Method and system for diagnosing an engine system with a continuously variable valve duration device

Abstract

A method for diagnosing an engine system comprising a continuously variable valve duration (CVVD) device, a CVVD device drive unit (300) having a first drive unit (301) and a second drive unit (303), a CVVD position detector configured to detect a position of the CVVD device, a camshaft position detector configured to detect a position of a camshaft (30), a front lambda sensor configured to detect a lambda value upstream of the intake valve, and a controller, the method comprising the following steps: - Starting the engine by the control system; - Recording of the measured values ​​of the front lambda sensor during combustion in the first to fourth cylinders by the control system, the measured values ​​being first to fourth lambda values; - Determining, based on the recorded first to fourth lambda values, whether the CVVD drive unit (300) is adjusted, and - Generation of a warning message by the controller when it is detected that the CVVD drive unit (300) is misaligned.

Description

AREA

[0001] The present invention relates to a method and a system for diagnosing an engine system with a device with continuously variable valve duration. BACKGROUND

[0002] The statements in this section merely provide background information related to the present invention and may not constitute prior art.

[0003] Generally, an internal combustion engine generates power by ingesting and burning fuel and air in a combustion chamber. When air is drawn in, a camshaft actuates an intake valve, and when the intake valve is open, air is drawn into the combustion chamber. Furthermore, an exhaust valve is actuated by the camshaft, and when the exhaust valve is open, air is expelled from the combustion chamber.

[0004] However, optimal intake / exhaust valve actuation varies depending on the engine speed. This means that the corresponding lift or valve opening / closing time varies depending on the engine speed. To achieve appropriate valve actuation depending on the engine speed, a continuously variable valve lift (CVVL) device was developed. This device has multiple configurations of the cam lobe that drives the valve, or a valve operates with a different lift depending on the engine speed.

[0005] In addition, CVVT (Continuous Variable Valve Timing) technology has been developed, which adjusts the valve opening time, that is, a technology that changes the valve opening / closing timing simultaneously in a state where the valve timing is fixed.

[0006] However, it was found that a conventional CVVL or CVVT has a complex configuration and high costs.

[0007] Therefore, a continuously variable valve duration (CVVD) device was developed, which can adjust the valve duration according to the operating condition of the engine.

[0008] In order to use the CVVD device in the engine system, a procedure is required to determine whether the CVVD device is operating normally.

[0009] In particular, in the CVVD device with two drive units, each drive unit is responsible for the valves of two cylinders, controlling a total of four cylinder valves. If the two drive units are not assembled correctly, resulting in misalignment (misalignment), the CVVD drive unit cannot control the valves normally. A diagnostic process is required to address these issues.

[0010] In addition, US 2005 / 0 204 805 A1 discloses a method for diagnosing an engine system, which comprises a device with continuously variable valve duration (CVVD), a drive unit of the CVVD device with a first drive unit and a second drive unit, a CVVD position detector which is set up to detect a position of the CVVD device, a camshaft position detector which is set up to detect a position of a camshaft, a lambda sensor which is set up to detect a lambda value, and a controller, the method comprising the following steps: detecting the measured values ​​of the lambda sensor during combustion in the first to fourth cylinders by the controller, the measured values ​​being first to fourth lambda values;Determining, by the controller, whether the CVVD drive unit is misaligned based on the detected first to fourth lambda values, and generating a warning message by the controller if it is determined that the CVVD drive unit is misaligned;

[0011] The foregoing information disclosed in this Background section is provided merely to facilitate understanding of the background of the present invention and may therefore contain non-prior art information that would be readily apparent to a person skilled in the art. OVERVIEW

[0012] It is therefore the object of the present invention to provide a method and a system for diagnosing an engine system including a continuously variable valve duration (CVVD) device, which is capable of diagnosing whether a misalignment (adjustment) occurs while assembling a drive unit of the CVVD device.

[0013] The object is achieved by a method having the features of claim 1 and a system having the features of claim 7. Advantageous further developments can be found in the subclaims.

