METHOD AND SYSTEM FOR CONTROLLING AN EGR DEVICE IN OVERLOAD OPERATION, AND INTERNAL COMBUSTION ENGINE VEHICLE WITH THE SYSTEM

Abstract

Method for controlling an exhaust gas recirculation or EGR device in overload operation, wherein the method comprises the following steps: (a) Comparing a ratio of pressures at a front end and a rear end of a throttle valve (20) with a predetermined critical value which is a reference value for determining overload operation; (b) Performing a full-load or WOT (Wide Open Throttle) control to fully open the throttle valve (20) when the ratio of the pressures is greater than the predetermined critical value; (c) Determining whether engine torque meets a driver's torque requirement as a result of WOT control and the use of EGR, where whether the torque requirement is met is determined by comparing a torque loss due to a loss of intake air volume through the inflow of EGR gas with a torque increase due to an improvement in ignition efficiency through the inflow of EGR gas; and (d) Correcting the throttle opening or preventing the use of EGR, depending on whether the engine torque meets the torque requirement as a result of the use of EGR together with WOT control.

Description

Technical field

[0001] The present disclosure relates to a method and a system for controlling an exhaust gas recirculation (EGR) device during overload operation, and in particular to a method and a system for controlling an exhaust gas recirculation (EGR) device during overload operation and to an internal combustion engine vehicle with the system. The method and the device enable exhaust gas recirculation during overload operating phases by using a pressure ratio between the front end and the rear end of a throttle valve through the strategic control of the throttle valve and an EGR valve. background

[0002] Nitrogen oxides (NOx) are environmentally harmful substances formed by the combination of oxygen and nitrogen under ambient conditions in a cylinder (e.g., in a high-pressure and high-temperature environment). A technology for reducing the formation of nitrogen oxides by lowering the maximum combustion temperature and oxygen saturation through the recirculation of a portion of the exhaust gas, which is otherwise discharged to the environment, back into an intake system to suppress the nitrogen oxides is generally referred to as an exhaust gas recirculation (EGR) device.

[0003] The amount of exhaust gas recirculated to the intake system via an EGR device determines the combustion efficiency of the fuel in the combustion chamber and has a crucial influence on the emission of nitrogen oxides (NOx) and particulate matter (PM2.5). Therefore, controlling or regulating the amount of exhaust gas recirculated to an engine's intake system can be important in EGR control.

[0004] On the other hand, engine torque is proportional to the amount of intake air and is determined by adjusting the ignition timing, air-fuel ratio, and other factors. Therefore, to increase engine torque, it is necessary to first increase the amount of intake air, and to increase the intake air volume, it is necessary to increase the throttle opening. That is, it is necessary to open the throttle valve a correspondingly wider.

[0005] However, when the throttle opening is increased (when a throttle valve is wide open), a differential vacuum condition is created in which the pressure difference between the front end (a position where air is supplied) and the rear end (a position connected to an intake manifold) of the throttle valve is significantly reduced. When EGR is used in this condition, the EGR gas forces an increase in pressure in the intake manifold, thus reducing the amount of intake air. A control system then further increases the throttle opening to compensate for the reduced air volume.

[0006] If the throttle opening is further increased in this way, the pressure differential between the front and rear ends of the EGR valve also increases, thus reducing the amount of EGR gas recirculated. Consequently, as the control unit opens the EGR valve further to achieve a target EGR rate, the pressure in the intake manifold continues to rise, preventing sufficient air from reaching the target amount. Therefore, the control unit repeats a vicious cycle, causing the throttle opening to increase even further.

[0007] When the throttle reaches a full-load phase, or WOT (Wide Open Throttle) phase, due to the vicious cycle of the control system, the difference in intake air flow rate becomes so high that the engine output power becomes unstable. Therefore, in state-of-the-art technology, intake efficiency is increased by disabling EGR (Exhaust Gas Recirculation) and by timing the opening and closing of the valve during the WOT phase, i.e., the overload operating phase. Fuel injection is also enriched to ensure sufficient power to counteract engine knock during combustion.

[0008] However, if the use of EGR is prevented and the fuel injection is enriched, the emission of nitrogen oxides will be increased accordingly, so that there is a limitation in meeting a CO emission quantity and the theoretical air-to-fuel ratio during operation over the entire period regulated by the Euro 7 emissions standard.

