Device and method for diagnosing EGR valve

Abstract

Disclosed are an apparatus and method for diagnosing an EGR valve. The apparatus for diagnosing an exhaust gas recirculation (EGR) valve comprises: an exhaust gas recirculation (EGR) apparatus, comprising an EGR pipe connecting an exhaust gas pipe and an intake pipe and an EGR valve installed in the EGR pipe; an electric supercharger installed in the intake pipe to change the internal pressure of an intake manifold; a manifold pressure sensor to measure the internal pressure of the intake manifold; and a controller to obtain the opening amount of the EGR valve, diagnose the fixation of the EGR method, and the leakage of the EGR valve based on the internal pressure of the intake manifold detected by the manifold pressure sensor when the engine stops during vehicle driving.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to and the benefit of Korean Patent Application No. 10-2019-0149866, filed on November 20, 2019, which is hereby incorporated by reference in its entirety. Technical Field

[0003] The present disclosure relates to an apparatus for diagnosing an EGR valve and a method thereof. Background Art

[0004] The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.

[0005] An exhaust gas recirculation (EGR) device is a system used in vehicles to reduce harmful exhaust gases. Generally, when the proportion of air in the air / fuel mixture is high, the amount of NOx in the exhaust gas increases. Therefore, the exhaust gas recirculation device feeds back a portion (e.g., 5% to 20%) of the exhaust gas exhausted from the engine to the air / fuel mixture to reduce the oxygen concentration in the air / fuel mixture, and thereby suppress the generation of NOx by interfering with combustion.

[0006] Typically, an exhaust gas recirculation device recirculates exhaust gas exhausted from a cylinder of an engine through an exhaust manifold and returns the exhaust gas to the cylinder of the engine through an exhaust pipe and a recirculation pipe. Typically, an EGR valve is used in the recirculation pipe to adjust the EGR ratio.

[0007] The exhaust gas recirculation system can be classified into a low pressure EGR (LP EGR) device and a high pressure EGR (HPEGR) device.

[0008] The high-pressure EGR device supplies recirculation gas (EGR gas) to the intake manifold by using the high pressure of the exhaust manifold. The low-pressure EGR device supplies recirculation gas from the downstream side of the exhaust purification device in the exhaust pipe to the upstream side of the compressor of the turbocharger in the intake pipe.

[0009] In this conventional exhaust gas recirculation system, exhaust gas is recirculated through an EGR pipe branched from an exhaust pipe and connected to an intake pipe. The EGR pipe is provided with an EGR cooler for cooling the recirculated exhaust gas and an EGR valve for adjusting the amount of the recirculated exhaust gas.

[0010] We have discovered that because it is difficult to detect the actual amount of EGR controlled by the opening of the EGR valve, a method of accurately predicting or diagnosing the operation and opening of the EGR valve is needed to improve NOx control.

[0011] The above information disclosed in this Background section is only for enhancement of understanding of the background of the present disclosure and therefore it may contain information that does not form the prior art already known to a person of ordinary skill in the art. Summary of the invention

[0012] The present disclosure provides a device for diagnosing an EGR valve and a method for using the same, which have the advantage of accurately diagnosing the normal operation and opening degree of the EGR valve of an exhaust gas recirculation device.

[0013] An exemplary device for diagnosing an EGR valve includes: an exhaust gas recirculation device including an EGR pipe and an EGR valve, the EGR pipe connecting an exhaust pipe and an intake pipe of an engine, the EGR valve installed in the EGR pipe; an electric supercharger installed in the intake pipe and configured to change the internal pressure of an intake manifold; a manifold pressure sensor that measures the internal pressure of the intake manifold; and a controller that is configured to, when the engine is stopped during vehicle driving, obtain an opening amount of the EGR valve and diagnose fixation of the EGR valve and leakage of the EGR valve based on the measured internal pressure of the intake manifold, wherein the measured internal pressure of the intake manifold changes according to the opening amount of the EGR valve.

[0014] The controller may be configured to learn the opening amount of the EGR valve after positioning the crank angle to a reference position when the engine is stopped, and to diagnose the sticking of the EGR valve and the leakage of the EGR valve.

[0015] In one form, the controller may operate the electric supercharger in a positive direction to generate a positive pressure in the intake manifold that is higher than atmospheric pressure; open the EGR valve by a first predetermined opening amount within a first predetermined period, and then, when the first predetermined period ends, close the EGR valve; and calculate a first pressure differential by comparing an internal pressure of the intake manifold measured during the first predetermined period with a first reference pressure so that the controller learns the opening amount of the EGR valve.

[0016] In another form, the controller can be configured to: open the EGR valve by a second predetermined opening amount within a second predetermined period; and then, after the second predetermined period expires, close the EGR valve, wherein the second predetermined opening amount is different from the first predetermined opening amount; calculate a second pressure differential by comparing the internal pressure of the intake manifold measured during the second predetermined period with a second reference pressure; calculate a ratio of the first pressure differential to the second pressure differential; and determine a compensation value for the opening of the EGR valve based on the calculated ratio of the first pressure differential to the second pressure differential.

[0017] The controller may be configured to determine EGR valve fixation when the internal pressure of the intake manifold detected from the manifold pressure sensor does not change while the electric supercharger operates in a positive direction to generate a positive pressure higher than atmospheric pressure in the intake manifold and sends an instruction to open the EGR valve to a different opening amount.

[0018] The controller may be configured to determine that the EGR valve is leaking when a difference between an internal pressure of the intake manifold detected by a manifold pressure sensor and a reference pressure is greater than a predetermined pressure when the electric supercharger is operated in a positive direction to generate a positive pressure higher than atmospheric pressure in the intake manifold and sends an instruction to open the EGR valve to different opening amounts.

