Method and device for diagnosing an engine system

Abstract

Method for diagnosing an engine system comprising an opening duration device (80) for a variable valve (CVVD) and an exhaust gas recirculation (EGR) device, the method comprising: Acquisition of data by a data acquisition device (90) for diagnosing the engine system; Based on the collected data, determine by a controller (100) whether a fuel cut-off condition is met; Actuation of an EGR valve (73) by the control unit (100) such that an opening value of the EGR valve (73) becomes a first opening value when the fuel cut-off condition is met; Determine by the control unit (100) whether the amount of the increase in intake pressure due to actuation of the EGR valve (73) is within a first predetermined range; Actuation of the CVVD device (80) by the control unit (100) such that an opening duration of an intake valve (14) becomes a first target duration when the amount of increase in intake pressure by actuation of the EGR valve (73) is in the first predetermined range; Determine by the control unit (100) whether a reduced amount of the intake pressure is within a second predetermined range by actuating the CVVD device (80); and Determine by the control unit (100) that the CVVD device (80) is in a fault condition when the reduced amount of the intake pressure by actuating the CVVD device (80) is outside the second predetermined range; Maintaining the opening amount of the EGR valve (73) at the first target opening amount and the opening duration of the intake valve (14) at the first target duration by the control unit (100) for a predetermined period when the reduced amount of the intake pressure is in the second predetermined range by actuation of the CVVD device (80); Monitoring the intake pressure by the controller (100) at a time when the predetermined period has elapsed; and Determine by the controller (100) whether the intake pressure is within a third predetermined range at the time when the predetermined period has elapsed.

Description

AREA OF INVENTION

[0001] The present disclosure relates to a method and a device for diagnosing an engine system. BACKGROUND

[0002] The explanations in this section merely provide background information relating to the present disclosure and may not represent the state of the art.

[0003] An internal combustion engine generates power by burning fuel in a combustion chamber using air drawn into the chamber. Intake valves are actuated by a camshaft to draw in air, which is drawn into the combustion chamber while the intake valves are open. Exhaust valves are also actuated by the camshaft, and exhaust gases are expelled from the combustion chamber while the exhaust valves are open.

[0004] The desired operation of the intake and exhaust valves depends on the engine's rotational speed. This means that the desired valve lift or opening / closing time can be determined based on the engine's rotational speed. To achieve the desired valve actuation as a function of engine speed, various investigations have been carried out, such as designing multiple cams and implementing continuous variable valve lift (CVVL), which can change the valve lift in accordance with engine speed.

[0005] To achieve the desired valve operation depending on the engine speed, tests were carried out on a continuous variable valve timing (CVVT) device, which allows for different valve timing sequences depending on the engine speed. The general CVVT can change the valve timing sequence with a fixed valve opening duration.

[0006] However, CVVL and CVVT are generally complex in their design and expensive in terms of their manufacturing costs.

[0007] Therefore, an opening duration device for a variable valve (CVVD-Continuous Variable Valve Duration) was investigated, which can adjust the opening duration of a valve according to an operating state of the engine.

[0008] An exhaust gas recirculation (EGR) device returns a portion of the exhaust gas emitted from the combustion chamber back into the chamber.

[0009] In order to apply the CVVD device and the EGR device to the engine system, a procedure for diagnosing whether the CVVD device and the EGR device are working normally is desirable.

[0010] The information disclosed above in this background section is provided solely for an improved understanding of the background of the present disclosure and may therefore contain information that is not prior art for the person skilled in the art.

[0011] Furthermore, patent application DE 10 2016 103 716 A1 discloses a control system for an internal combustion engine that includes an exhaust gas recirculation device. Additionally, patent application JP 2000 - 110 594 A deals with a variable valve mechanism for variable control of the timing of valve actuation or valve lift in an internal combustion engine. SUMMARY OF THE INVENTION

[0012] The present disclosure provides a method and a device for diagnosing an engine system, which have the advantages of being able to diagnose an engine system that includes an opening duration device for a variable valve and a low-pressure exhaust gas recirculation device.

[0013] In one embodiment of the present disclosure, a method for diagnosing an engine system comprising a continuously variable valve (CVVD) opening duration device and a low-pressure exhaust gas recirculation (LP-EGR) device may include: acquiring data by a data acquisition device for diagnosing the engine system; determining by a controller whether a fuel cut-off condition is met based on the acquired data; actuating an EGR valve by the controller such that an opening amount of the EGR valve becomes a first target opening amount when the fuel cut-off condition is met; determining by the controller whether an increased amount of intake pressure resulting from actuating the EGR valve is within a first predetermined range;Actuation of the CVVD device by the control unit, such that an intake valve opening duration becomes a first target duration when the amount of the increase in intake pressure due to actuation of the EGR valve is within the first predetermined range; Determination by the control unit whether a reduced amount of intake pressure due to actuation of the CVVD device is within a second predetermined range; and Determination by the control unit that the CVVD device is in a fault condition when the reduced amount of intake pressure due to actuation of the CVVD device is outside the second predetermined range.