[0009] DE 10 2017 211 834 A1 discloses a method for exhaust gas recirculation (EGR) to prevent surge in a vehicle. For this purpose, an intake pressure is compared with an exhaust pressure to determine whether the intake pressure is higher than the exhaust pressure by a predetermined amount. If the intake pressure is increased by the predetermined amount, a control unit opens a throttle valve and an EGR valve. The throttle valve and the EGR valve remain open for a predetermined duration, and the opening degree can be up to 100%.

[0010] US 2017 / 0350326 A1 discloses a device for controlling an internal combustion engine with a throttle valve and an EGR valve. The device is configured to calculate a target opening degree by means of a first or a second arithmetic operation, based on whether or not a temporary reduction in efficiency is to be expected. Summary

[0011] The object of the invention is to provide a method and a system for controlling an EGR device in overload operation, wherein the method and the system are able to determine whether a torque demand by a driver can be met by the inflow of EGR gas by comparing a torque loss due to a loss of intake air volume through the inflow of EGR gas with a torque increase due to an improvement in ignition efficiency through the inflow of EGR gas, and are able to improve performance in reducing nitrogen oxides and exhaust gases by using an EGR even in an overload phase if the torque demand by a driver can be met, and to provide an internal combustion engine vehicle that includes the device.

[0012] This problem is solved by the features of the independent patent claims. Advantageous embodiments of the invention are the subject of the dependent claims.

[0013] According to one aspect of the present disclosure, a method for controlling an exhaust gas recirculation or EGR device in overload operation is provided, wherein the method comprises the following steps: (a) a step of comparing a ratio of pressures at a front end and a rear end of a throttle valve with a predetermined critical value which is a reference value for determining overload operation; (b) a step of performing a full-load or WOT (Wide Open Throttle) control to fully open the throttle valve when the ratio of the pressures is greater than the predetermined critical value; (c) a step of determining whether engine torque meets the torque requirement of a driver as a result of WOT control and the use of EGR, wherein whether the torque requirement is met is determined by comparing a torque loss due to a loss of intake air volume through the inflow of EGR gas with a torque increase due to an improvement in ignition efficiency through the inflow of EGR gas; and (d) a step of correcting the throttle opening or preventing the use of EGR, depending on whether the engine torque meets the torque requirement as a result of the use of EGR together with WOT control.

[0014] One or more of the steps (a) to (d) mentioned above can be performed using a processor or a control unit.

[0015] A process can be set such that the throttle valve is controlled (throttle normal control) in such a way that a throttle opening width is set according to a target air quantity to achieve the torque requirement using an intake allocation rule which has the torque as a factor when the pressure ratio is the predetermined critical value or less than the comparison result in (a).

[0016] It can be determined that the torque requirement is not met if the torque loss due to a loss of intake air volume through the inflow of EGR gas is greater than the torque increase due to the improvement in ignition efficiency through the inflow of EGR gas, and it can be determined that the torque requirement is met if the torque increase due to the improvement in ignition efficiency through the inflow of EGR gas is greater than the torque loss due to a loss of intake air volume through the inflow of EGR gas.

[0017] In certain aspects, in the previously specified step (d), if the engine torque meets the torque requirement due to the use of EGR together with WOT, the inflow of EGR gas can be facilitated by the throttle recirculation control, which reduces the throttle opening, and if the engine torque does not meet the torque requirement due to the use of EGR together with WOT, the use of EGR can be prevented.

[0018] In throttle recirculation control, a throttle opening width can be controlled by a PI control that uses mapping data obtained by mapping increases to air volume errors (target air volume - actual air volume) due to the use of EGR.