[0014] According to one aspect of the invention, a method for diagnosing an engine system comprising a continuously variable valve duration (CVVD) device, a drive unit of the CVVD device having a first drive unit and a second drive unit, a CVVD position detector configured to detect a position of the CVVD device, a camshaft position detector configured to detect a position of a camshaft, a front lambda sensor configured to detect a lambda value upstream of the intake valve, and a controller, comprising the following steps: starting the engine by the controller, detecting the measured values ​​of the front lambda sensor during combustion of a first to fourth cylinder by the controller (the measured values ​​are first to fourth lambda values), determining, based on the detected first to fourth lambda values, whether the CVVD drive unit is adjusted,and generating a warning message by the controller when the CVVD drive unit is detected as being out of adjustment.,

[0015] The step of determining whether the CVVD drive unit is out of adjustment may comprise the steps of the controller determining whether the CVVD drive unit is out of adjustment when the first and second lambda values ​​are rich and the third and fourth lambda values ​​are lean, or when the first and second lambda values ​​are lean and the third and fourth lambda values ​​are rich, and the controller re-performing the detection of the first to fourth lambda values.

[0016] The step of detecting the first to fourth lambda values ​​may include the steps of performing lambda 1 control of the engine, checking the measured value of the front lambda sensor during combustion of the first cylinder (the first lambda value), checking the measured value of the front lambda sensor during combustion of the third cylinder (the third lambda value), checking the measured value of the front lambda sensor during combustion of the fourth cylinder (the fourth lambda value), checking the measured value of the front lambda sensor during combustion of the second cylinder (the second lambda value); and outputting the first to fourth lambda values ​​to the controller.

[0017] The step of determining whether the CVVD drive unit is out of adjustment may further comprise the steps of, if one of the first to fourth lambda values ​​is less than or equal to a first predetermined value, determining the lambda value as lean, if one of the first to fourth lambda values ​​is greater than or equal to a second predetermined value, determining the lambda value as rich, and if one of the first to fourth lambda values ​​is greater than the first predetermined value and less than the second predetermined value, determining the lambda value as a theoretical value of the air-fuel ratio.

[0018] The step of starting the engine may include the steps of starting the engine, determining whether a CVVD learning process is complete, and performing the engine start-up control.

[0019] The step of determining whether the CVVD learning is complete may include the step of performing the CVVD learning if the CVVD learning process is not complete.

[0020] According to a further aspect of the invention, a system for diagnosing an engine system comprising a continuously variable valve duration (CVVD) device comprises a drive unit of the CVVD device with a first drive unit and a second drive unit, a CVVD position detector configured to detect a position of the CVVD device, and a camshaft position detector configured to detect a position of the camshaft, a front lambda sensor configured to detect a lambda value upstream of the intake valve, and a controller configured to detect measured values ​​of the front lambda sensor during combustion of the first to fourth cylinders (the measured values ​​being first to fourth lambda values), and to determine, based on the detected first to fourth lambda values, whether the CVVD is adjusted, and to generate a warning message if it is determinedthat the CVVD drive unit is misaligned.

[0021] If the first and second lambda values ​​are rich and the third and fourth lambda values ​​are lean, or if the first and second lambda values ​​are lean and the third and fourth lambda values ​​are rich, the controller may determine the CVVD actuator to be out of adjustment, and if the controller does not determine the CVVD actuator to be out of adjustment in the previous step, the controller may detect the first to fourth lambda values ​​again.

[0022] If one of the first to fourth lambda values ​​is less than or equal to a first predetermined value, the controller determines the lambda value as lean. If one of the first to fourth lambda values ​​is greater than or equal to a second predetermined value, the controller determines the lambda value as rich. Furthermore, if one of the first to fourth lambda values ​​is greater than the first predetermined value and less than the second predetermined value, the controller determines the lambda value as the theoretical value of the air-fuel ratio.

[0023] When the engine is started, the controller determines whether CVVD learning is complete. If CVVD learning is not complete, the controller performs CVVD learning. Furthermore, after CVVD learning is completed, the controller performs engine start-up control.

[0024] Further areas of applicability will become apparent from the description provided herein. It is to be understood that the description and specific examples are for illustrative purposes only and are not intended to limit the scope of the invention. DRAWING FIGURES