[0014] The procedure may also include determining by the control system that the EGR valve is in a fault condition if the amount of the increase in intake pressure due to actuation of the EGR valve is outside the first predetermined range.

[0015] The procedure further includes: maintaining the opening amount of the EGR valve at the first target opening amount and the opening duration of the intake valve at the first target opening duration for a predetermined period by the control unit if the reduced amount of intake pressure is within the second predetermined range due to actuation of the CVVD device; monitoring the intake pressure by the control unit at a time when the predetermined period has elapsed; and determining by the control unit whether the intake pressure is within a third predetermined range at the time when the predetermined period has elapsed.

[0016] The procedure may further include: Determining by the control system that the CVVD device is in the fault state if the intake pressure is outside the third predetermined range at the time when the predetermined period has elapsed.

[0017] The procedure may further include: actuating the EGR valve by the control unit, such that the opening amount of the EGR valve becomes a second target opening amount when the intake pressure is in the third predetermined range at the time when the predetermined period has elapsed, wherein the second target opening amount is less than the first target opening amount.

[0018] The procedure may further include: determining by the control system whether the reduced amount of intake pressure by actuating the EGR valve is within a fourth predetermined range, and determining by the control system that the EGR valve is in a fault condition if the reduced amount of intake pressure by actuating the EGR valve is outside the fourth predetermined range.

[0019] The procedure may further include: actuating the CVVD device by the control unit, so that the opening duration of the intake valve becomes a second target duration when the reduced amount of intake pressure by actuating the EGR valve is in the fourth predetermined range, wherein the second target duration is less than the first target duration.

[0020] The procedure may further include: determining by the control system whether the amount of the increase in intake pressure due to actuation of the CVVD device is within a fifth predetermined range; and determining by the control system that the CVVD device is in the fault state if the amount of the increase in intake pressure due to actuation of the CVVD device is outside the fifth predetermined range.

[0021] The procedure may further include determining by the control system that the CVVD device and the EGR valve are in a normal state when the amount of the increase in intake pressure by actuating the CVVD device is in the fifth predetermined range.

[0022] A device for diagnosing an engine system, which includes a variable valve timing device (CVVD) and an exhaust gas recirculation (EGR) device in accordance with an exemplary embodiment of the present disclosure, may comprise: an accelerator pedal position sensor configured to detect the position of an accelerator pedal; a brake pedal position sensor configured to detect the position of a brake pedal; a vehicle speed sensor configured to detect the speed of a vehicle; an intake manifold pressure sensor configured to detect the intake manifold pressure; and a controller configured to control an EGR valve and the CVVD device and to determine whether a fuel cut-off condition is met and whether the CVVD device and the EGR valve are in a fault condition when the fuel cut-off condition is met.

[0023] Specifically, when the fuel cut-off condition is met, the opening amount of the EGR valve is controlled to be a first target opening amount, and when the amount of intake pressure increased by actuating the EGR valve is within a first predetermined range, the opening duration of an intake valve is controlled by the CVVD device to be a first target duration. The control system further determines that the CVVD device is in a fault state if the amount of intake pressure reduced by actuating the CVVD device exceeds a second predetermined range.

[0024] The control unit can determine that the EGR valve is in a fault condition if the amount of the increase in intake pressure caused by actuating the EGR valve exceeds the first predetermined range.

[0025] The control unit maintains the opening value of the EGR valve at the first target opening value and the opening duration of the intake valve at the first target duration for a predetermined period if the reduced intake pressure, caused by actuating the CVVD device, is within the second predetermined range. The control unit also monitors the intake pressure at the end of the predetermined period and determines whether the intake pressure is within a third predetermined range at that time.

[0026] The control system can determine that the CVVD device is in the fault state if the intake pressure is not within the third predetermined range at the time when the predetermined period has elapsed.

[0027] If the intake pressure is within the third predetermined range at the end of the predetermined period, the EGR valve's opening value is controlled by the EGR valve itself, resulting in a second target opening value. This second target opening value can be lower than the first target opening value.

[0028] The control unit can determine whether a reduced amount of intake pressure due to actuation of the EGR valve is within a fourth predetermined range, and determine that the EGR valve is in the fault condition if the reduced amount of intake pressure due to actuation of the EGR valve is not within the fourth predetermined range.

[0029] The control unit can actuate the CVVD device so that the intake valve opening duration becomes a second target duration when the reduced intake pressure due to EGR valve actuation is within the fourth predetermined range. In this case, the second target duration can be shorter than the first target duration.

[0030] The control unit can determine whether the amount of the increase in intake pressure due to actuation of the CVVD device is within a fifth predetermined range, and determine that the CVVD device is in the fault state if the amount of the increase in intake pressure due to actuation of the CVVD device is not within the fifth predetermined range.

[0031] The control unit can determine that the CVVD device and the EGR valve are in a normal state if the amount of the increase in intake pressure by actuating the CVVD device is within the fifth predetermined range.