[0019] The controller can be configured to obtain the opening of the EGR valve by the following operations, namely, operating the electric supercharger in the reverse direction to generate a negative pressure lower than the atmospheric pressure in the intake manifold; after opening the EGR valve to a first predetermined opening amount within a first predetermined period of time, closing the EGR valve; and comparing the internal pressure of the intake manifold with a first reference pressure.

[0020] The controller can be configured to: send an instruction to close the EGR valve after sending an instruction to open the EGR valve to a second predetermined opening amount within a first predetermined period of time, the second predetermined opening amount being different from the first predetermined opening amount; compare the internal pressure of the intake manifold with a second reference pressure; and determine a compensation value for the opening of the EGR valve as a ratio of the pressure difference between the first reference pressure and the internal pressure of the intake manifold measured when the instruction to open the EGR valve to the first predetermined opening amount is sent, and the pressure difference between the second reference pressure and the internal pressure of the intake manifold measured when the instruction to open the EGR valve to the second predetermined opening amount is sent.

[0021] The controller may be configured to determine that the EGR valve is fixed when the internal pressure of the intake manifold detected from the manifold pressure sensor does not change when the electric supercharger operates in a reverse direction to generate a negative pressure below atmospheric pressure in the intake manifold and sends an instruction to open the EGR valve to a different opening amount.

[0022] The controller may be configured to determine that the EGR valve is leaking when a difference between an internal pressure of the intake manifold detected by a manifold pressure sensor and a reference pressure is greater than a predetermined pressure when the electric supercharger operates in a reverse direction to generate a negative pressure below atmospheric pressure in the intake manifold and sends an instruction to open the EGR valve to a different opening amount.

[0023] An exemplary method for diagnosing an EGR valve provided in an exhaust gas recirculation device includes: determining, by a controller, whether an engine is stopped while a vehicle is traveling; operating an electric supercharger, by the controller; detecting, by a manifold pressure sensor, an internal pressure of an intake manifold according to an opening of the EGR valve; and obtaining, by the controller, an opening of the EGR valve from the internal pressure of the intake manifold detected by the manifold pressure sensor.

[0024] The exemplary method may further include: operating the electric supercharger in a positive direction to generate a positive pressure in the intake manifold that is higher than atmospheric pressure; sending an instruction to open the EGR valve to a first predetermined amount within a predetermined period of time; sending an instruction to close the EGR valve; and knowing the opening of the EGR valve by comparing the internal pressure of the intake manifold with a first reference pressure.

[0025] An exemplary method may further include: sending an instruction to open the EGR valve to a second predetermined amount within a predetermined period, the second predetermined amount being different from the first predetermined amount; sending an instruction to close the EGR valve; and comparing the internal pressure of the intake manifold with a second reference pressure; and determining a compensation value for the opening of the EGR valve as a ratio of the pressure difference between the first reference pressure and the internal pressure of the intake manifold measured when the instruction to open the EGR valve to the first predetermined amount is sent, and the pressure difference between the second reference pressure and the internal pressure of the intake manifold measured when the instruction to open the EGR valve to the second predetermined amount is sent.

[0026] The exemplary method may further include: operating the electric supercharger in a reverse direction to generate a negative pressure in the intake manifold that is lower than atmospheric pressure; sending an instruction to open the EGR valve to a first predetermined amount within a predetermined period of time; sending an instruction to close the EGR valve; and obtaining the opening degree of the EGR valve by comparing the internal pressure of the intake manifold with a first reference pressure.

[0027] An exemplary method may further include: sending an instruction to open the EGR valve to a second predetermined amount within a predetermined period, the second predetermined amount being different from the first predetermined amount; sending an instruction to close the EGR valve; and comparing the internal pressure of the intake manifold with a second reference pressure; and determining a compensation value for the opening of the EGR valve as a ratio of the pressure difference between the first reference pressure and the internal pressure of the intake manifold measured when the instruction to open the EGR valve to the first predetermined amount is sent, and the pressure difference between the second reference pressure and the internal pressure of the intake manifold measured when the instruction to open the EGR valve to the second predetermined amount is sent.

[0028] Another exemplary method for diagnosing an EGR valve provided in an exhaust gas recirculation device includes: determining, by a controller, whether an engine is stopped and whether conditions required for diagnosis are satisfied and obtaining available conditions; operating an electric supercharger by the controller; detecting, by a manifold pressure sensor, an internal pressure of an intake manifold according to an opening of the EGR valve; and determining, by the controller, the fixation of the EGR valve from the internal pressure of the intake manifold detected by the manifold pressure sensor.

[0029] The exemplary method may further include: operating the electric supercharger in a positive direction to generate a positive pressure higher than atmospheric pressure in the intake manifold; sending an instruction to open the EGR valve to different sizes of openings; stopping the electric supercharger; sending an instruction to close the EGR valve; and in the case of sending an instruction to open the EGR valve to different sizes of openings, when the internal pressure of the intake manifold detected from the manifold pressure sensor does not change, determining that the EGR valve is fixed.

[0030] The exemplary method may further include: operating the electric supercharger in a reverse direction to generate a negative pressure in the intake manifold that is lower than the atmospheric pressure; sending an instruction to open the EGR valve to different opening sizes; stopping the electric supercharger; sending an instruction to close the EGR valve; and in the case of sending an instruction to open the EGR valve to different opening sizes, when the internal pressure of the intake manifold detected from the manifold pressure sensor does not change, determining that the EGR valve is fixed.

[0031] Another exemplary method for diagnosing an EGR valve provided in an exhaust gas recirculation device includes: determining, by a controller, whether an engine is stopped and whether conditions required for diagnosis are satisfied and obtaining available conditions; operating an electric supercharger by the controller; detecting, by a manifold pressure sensor, an internal pressure of an intake manifold according to an opening of the EGR valve; and determining, by the controller, leakage of the EGR valve from the internal pressure of the intake manifold detected by the manifold pressure sensor.