[0019] To solve the problems according to another aspect of the present disclosure, a system for controlling an exhaust gas recirculation or EGR device in overload operation is provided, the system comprising: a throttle control system designed to adjust the amount of intake air by controlling an electronic throttle valve installed in an intake duct; an EGR control system designed to adjust the amount of EGR (the quantity of recirculated exhaust gas) by controlling an electronic EGR valve installed in the EGR line connecting an exhaust pipe and the intake pipe; and an integrated control unit configured to issue a control instruction to the throttle control unit and the EGR control unit, wherein the integrated control unit a full-load instruction (wide-open throttle instruction or WOT instruction) to fully open the throttle valve is sent to the throttle control unit when the ratio of the pressures at the front and rear ends of the throttle valve, measured by pressure sensors at the front and rear ends of the throttle valve, is greater than a predetermined critical value, which is a reference value for detecting overload operation, and determines whether engine torque, due to the WOT control and the use of EGR, meets the torque demand from a driver, and sends a throttle opening correction instruction to the throttle control unit or an instruction to disable the use of EGR to the EGR control unit, depending on whether the torque demand is met, and the integrated control determines whether the torque requirement is met by comparing a torque loss due to a loss of intake air volume through the inflow of EGR gas with a torque increase due to an improvement in ignition efficiency through the inflow of EGR gas.

[0020] In certain situations, if the pressure ratio is the predetermined critical value or lower, the throttle control can, in response to an instruction from the integrated control, control the throttle valve (normal throttle control) in such a way that a throttle opening width is set to correspond to a target air volume to achieve the torque requirement using an intake mapping that incorporates torque as a factor.

[0021] The integrated control unit can determine that the torque requirement is not met if the torque loss due to a loss of intake air volume through the inflow of EGR gas is greater than the torque increase due to the improvement in ignition efficiency through the inflow of EGR gas, and can determine that the torque requirement is met if the torque increase due to the improvement in ignition efficiency through the inflow of EGR gas is greater than the torque loss due to a loss of intake air volume through the inflow of EGR gas.

[0022] The integrated control unit can issue a throttle opening correction instruction to the throttle control unit, reducing the throttle opening, if the engine torque meets the torque requirement due to the use of EGR together with WOT control, and can issue an instruction to the EGR control unit, preventing the use of EGR, if the engine torque does not meet the torque requirement due to the use of EGR together with WOT control.

[0023] The throttle control, which receives the throttle opening correction instruction from the integrated control, can control a throttle opening width through a PI control that uses mapping data obtained by mapping the increase in intake air quantity error (target air quantity - actual air quantity) due to the use of the EGR.

[0024] To solve the tasks specified above, according to another aspect of the present disclosure, an internal combustion engine vehicle is provided which has the previously described system for controlling an EGR device in overload operation.

[0025] According to one embodiment of the present disclosure, it is determined whether a torque requirement by a driver can be achieved by the inflow of EGR gas by comparing a torque loss due to a loss of intake air volume through the inflow of EGR gas and a torque increase due to an improvement in ignition efficiency through the inflow of EGR gas, and if this is the case, the performance can be improved in terms of reducing nitrogen oxides and exhaust gases by using the EGR itself in an overload operating phase.

[0026] Furthermore, vehicles are proposed that incorporate a device and / or method as described herein, including a passenger vehicle, a truck or other vehicles.

[0027] As stated herein, overload operation includes, for example, driving uphill at low speed. Brief description of the drawings

[0028] The aforementioned and other tasks, features and further advantages of the present invention will become apparent from the following detailed description with reference to the accompanying drawings, in which: Fig. 1 is a schematic view showing the essential structure of a vehicle with an internal combustion engine, which includes an EGR device according to an embodiment of the present disclosure; Fig. 2 is a schematic view showing a device setup of a device for controlling an EGR device in overload operation according to an embodiment of the present disclosure; and Fig. 3 is a flowchart that sequentially shows a sequence of operations for controlling an EGR device in overload operation, which is carried out by the device for controlling an EGR device in overload operation, which is in Fig. As shown in 1, it will be executed. Detailed description

[0029] Exemplary embodiments of the present disclosure are described in detail below with reference to the drawings.

[0030] The terminology used herein serves solely to describe the embodiments and does not constitute a limitation of the present disclosure. Singular forms also include plural forms unless the context indicates otherwise.

[0031] It is clear that terms such as "exhibit" or "have" used in the present description specify the presence of certain features, steps, orientations, components, parts, or a combination thereof, but do not exclude the presence or addition of one or more further features, numbers, steps, operations, components, parts, or a combination thereof.