[0032] A method for diagnosing an engine system, which includes a variable valve timing device (CVVD) and an exhaust gas recirculation (EGR) device in accordance with a further exemplary embodiment of the present disclosure, may comprise: acquiring data by a data acquisition device for diagnosing the engine system; determining by a controller whether a fuel cut-off condition is met based on the acquired data; actuating an EGR valve by the controller such that an opening amount of the EGR valve becomes a first target opening amount when the fuel cut-off condition is met; determining by the controller whether an increase in an intake pressure by actuating the EGR valve is within a first predetermined range;Actuating the CVVD device by the control unit, so that an exhaust valve opening duration becomes a first target duration, when the amount of the intake pressure increase due to actuation of the EGR valve is within the first predetermined range; Determining by the control unit whether a reduced amount of intake pressure due to actuation of the CVVD device is within a second predetermined range; Determining by the control unit that the CVVD device is in a fault condition when the reduced amount of intake pressure due to actuation of the CVVD device is outside the second predetermined range; Maintaining the opening amount of the EGR valve at the first target opening amount and the opening duration of the exhaust valve at the first target duration by the control unit for a predetermined period when the reduced amount of intake pressure due to actuation of the CVVD device is within the second predetermined range;Monitoring the intake pressure at a time when the predetermined period has elapsed; and determining by the control unit whether the intake pressure is within a third predetermined range at the time when the predetermined period has elapsed.

[0033] A device for diagnosing an engine system, which includes a variable valve opening duration device (CVVD) and a low-pressure exhaust gas recirculation (EGR) device in accordance with a further exemplary embodiment of the present disclosure, may comprise: an accelerator pedal position sensor configured to detect the position of an accelerator pedal; a brake pedal position sensor configured to detect the position of a brake pedal; a vehicle speed sensor configured to detect the speed of a vehicle; an intake pressure sensor configured to detect an intake pressure;and a control system configured to determine, based on signals from the accelerator pedal position sensor, the brake pedal position sensor, the vehicle speed sensor and / or the intake manifold pressure sensor, whether a fuel cut-off condition is met, and is configured to determine whether the CVVD device and an EGR valve are in a fault condition when the fuel cut-off condition is met.

[0034] The control unit regulates the opening value of the EGR valve via the EGR valve, setting it to a first target opening value when the fuel cut-off condition is met. It also regulates the opening duration of an exhaust valve via the CVVD device, setting it to a first target duration when the increase in intake pressure due to EGR valve actuation falls within a first predetermined range. Furthermore, the control unit determines that the CVVD device is in a fault state if the reduced intake pressure resulting from CVVD actuation falls outside a second predetermined range.

[0035] Furthermore, the control system is configured to maintain the opening amount of the EGR valve at the first target opening amount and the opening duration of the exhaust valve at the first target duration for a predetermined period if the reduced amount of the intake pressure by actuating the CVVD device is in the second predetermined range, and wherein the control system is configured to monitor the intake pressure at a time when the predetermined period has elapsed, and is configured to determine whether the intake pressure is in a third predetermined range at the time when the predetermined period has elapsed.

[0036] In accordance with an exemplary embodiment of the present disclosure, faults of the CVVD device and the EGR device can be diagnosed.

[0037] Further areas of application will become clear from the description provided herein. It is understood that the description and specific examples are for illustrative purposes only and are not intended to limit the scope of protection of this disclosure. DRAWINGS

[0038] To make the revelation easily understandable, various forms of it will now be described through examples, with reference to the accompanying drawings in which: Fig. 1 a schematic representation of an engine system in an exemplary embodiment of the present disclosure; Fig. 2 a block diagram of a device for diagnosing an engine system in an exemplary embodiment of the present disclosure; and

[0039] The Fig. Figures 3A to 3B are flowcharts illustrating a method for diagnosing an engine system in an exemplary embodiment of the present disclosure.

[0040] The drawings described herein are for illustrative purposes only and are not intended to limit the scope of protection of this disclosure in any way. DETAILED DESCRIPTION

[0041] The present disclosure is described in more detail below with reference to the accompanying drawings, which show exemplary embodiments of the present disclosure. However, the present disclosure is not limited to the exemplary embodiments described herein and can be modified in many different ways.

[0042] The drawings and descriptions are to be regarded as illustrative and not limiting. The same reference numerals denote the same elements throughout the description. The configurations illustrated in the drawings are shown arbitrarily for better understanding and easier description; however, the present disclosure is not limited to them.

[0043] Fig. Figure 1 is a schematic representation of an engine system in accordance with an exemplary embodiment of the present disclosure, and Fig. Figure 2 is a block diagram of a device for diagnosing an engine system in accordance with an exemplary embodiment of the present disclosure.

[0044] Referring to the Fig. 1 and Fig. 2 An engine system can include an engine 10, a turbocharger 20, an intake manifold 30, a throttle valve 40, a first exhaust manifold 50, a second exhaust manifold 60, a low pressure exhaust gas recirculation (LP-EGR) device 70 and a variable valve opening duration (CVVD) device 80.

[0045] The engine 10 burns fuel and air to convert chemical energy into mechanical energy. The engine 10 includes a cylinder 11, a piston 12, a crankshaft 13, an intake valve 14, and an exhaust valve 15.

[0046] The piston 12 and the crankshaft 13 are mounted in the cylinder 11. The piston 12 moves back and forth due to the explosive force of the fuel and rotates the crankshaft 13. A combustion chamber 16 is formed between the cylinder 11 and the piston 12.