[0032] The exemplary method may further include: operating the electric supercharger in a positive direction to generate a positive pressure higher than atmospheric pressure in the intake manifold; sending an instruction to open the EGR valve to different sizes of opening; stopping the electric supercharger; sending an instruction to close the EGR valve; and when the difference between the internal pressure of the intake manifold detected from the manifold pressure sensor and the reference pressure is greater than a predetermined pressure, determining that the EGR valve is leaking.

[0033] The exemplary method may further include: operating the electric supercharger in a reverse direction to generate a negative pressure in the intake manifold that is lower than the atmospheric pressure; sending an instruction to open the EGR valve to different opening sizes; stopping the electric supercharger; sending an instruction to close the EGR valve; and determining that the EGR valve is leaking when the difference between the internal pressure of the intake manifold detected from the manifold pressure sensor and the reference pressure is greater than a predetermined pressure.

[0034] According to an exemplary embodiment of the apparatus for diagnosing an EGR valve and method thereof, normal / abnormal operation and opening degree of the EGR valve can be accurately diagnosed by operating an electric supercharger to measure the internal pressure of the intake manifold according to the opening degree of the EGR valve.

[0035] Further areas of applicability will become apparent from the description provided herein.It should be understood that the summary and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order that the present disclosure may be readily understood, its various forms given by way of example will now be described with reference to the accompanying drawings, in which:

[0037] Figure 1 is a schematic diagram showing an engine system to which an apparatus for diagnosing an EGR valve in an exemplary form of the present disclosure is applied;

[0038] Figure 2 is a block diagram showing a configuration of an apparatus for diagnosing an EGR valve in an exemplary form of the present disclosure;

[0039] Figure 3 A method for adjusting the crank angle of an apparatus for diagnosing an EGR valve in an exemplary form of the present disclosure is shown;

[0040] Figure 4 is a flow chart illustrating a method for diagnosing an EGR valve in an exemplary form of the present disclosure;

[0041] Figure 5 is a drawing for explaining a method of obtaining an EGR amount according to an opening degree of an EGR valve according to an exemplary form of the present disclosure;

[0042] Figure 6 is a diagram for illustrating a method of diagnosing a fixation of an EGR valve in an exemplary form of the present disclosure;

[0043] Figure 7 is a diagram for illustrating a method of diagnosing leakage of an EGR valve according to an exemplary form of the present disclosure;

[0044] Figure 8 is a diagram for explaining another exemplary form of the present disclosure, a method of diagnosing and obtaining an EGR amount according to an opening degree of an EGR valve;

[0045] Fig. 9 is a diagram for illustrating a method of diagnosing a fixation of an EGR valve in another exemplary form of the present disclosure; and

[0046] Fig.10is a diagram for explaining a method of diagnosing leakage of an EGR valve according to another exemplary form of the present disclosure.

[0047] The drawings described herein are for illustrative purposes only and are not intended to limit the scope of the present disclosure in any way. DETAILED DESCRIPTION

[0048] The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses.It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features.

[0049] The present disclosure will be described more fully below with reference to the accompanying drawings, which show exemplary forms of the present disclosure. It will be appreciated by those skilled in the art that the described forms may be changed in various different ways without departing completely from the spirit or scope of the present disclosure.

[0050] In order to clearly illustrate the present disclosure, parts irrelevant to the description will be omitted, and the same reference numerals refer to the same elements or equivalents throughout the specification.

[0051] Furthermore, the size and thickness of each element are arbitrarily shown in the drawings, but the present disclosure is not necessarily limited thereto, and in the drawings, the thickness of layers, films, panels, regions, etc., are exaggerated for clarity.

[0052] Hereinafter, an apparatus for diagnosing an EGR valve according to an exemplary form of the present disclosure will be described in detail with reference to the accompanying drawings.

[0053] Figure 1 is a schematic diagram showing an engine system to which an apparatus for diagnosing an EGR valve in an exemplary form of the present disclosure is applied. Figure 2 is a block diagram showing a configuration of an apparatus for diagnosing an EGR valve according to one form of the present disclosure.

[0054] First, an engine system to which an apparatus for diagnosing an EGR valve according to one form of the present disclosure is applied is described in detail. The vehicle to which the apparatus for diagnosing an EGR valve is applied may be a vehicle having only an internal combustion engine or a hybrid vehicle having an internal combustion engine and a drive motor.

[0055] like Figure 1 and Figure 2As shown, one form of an engine system of the present disclosure includes: an engine 10 having a plurality of combustion chambers that generate a driving torque by burning fuel; an intake duct 60 that receives intake air to be supplied to the combustion chamber; a throttle valve 64 that is disposed on the upstream side of an intake manifold 70 and adjusts the amount of air to be supplied to the combustion chamber; an electric supercharger 50 that is disposed on the upstream side of the throttle valve 64 in the intake duct 60 and includes an electric motor 51 and an electric compressor 53 that is operated by the electric motor 51 to supply pressurized air to the combustion chamber; a catalytic converter 80 that purifies exhaust gas released from the combustion chamber; and an exhaust gas recirculation (EGR) device 40 that supplies a portion of the released exhaust gas from the combustion chamber back to the combustion chamber.

[0056] The electric supercharger 50 that supplies the boost air to the combustion chamber includes an electric motor 51 and an electric compressor 53. The electric compressor 53 is operated by the electric motor 51 and compresses the ambient air according to the driving conditions to supply the compressed air to the combustion chamber.

[0057] The intake duct 60 is provided with a bypass duct 62 for bypassing a part of the air to be supplied to the electric supercharger 50. A bypass valve 63 is installed on the bypass duct 62. The amount of air to be supplied to the electric supercharger 50 is adjusted by the bypass valve 63.

[0058] The exhaust gas recirculation device 40 includes an EGR pipe 41 through which a portion of the exhaust gas exhausted from the combustion chamber (recirculation gas) flows, an EGR cooler 43 installed in the EGR pipe 41, and an EGR valve 45 that adjusts the amount of recirculation gas.

