the controller 100 determines whether to terminate the idle purge based on the information detected by the operation information detection unit 110 (S70). Upon termination of the idle purge based on the detected information, the controller 100 further calculates an idle purge reduction rate based on the difference between a target lambda value and the currently measured lambda value (S90). According to the present disclosure, the purge gas reduction rate is set separately during partial load and idle.

[0074] If the idle purge reduction rate is excessively high, the amount of high-concentration purge gas supplied to the engine intake system will rapidly decrease, affecting the engine speed. Therefore, it is necessary to adjust the purge reduction rate so that the purge rate decreases smoothly when idle purge is terminated to avoid problems caused by excessively rapid purge rate reduction. As described above, the air volume is larger during a partial load condition than during idle, so the effects of purge rate reduction are different. Therefore, it is preferable to adjust the purge reduction rate differently during the partial load condition and during idle.

[0075] When the reduction rate of the idle purge is determined, the controller 100 terminates the idle purge by gradually decreasing the opening ratio of the second valve 40 based on the determined reduction rate of the idle purge (S100).

[0076] As described above, when the second valve 40 is closed and the purge gas flow is terminated, a transitional air-fuel ratio should be controlled only by injection based on the feedback from the lambda sensor, so there is a high probability of a lean peak air-fuel ratio during this period. Furthermore, this problem is exacerbated when the evaporative gas concentration in the accumulator is high or when the purge gas concentration learning has not been performed normally.

[0077] Therefore, according to an embodiment of the present disclosure, it is determined whether a predetermined condition is satisfied when the idle purge is terminated (S100), and if the condition is satisfied, the torque control unit 150 of the internal combustion engine is required to ensure a predetermined amount of reserve torque in order to be able to prevent speed fluctuations of the internal combustion engine due to a lean peak of the air-fuel ratio (S120).

[0078] In one embodiment of the present disclosure, the controller 100 requests discrimination of the reserve torque according to the purge gas concentration. If the purge gas concentration learning has not been performed normally despite an excessive purge gas concentration, and a value of the lambda control reaches a predetermined value or less, a reserve torque different from that during purge is requested for a predetermined time after the purge is completed. The controller 100 sets the different reserve torque and requests the engine torque control unit 150 to ensure the different reserve torque.

[0079] In another embodiment of the present disclosure, the purge gas concentration learning time of the accumulator purge system 160 of the internal combustion engine serves as a condition for requiring reserve torque assurance when idle purge is terminated. If the purge gas concentration learning is not performed normally, it is impossible to estimate the precise influence of the purge gas on the air-fuel ratio, so that when the air-fuel ratio is controlled only by injection after idle purge is terminated, there is a high probability of engine speed fluctuation.

[0080] Therefore, when the learning time of the purge gas concentration of the accumulator is shorter than a target time, the controller 100 sets the reserve torque for suppressing speed fluctuations of the internal combustion engine and requests the securing of the reserve torque from the torque control unit 150 of the internal combustion engine.

[0081] In another embodiment of the present disclosure, the output value of the lambda control serves as a condition for the request to ensure the reserve torque at the end of the idle purge.

[0082] If the value of the lambda control using the oxygen sensor falls outside a predetermined set reference range, the air-fuel ratio becomes unstable, so that if the air-fuel ratio is controlled only by injection after the idle purge is completed, there is a high probability of engine speed fluctuations.

[0083] Therefore, if the value of the lambda control falls outside the predetermined reference range, the controller 100 sets the reserve torque to suppress the speed fluctuations of the internal combustion engine and requests the torque control unit 150 of the internal combustion engine to ensure the reserve torque.

[0084] The amount of reserve torque required to prevent a rapid change in engine speed during idle purge and the amount of reserve torque required to prevent a rapid change in engine speed upon idle purge completion are different. Consequently, in embodiments of the present disclosure, the amount of reserve torque set by controller 100 is different from the amount of reserve torque set during idle purge.

[0085] According to the method and apparatus for controlling an internal combustion engine according to an embodiment of the present disclosure, when learning of the purge gas concentration in a high-concentration reservoir during idling is not completed, it is possible to request additional reserve torque for purging, so that the amount of the requested reserve torque can be reduced compared to the reserve torque requested during general purging.

[0086] Furthermore, when a purge reserve torque is used to eliminate the problem of a decrease in the engine speed when the idle purge is completed, a requested torque amount can be increased only when there is a need to increase the purge reserve torque, but when there is no need, the requested reserve torque amount can be minimized, so that the full use of the purge reserve torque during driving can be reduced, thereby improving fuel efficiency.