[0032] The terminology used herein serves solely to describe the embodiments and does not constitute a limitation of disclosure. As used herein, the singular forms "a," "the," "a," and "a" also include the plural forms unless otherwise indicated by the context. As used herein, the expression "and / or" includes any and all combinations of one or more of the elements listed in this respect. Throughout this description, unless otherwise stated, the word "exhibit" and variations such as "indicates" or "showing" are to be understood as implying the inclusion of listed features but not the exclusion of any other elements.

[0033] The terms used in the description, such as "first," "second," etc., can be used to describe different components; however, these components do not restrict the use of these terms. The terms are used solely to distinguish one component from another.

[0034] Terms such as "-er", "-unit", "-module", etc., used herein refer to units for performing at least one function or operation, which may be implemented by hardware, software, or a combination of hardware and software.

[0035] Furthermore, the control logic of the present disclosure can be implemented as a permanently computer-readable medium containing executable program instructions that are executed by a processor, controller, or the like. Examples of computer-readable media include, but are not limited to, ROMs, RAMs, compact discs (CD)-ROMs, magnetic tapes, floppy disks, memory sticks, smart cards, and optical data storage devices. The computer-readable medium can also be distributed decentrally in a network coupled with computer systems, such that the computer-readable medium is stored and executed in a decentralized manner, such as through a telematics server or a CAN bus (Controller Area Network).

[0036] It is clear that the term "vehicle" or "vehicle" or other terms used herein are to be understood generally as including motor vehicles, such as passenger cars including SUVs (sport utility vehicles), buses, trucks, various commercial vehicles, watercraft including a selection of boats and ships, aircraft, and the like, and includes hybrid vehicles, electric vehicles, plug-in hybrid electric vehicles, hydrogen-powered vehicles, and other vehicles using alternative fuels (e.g., fuels derived from raw material sources other than petroleum). As stated herein, a hybrid vehicle is a vehicle that has two or more sources of propulsion, such as gasoline-powered and electric-powered vehicles.

[0037] In the following description, identical components are designated with the same reference numerals in relation to the accompanying drawings and are therefore not described again. However, the present disclosure omits a detailed description of technologies known from the prior art in order to avoid distorting the description of the present disclosure with superfluous details.

[0038] First, the construction of an exhaust gas recirculation device will be described using the following examples: Fig. 1 described.

[0039] Fig. Figure 1 is a schematic view showing the essential structure of a vehicle with an internal combustion engine, which includes an EGR device according to an embodiment of the present disclosure.

[0040] In relation to Fig. 1 comprises an internal combustion engine vehicle, which includes an exhaust gas recirculation device, an engine 30, an intake line 10 through which the air supplied to the engine combustion chambers 31 (intake air) flows, and an exhaust line 40 through which the exhaust gas expelled from the combustion chambers 31 flows. The vehicle further comprises an exhaust gas recirculation device 50 (hereinafter referred to as an "EGR device"), which is installed from the high-pressure side of the exhaust line 40 to an intake manifold unit 36, to which the intake line 10 is connected.

[0041] The engine 30 converts chemical energy into mechanical energy by burning a gas mixture of fuel and air. The engine 30 is connected to the intake manifold 36, so that air flows into the combustion chambers 31 for combustion, and exhaust gas produced during the combustion process is collected in the exhaust manifold 38 and then released to the environment through the exhaust pipe 40. An injection device (not shown) is installed in each of the combustion chambers 31 and injects fuel into the combustion chambers.

[0042] The exhaust pipe 40 is connected to the exhaust distribution unit 38 and discharges exhaust gas from the vehicle. Depending on the application, a turbocharger turbine (not shown), which is set in rotation by the pressure of the exhaust gas flowing through the exhaust pipe 40, may be arranged in the exhaust pipe, and a compressor (not shown), which compresses the intake air supplied to the engine combustion chambers 31, may be arranged in the intake pipe 10 while being set in rotation by the torque of the turbine.

[0043] The EGR device 50 lowers the combustion temperature by recirculating a portion of the exhaust gas flowing through the exhaust pipe 40 to the intake pipe 10, thereby reducing the formation of nitrogen oxides. The EGR device 50 comprises an EGR line 51, which connects the exhaust pipe 40 and the intake manifold 36, and an EGR cooler 52, located in the center of the EGR line 51, which lowers the temperature of the recirculated exhaust gas (hereinafter referred to as "EGR gas").