[0059] The EGR conduit 41 branches from the exhaust conduit 30 at the downstream side of the catalytic converter 80 for exhaust gas generated at the combustion chamber, and joins to the intake conduit 60 at the downstream side of the electric supercharger 50 installed in the intake conduit 60 .

[0060] The EGR cooler 43 cools the recirculation gas (EGR gas) flowing through the EGR pipe 41 and supplies the cooled gas to the combustion chamber.

[0061] The engine system according to the exemplary form may be applied to a hybrid vehicle having a drive motor 110 that assists the power of the engine 10 .

[0062] The drive motor 110 assists the power of the engine 10 and selectively operates as a generator to generate electric energy. The drive motor 110 is operated using electric energy charged in a battery (not shown), and the electric energy generated by the drive motor 110 is charged in the battery.

[0063] The data detection unit 90 detects various data used in the method of diagnosing the EGR value according to the exemplary form and transmits the detected data to the controller 100 .

[0064] The data detected by the data detection unit 90 may include an internal pressure of the intake manifold, a crank angle, a coolant temperature, and a stop signal of the engine.

[0065] For this purpose, the data detection unit 90 may include: a manifold pressure sensor (MAP sensor: manifold absolute pressure sensor) 71 for detecting the internal pressure of the intake manifold; a crank angle position sensor (Crank Angle Position Sensor) for detecting the crank angle; and a coolant temperature sensor for detecting the temperature of the coolant.

[0066] In addition, the engine stop condition may include an ignition switch off stop, an engine flameout stop, and an idle stop. In one form, the data detection unit 90 may include an ignition switch sensor for detecting an ignition switch off stop, an RPM sensor for detecting an engine flameout stop, and / or an accelerator pedal sensor and a brake pedal sensor for detecting an idle stop.

[0067] The controller 100 operates the electric supercharger based on the data detected by the data detection unit 90 and learns the opening amount of the EGR valve 45 from the internal pressure of the intake manifold. The controller can determine the fixation of the EGR valve 45 and the leakage of the EGR valve 45 based on the detected data.

[0068] For this purpose, the controller 100 may be configured as at least one processor operated by a predetermined program, wherein the predetermined program may include instructions for corresponding steps of a method for diagnosing the EGR valve 45 according to an exemplary form of the present disclosure.

[0069] Hereinafter, a method for diagnosing an EGR valve according to an exemplary form is described in detail with reference to the accompanying drawings.

[0070] Figure 4 is a flow chart illustrating a method for diagnosing an EGR valve according to an exemplary form of the present disclosure.

[0071] like Figure 4 As shown in FIG. 1 , first, at step S10 , the controller 100 determines whether the engine is stopped based on data detected by the data detection unit 90 .

[0072] When the engine is stopped while the vehicle is running (S10-Y), the controller 100 determines whether the diagnosis required condition and the learning available condition of the EGR valve 45 are satisfied in step S20.

[0073] The diagnosis required condition means that the controller 100 has not performed a diagnosis on the EGR valve 45 within a predetermined period of time. For example, when the engine of the vehicle is turned on after being turned off for a long time (for example, more than 6 hours), or when the EGR valve 45 has not been diagnosed for a long time (for example, 5 hours or 6 hours) while the vehicle is running, the diagnosis required condition may be satisfied.

[0074] The available conditions for learning are used to determine whether the EGR valve is in a condition that is not suitable for diagnosis. When the coolant temperature is lower than a predetermined temperature (e.g., 60 degrees Celsius), when the battery voltage is lower than a predetermined value (e.g., 11V), when the electrical signal of a major component (e.g., MAP sensor, EGR valve, etc.) is abnormal (e.g., short circuit, etc.), when the atmospheric pressure is lower than a predetermined pressure (e.g., 950HPa), when the ambient air temperature is lower than a predetermined temperature (e.g., minus 30 degrees Celsius), when there is a misfire in the engine or a major component such as a catalyst is damaged, when the driver is not wearing a seat belt, or when the hood or door is open, the available conditions for learning can be set to not be satisfied.

[0075] When the diagnosis required condition is satisfied and the available condition is known (S20-Yes), the controller 100 adjusts the position of the crankshaft 19 by driving the motor 110 and / or the throttle valve 64 so that the crankshaft angle is positioned at the reference position. At this time, the reference position may be set to a position where the valve overlap of the intake valve 15 and the exhaust valve 17 of the corresponding cylinder becomes the smallest (reference position). Figure 3 ).

[0076] Subsequently, at step S30, the controller 100 operates the electric supercharger in the positive direction to generate a positive pressure higher than the atmospheric pressure in the intake manifold 70. Then, at step S40, the controller 100 sends an instruction to open the EGR valve 45 to a first predetermined amount within a predetermined period, and then, generates a control signal to close the EGR valve 45. At this time, the bypass valve 63 may be closed.

[0077] Alternatively, before closing the EGR valve 45 , the controller 100 may generate a control signal to further open the EGR valve 45 to a second predetermined amount that is different from the first predetermined amount.

[0078] Thereafter, the controller 100 obtains the opening amount of the EGR valve 45 from the internal pressure of the intake manifold 70 , or diagnoses the fixation of the EGR valve 45 and / or the leakage of the EGR valve 45 at step S60 .

[0079] Furthermore, at step S70 , when diagnosing that the EGR valve 45 is stuck and / or leaking, the controller 100 may alert the driver of the state of the EGR valve 45 through a center instrument panel or the like.

[0080] More specifically, the process of obtaining the opening degree of the EGR valve 45 will be described in detail.

[0081] Figure 5 4 is a diagram for explaining a method for obtaining the EGR amount according to the opening degree of the EGR valve 45 in an exemplary form. Figure 5 , the horizontal axis is the time axis, the left vertical axis is the internal pressure of the intake manifold 70 , and the right vertical axis represents the opening degree of the EGR valve 45 .