[0047] The motor 10 is connected to the intake duct 30 to draw in air, and exhaust gas produced during a combustion process is discharged from the motor 10 to the outside through the first exhaust duct 50. The intake duct 30 is opened or closed by the intake valve 14, and the first exhaust duct 50 is opened or closed by the exhaust valve 15. The intake valve 14 can be actuated by an intake cam 81 of the CVVD device 80, and the exhaust valve 15 can be actuated by an exhaust cam 83.

[0048] An injection system 17 injects fuel into the combustion chamber 16, and a spark plug 18 ignites a mixed gas in which the fuel and air are mixed.

[0049] A coolant temperature sensor 11a, a knock sensor 11b, and a crankshaft position sensor 11c are mounted on cylinder 11. The coolant temperature sensor 11a detects the temperature of the coolant and transmits a corresponding signal to a controller 100. The knock sensor 11b detects vibration and transmits a corresponding signal to the controller 100, and the controller 100 determines whether knocking is occurring based on the signal from the knock sensor 11b. The crankshaft position sensor 11c detects the rotation angle of the crankshaft 13 and transmits a corresponding signal to the controller 100, and the controller 100 calculates the engine speed 10 based on the crankshaft position sensor 11c.

[0050] The turbocharger 20 includes a turbine 21 and a compressor 22; the turbine 21 can be rotated by the exhaust gas and the compressor 22 can rotate by the power generated by the rotation of the turbine 21.

[0051] The intake line 30 supplies air to the motor 10. As the compressor 22 rotates, the incoming air is compressed before being supplied to the motor 10. This compressed air is then supplied to improve the output of the motor 10. To cool the air passing through the compressor 22, an intercooler 31 can be mounted on the intake line 30.

[0052] The throttle valve 40 is mounted on the intake pipe 30, and an airflow directed from the intake pipe 30 to the engine 10 is controlled according to an opening dimension of the throttle valve 40.

[0053] An intake pressure sensor 94 is mounted on the intake line 30 between the throttle valve 40 and the engine 10 and detects an intake pressure in order to transmit a corresponding signal to the control unit 100.

[0054] The first exhaust pipe 50 discharges the exhaust gas emitted by the engine 10 to the exterior of the vehicle. A catalytic converter 51 can be mounted on the first exhaust pipe 50 to reduce a harmful component of the exhaust gas.

[0055] The second exhaust pipe 60 is designed such that a portion of the exhaust gas passes through the turbine 21 and is added to the first exhaust pipe 50. The amount of exhaust gas passing through the turbine 21 is controlled according to the opening position of a wastegate valve 52, which is mounted on the first exhaust pipe 50.

[0056] An exhaust pressure sensor 95 is mounted on the first exhaust pipe 50 and detects an exhaust pressure in order to transmit a corresponding signal to the control unit 100.

[0057] The low-pressure EGR device 70 can include an EGR line 71, an EGR cooler 72 and an EGR valve 73.

[0058] The EGR line 71 can be connected downstream of the catalyst 51 and the intake manifold 30. A portion of the exhaust gas emitted by the catalyst 51 can be recirculated to the engine 10 via the EGR line 71.

[0059] The EGR cooler 72 is mounted on the EGR line 71 to cool the exhaust gas supplied to the intake line 30.

[0060] The EGR valve 73 is mounted on the EGR line 71. When the EGR valve 73 is open, a portion of the exhaust gas emitted by the catalyst 51 can be recirculated to the engine 10 via the EGR line 71. When the EGR valve 73 is closed, the exhaust gas emitted by the catalyst 51 is not recirculated to the engine 10 via the EGR line 71. Exhaust gas routed to the intake manifold 30 via the EGR line 71, corresponding to the opening degree of the EGR valve 73, is referred to as external EGR gas.

[0061] The CVVD device 80 sets the opening duration of the intake valve 14. The opening duration is the time that elapses while the intake valve 14 is open. The CVVD device 80 includes the intake cam 81 and a camshaft 82. The CVVD device 80 can change the relative rotational speed of the intake cam 81 with respect to the camshaft 82. In other words, the opening duration of the intake valve 14 increases or decreases according to the actuation of the CVVD device 80. Since reference can be made to KR 10 1 655 228 B1 for details of the CVVD device, a duplicate description is omitted here. The CVVD device described in KR 10 1 655 228 B1 is an example of a CVVD device, and the present disclosure can be applied to many other CVVD devices known from the prior art.

[0062] In the prior art, the term "valve overlap" is known to describe a period during which an intake valve and an exhaust valve 15 are open simultaneously (for example, a simultaneous opening duration of the intake and exhaust valves). Valve overlap occurs corresponding to the actuation of the CVVD 80, allowing a portion of the exhaust gas discharged from the combustion chamber 16 to be recirculated back to the combustion chamber 16. This recirculated exhaust gas, directed to the combustion chamber 16 by actuation of the CVVD device 80, is referred to as internal EGR gas. The temperature of the combustion chamber 16 can be reduced by utilizing this internal EGR gas.In an exemplary embodiment of the present disclosure, it is illustrated that the CVVD device 80 sets the opening duration of the inlet valve 14, however, the present disclosure can be applied to a case in which the CVVD device 80 sets an opening duration of the outlet valve 15.