[0044] An electronic EGR valve 54, which regulates the amount of EGR gas recirculated to the intake side, is installed in the EGR line 51 between the EGR cooler 52 and the intake manifold assembly 36. A pair of differential pressure sensors (not shown) is mounted at the front and rear ends of the EGR valve 54 in the direction of EGR gas flow. A controller performs recirculation control at the EGR valve 54 based on the pressure sensor readings, maintaining an EGR ratio at a setpoint.

[0045] In this context, the EGR ratio is the ratio of the amount of exhaust gas recirculated to the intake side via the EGR device to the total amount of gas flowing in the cylinders. This ratio can be stored in a storage medium, such as a matrix memory, for two factors: engine revolutions per minute (RPM) and engine load, as determined by the engine optimization control unit. In other words, it can be stored in the form of a mapping table.

[0046] In Fig. Reference numeral 14 denotes an air purification device for filtering out foreign substances contained in the intake air, and reference numeral 20 denotes a throttle valve that regulates the amount of air supplied to the engine combustion chambers 31. Reference numeral 12 denotes an air mass flow measuring device for measuring the flow velocity of air upstream of the throttle valve, and reference numerical MAP sensor for measuring the internal pressure of the intake manifold.

[0047] Fig. 2 is a view that schematically shows a device setup for controlling an EGR device in overload operation according to an embodiment of the present disclosure, which is used in a vehicle with an internal combustion engine equipped with the Fig. is equipped with the EGR device shown in 1.

[0048] In relation to Fig. 2 together with Fig. 1 comprises a system 100 for controlling an EGR device in overload operation according to an embodiment of the present disclosure, a throttle control 60 that controls the throttle valve 20, and an EGR control 70 that controls the EGR valve 54. The system further comprises an integrated control 80, such as an engine control unit (ECU), which holistically controls the throttle control 60 and the EGR control 70.

[0049] The throttle control 60 adjusts the amount of intake air by controlling the electric throttle valve 20, which is installed in the intake manifold 10. Specifically, the throttle control 60 adjusts the throttle valve opening width according to an output signal from an accelerometer position sensor (APS) in response to a control instruction from the integrated control unit 80 based on the measurement information from the APS. For example, the throttle opening is increased when the APS output signal value is higher, and the throttle opening is decreased when the APS output signal value is lower.

[0050] The EGR control unit 70 sets an EGR quantity (or EGR ratio) by controlling the electric EGR valve 54, which is installed in the EGR line 51 connecting the exhaust line 40 and the intake line 10. Specifically, the opening width of the EGR valve 54 is set based on the EGR ratio, which is determined by a single mapping table (EGR mapping table) according to an engine state and a control instruction from the integrated control unit 80 based on the output signals of the differential pressure sensors at the front and rear ends.

[0051] The integrated control unit 80, e.g., the ECU, determines control values ​​for the throttle valve 20 and the EGR valve 54, e.g., based on information provided to control the throttle valve 20 and the EGR valve 54 by measuring devices installed on the vehicle, such as differential pressure sensors, the APS, etc. The determined control values ​​are then sent as control instructions to the throttle control unit 60 and the EGR control unit 70, thus achieving the desired control.

[0052] The integrated control unit 80, according to one embodiment of the present disclosure, compares in particular the ratio of the pressures at the front end and the rear end of the throttle valve 20, measured by the pressure sensors at the front and rear ends of the throttle valve 20, with a predetermined critical value, which is a difference used to detect an overload condition. If the ratio of the pressures at the front and rear ends of the throttle valve 20 is greater than the predetermined critical value, the integrated control unit 80 detects that an overload condition is present and issues a full-load instruction (wide-open throttle instruction or WOT instruction) to the throttle controller 60 to fully open the throttle valve 20.

[0053] The system further includes a processor programmed to determine whether the engine torque, even with the use of EGR in WOT control, meets the torque demand from the driver, which is detected by the actuation level of an accelerator pedal, vehicle speed, engine speed (RPM), load, etc. when the accelerator pedal is actuated, and to execute a sequence of controls step by step to issue a throttle opening correction instruction to the throttle control 60 or to issue an EGR use suppression instruction to the EGR control 70, depending on whether the previously specified condition is met.