[0082] refer to Figure 5 , when the controller 100 has generated a control signal to close the EGR valve 45, when the electric supercharger operates in the positive direction, the internal pressure of the intake manifold 70 changes according to the opening amount of the EGR valve 45. At this time, in the case where the EGR valve 45 ideally follows the control signal of the controller 100, the reference pressure is the internal pressure of the intake manifold 70.

[0083] That is, in the case where the EGR valve 45 normally follows the control signal of the controller 100, when the control signal for operating the electric supercharger 50 and closing the EGR valve 45 is generated, the internal pressure of the intake manifold 70 becomes a positive pressure higher than the atmospheric pressure (refer to Figure 5 When the control signal for opening the EGR valve 45 to the first predetermined amount is generated, the internal pressure of the intake manifold 70 becomes a positive pressure lower than when the EGR valve 45 is closed (refer to Figure 5 In addition, when a control signal is generated to open the EGR valve 45 to a second predetermined amount greater than the first predetermined amount, the internal pressure of the intake manifold 70 becomes a positive pressure lower than when the EGR valve 45 is opened to the first predetermined amount (refer to Figure 5 Finally, when the EGR valve 45 is closed and the electric supercharger 50 is stopped, the internal pressure of the intake manifold 70 is maintained at the atmospheric pressure level (refer to Figure 5 middle 'D').

[0084] However, when the EGR valve 45 cannot accurately follow the control signal of the controller 100, the internal pressure of the intake manifold 70 becomes different from the reference pressure. That is, in the case where the controller 100 has generated a control signal to open to the first predetermined amount, when the internal pressure of the intake manifold 70 measured by the manifold pressure sensor 71 is different from the reference pressure, it can be determined that the EGR valve 45 cannot accurately follow the control signal of the controller 100.

[0085] Therefore, the controller 100 generates a control signal to open the EGR valve 45 to a second predetermined amount different from the first predetermined amount for a predetermined period, and compares the internal pressure of the intake manifold 70 with a reference pressure.

[0086] In addition, the controller 100 can determine that the compensation value of the opening of the EGR valve 45 is a ratio of the pressure difference, that is, the ratio of the pressure difference between the reference pressure and the internal pressure of the intake manifold 70 measured when the controller 100 generates a control signal to open the EGR valve 45 to a first predetermined amount, and the pressure difference between the reference pressure and the internal pressure of the intake manifold 70 measured when the controller 100 generates a control signal to open the EGR valve 45 to a second predetermined amount.

[0087] At this time, the EGR amount can be calculated by the following equation.

[0088] [Equation 1]:

[0089] EGR amount = effective cross-section of the EGR pipe * compensation value * pressure difference between the upstream and downstream sides of the EGR valve * flow function * temperature of the EGR gas

[0090] By setting the compensation value of the opening degree of the EGR valve in Equation 1 to the ratio of the pressure difference, the controller 100 can accurately calculate the EGR amount.

[0091] A process of diagnosing a sticking of an EGR valve according to an exemplary form is described in detail.

[0092] Figure 6 is a diagram for explaining a method of diagnosing a stationary EGR valve according to an exemplary form. Figure 6 , the horizontal axis is the time axis, the left vertical axis is the internal pressure of the intake manifold 70, and the right vertical axis represents the opening degree of the EGR valve.

[0093] refer to Figure 6 When the controller 100 has generated a control signal to close the EGR valve 45, the controller 100 operates the electric supercharger 50 in the positive direction to generate a positive pressure higher than the atmospheric pressure in the intake manifold 70 (refer to Figure 6 At this time, the bypass valve 63 is closed.

[0094] In addition, the controller 100 generates a control signal to open the EGR valve 45 to different openings (ie, different opening amounts). For example, after generating a control signal to open the EGR valve 45 to a first predetermined opening amount (refer to Figure 6 'B' in FIG. 1 ), the controller 100 may generate a control signal (reference signal) that opens the EGR valve 45 to a second predetermined opening amount that is larger than the first predetermined opening amount. Figure 6 in the text box).

[0095] After that, the controller 100 generates a control signal to close the EGR valve 45, and then stops the electric supercharger 50 (refer to Figure 6 'D' in the text box.

[0096] Controller 100 may determine that EGR valve 45 is fixed (ie, stuck) when the internal pressure of intake manifold 70 measured by the manifold pressure sensor does not change even if a control signal is generated to open EGR valve 45 to different opening degrees.

[0097] Therefore, for example, the controller 100 may notify the driver that the EGR valve 45 is malfunctioning by using an alarm or the like through a center instrument panel or the like installed in the vehicle.

[0098] A process of diagnosing leakage of an EGR valve according to an exemplary form will be described in detail.

[0099] Figure 7 is a diagram for explaining a method of diagnosing leakage of an EGR valve according to an exemplary form. Figure 7 , the horizontal axis is the time axis, the left vertical axis is the internal pressure of the intake manifold 70, and the right vertical axis represents the opening degree of the EGR valve.

[0100] refer to Figure 7 When the controller 100 has generated a control signal to close the EGR valve 45, the controller 100 operates the electric supercharger 500 in the positive direction to generate a positive pressure higher than the atmospheric pressure in the intake manifold 70 (refer to Figure 7 in the text box).

[0101] In addition, the controller 100 generates a control signal for opening the EGR valve 45 to different openings. For example, after generating a control signal for opening the EGR valve 45 to a first predetermined amount (refer to Figure 7 'B' in FIG. 1 ), the controller 100 may generate a control signal (reference signal) that opens the EGR valve 45 to a second predetermined amount greater than the first predetermined amount. Figure 7 in the text box).

[0102] After that, the controller 100 generates a control signal to close the EGR valve 45, and then stops the electric supercharger 50 (refer to Figure 7 in the text box).