[0063] In one embodiment, a device for diagnosing an engine system can be used with reference to Fig. 2 include a data acquisition device 90, the control unit 100, the EGR valve 73 and the CVVD device 80.

[0064] The data acquisition device 90 acquires data for diagnosing the engine system, and the data acquired by the data acquisition device 90 is transmitted to the control unit 100. The data acquisition device 90 may include an accelerator pedal position sensor 91, a brake pedal position sensor 92, a vehicle speed sensor 93, and an intake manifold pressure sensor 94. The data acquisition device 90 may also include sensors (for example, an oxygen sensor, etc.) for controlling the engine system.

[0065] The accelerator pedal position sensor 91 detects the position of the accelerator pedal, i.e., the amount of pressure applied to the accelerator pedal, and transmits a corresponding signal to the control unit 100. When the accelerator pedal is fully depressed, the position of the accelerator pedal is 100%, and when the accelerator pedal is not depressed (for example, fully released), the position of the accelerator pedal is 0%.

[0066] The brake pedal position sensor 92 detects the position of the brake pedal, i.e., the amount of pressure applied to the brake pedal, and transmits a corresponding signal to the control unit 100. When the brake pedal is fully depressed, the position of the brake pedal is 100%, and when the brake pedal is not depressed, the position of the brake pedal is 0%.

[0067] The vehicle speed sensor 93 detects a vehicle speed and transmits a corresponding signal to the control unit 100.

[0068] The inlet pressure sensor 94 detects the inlet pressure of air flowing into the engine 10 and transmits a corresponding signal to the control unit 100.

[0069] The controller 100 can diagnose a failure of the CVVD device 80 and the EGR valve 73 based on data acquired by the data acquisition device 90. The controller 100 can be implemented with at least one processor executed by a predetermined program, and the predetermined program can include a series of instructions for executing each step of a method for diagnosing an engine system in accordance with an exemplary embodiment of the present disclosure. Furthermore, the controller 100 can control the actuation of the throttle valve 40, the EGR valve 73, and the CVVD device 80 based on data acquired by the data acquisition device 90.

[0070] The Fig. 3A and Fig. Figure 3B are flowcharts illustrating a method for diagnosing an engine system in accordance with an exemplary embodiment of the present disclosure.

[0071] As in the Fig. 3A and Fig. As shown in Figure 3B, the control unit 100 acquires data for diagnosing the engine system in step S101. In other words, the accelerator pedal position sensor 91 detects the position of the accelerator pedal, the brake pedal position sensor 92 detects the position of the brake pedal, the vehicle speed sensor 93 detects the vehicle speed, and the intake pressure sensor 94 detects the intake pressure.

[0072] In step S102, the control unit 100 determines, based on the data, whether a fuel cut-off condition is met. For example, the fuel cut-off condition may be met when the vehicle is coasting, and the control unit 100 can determine whether the fuel cut-off condition is met based on the accelerator pedal position, the brake pedal position, and the vehicle speed. For example, if the vehicle speed is equal to or greater than a predetermined speed, and if the accelerator pedal position and the brake pedal position are at 0%, the fuel cut-off condition may be met. In the fuel cut-off state, the intake pressure can be changed according to an opening amount of the EGR valve 73 or an opening duration of the intake valve 14.

[0073] If the fuel cut-off condition is not met in step S102, the engine system diagnostics process is terminated and reset for a new round.

[0074] If the fuel cut-off condition in step S102 is met, the control unit 100 actuates the EGR valve 73 in step S103 to allow the opening of the EGR valve 73 to reach its initial target opening value. As the opening value of the EGR valve 73 increases, the intake pressure also increases.

[0075] In step S104, the controller can determine whether the increase in intake pressure resulting from actuation of the EGR valve 73 falls within a first predetermined range. The first target opening value can be set experimentally, ensuring that the increase in intake pressure corresponds to a predetermined value within this first predetermined range. In other words, the increase in intake pressure corresponding to the opening value of the EGR valve 73 can be determined experimentally (for example, through an engine test), and the first target opening value and the first predetermined range can vary depending on the size and operating mode of the engine. The value and range can be obtained through various tests known to those skilled in the art and stored in a memory of the controller 100.

[0076] If the amount of increase in intake pressure in step S104 is not within the first predetermined range, the controller 100 can determine in step S105 that the EGR valve 73 is in a fault condition. In other words, the controller 100 can determine that the EGR valve 73 is stuck and that the opening value of the EGR valve 73 does not follow the first target opening value.

[0077] If the amount of increase in intake pressure in step S104 is within the first predetermined range, the controller 100 actuates the CVVD device 80 in step S106 to allow an opening duration of the intake valve 14, which is a first target opening duration. While the opening duration of the intake valve 14 increases, the intake pressure decreases.