[0025] For a better understanding of the invention, various embodiments thereof will now be described by way of example, reference being made to the accompanying drawing figures, in which: Fig. 1 is a perspective view of an engine having a continuously variable valve duration device according to an exemplary embodiment of the present invention; Fig. 2 is a perspective view of a continuously variable valve duration device according to an exemplary embodiment of the invention; Fig. 3 is a side view of a continuously variable valve duration device according to an exemplary embodiment of the invention; Fig. 4 is an exploded perspective view of a continuously variable valve duration device according to an exemplary embodiment of the present invention; Fig. 5 is a partially exploded perspective view of a continuously variable valve duration device according to an exemplary embodiment of the present invention; Fig. 6 is a partially exploded perspective view of a continuously variable valve duration device according to an exemplary embodiment of the present invention; Fig. 7 is a cross-sectional view along the line VII-VII of Fig. 5; Fig. 8 and Fig. 9 show an inner wheel and a cam unit of a device with continuously variable valve duration according to an exemplary embodiment of the invention; Fig. 10 is a cross-sectional view along the line XX of Fig. 6; Fig. 11 to Fig. 13 shows an inner wheel of a device with continuously variable valve duration according to an exemplary embodiment of the invention; Fig. 14A and Fig. 14B shows a cam slot of a continuously variable valve duration device according to an exemplary embodiment of the invention; The Fig. are diagrams showing the valve profile of a continuously variable valve duration device according to an exemplary embodiment of the invention; The Fig. 16A and Fig. 16B illustrate the process of assembling the control shaft and drive unit of a CVVD (Continuous Variable Valve Duration) device according to an exemplary embodiment of the invention; and Fig. 17 is a flowchart illustrating a method for diagnosing an engine system having a CVVD (Continuous Variable Valve Duration) device according to an exemplary embodiment of the present invention.

[0026] The drawing figures described here are for illustrative purposes only and are not intended to limit the scope of protection of the invention in any way. DETAILED DESCRIPTION

[0027] The following description is merely exemplary and is not intended to limit the present invention, its application, or uses. It should be understood that like reference numerals designate like or corresponding parts and features throughout the drawings.

[0028] In the drawings, the thicknesses of layers, foils, panels, regions, etc. are exaggerated for clarity.

[0029] In the description, unless expressly stated otherwise, the word "comprise" and variations such as "comprises" or "include" are understood to imply the inclusion of the specified elements but not the exclusion of others.

[0030] Fig. 1 is a perspective view of an engine provided with a continuously variable valve duration (CVVD) device according to an exemplary embodiment of the present invention, and Fig. Figure 2 is a perspective view of the continuously variable valve duration (CVVD) device of Fig. 1.

[0031] Fig. 3 is a side view of the CVVD (Continuous Variable Valve Duration) device of Fig. 2 and Fig. 4 is a perspective exploded view of the CVVD device of Fig. 2.

[0032] Fig. 5 is a partially exploded perspective view of the continuously variable valve duration (CVVD) device of Fig. 2, Fig. 6 is a partially exploded perspective view of the continuously variable valve duration (CVVD) device of Fig. 2, and Fig. 7 is a cross-sectional view along the line VII-VII of Fig. 5.

[0033] Referring to Fig. 1 to Fig. 7, an engine 1 according to an exemplary embodiment of the invention comprises a continuously variable valve duration (CVVD) device.

[0034] As in Fig. 3, four (4) cylinders 201, 202, 203 and 204 are formed into an engine, but not limited thereto.

[0035] A continuously variable valve duration (CVVD) device according to an exemplary embodiment of the invention comprises a camshaft 30, a cam unit 70 on which a cam 71 is formed and into which the camshaft 30 is inserted, an internal gear 80 configured to transmit the rotation of the camshaft 30 to the cam unit 70, a gear housing 90 into which the internal gear 80 is rotatably inserted and movable perpendicular to the camshaft 30, a guide shaft 132 on which a guide screw thread 130 is formed and which is arranged perpendicular to the camshaft 30, a worm gear 50 in which an internal screw thread 52 is formed is configured to engage with the guide screw thread 130, the worm gear 50 is arranged within the gear housing 90, and a control shaft 102 with a control worm 104 configured to engage with the worm gear 50 trained.The control worm 104 engages with an external thread 54 on the outer circumference of the worm wheel 50.

[0036] The device with continuously adjustable valve duration also comprises a guide bracket 134 to which the guide shaft 132 is attached.

[0037] In this case, valve duration refers to the duration a valve is open. This is the time period from the opening of the valve to its closing.

[0038] The camshaft 30 may be an intake camshaft or an exhaust camshaft.

[0039] On the guide bracket 134, a fastening hole 137 to which the guide shaft 132 is fastened and a movement space 138 in which the wheel housing is movable are formed.

[0040] On each guide wall 92, two guide walls 92 protruding from the wheel housing 90 and a movable bore 94 into which the guide shaft 132 is inserted are formed.