[0103] When the electric supercharger 50 operates and controls the EGR valve 45 to be opened, the controller 100 may determine that the EGR valve 45 leaks when the difference between the internal pressure of the intake manifold 70 detected by the manifold pressure sensor and the reference pressure is greater than a predetermined pressure.

[0104] Therefore, for example, the controller 100 may notify the driver that the EGR valve 45 is malfunctioning by using an alarm or the like through a center instrument panel or the like installed in the vehicle.

[0105] Hereinafter, a method of obtaining an opening degree of an EGR valve, diagnosing a fixation, and diagnosing a leakage method according to another exemplary form will be described in detail.

[0106] A process of learning the opening degree of the EGR valve will be described in detail.

[0107] Figure 8 FIG. 2 is a diagram for explaining a method for diagnosing the opening degree of the EGR valve 45 and obtaining the EGR amount according to another exemplary form. Figure 8 , the horizontal axis is the time axis, the left vertical axis is the internal pressure of the intake manifold 70 , and the right vertical axis represents the opening degree of the EGR valve 45 .

[0108] refer to Figure 8 , when the controller 100 has generated a control signal to close the EGR valve 45, when the electric supercharger operates in the reverse direction, the internal pressure of the intake manifold 70 changes according to the opening degree of the EGR valve 45. At this time, in the case where the EGR valve 45 ideally follows the control signal of the controller 100, the reference pressure is the internal pressure of the intake manifold 70.

[0109] That is, in the case where the EGR valve 45 normally follows the control signal of the controller 100, when a control signal is generated to operate the electric supercharger 50 and close the EGR valve 45, the internal pressure of the intake manifold 70 becomes a negative pressure lower than the atmospheric pressure (refer to Figure 8 When the control signal for opening the EGR valve 45 to the first predetermined amount is generated, the internal pressure of the intake manifold 70 becomes a negative pressure higher than when the EGR valve 45 is closed (refer to Figure 8 In addition, when a control signal is generated to open the EGR valve 45 to a second predetermined amount greater than the first predetermined amount, the internal pressure of the intake manifold 70 becomes a negative pressure higher than when the EGR valve 45 is opened to the first predetermined amount (refer to Figure 8 Finally, when the EGR valve 45 is closed and the electric supercharger 50 is stopped, the internal pressure of the intake manifold 70 is maintained at the atmospheric pressure level (refer to Figure 8 in the text box).

[0110] However, when the EGR valve 45 does not accurately follow the control signal of the controller 100, the internal pressure of the intake manifold 70 becomes different from the reference pressure. That is, in the case where the controller 100 has generated a control signal to open to the first predetermined amount, when the internal pressure of the intake manifold 70 measured by the manifold pressure sensor is different from the reference pressure, it can be inferred that the EGR valve 45 does not accurately follow the control signal of the controller 100.

[0111] The controller 100 generates a control signal to open the EGR valve 45 to a second predetermined amount different from the first predetermined amount for a predetermined period, and compares the internal pressure of the intake manifold 70 with a reference pressure.

[0112] In addition, the controller 100 can determine a compensation value for the opening of the EGR valve 45 based on a ratio of pressure differences, i.e., a ratio of a pressure difference between a reference pressure and the internal pressure of the intake manifold 70 measured when the controller 100 generates a control signal to open the EGR valve 45 to a first predetermined amount, and a pressure difference between a reference pressure and the internal pressure of the intake manifold 70 measured when the controller 100 generates a control signal to open the EGR valve 45 to a second predetermined amount.

[0113] The EGR amount can be calculated by the following equation.

[0114] [Equation 1]:

[0115] EGR amount = effective cross-section of the EGR pipe * compensation value * pressure difference between the upstream and downstream sides of the EGR valve * flow function * temperature of the EGR gas

[0116] By setting the compensation value of the opening degree of the EGR valve in Equation 1 to the ratio of the pressure difference, the controller 100 can accurately calculate the EGR amount.

[0117] A process of diagnosing the sticking of the EGR valve according to another exemplary form will be described in detail.

[0118] Fig. 9 is a diagram for explaining a method of diagnosing a stationary EGR valve according to an exemplary form. Fig. 9 , the horizontal axis is the time axis, the left vertical axis is the internal pressure of the intake manifold 70, and the right vertical axis represents the opening degree of the EGR valve.

[0119] refer to Fig. 9 When the controller 100 has generated a control signal to close the EGR valve 45, the controller 100 operates the electric supercharger 50 in the reverse direction to generate a negative pressure lower than the atmospheric pressure in the intake manifold 70 (refer to Fig. 9 in the text box).

[0120] In addition, the controller 100 generates a control signal for opening the EGR valve 45 to different openings. For example, after generating a control signal for opening the EGR valve 45 to a first predetermined amount (refer to Fig. 9 'B' in FIG. 1 ), the controller 100 may generate a control signal (reference signal) that opens the EGR valve 45 to a second predetermined amount greater than the first predetermined amount. Fig. 9 in the text box).

[0121] After that, the controller 100 generates a control signal to close the EGR valve 45, and then stops the electric supercharger 50 (refer to Fig. 9 in the text box).

[0122] The controller may determine that the EGR valve 45 is stuck when the internal pressure of the intake manifold 70 measured by the manifold pressure sensor does not change even if a control signal is generated to open the EGR valve 45 to different sizes of opening degrees.

[0123] Therefore, for example, the controller 100 may notify the driver that the EGR valve 45 is malfunctioning by using an alarm or the like through a center instrument panel or the like installed in the vehicle.

[0124] A process of diagnosing leakage of the EGR valve according to another exemplary form will be described in detail.

[0125] Fig.10 is a diagram for explaining a method of diagnosing leakage of an EGR valve according to an exemplary form. Fig.10 , the horizontal axis is the time axis, the left vertical axis is the internal pressure of the intake manifold 70, and the right vertical axis represents the opening degree of the EGR valve.