[0078] The controller 100 can determine in step S107 that a reduced amount of intake pressure occurs within a second predetermined range by actuating the CVVD device 80. The first target opening duration, or target duration, can be set experimentally such that the reduced amount of intake pressure has a predetermined value within the second predetermined range. In other words, a reduced amount of intake pressure can be determined experimentally in accordance with the operation of the CVVD device 80, and the first target duration and the second predetermined range can be set to a value and range that a person skilled in the art would determine as a desired value and range.

[0079] If the reduced amount of the intake pressure in step S107 is not within the second predetermined range, the controller 100 can determine in step S108 that the CVVD device 80 is in a fault condition. In other words, if the CVVD device 80 is in a fault condition, the controller 100 can determine that the opening duration of the inlet valve 14 does not follow the first target duration.

[0080] If the reduced amount of the intake pressure in step S107 is in the second predetermined range, the control in step S109 maintains the opening amount of the EGR valve 73 at the first target opening amount and the opening duration of the intake valve 14 at the first target duration for a predetermined time and monitors the intake pressure at a time when the predetermined time has elapsed.

[0081] The controller 100 can determine in step S110 whether the intake pressure is within a third predetermined range at the time the predetermined time has elapsed. An intake pressure, where the opening value of the EGR valve 73 is the first target opening value and the opening duration of the intake valve 14 is the first target duration, over the predetermined period, can be determined experimentally, and the third predetermined range can be set to a range determined by a person skilled in the art as the desired range.

[0082] If the intake pressure in step S110 is not within the third predetermined range, the controller 100 can determine in step S111 that the CVVD device 80 is in a fault condition. In other words, if the CVVD device 80 is in a fault condition, the controller 100 can determine that the intake pressure deviates from the third predetermined range.

[0083] If the intake pressure in step S110 is within the third predetermined range, the controller 100 actuates the EGR valve 73 in step S112 to allow the opening value of the EGR valve 73 to become a second target opening value. The second target opening value is lower than the first target opening value, and as the opening value of the EGR valve 73 decreases, the intake pressure also decreases.

[0084] The controller 100 can determine in step S113 whether a reduced amount of intake pressure occurs due to actuation of the EGR valve 73 within a fourth predetermined range. The second target opening value can be set experimentally such that a reduced amount of intake pressure has a predetermined value within the fourth predetermined range. In other words, a reduced amount of intake pressure corresponding to an opening value of the EGR valve 73 can be determined experimentally, and the second target opening value and the fourth predetermined range can be set to a value and range determined by a person skilled in the art as a desired value and range.

[0085] If the reduced intake pressure in step S113 is not within the fourth predetermined range, the control unit can determine in step S114 that the EGR valve 73 is in a fault condition. In other words, the control unit 100 can determine that the EGR valve 73 is stuck and that the opening value of the EGR valve 73 does not follow the second target opening value.

[0086] If the reduced amount of the intake pressure in step S113 is within the fourth predetermined range, the controller 100 actuates the CVVD device 80 in step S115 to allow the opening duration of the intake valve 14 to be a second target duration. The second target duration is shorter than the first target duration, and as the opening duration of the intake valve decreases, the intake pressure also decreases.

[0087] In step S116, the control system can determine whether a reduced amount of intake pressure occurs within a fifth predetermined range due to actuation of the CVVD device 80. The second target duration can be set experimentally such that a reduced amount of intake pressure exhibits a predetermined value within the fifth predetermined range. In other words, a reduced amount of intake pressure can be detected experimentally in accordance with actuation of the CVVD device 80, and the second target duration and the fifth predetermined range can be set to a value and range determined by a person skilled in the art as a desired value and range.

[0088] If the reduced amount of the intake pressure in step S116 is not within the fifth predetermined range, the controller can determine in step S117 that the CVVD device 80 is in a fault condition. In other words, if the CVVD device 80 is in the fault condition, the controller 100 can determine that the opening duration of the inlet valve 14 does not follow the second target duration.

[0089] If the amount of the intake pressure increase in step S116 is within the fifth predetermined range, control unit 100 completes the engine system diagnosis in step S118. In other words, control unit 100 can determine that the CVVD device 80 and the EGR valve 73 are in a normal condition.

[0090] In an exemplary embodiment of the present disclosure, it is illustrated that the CVVD device 80 sets an opening duration of the inlet valve 14, however, even in one case, a fault in the CVVD device 80 and the EGR valve 73 can be diagnosed using the method for diagnosing an engine system by having the CVVD device 80 set an opening duration of the exhaust valve 15.

[0091] As described above, faults of the CVVD device 80 and the EGR valve 73 can be diagnosed in accordance with an exemplary embodiment of the present disclosure.