[0087] The above embodiments are intended to enable a person of ordinary skill in the art (hereinafter referred to as a person skilled in the art) to whom the present disclosure is directed to easily implement the present disclosure.

Claims

[1] A method for controlling an internal combustion engine during accumulator purge at idle, the method comprising: Determining by a controller (100) whether the current operating information of a vehicle satisfies an idle purge condition; Performing a purge of the collection container (20) by the controller (100) during a partial load condition; Determining by the controller (100) whether the learning time of the accumulator purge performed during the part-load condition is greater than or equal to a target time when a purge operation condition is met; and Carrying out a flushing of the collecting tank (20) at idle by the controller (100) if the learning time of the collecting tank flushing carried out during the partial load condition is greater than or equal to a target time, wherein the idle purging is performed at an idle condition of less than 700 rpm without operation of an accelerator pedal; Determining whether an idle purge termination condition is met; Calculating a reduction rate of the idle purge when the idle purge is completed when the idle purge completion condition is met; and Controlling the closing of a purge valve (40) according to the calculated idle purge reduction rate after idle purge has ended, wherein the idle purge reduction rate is different from a purge reduction rate during the part-load condition. [2] The method of claim 1, further comprising: Determining by the controller (100) whether the diagnosis is for fuel vapor gas leaks; Setting an amount of reserve torque by the controller (100) according to the diagnosis for fuel vapor leaks; and Requesting the safe setting of a reserve torque amount from the torque control unit of the internal combustion engine by the controller (100). [3] The method of claim 1, further comprising: Setting a reserve torque to suppress engine speed fluctuations after purging has ended if a learning time of the accumulator purge gas concentration is shorter than a specified target time or an output value of the lambda measurement is not within a specified range; and Requesting the safe setting of a reserve torque amount from the engine torque control unit when idle purge is complete. [4] The method of claim 3, wherein the amount of reserve torque set during the idle purge is different from the amount of reserve torque set when the idle purge is completed. [5] The method of claim 3, wherein the amount of reserve torque set when starting the idle purge is different from the amount of reserve torque set when the idle purge is finished. [6] The method of claim 2, wherein during the fuel evaporative gas leakage diagnosis, a set amount of reserve torque is increased compared to when the fuel evaporative gas leakage diagnosis is not performed. [7] Device for controlling an internal combustion engine, the device comprising: a reservoir purge system (160) that collects evaporative gas in a fuel tank (10) connected to an intake system (80) of an internal combustion engine via a purge valve (40) and purges the collected evaporative gas to the intake system (80) of the internal combustion engine, wherein purging of a reservoir (20) is carried out during a part-load condition; an operating information detection unit (110) that detects an operating state of the internal combustion engine; and a controller (100) that determines whether an idle purge is being performed and that controls the purge valve (40) based on operating information of a vehicle and the learning time of the purge gas concentration of the accumulator (20), thereby controlling the accumulator purge system (160); and wherein the controller (100) is configured to open the purge valve (40) and perform the idle purge of the accumulator (20) when the current operating information of a vehicle satisfies an idle purge condition and the learning time for the purge concentration of the accumulator (20) is greater than or equal to a set time, wherein the idle purge is performed under an idle condition of less than 700 rpm without operation of an accelerator pedal, wherein the controller (100) determines whether an idle purge termination condition is met, calculates an idle purge reduction rate when the idle purge is terminated when the idle purge termination condition is met, and controls the closing of the purge valve (40) in accordance with the calculated idle purge reduction rate when the idle purge is terminated, and wherein the idle purge reduction rate differs from a purge reduction rate during the part-load condition. [8] The device according to claim 7, further comprising a torque control unit of the internal combustion engine, wherein the controller (100) determines during the purging whether a diagnosis for leakage of fuel evaporative gas is being performed, sets an amount of reserve torque based on the determination result, and requests the torque control unit of the internal combustion engine to safely set an amount of reserve torque to ensure the set reserve torque. [9] The device according to claim 8, further comprising an oxygen sensor (120) for detecting an oxygen concentration in the exhaust gas, wherein when an output value of a lambda control with the oxygen sensor (120) falls outside a predetermined range, an amount of reserve torque for suppressing the speed fluctuations of the internal combustion engine after completion of the purging is set and the torque control unit of the internal combustion engine is requested to ensure the set amount of reserve torque.

Images