[0041] The worm wheel 50 is arranged between the guide walls 92 and pushes the guide wall 92 by targeted rotation to move the wheel housing 90.

[0042] The continuously variable valve duration device further includes a sliding shaft 135 fixed to the guide bracket 134 through a bore 135c and adapted to guide the movement of the gear housing 90, and a sliding bore 96 into which the sliding shaft 135 is inserted is formed on the gear housing 90.

[0043] The continuously variable valve duration device also includes a worm shaft cap 139, which is attached to the guide bracket 134 and serves to support the control shaft 102. The worm shaft cap 139 can be attached to the guide bracket 134 with screws 136.

[0044] The connection diagram of the guide bracket 134, the wheel housing 90 and the worm wheel 50 can simplify and reduce the cost of the device with continuously adjustable valve duration.

[0045] The guide shaft 132 can be mounted on the guide bracket 134 through a bore 132b formed on the guide bracket 134 by inserting a connecting pin 132a.

[0046] Furthermore, the sliding shaft 135 can be attached to the guide bracket 134 through a hole 135b formed on the guide bracket 134 by inserting a connecting pin 135a.

[0047] Fig. 8 and Fig. 9 show an inner wheel and a cam unit of a device with continuously variable valve duration according to an exemplary embodiment of the invention, and Fig. 10 is a cross-sectional view along the line XX of Fig. 6.

[0048] Referring to the Fig. 1 to Fig. 10, a first sliding bore 86 and a second sliding bore 88 are formed in the inner wheel 80 and a cam slot 74 is formed on the cam unit 70.

[0049] The continuously variable valve duration device further includes a roller gear 60 connected to the camshaft 30 and rotatably inserted into the first sliding bore 86, and a roller cam 82 slidably inserted into the cam slot 74 and rotatably inserted into the second sliding bore 88.

[0050] The roller cam 82 includes a roller cam body 82a slidably fitted into the cam slot 74 and a cam head 82b rotatably fitted into the second sliding bore 88.

[0051] A projection 82c is formed on the roller cam 82, which prevents or inhibits the roller cam 82 from being separated from the inner gear 80 in the longitudinal direction of the camshaft 30.

[0052] The roller wheel 60 comprises a wheel body 62 slidably connected to the camshaft 30 and a wheel head 64 rotatably inserted into the first sliding bore 86, wherein the wheel body 62 and the wheel head 64 can be formed in one piece.

[0053] The camshaft 30 is provided with a camshaft bore 34, the wheel body 62 of the roller wheel 60 is movably inserted into the camshaft bore 34 and the wheel head 64 is rotatably inserted into the first sliding bore 86.

[0054] A camshaft oil hole 32 is formed inside the camshaft 30 along its longitudinal direction, a body oil hole 66 communicating with the camshaft oil hole 32 is formed on the wheel body 62 of the roller wheel 60, and an oil groove 68 communicating with the body oil hole 66 (see Fig. 11) is formed on the wheel head 64 of the roller wheel 60.

[0055] Lubricant of the camshaft oil bore 32 can be supplied to the inner gear 80 through the body oil bore 66, the connecting bore 69 and the oil groove 68.

[0056] The cam unit 70 includes a first cam part 70a and a second cam part 70b, which are arranged corresponding to a cylinder and an adjacent cylinder, e.g., the first cylinder 201 and the adjacent second cylinder 202. The internal gear 80 includes a first internal gear 80a and a second internal gear 80b, which transmit the rotation of the camshaft 30 to the first cam part 70a and the second cam part 70b, respectively.

[0057] Two cams 71 and 72 may be formed as a pair on the first and second cam parts 70a and 70b, and a cam attachment connecting part 76 is formed between the paired cams 71 and 72 of the first and second cam parts 70a and 70b.

[0058] Cams 71 and 72 rotate and open valve 200.

[0059] The continuously variable valve duration device further comprises a cam cap 40 on which a cam support member 46 configured to rotatably support the cam cap connecting member 76 is formed on the cam cap 40.

[0060] Fig. 11 to Fig. 13 show the operation of an internal gear 80 of a device with continuously variable valve duration according to an exemplary embodiment of the invention.

[0061] As in Fig. 11, the cams 71 and 72 rotate at the same phase angle of the camshaft 30 when the rotation centers of the camshaft 30 and the cam unit 70 coincide.

[0062] Depending on the operating state of the engine, a control unit (engine control unit or electrical control unit) sends control signals to the control part 100, and then the control motor 106 rotates the control shaft 102.