[0054] If the ratio of the pressures at the front and rear ends of the throttle valve 20 is a predetermined critical value, which is the reference value for detecting overload operation, or exceeds it, the integrated controller 80 controls the throttle controller 60 to operate the throttle valve 20 normally. Normal throttle control of the throttle valve 20 refers to throttle normal control, which sets the throttle opening according to a set air volume (a set air volume to achieve the requested torque) determined by an intake mapping table that includes torque as a factor.

[0055] When EGR gas flows into the intake manifold via the EGR control unit during overload operation, the pressure increase within the intake manifold is accelerated, and the pressure differential between the intake manifold and ambient pressure becomes small. Consequently, during an overload phase, the amount of intake air drawn into the engine decreases, and the engine torque also decreases by the same amount. In other words, there is a loss of intake air volume, and consequently, a loss of torque.

[0056] In the meantime, an increase in torque can be expected due to the inflow of EGR gas. Since EGR gas is an exhaust gas, it inherently contains thermal energy. Consequently, when EGR gas enters the system, the temperature of the air supplied to the combustion chambers via the intake manifold increases. Furthermore, when the temperature of the air supplied to the combustion chambers increases, ignition is facilitated, thus improving the ignition efficiency.

[0057] Accordingly, when determining whether an engine torque meets the torque requirement of a driver due to the use of EGR in WOT control, the integrated control 80 used in the present disclosure determines whether the engine torque meets the torque requirement by comparing a torque loss due to a loss of intake air quantity through the inflow of EGR gas with a torque increase due to the improvement in ignition efficiency through the inflow of EGR gas.

[0058] Specifically, if the torque loss due to the inflow of EGR gas is greater than the torque increase due to the inflow of EGR gas when EGR is used, i.e., if a loss is greater than an increase due to the use of EGR, the integrated control 80 determines that the torque request by a driver is not being met at the present time and may issue an instruction to disable the use of EGR to the EGR control.

[0059] In contrast, if the torque increase due to the inflow of EGR gas is greater than the torque loss due to the inflow of EGR gas when EGR is used, i.e., if an increase due to the use of EGR is greater than a loss, the situation arises in which the EGR can continue to be used, so that the integrated control 80 determines that the torque demand by the driver is met, and can issue a throttle opening correction instruction to the throttle control 60, which stabilizes the flow velocity of the intake air by reducing the throttle opening.

[0060] In this case, the throttle opening can be corrected by a feedback control of the throttle control unit 60 with respect to the throttle valve 20 based on information about an air flow error. Specifically, the throttle opening can be corrected by a PI (Proportional Integral Control) control of the throttle control unit 60, which uses data obtained by mapping increases to air flow errors (target air flow - actual air flow) resulting from the use of the EGR.

[0061] A sequence of operations for controlling an EGR device in overload operation, which are carried out by the device for controlling an EGR device in overload operation according to an embodiment of the present disclosure as described above, is shown by reference to the control flow diagram in Fig. 3 described. For the purpose of simpler description, the following are omitted. Fig. The components shown in section 1 are described using their reference symbols.

[0062] Fig. 3 is a flowchart that sequentially shows a sequence of operations for controlling an EGR device in overload operation, which is carried out by the device for controlling an EGR device in overload operation, which is in Fig. As shown in 1, it will be executed.

[0063] In relation to Fig. 3. The method for controlling an EGR device in overload operation according to an embodiment of the present disclosure begins with a step of determining whether overload operation is being carried out (S100). In step S100, it can be determined whether overload operation is occurring by comparing the ratio of the pressures at the front end and at the rear end of the throttle valve 20 with a predetermined critical value, which is the reference value for determining overload operation. The predetermined critical value can be 0.95, but is not limited to this.

[0064] If an overload operation is detected in step S100, where the ratio of the pressures at the front end and rear end of the throttle valve 20 is greater than the predetermined critical value, the procedure continues in step S200 by performing a full-load control or WOT (Wide Open Throttle) control to fully open the throttle valve 20. If the ratio is the predetermined critical value or less, the throttle valve 20 is controlled (normal throttle control) such that the throttle opening is set according to the target air volume to achieve the torque requirement using an intake mapping rule (S210).