[0092] While the present disclosure has been described in connection with what is currently considered to be practical exemplary embodiments, it is understandable that the present disclosure is not limited to these disclosed embodiments, but on the contrary is intended to cover a wide variety of modifications and equivalent arrangements that fall within the scope and protection of the present disclosure. DESCRIPTION OF REFERENCE MARKS 10 Motor 20 turbochargers 30 Intake pipe 40 Throttle valve 50 first exhaust pipe 60 second exhaust pipe 70 Low-pressure EGR device 80 Opening duration device for a variable valve 90 Data collection device 100 Control

Claims

[1] Method for diagnosing an engine system comprising an opening duration device (80) for a variable valve (CVVD) and an exhaust gas recirculation (EGR) device, the method comprising: Acquisition of data by a data acquisition device (90) for diagnosing the engine system; Based on the collected data, determine by a controller (100) whether a fuel cut-off condition is met; Actuation of an EGR valve (73) by the control unit (100) such that an opening value of the EGR valve (73) becomes a first opening value when the fuel cut-off condition is met; Determine by the control unit (100) whether the amount of the increase in intake pressure due to actuation of the EGR valve (73) is within a first predetermined range; Actuation of the CVVD device (80) by the control unit (100) such that an opening duration of an intake valve (14) becomes a first target duration when the amount of increase in intake pressure by actuation of the EGR valve (73) is in the first predetermined range; Determine by the control unit (100) whether a reduced amount of the intake pressure is within a second predetermined range by actuating the CVVD device (80); and Determine by the control unit (100) that the CVVD device (80) is in a fault condition when the reduced amount of the intake pressure by actuating the CVVD device (80) is outside the second predetermined range; Maintaining the opening amount of the EGR valve (73) at the first target opening amount and the opening duration of the intake valve (14) at the first target duration by the control unit (100) for a predetermined period when the reduced amount of the intake pressure is in the second predetermined range by actuation of the CVVD device (80); Monitoring the intake pressure by the controller (100) at a time when the predetermined period has elapsed; and Determine by the controller (100) whether the intake pressure is within a third predetermined range at the time when the predetermined period has elapsed. [2] Method according to claim 1, further comprising: Determining by the control (100) that the EGR valve (73) is in a fault state when the amount of the increase in intake pressure by actuating the EGR valve (73) is outside the first predetermined range. [3] Method according to one of the preceding claims, further comprising: Determining by the control (100) that the CVVD device (80) is in the fault state when the intake pressure at the time when the predetermined period has elapsed is outside the third predetermined range. [4] Method according to one of the preceding claims, further comprising: actuating the EGR valve (73) by the control unit (100) such that the opening amount of the EGR valve (73) becomes a second target opening amount when the intake pressure at the time when the predetermined period has elapsed is in the third predetermined range, wherein the second target opening amount is less than the first target opening amount. [5] Method according to claim 4, further comprising: determining by the control unit (100) whether the reduced amount of the intake pressure by actuating the EGR valve (73) is within a fourth predetermined range; and determining by the control unit (100) that the EGR valve (73) is in a fault condition if the reduced amount of the intake pressure by actuating the EGR valve (73) is outside the fourth predetermined range. [6] Method according to claim 5, further comprising: actuating the CVVD device (80) by the control (100) such that the opening duration of the inlet valve (14) becomes a second target duration when the reduced amount of the intake pressure by actuating the EGR valve (73) is in the fourth predetermined range, wherein the second target duration is less than the first target duration. [7] Method according to claim 6, further comprising: Determine by the control unit (100) whether the amount of the increase in intake pressure by actuating the CVVD device (80) is within a fifth predetermined range; and Determine by the control (100) that the CVVD device (80) is in the fault state when the amount of the increase in intake pressure by actuating the CVVD device (80) is outside the fifth predetermined range. [8] Method according to claim 7, further comprising: Determining by the control (100) that the CVVD device (80) and the EGR valve (73) are in a normal state when the amount of the increase in intake pressure by actuating the CVVD device (80) is in the fifth predetermined range. [9] Device for diagnosing an engine system comprising an opening duration device (80) for a variable valve (CVVD) and an exhaust gas recirculation (EGR) device, wherein the device comprises: an accelerator pedal position sensor (91) which is configured to detect the position of an accelerator pedal; a brake pedal position sensor (92) configured to detect the position of a brake pedal; a vehicle speed sensor (93) which is configured to detect a vehicle speed; an intake pressure sensor (94) configured to detect an intake pressure; and a control unit (100) which is configured to control an EGR valve (73) and the CVVD device (80), and to determine whether a fuel cut-off condition is met and whether the CVVD device (80) and the EGR valve (73) are in a fault condition when the fuel cut-off condition is met, wherein, when the fuel cut-off condition is met, an opening amount of the EGR valve (73) is controlled to be a first target opening amount, wherein, if the amount of the increase in intake pressure is within a first predetermined range due to actuation of the EGR valve (73), the opening duration of an intake valve (14) is controlled by the CVVD device (80) to be a first target duration, wherein the control (100) is configured to determine that the CVVD device (80) is in the fault state when a reduced amount of the intake pressure exceeds a second predetermined range by actuating the CVVD device (80), wherein the control unit (100) is configured to maintain the opening amount of the EGR valve (73) at the first target opening amount and the opening duration of the intake valve (14) at the first target duration for a predetermined period when the reduced amount of intake pressure is in the second predetermined range by actuating the