[0063] Subsequently, the control worm 104 rotates the shaped outer circumference of the worm wheel 50. And since the internal thread 52 formed into the worm wheel 50 engages with the guide thread 130, the worm wheel 50 moves on the guide thread 130.

[0064] As in the Fig. 10, Fig. 12 and Fig. 13, the worm gear 50 moves on the guide shaft 132 according to the rotation of the control shaft 102, and the worm gear 50 presses on the guide wall 92, so that a relative position of the gear housing 90 to the camshaft 30 is changed.

[0065] If the relative position of the wheel housing 90 with respect to the camshaft 30 is changed, the relative rotational speed of the cams 71 and 72 with respect to the rotational speed of the camshaft 30 is changed.

[0066] As the slide pin 60 rotates together with the camshaft 30, the pin body 62 is slidable in the camshaft bore 34, the pin head 64 is rotatable in the first sliding bore 86, and the roller cam 82 is rotatably disposed in the second sliding bore 88 and slidable in the cam receiver 74. This changes the relative rotational speed of the cams 71 and 72 with respect to the rotational speed of the camshaft 30.

[0067] Fig. 14A and Fig. 14B show a cam slot of a device with continuously variable valve duration according to an exemplary embodiment of the invention and the Fig. 15A, Fig. 15B and Fig. 15C are diagrams showing the valve profile of a continuously variable valve duration device according to an exemplary embodiment of the present invention.

[0068] As in Fig. 14A and Fig. 14B, the cam slot 74 may be more retarded than a position of the cam 71 or 72 (see (74a) of Fig. 14A), the cam slot 74 can be advanced further than a position of the cam 71 or 72 (see (74b) of Fig. 14B) or the cam slot 74 can be formed with the same phase of the cam 71 or 72. Various valve profiles can be achieved using the above scheme.

[0069] Although the maximum lift of the valves 200 is constant, the rotational speed of the cams 71 and 72 is changed with respect to the rotational speed of the camshaft 30 according to the relative positions of the slide housing 90 so that the closing and opening times of the valves 200 change. That is, the duration of the valves 200 is changed.

[0070] According to the relative position of the cam slot 74, the mounting angle of the valves 200, etc., the opening and closing times of the valves can be changed simultaneously, as shown in Fig. 15A.

[0071] While the opening time of the valves 200 is constant, the closing time of the valves 200 can be delayed or advanced, as in Fig. 15B.

[0072] While the closing time of the valves 200 is constant, the opening time of the valve 200 can be delayed or advanced, as in Fig. 15C.

[0073] A method for diagnosing an engine system having a continuously variable valve duration (CVVD) device according to an exemplary embodiment of the present invention will now be described with reference to drawing figures 16A, 16B and 17.

[0074] The Fig. 16A and Fig. 16B illustrate the assembly process of the control shaft and drive unit of a CVVD (Continuous Variable Valve Duration) device according to an exemplary embodiment of the present invention.

[0075] With reference to the Fig. 16A and Fig. 16B, a drive unit 300 of a continuously variable valve duration (CVVD) device according to an exemplary embodiment of the invention (hereinafter "CVVD drive unit") comprises a first drive unit 301 and a second drive unit 303.

[0076] The first drive unit 301 drives the valves of the first and second cylinders and the second drive unit 303 drives the valves of the third and fourth cylinders of the four-cylinder engine.

[0077] The CVVD drive unit 300 is formed by assembling the first drive unit 301 and the second drive unit 303 and mounted on a control shaft 102. Specifically, in CVVD devices with two drive units, each drive unit is responsible for two cylinder valves to drive a total of four cylinder valves. If the two drive units are not assembled normally, resulting in misalignment of the drive units, the valve control by the CVVD drive unit cannot be performed normally. Accordingly, a diagnostic process is required for these conditions.

[0078] Fig. 17 is a flowchart illustrating a method for diagnosing an engine system having a CVVD (Continuous Variable Valve Duration) device according to an exemplary embodiment of the present invention.

[0079] Generally, four-cylinder engines are designed such that each of the four cylinders is fired in the order of first, third, fourth, and second cylinders. Therefore, the following assumes a four-cylinder engine with such a sequence. However, the present invention is not limited to this.