[0065] Step S300, which determines whether the engine torque meets the driver's torque request due to the use of EGR, is performed next after WOT control by step S200. Finally, the throttle opening is corrected (S410) or the use of EGR is prevented by the throttle recirculation control, depending on whether the engine torque meets the torque request due to the use of EGR together with WOT control (S420).

[0066] In step S300, it is possible to determine whether the torque requirement is met by comparing a torque loss due to a reduction in intake air volume caused by the introduction of EGR gas with a torque increase due to the improvement in ignition efficiency caused by the introduction of EGR gas. The ignition efficiency can be determined based on a single mapping rule that defines the relationship between an EGR flow rate and the ignition efficiency (the change in ignition efficiency due to a change in EGR flow rate) in the form of a mapping table.

[0067] In step S300, it is possible to determine that the torque requirement is not met if the torque loss due to the inflow of EGR gas is greater than the torque increase due to the inflow of EGR gas, and it is possible to determine that the torque requirement is met if the torque increase due to the inflow of EGR gas is greater than the torque loss due to the inflow of EGR gas.

[0068] If it is determined that the engine torque, due to the use of EGR together with WOT control, meets a torque level required by an engine management system (EMS) (the torque requirement), the airflow rate is stabilized and the inflow of EGR gas is facilitated by maintaining a strategy for using EGR in an overload operating phase and by implementing throttle recirculation control that reduces the throttle opening.

[0069] In contrast, if it is determined that the engine torque does not meet the torque requirement requested by an engine management system (EMS) due to the use of EGR together with WOT control, the use of EGR will be prevented and control will first be implemented to ensure a maximum intake air quantity (the existing WOT throttle control, S420) in order to avoid the problem of a vicious cycle of control in which EGR is used together.

[0070] Meanwhile, in the throttle recirculation control for throttle opening correction (correction to reduce the throttle opening) in step S410, a correction of the reduction of the throttle opening can be achieved by a PI control (Proportional Integral (PI) Control) of the throttle control, which uses data obtained by assigning increases to air quantity errors due to the use of the EGR (target air quantity - actual air quantity).

[0071] If EGR is used during an overload operating phase, a target air intake rate cannot be adequately ensured, and the control system increases the throttle opening. In this case, a condition is created that is detrimental to generating a pressure differential between the front and rear ends of the EGR valve, thus repeating a vicious cycle in which the control system opens the EGR valve further to achieve a target EGR flow rate. Prior art prevents the use of EGR during an overload operating phase to avoid this problem.

[0072] However, in one embodiment of the present disclosure, it can be determined whether a torque requirement by a driver can be achieved by the inflow of EGR gas by comparing a torque loss due to a loss of intake air volume through the inflow of EGR gas with a torque increase due to an improvement in ignition efficiency through the inflow of EGR gas, and if this is the case, the performance in reducing nitrogen oxides and exhaust gases can be improved by using the EGR itself in an overload operating phase.

[0073] Only one specific embodiment was described in the detailed description provided above. The present disclosure is not limited to the specific embodiment described above, but includes all modifications, equivalents, and substitutions within the scope of the inventive concept defined in the claims of the present disclosure.