CVVD device (80), and wherein the control (100) is configured to monitor the intake pressure at a time when the predetermined period has elapsed, and is configured to determine whether the intake pressure is within a third predetermined range at the time when the predetermined period has elapsed. [10] Device according to claim 9, wherein the control (100) determines that the EGR valve (73) is in the fault state when the amount of the increase in intake pressure by actuating the EGR valve (73) exceeds the first predetermined range. [11] Device according to claim 9 or 10, wherein the control (100) determines that the CVVD device (80) is in the fault state when the intake pressure exceeds the third predetermined range at the time when the predetermined period has elapsed. [12] Device according to one of claims 9 to 11, wherein, when the intake pressure is in the third predetermined range at the time when the predetermined period has elapsed, the opening amount of the EGR valve (73) is controlled by the EGR valve (73) to be at a second target opening amount, and wherein the second target opening amount is less than the first target opening amount. [13] Device according to claim 12, wherein the control (100) determines whether the reduced amount of the intake pressure by actuating the EGR valve (73) is within a fourth predetermined range, and determines that the EGR valve (73) is in the fault state if the reduced amount of the intake pressure by actuating the EGR valve (73) exceeds the fourth predetermined range. [14] Device according to claim 13, wherein the control (100) actuates the CVVD device (80) such that the opening duration of the inlet valve (14) becomes a second target duration when the reduced amount of the intake pressure by actuating the EGR valve (73) is in the fourth predetermined range, and wherein the second target duration is less than the first target duration. [15] Device according to claim 14, wherein the control (100) determines whether the amount of the increase in intake pressure by actuating the CVVD device (80) is in a fifth predetermined range, and determines that the CVVD device (80) is in the fault state if the amount of the increase in intake pressure by actuating the CVVD device (80) exceeds the fifth predetermined range. [16] Device according to claim 15, wherein the control (100) determines that the CVVD device (80) and the EGR valve (73) are in a normal state when the amount of the increase in intake pressure by actuating the CVVD device (80) is in the fifth predetermined range. [17] Method for diagnosing an engine system comprising an opening duration device (80) for a variable valve (CVVD) and an exhaust gas recirculation (EGR) device, the method comprising: Acquisition of data by a data acquisition device (90) for diagnosing the engine system; Based on the collected data, determine by a controller (100) whether a fuel cut-off condition is met; Actuation of an EGR valve (73) by the control unit (100) such that an opening value of the EGR valve (73) becomes a first target opening value when the fuel cut-off condition is met; Determine by the control unit (100) whether the amount of the increase in intake pressure by actuating the EGR valve (73) is within a first predetermined range; Actuating the CVVD device (80) by the control unit (100) so that an opening duration of an exhaust valve (15) becomes a first target duration when the amount of the increase in intake pressure by actuating the EGR valve (73) is in the first predetermined range; Determine by the control unit (100) whether a reduced amount of the intake pressure is in a second predetermined range by actuating the CVVD device (80); Determine by the control unit (100) that the CVVD device (80) is in a fault condition when the reduced amount of the intake pressure by actuating the CVVD device (80) is outside the second predetermined range; Maintaining the opening amount of the EGR valve (73) at the first target opening amount and the opening duration of the exhaust valve (15) at the first target duration by the control (100) for a predetermined period when the reduced amount of the intake pressure by actuation of the CVVD device (80) is in the second predetermined range; Monitoring the intake pressure by the controller (100) at a time when the predetermined period has elapsed; and Determine by the controller (100) whether the intake pressure is within a third predetermined range at the time when the predetermined period has elapsed. [18] Device for diagnosing an engine system comprising an opening duration device (80) for a variable valve (CVVD) and a low-pressure exhaust gas recirculation (EGR) device, wherein the device comprises: an accelerator pedal position sensor (91) which is configured to detect the position of an accelerator pedal; a brake pedal position sensor (92) configured to detect the position of a brake pedal; a vehicle speed sensor (93) which is configured to detect a vehicle speed; an intake pressure sensor (94) configured to detect an intake pressure; and a control unit (100) configured to determine, based on signals from the accelerator pedal position sensor (91), brake pedal position sensor (92), vehicle speed sensor (93) and / or intake manifold pressure sensor (94), whether a fuel cut-off condition is met, and configured to determine whether the CVVD device (80) and an EGR valve (73) are in a fault condition when the fuel cut-off condition is met, wherein the control unit (100) is configured to control an opening amount of the EGR valve (73) via the EGR valve (73) such that it is a first target opening amount when the fuel cut-off condition is met, wherein the control unit (100) is configured to control an opening duration of an exhaust valve (15) via the CVVD device (80) such that it is a first target duration when an increase in intake pressure by actuating the EGR valve (73) is in a first predetermined range, wherein the control (100) is configured to determine that the CVVD device (80) is in the fault condition when a reduced amount of the intake pressure by actuating the CVVD device (80) is outside a second predetermined range, wherein the control unit (100) is configured to maintain the opening amount of the EGR valve (73) at the first target opening amount and the opening duration of the exhaust valve (15) at the first target duration for a predetermined period when the reduced amount of the intake pressure is in the second predetermined range by actuating the CVVD device (80), and wherein the control (100) is configured to monitor the intake pressure at a time when the predetermined period has elapsed, and is configured to determine whether the intake pressure is within a third predetermined range at the time when the predetermined period has elapsed.

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