[0080] Even for lambda values ​​measured with a front lambda sensor configured to detect a lambda value upstream of the intake valve, lambda values ​​that are less than or equal to a first predetermined value are referred to below as lean. Lambda values ​​that are greater than or equal to a second predetermined value are referred to as rich. Furthermore, lambda values ​​that are greater than the first and less than the second predetermined value are referred to as the theoretical value of the air / fuel ratio.

[0081] The condition corresponding to the theoretical air / fuel ratio is referred to below as “lambda=1”.

[0082] According to Fig. 17, an electronic control unit (ECU) or generally a controller (not shown) of a system for diagnosing an engine system with a continuously variable valve duration (CVVD) device according to an exemplary embodiment of the invention performs the engine cranking to start the engine in step S101.

[0083] When the engine is started, the controller determines whether the CVVD learning of the minimum and maximum values ​​is completed in step S102. If the CVVD learning is not completed, the controller performs the CVVD learning in step S103. The CVVD learning value indicates the minimum and maximum values ​​of the CVVD device to be learned for feedback control of the CVVD device. The controller may learn a long-term value as the minimum value of the CVVD device and a short-term value as the maximum value of the CVVD device. Specifically, by setting the CVVD minimum value to 0% and the maximum value to 100%, the controller may perform feedback control by converting the CVVD target value for the intake pipe and the CVVD target value for the exhaust pipe into a percentage value.

[0084] If the CVVD learning is determined to be completed, the controller executes the motor start control in step S105.

[0085] Once the engine start is complete, the controller performs Lambda=1 control. Lambda=1 control indicates that the controller operates the CVVD device according to the condition where the air / fuel ratio is Lambda=1.

[0086] To further determine whether the CVVD device is normally mounted and aligned, the controller also detects the measured value of a front oxygen sensor (not shown) configured to detect a pre-intake valve oxygen sensor value. Specifically, the controller detects the measured value of the front oxygen sensor during combustion of the first through fourth cylinders in stages S107, S111, S114, S117, S121, S124, and S127.

[0087] In the following, the measured values ​​of the front lambda sensor during combustion of the first to fourth cylinders are referred to as the first to fourth lambda values.

[0088] If the controller detects the first lambda value in step S107 and the detected first lambda value is determined to be lambda=1 in step S108, the controller performs a lambda=1 control in step S106.

[0089] If the first lambda value in step S109 is lean, the controller detects the third lambda value in step S111.

[0090] Next, if the third lambda value is rich in step S112, the controller detects the fourth lambda value in step S114.

[0091] Next, if the fourth lambda value is rich in step S115, the controller detects the second lambda value in step S117.

[0092] Next, if the second lambda value is lean in step S118, the controller determines in step S131 that the drive unit is misadjusted and generates a warning signal that informs the driver in step S133.

[0093] However, if the first lambda value is rich in step S109, the controller detects the third lambda value in step S121.

[0094] Next, if the third lambda value is lean in step S122, the controller detects the fourth lambda value in step S124.

[0095] Next, if the fourth lambda value is lean in step S125, the controller detects the second lambda value in step S127.

[0096] Next, if the second lambda value is rich in step S128, the controller determines in step S131 that the drive unit is misaligned and generates a warning signal to inform the driver in step S133.

[0097] As described above, if the answer is “No” in each of steps S118 and S128, the controller performs a lambda=1 control again in step S106.

[0098] If the first drive unit 301 and the second drive unit 303 are improperly assembled with a certain misalignment, the first and second cylinder valves driven by the first drive unit and the third and fourth cylinder valves driven by the second drive unit will be actuated differently. In this case, the first and second lambda values ​​and the third and fourth lambda values ​​may have opposite directions of lambda values. Specifically, if the first and second lambda values ​​are lean, the third and fourth lambda values ​​may be rich. On the other hand, if the first and second lambda values ​​are rich, the third and fourth lambda values ​​may be lean.

[0099] As described above, the diagnosis can be performed during the vehicle's manufacturing and testing process. In this case, the manufacturer or inspector can readjust or reassemble the powertrain when the warning signal is generated.

[0100] As also described above, the diagnosis can also be performed while driving. In this case, if the warning signal is generated, the driver can contact the manufacturer or vehicle repair shop for inspection and reinstallation.

[0101] As described above, an exemplary embodiment of the present invention may provide a method and apparatus for diagnosing an engine system including a continuously variable valve duration (CVVD) device capable of diagnosing whether a misalignment occurs while assembling a drive unit of the CVVD device.