[0126] refer to Fig.10 When the controller 100 has generated a control signal to close the EGR valve 45, the controller 100 operates the electric supercharger 50 in the reverse direction to generate a negative pressure lower than the atmospheric pressure in the intake manifold 70 (refer to Fig.10 in the text box).

[0127] In addition, the controller 100 generates a control signal for opening the EGR valve 45 to different openings. For example, after generating a control signal for opening the EGR valve 45 to a first predetermined amount (refer to Fig.10 'B' in FIG. 1 ), the controller 100 may generate a control signal (reference signal) that opens the EGR valve 45 to a second predetermined amount greater than the first predetermined amount. Fig.10 in the text box).

[0128] After that, the controller 100 generates a control signal to close the EGR valve 45, and then stops the electric supercharger 50 (refer to Fig.10 in the text box).

[0129] When the electric supercharger 50 operates and controls the EGR valve 45 to be opened, the controller 100 may determine that the EGR valve 45 leaks when the difference between the internal pressure of the intake manifold 70 detected by the manifold pressure sensor and the reference pressure is greater than a predetermined pressure.

[0130] Therefore, for example, the controller 100 may notify the driver that the EGR valve 45 is malfunctioning by using an alarm or the like through a center instrument panel or the like installed in the vehicle.

[0131] Although the present disclosure has been described in connection with what are presently considered to be practical exemplary forms, it should be understood that the present disclosure is not limited to the forms disclosed, but is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

[0132] <symbol description>

[0133] 10: Engine

[0134] 11: Combustion Chamber

[0135] 15: Intake valve

[0136] 17: Exhaust valve

[0137] 30: Exhaust duct

[0138] 35: Exhaust manifold

[0139] 40: Exhaust gas recirculation device

[0140] 41: EGR pipe

[0141] 43: EGR cooler

[0142] 45: EGR valve

[0143] 50: Electric supercharger

[0144] 51: Electric motor

[0145] 53: Electric compressor

[0146] 60: Intake duct

[0147] 62: Bypass pipe

[0148] 63: Bypass valve

[0149] 64: Throttle valve

[0150] 68: Air Purifier

[0151] 70: Intake manifold

[0152] 71: Manifold pressure sensor

[0153] 80: Catalytic converter

[0154] 90: Data detection unit

[0155] 100: Controller

[0156] 110: Driving motor

Claims

1. A device for diagnosing an exhaust gas recirculation valve, include: Exhaust gas recirculation device, including: an exhaust gas recirculation duct connecting the exhaust duct and the intake duct of the engine; and an exhaust gas recirculation valve installed in the exhaust gas recirculation pipeline; an electric supercharger installed in the intake duct and configured to change the internal pressure of the intake manifold; a manifold pressure sensor configured to measure the internal pressure of the intake manifold; and a controller configured to obtain the opening amount of the exhaust gas recirculation valve and diagnose the fixation of the exhaust gas recirculation valve and the leakage of the exhaust gas recirculation valve based on the measured internal pressure of the intake manifold when the engine is stopped during vehicle driving, Wherein, the controller is configured as: operating the electric supercharger in a positive direction to generate a positive pressure above atmospheric pressure in the intake manifold; opening the exhaust gas recirculation valve by a first predetermined opening amount within a first predetermined period, and then, after the first predetermined period expires, closing the exhaust gas recirculation valve; and calculating a first pressure difference by comparing the internal pressure of the intake manifold measured during the first predetermined period with a first reference pressure so that the controller learns the opening amount of the exhaust gas recirculation valve, opening the exhaust gas recirculation valve by a second predetermined opening amount within a second predetermined period, and then, after the second predetermined period expires, closing the exhaust gas recirculation valve, wherein the second predetermined opening amount is different from the first predetermined opening amount; calculating a second pressure difference by comparing the internal pressure of the intake manifold measured during the second predetermined period with a second reference pressure; calculating a ratio of the first pressure difference to the second pressure difference; and A compensation value for the opening degree of the exhaust gas recirculation valve is determined based on the calculated ratio of the first pressure difference to the second pressure difference.

2. The device according to claim 1, in, The controller is configured to, when the engine is stopped, obtain the opening amount of the exhaust gas recirculation valve after positioning the crank angle to a reference position, and diagnose the fixation of the exhaust gas recirculation valve and the leakage of the exhaust gas recirculation valve, wherein the reference position is a position where the valve overlap of the intake valve and the exhaust valve of the corresponding cylinder becomes minimal.

3. The device according to claim 1, in, The controller is configured to determine that the exhaust gas recirculation valve is fixed when the measured internal pressure of the intake manifold does not change, when the electric supercharger is operated in a positive direction to generate a positive pressure above atmospheric pressure in the intake manifold and sends an instruction to open the exhaust gas recirculation valve to different opening amounts.

4. The device according to claim 1, in, The controller is configured to determine that the exhaust gas recirculation valve is leaking when a difference between the measured internal pressure of the intake manifold and a reference pressure is greater than a predetermined pressure when the electric supercharger is operated in a positive direction to generate a positive pressure higher than atmospheric pressure in the intake manifold and sends an instruction to open the exhaust gas recirculation valve to different opening amounts.