Claims

[1] Method for controlling an exhaust gas recirculation or EGR device in overload operation, wherein the method comprises the following steps: (a) Comparing a ratio of pressures at a front end and a rear end of a throttle valve (20) with a predetermined critical value which is a reference value for determining overload operation; (b) Performing a full-load or WOT (Wide Open Throttle) control to fully open the throttle valve (20) when the ratio of the pressures is greater than the predetermined critical value; (c) Determining whether engine torque meets a driver's torque requirement as a result of WOT control and the use of EGR, where whether the torque requirement is met is determined by comparing a torque loss due to a loss of intake air volume through the inflow of EGR gas with a torque increase due to an improvement in ignition efficiency through the inflow of EGR gas; and (d) Correcting the throttle opening or preventing the use of EGR, depending on whether the engine torque meets the torque requirement as a result of the use of EGR together with WOT control. [2] Method according to claim 1, wherein, if the pressure ratio is the predetermined critical value or less than the comparison result in (a), the throttle valve (20) is controlled (throttle normal control) such that a throttle opening width is set according to a target air quantity to achieve the torque requirement by applying an intake allocation rule which has the torque as a factor. [3] Method according to claim 1, where it is determined that the torque requirement is not met if the torque loss due to a loss of intake air volume through the inflow of EGR gas is greater than the torque increase due to the improvement in ignition efficiency through the inflow of EGR gas, and where it is determined that the torque requirement is met if the increase in torque due to the improvement in ignition efficiency through the inflow of EGR gas is greater than the loss in torque due to a loss in the intake air volume through the inflow of EGR gas. [4] Method according to claim 1, where in (d) if the engine torque meets the torque requirement due to the use of EGR together with WOT, the inflow of EGR gas is facilitated by the throttle recirculation control, which reduces the throttle opening, and where in (d) if the engine torque does not meet the torque requirement due to the use of EGR together with WOT, the use of EGR is stopped. [5] Method according to claim 4, wherein, in the throttle recirculation control, a throttle opening width is controlled by a PI control which uses mapping data obtained by mapping increases to air quantity errors (target air quantity - actual air quantity) due to the use of the EGR. [6] System for controlling an exhaust gas recirculation or EGR device in overload operation, wherein the system comprises: a throttle control (50) which is configured to adjust the intake air quantity by controlling an electronic throttle valve (20) which is arranged in an intake duct; an EGR control unit (70) configured to adjust an EGR quantity (the amount of recirculated exhaust gas) by controlling an electronic EGR valve (54) installed in the EGR line connecting an exhaust pipe and the intake pipe; and an integrated control unit (80) which is configured to issue a control instruction to the throttle control unit (50) and the EGR control unit (70), the integrated control (80) is further configured to to issue a full-load instruction (wide-open throttle instruction or WOT instruction) to the throttle control (50) to fully open the throttle valve (20) when a ratio of the pressures at the front and rear ends of the throttle valve (20), measured by pressure sensors at the front and rear ends of the throttle valve (20), is greater than a predetermined critical value, which is a reference value for detecting overload operation, and to determine whether an engine torque meets the torque requirement of a driver due to WOT control and the use of EGR, and to issue a throttle opening correction instruction to the throttle control (50) or a command to disable the use of EGR, to be sent to the EGR control (70), depending on whether the torque requirement is met, and to determine whether the torque requirement is met by comparing a torque loss due to a loss of intake air volume through the inflow of EGR gas with a torque increase due to an improvement in ignition efficiency through the inflow of EGR gas. [7] System according to claim 6, wherein, when the ratio of the pressures is the predetermined critical value or less, the throttle control (50) controls the throttle valve (20) (throttle normal control) in response to an instruction from the integrated control (80) such that a throttle opening width is set to correspond to a target air quantity to achieve the torque requirement using an intake mapping which has the torque as a factor. [8] System according to claim 6, wherein the integrated control (80) determines that the torque requirement is not met if the torque loss due to a loss of intake air volume through the inflow of EGR gas is greater than the torque increase due to the improvement in ignition efficiency through the inflow of EGR gas, and determines that the torque requirement is met if the increase in torque due to the improvement in ignition efficiency through the inflow of EGR gas is greater than the loss in torque due to a loss in the intake air volume through the inflow of EGR gas. [9] System according to claim 6, wherein the integrated control (80) a throttle opening correction instruction, which reduces the throttle opening, is sent to the throttle control (50) when the engine torque meets the torque requirement due to the use of the EGR together with the WOT control, and a directive which prevents the use of EGR, to the EGR control (70) if the engine torque does not meet the torque requirement due to the use of EGR together with the WOT control. [10] System according to claim 9, wherein the throttle control (50), which receives the throttle opening correction instruction from the integrated control (80), controls a throttle opening width by means of a PI control which uses mapping data obtained by mapping the increase of intake air quantity error (target air quantity - actual air quantity) due to the use of the EGR. [11] Internal combustion engine vehicle comprising the system for controlling an EGR device in overload operation according to claim 6.

Images