Claims

[1] A method for diagnosing an engine system comprising a continuously variable valve duration (CVVD) device, a CVVD device drive unit (300) having a first drive unit (301) and a second drive unit (303), a CVVD position detector configured to detect a position of the CVVD device, a camshaft position detector configured to detect a position of a camshaft (30), a front lambda sensor configured to detect a lambda value upstream of the intake valve, and a controller, the method comprising the following steps: - Starting the engine by the control system; - Recording of the measured values ​​of the front lambda sensor during combustion in the first to fourth cylinders by the control system, the measured values ​​being first to fourth lambda values; - Determining, based on the recorded first to fourth lambda values, whether the CVVD drive unit (300) is adjusted, and - Generation of a warning message by the controller when it is detected that the CVVD drive unit (300) is misaligned. [2] The method of claim 1, wherein the step of determining whether the CVVD drive unit (300) is misaligned comprises the following steps: - determining by the controller that the CVVD drive unit (300) is adjusted when the first and second lambda values ​​are rich and the third and fourth lambda values ​​are lean, - or if the first and second lambda values ​​are lean and the third and fourth lambda values ​​are rich; and - Repeated recording of the first to fourth lambda values ​​by the controller. [3] The method of claim 1, wherein the step of detecting the first to fourth lambda values ​​comprises the following steps: - Implementation of the Lambda 1 control of the engine; - Checking the reading of the front lambda sensor during combustion of the first cylinder (first lambda value); - Checking the reading of the front lambda sensor during combustion of the third cylinder (the third lambda value); - Checking the reading of the front lambda sensor during combustion of the fourth cylinder (the fourth lambda value); - Checking the measured value of the front lambda sensor during the combustion of the second cylinder (the second lambda value); and - Output of the first to fourth lambda values ​​to the controller. [4] The method of claim 1, wherein the step of determining whether the CVVD drive unit (300) is misaligned further comprises the steps of: - if one of the first to fourth lambda values ​​is less than or equal to a first predetermined value, the lambda value is determined to be lean; - if one of the first to fourth lambda values ​​is greater than or equal to a second specified value, the lambda value is determined to be rich; and - Determining the lambda value as a theoretical value of the air-fuel ratio when one of the first to fourth lambda values ​​is greater than the first predetermined value and less than the second predetermined value. [5] The method of claim 1, wherein the step of starting the engine comprises the following steps: - Starting the engine; - Determine whether a CVVD learning process is complete; and - Carrying out a motor start-up control. [6] The method of claim 1, wherein the step of determining whether CVVD learning is complete comprises the step of - Perform the CVVD learning process if the CVVD learning process is not completed. [7] A system for diagnosing an engine system including a continuously variable valve duration (CVVD) device, the system comprising: - a drive unit (300) of the CVVD device with a first and a second drive unit (301, 303); - a CVVD position detector configured to detect a position of the CVVD device; - a camshaft position detector configured to detect a position of the camshaft (30); - a front lambda probe configured to detect a lambda value upstream of the intake valve; and - a controller configured to detect measured values ​​of the front lambda sensor during combustion of the first to fourth cylinders, the measured values ​​being first to fourth lambda values, to determine whether the CVVD drive unit (300) is misadjusted based on the detected first to fourth lambda values, and to generate a warning message if it is determined that the CVVD drive unit (300) is misadjusted. [8] System according to claim 7, wherein: - if the first and second lambda values ​​are rich and the third and fourth lambda values ​​are lean, or if the first and second lambda values ​​are lean and the third and fourth lambda values ​​are rich, the controller determines that the CVVD drive unit (300) is misadjusted, and - if in the previous step the controller does not determine that the CVVD drive unit (300) is misadjusted, the controller detects the first to fourth lambda values ​​again. [9] System according to claim 7, - wherein, if one of the first to fourth lambda values ​​is less than or equal to a first predetermined value, the controller determines the lambda value as lean, - wherein, if one of the first to fourth lambda values ​​is greater than or equal to a second predetermined value, the controller determines that the lambda value is rich, and - wherein, when one of the first to fourth lambda values ​​is greater than the first predetermined value and less than the second predetermined value, the controller determines the lambda value as a theoretical value of the air-fuel ratio. [10] The system of claim 7, wherein the controller determines whether a CVVD learning process is complete upon engine start-up, - wherein the controller performs the CVVD learning if the CVVD learning process is not completed, and - after completion of the CVVD learning process, the controller performs a motor start-up control.

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