5. A device for diagnosing an exhaust gas recirculation valve, include: Exhaust gas recirculation device, including: an exhaust gas recirculation duct connecting the exhaust duct and the intake duct of the engine; and an exhaust gas recirculation valve installed in the exhaust gas recirculation pipeline; an electric supercharger installed in the intake duct and configured to change the internal pressure of the intake manifold; a manifold pressure sensor configured to measure the internal pressure of the intake manifold; and a controller configured to obtain the opening amount of the exhaust gas recirculation valve and diagnose the fixation of the exhaust gas recirculation valve and the leakage of the exhaust gas recirculation valve based on the measured internal pressure of the intake manifold when the engine is stopped during vehicle driving, Wherein, the controller is configured as: operating the electric supercharger in a reverse direction and generating a negative pressure in the intake manifold that is lower than atmospheric pressure; opening the exhaust gas recirculation valve by a first predetermined opening amount within a first predetermined period of time; closing the exhaust gas recirculation valve after expiration of the first predetermined period; and comparing the internal pressure of the intake manifold measured during the first predetermined period with a first reference pressure to obtain the opening amount of the exhaust gas recirculation valve, opening the exhaust gas recirculation valve by a second predetermined opening amount within a second predetermined period of time; After the second predetermined period of time expires, closing the exhaust gas recirculation valve, wherein the second predetermined opening amount is different from the first predetermined opening amount; calculating a first pressure difference by comparing the internal pressure of the intake manifold measured during the first predetermined period with the first reference pressure; calculating a second pressure difference by comparing the internal pressure of the intake manifold measured during the second predetermined period with a second reference pressure; calculating a ratio of the first pressure difference to the second pressure difference; and A compensation value for the opening degree of the exhaust gas recirculation valve is determined based on the calculated ratio of the first pressure difference to the second pressure difference.

6. The device according to claim 5, in, The controller is configured to, when the engine is stopped, obtain the opening amount of the exhaust gas recirculation valve after positioning the crank angle to a reference position, and diagnose the fixation of the exhaust gas recirculation valve and the leakage of the exhaust gas recirculation valve, wherein the reference position is a position where the valve overlap of the intake valve and the exhaust valve of the corresponding cylinder becomes minimal.

7. The device according to claim 5, in, The controller is configured to determine that the exhaust gas recirculation valve is fixed when the internal pressure of the intake manifold detected from the manifold pressure sensor does not change, when the electric supercharger operates in a reverse direction to generate a negative pressure below atmospheric pressure in the intake manifold and sends an instruction to open the exhaust gas recirculation valve to a different opening amount.

8. The device according to claim 5, in, The controller is configured to determine that the exhaust gas recirculation valve is leaking when a difference between the internal pressure of the intake manifold detected from the manifold pressure sensor and a reference pressure is greater than a predetermined pressure when the electric supercharger is operated in a reverse direction to generate a negative pressure below atmospheric pressure in the intake manifold and sends an instruction to open the exhaust gas recirculation valve to a different opening amount.

9. A method for diagnosing an exhaust gas recirculation valve provided in an exhaust gas recirculation device, the method include: determining, by a controller, whether the engine is stopped while the vehicle is traveling; operating an electric supercharger by the controller, the electric supercharger being configured to change an internal pressure of an intake manifold; measuring the internal pressure of the intake manifold by a manifold pressure sensor, the internal pressure of the intake manifold changing based on the opening amount of the exhaust gas recirculation valve; and The controller obtains the opening amount of the exhaust gas recirculation valve based on the measured internal pressure of the intake manifold, Wherein, the method further comprises: operating the electric supercharger in a positive direction by the controller to generate a positive pressure in the intake manifold that is higher than atmospheric pressure; opening the exhaust gas recirculation valve by the controller within a first predetermined period of time and at a first predetermined opening amount; After the first predetermined period expires, closing the exhaust gas recirculation valve by the controller; and The opening amount of the exhaust gas recirculation valve is obtained by comparing the measured internal pressure of the intake manifold with a first reference pressure, opening the exhaust gas recirculation valve by a second predetermined opening amount within a second predetermined period of time by the controller, wherein the second predetermined opening amount is different from the first predetermined opening amount; After the second predetermined period expires, closing the exhaust gas recirculation valve by the controller; calculating, by the controller, a first pressure difference by comparing the internal pressure of the intake manifold measured during the first predetermined period with a first reference pressure, and calculating, by the controller, a second pressure difference by comparing the internal pressure of the intake manifold measured during the second predetermined period with a second reference pressure; and The controller determines a compensation value for the opening of the exhaust gas recirculation valve as a ratio of the first pressure difference to the second pressure difference.

10. A method for diagnosing an exhaust gas recirculation valve provided in an exhaust gas recirculation device, the method include: determining, by a controller, whether the engine is stopped while the vehicle is traveling; operating an electric supercharger by the controller, the electric supercharger being configured to change an internal pressure of an intake manifold; measuring the internal pressure of the intake manifold by a manifold pressure sensor, the internal pressure of the intake manifold changing based on the opening amount of the exhaust gas recirculation valve; and The controller obtains the opening amount of the exhaust gas recirculation valve based on the measured internal pressure of the intake manifold, Wherein, the method further comprises: operating the electric supercharger in a reverse direction by the controller to generate a negative pressure in the intake manifold that is lower than atmospheric pressure; opening the exhaust gas recirculation valve by the controller within a first predetermined period of time and at a first predetermined opening amount; After the first predetermined period expires, closing the exhaust gas recirculation valve by the controller; and the controller obtaining the opening amount of the exhaust gas recirculation valve by comparing the internal pressure of the intake manifold measured during the first predetermined period with a first reference pressure, opening the exhaust gas recirculation valve by a second predetermined opening amount within a second predetermined period of time by the controller, wherein the second predetermined opening amount is different from the first predetermined opening amount; After the second predetermined period expires, closing the exhaust gas recirculation valve by the controller; comparing the internal pressure of the intake manifold measured during the second predetermined period with a second reference pressure; and The controller determines a compensation value for the opening of the exhaust gas recirculation valve based on a first pressure difference between the first reference pressure and the internal pressure of the intake manifold measured when the exhaust gas recirculation valve is opened by the first predetermined opening amount, and a second pressure difference between the second reference pressure and the internal pressure of the intake manifold measured when the exhaust gas recirculation valve is opened by the second predetermined opening amount.

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